Page 1
DEVELO
OF
WILLAGE IRRIGAT
B
SARUMU GAMESC (
M.H.GEE, M.IMAY.E.
TDegrego Erregeor of Zorriak
I riya:İzmir Keyplereyev
RISEE FROM THE TIONOFENGIN
Ann Eig
 
 
 
 
 
 
 
 
 
 

LAND) ES isang (INE).
TERANTSATTANS FTTHAF DERSCFLON HET

Page 2


Page 3
Development of
Wo
B
S. ARUMUGAM, B.sc. (LoND.), Bišĉ.
Deputy Directe
Irrigation Depa
2-B 1103 (6711)

Village Irrigation rks
ү
(ENGINEERING, LOND - M.I.C.E., M.I.W.E.
or of Irrigation
Irtment, Ceylon

Page 4

EPRINTED FROM THE TRANSACTIONS OF THE NSTITUTION OF ENGINEER'S, CEYLON, 1957
PRINTED IN 1967

Page 5
Development of Will Works
PREFAC
AT the Annual Conference of the Engine in August, 1933, the late Mr. J. S. Kennedy, of Irrigation, 1935-1939, read a paper enti Development of Village Irrigation Works great demand by engineers and technicals reprinted the contribution as a separate boo
With the increased interest in the developm food production activities, there has been booklet by young technical officers, to who
Much water has however flown since M 1933 and many are the changes since then, village irrigation works in Ceylon. A fre village irrigation work has therefore becom Mr. Kennedy’s original approach to the su for the inclusion both in the text and in the a the original contribution ; extracts have als tion to Anti-Silt Measures on Up-country Ir the Association in 1936, by Mr. W. A. C Irrigation, 1950-1952.
The scope has been extended and useful c guide to the young engineer, in his practi inquiring mini will also discern, in addi further studie in irrigation engineering.
A village irrigation work is a major ir study of the one leads to the other.
S. ARUMUGAM, B.sc. (LOND.), B.sc. (ENC
Deputy Director a
Irrigation Departm

lage Irrigation
E
aring Association of Ceylon, held , M.C., M.A., B.S.C., M.I.C.E., Director tled “The Evolution of Scientific '. Copies of the paper were in taff and the Association therefore klet.
nent of village irrigation works and a large demand for reprints of the m it had become indispensable.
r. Kennedy prepared his paper in both in the definition and scope of sh contribution on the subject of le necessary, maintaining however, bject; no apology is therefore made appendices of suitable extracts from o been made from “An Introducrigation. Elas ”, a paper read before uthrie, B.S.C., M.I.C.E., Director of
lata added so as to present a useful ce of village irrigation works ; the tion, sufficient matter to provoke
igation scheme in miniature; the
SINEERING, LOND.), M.I.C.E., M.I.W.E.
f Irrigation
ent, Ceylor

Page 6


Page 7
ACKNOW
The author acknowledges the kind Irrigation to utilise information avail the assistance given by Mr. S. Verak A.M.I.C.E., Irrigation Engineer, and ot

LEDGEMENT
permission granted by the Director of able in the departmental documents and athy, B.S.C. (LOND.), B.E. (HONS.) MADRAS, her officers of the Irrigation Department.

Page 8


Page 9
CHA
THE WILLAGE
Origin of Systematic Study
The Railway disaster of 1923 forcibly that every village tank lying above
was decided that the Irrigation Depa into the safety of every village tank was in any way a potential danger to and Jaffna. The investigation of th commenced by Messrs. Emerson and quently completed by Mr. Kennedy i object, namely the safety of the rail of village tanks, the investigation soon ment that many of the tanks offered In this investigation, knowledge of
first time systematically collected a foundation of systematic study for ti lished. A considerable advance has
in all its many ramifications.
Adoption of Policy
2. In 1932 the Executive Committe
recommendation of its sub-committe
Department for the production of industry the country should look mc merable village works throughout was voted for the improvement of vill Works Division of the Department at Anuradhapura.
3. The Irrigation Policy of 1932 benefit of the dry zone of Ceylon, wh to paddy development, its main obje

PTER I
RRGATION WORK
directed attention to the potential danger the railway constituted. As a result, it rtment should conduct a full investigation whether "worked ' or abandoned...that the railway between Polgahawela Mannar ese tanks-354 on the original list-was Biddell in October, 1923 and was subsen 1926. Apart from pursuing its original way from floods caused by the breaching revealed the great possibilities of develop, and its scope was accordingly extended. the subject of village tanks was for the und collated on scientific lines and the heir scientific development soundly estabsubsequently been made with the subject
e for Agriculture and Lands accepted the e on the re-organisation of the Irrigation
paddy and the development of the rice ore to the latent possibilities of the innuthe island-'. A sum of Rs. 200,000 age irrigation works and a special Village attended to this work with headquarters
was not inaugurated exclusively for the Lere shortage of water is the chief obstacle 2ctive was an extensive improvement and

Page 10
8 DEVELOPMENT OF
extension of paddy cultivation th attention of the Irrigation Departn works-village tanks, village elas,
4. In 1939, Rules of Procedure fo adopted which defined Village Irrig the land-holders do not, as a gener work and jungle clearing, necessal in part or whole .
Priority List of Village Irrigation W
5. The District Agricultural Com their area for preliminary investig causes an Irrigation Reconnaissanc prepared on the appropriate Prelim Appendices III to VI. He makes the project as an engineering prop work necessary and the benefits lik forecast of probable cost.
6. The purpose of this prelimina Agricultural Committee to decide v priority list of village works for ful the decision is favourable, the Divis carried out and frame proposals, pla ments required for the work. If economic limit of expenditure pres Revenue Officer the proprietors' a XXVI) in terms of Irrigation Ordi placed on the construction prio construction.
Contribution by the Proprietors
7. In consideration of the above de ments to a village irrigation work, t work were required to, and agreed to contribute towards the cost of im work, e.g. jungle clearing and earthy tary contribution in addition to the The proprietors” contribution was 1 lent of two years' earthwork as pre the District. Later, this contribut for Government to meet the entire ( the proprietors being responsible tenance of the completed work.

/ILLAGE IRRIGATION WORKS
roughout the country. This focussed the ent on the development of village irrigation κο.
r the preparation of Irrigation Works were ation Works as those works under which al rule, pay any rate but carry out the earth y for their construction and maintenance,
orks
mittee prepares a list of village works in ation. The Divisional Irrigation Engineer e to be made of the work. This report is Linary Investigation Report form, shown in his recommendations on the feasibility of osition, stating the nature of improvement ely to be derived therefrom together with a
vry investigation is tọ, enable the District whether the project should be placed on the l survey investigation, in greater detail. If ional Irrigation Engineer will have a survey Lns and estimates for the necessary improvethe cost of improvements be within the cribed, then, he will also obtain from the greement on form Irrigation 24 (Appendix nance No. 32 of 1946. The work is then ity list of village irrigation works for
cision of the Government to effect improvehe proprietors of the lands benefited by the , in terms of the agreement on Form 24, provements either by executing part of the fork in bund raising, or by making a moner general obligation to maintain the work. 'ormally fixed as not to exceed the equivaSribed by the Irrigation Rules in force in on was waived and the present policy is ost of improvement to the irrigation work, only for doing earthwork towards main
ጳ

Page 11
DEVELOPMENT OF VE
Economic Value of Village Irrigation
8. Ceylon is essentially an agricult people is rice. The total area unde was as follows :-
(1) Cultivated under major irrigation (2) Culrivated under village irrigatio (3) Cultivated by direct rainfall
For our consideration, we are conc tanks, village elas, &c., of which th condition today. These between t which forms 30 per cent. of the total
9. There are some 12,500 village ta more lie abandoned. In the bunds be 30 million cubes of earthwork an waiting in the jungle to be restored a tribute of awe-struck admiration days who were able achieve such a permanent asset to the country in the TCSOLIC6:S.
Their Domestic Importance
10. Everybody who is acquainted W. the predominant importance to the and it is unnecessary to enlarge on th
In the dry zone areas, it has been village means a tank. The tank is of village life; when a tank breaches
11. To a much less, but still appré accomplished in the construction of development. In the Central Pro' there are at least 3,500 village irrigat The scope for extensive developmen limited, both by the small extent of the economic conditions attendant
development, in a wide commercial but their domestic importance to th as vital as that of the village tank in this fact that their improvement on
view to improving the irrigation ame the cultivator more time to attend to

LAGE IRRIGATION WORKS
Works
ural country and the staple food of her r paddy cultivation in Ceylon in 1954/55
Acres
works o P. ... 269,853 n works 292,669 469,089
Total ... 1,031,611
cerned only with village works, viz. village ere are approximately 16,500 in working hem benefit an extent of 292,669 acres
lands under paddy.
links in a working condition and possibly of the working tanks alone there must d possibly another 30 million cubes stand to usefulness. One is compelled to pay to the labour commissioners of by-gone monumental output. This is a valuable : practical development of her agricultural
ith the village life of this Island will realise villager of his village tank or village ela, heir sociological aspect.
said, that “a tank means a village and a the provider of all the material needs the village migrates.
:ciable extent, the work our predecessors village elas, remains an asset for modern vince, Upper Uva, and Sabaragamuwa on works, other than tanks, in use today. t of the great majority of these works is otential paddy land undeveloped, and by on agriculture under them. Large scale
sense, is impossible under these works, e villagers immediately concerned is just the Low Country. It is in recognition of scientific lines is being prosecuted, with a lities of existing cultivation, and to giving his other agricultural operations.

Page 12
SCIENTIFIC TECHNI
VILLAG
Criteria of Development
12. With this prefatory sket village irrigation works of C subject, namely, the evolutio problem and possibilities that nique must be evolved, not f experiment in the utilization ( instance, hydraulic phenomen problem. There are four 1 scheme :-
(i) Accurate estimation of amount of water avail maximum flood run-of
(ii) Sound appreciation of for storage or diversior
(iii) Definite information a for irrigation under the
(iv) Scope of the developme
The first of these criteria is data. Trained judgement will of the principles involved, part data are scanty, but the princi of scientific laws. The seco investigation of the topograph
at the site or alternative sites facts in the most concise and for the third criterion, so fa circumstances will seldom jus potential irrigable area. The to establish; development is of Land Development. The Works on a practical, econom establishment of these four cr related effects, and on the pro use of the possibilities offered

CHAPTER II
(QUE FOR THE DEVELOPMENT OF
E IRRIGATION WORKS
:h of the general position and possibilities of the leylon, we may pass on to the more immediate n of a scientific technique for dealing with the t these works present. Essentially, such a techrom tradition, but from deliberate research and of the natural forces concerned, of which, in this a present neither the only, nor the most difficult, main criteria in every irrigation development
the average yield of the catchment, i.e., of the able in normal years for irrigation, and of the f that will have to be discharged;
the natural or existing psibilities of the site l
s to the extent of potential paddy land available
scheme ;
ent of land.
concerned with meteorological and hydrological | always be necessary for the accurate application icularly when, as is usually the case, the available iples themselves have already acquired the status ld criterion requires a complete and thorough lical, artificial, and geological conditions existing of the work, and the presentation of all relevant coherent form. Judgement us again required r as village irrigation works are concerned, as tify the expense of a preliminary survey of the 2 fourth is a concern for the Revenue Officer dealt by him in consultation with the Director
whole art of development of village irrigation lic, and efficient basis, depends on the accurate iteria, on the sound appreciation of their interduction of a scheme that makes the best possible by all four.

Page 13
DEVELOPMENT OF VILL
Co-operation of the Proprietors
13. The creation and encouragement must be the constant aim of all con course, be no sentimental interference sense of personal responsibility for appreciation of the improvement effe he is to be relied on to exploit, and m there is no way of establishing such
are sound and suitable, and unless ht plishment. It must be remembered practical irrigator. His knowledge oy supply is extensive, and, though found is generally valuable to the scientifi the villager are always worth consid it would be as imprudent to accept a the data he suggests, as it would be
merits, the mere fact that he has be inclining him to appreciate the offer
Scientific analysis and synthesis for th
14. The procedure of the engineer and designs, what he considers the development for the work, may be a1
(i) The formation of accurate gene of development specified in pa
(ii) The checking, confirmation,
given in the plans and report.
(iii) Visualization of possible de
detail.
(iv) Selection of a final scheme o completion of the component c
(v) Production of detailed plans :
general criteria of the project.
This, in the barest outline, summa and production of a scheme, by the constructive process intelligible, som have to be considered in more detail
15. Every village irrigation work i but with its own problems, hydraulic be appreciated that minor irrigatic

AGE IRRIGATION WORKS 1
of a spirit of co-operation in the villagers zerned with the project. There must, of with the villager's healthy and traditional his own village irrigation work. His cted must be sincere and spontaneous, if aintain them to his own advantage ; and appreciation unless he is convinced they 2 has himself co-operated in their accomthat the average villager is an experienced the records and possibilities of his water 2d on tradition and untrained observation, c investigator. Practical suggestions by eration on their own merits, and, while s established, without further verification, foolish to ignore his suggestions on their 2n consulted will go a long way towards of scientific assistance.
eir Development
and the lines along which he conceives : best scheme or alternative schemes of halyzed thus :-
ral impressionin regard to the four criteria ra 12. V
completion, and expansion of the data
velopment schemes both in scope and
r alternative schemes in outline and the letails.
and estimate, and his own report on the
rizes the process of assimilation of data, engineer, and, in order to make the latter e of the items in the first two stages will
s a major irrigation scheme in miniature, and otherwise occurring 'full size; it will n Works offer an ideal training ground,

Page 14
12 DEVELOPMEN
both for the embryo enginee problems they present are
confront the engineer on lar development of village works that may arise and be trained

OF WILLAGE IRRGATION WORKS
and for the intelligent technical assistant. The he same problems in concentrated form that er projects. Officers engaged in the systematic should be thoroughly familiar with the problems to solve such difficulties .

Page 15
CHAP
PRELIMINARY RECONN.
INVESTIGATION--
Location on Map
16. The first thing that must be know is its precise position on the map. The produced by the Survey Department a sheets contain valuable and very often to exaggerate the importance of these Engineer; their indispensable assistan
17. A system of "co-ordinates' is
to locate the position of an irrigatio West co-ordinate is always given first bunds, the convention is standardized be the 'left bank end of the bund. wewa, G122 (12:45 x 1:9) locates the Ve convenience and absolute definiteness ( adopted.
Catchment Area
18. Having fixed the precise positio catchment area or the area which drail then determined. Even on an up-to
the marking of the perimeter of the ( experience and judgement, particularl must be drawn from the position an boundaries and other topo features. supplemented and confirmed by local before finally fixing the definite area ar parison of the maximum theoretical an point should be made, for reconciliat the natural features cannot be well d shed line should be marked on the ma if necessary by a catchment area surve catchment is computed by planimete 10 miles in length or 20 square miles ir be noted.
19. In addition to providing the me one-inch topo map generally offers

ER III
AISSANCE AND SURVEY
ILLAGE WORKS
n definitely about an irrigation scheme one inch to the mile topographic maps re used for the purpose. These 'topo exhaustive, information. It is difficult contoured topo maps to the Irrigation :e has to be gratefully appreciated.
adopted in the Irrigation Department 1 scheme on the map. The East and , and in the case of village tanks and that the point defined shall in all cases Thus G716 (3:3x43) defines Moragasheragoda Trig. In view of the obvious of this method of location it is generally
n of the work on the topo map, the hs into the streams that feed the work is date coloured and contoured topo map catchment requires a certain amount of y in flat country, and correct inference d lie of adjacent tanks, roads, paths,
The information on the map must be
enquiry during the investigation, and, ld shape of the catchment, a rough comdi recorded flood run-off at the discharge ion of these factors. Where, however, efined from the topo sheets, the water ps by actual verification on the ground, y. When finally plotted, the area of the r, and, if extensive (e.g., if more than
area), its mean length and shape should
ans of defining the catchment area, the he engineer a considerable amount of

Page 16
14 DEVELOPMENT OF
valuable information in regard to and this “one inch to the mile' vie the study of the detailed “40 feet t
The catchment areas of princi Plate I and their values given in A
Preliminary Investigation Report
20. The initial step towards syst preliminary schedule of the hydrowork, after a reconnaissance of collected is used to prepare a Prel the work.
21. The first reconnaissance Investigation Report form a very work and it is absolutely essential th with the work. Every village irrig and the inspecting officer should individuality.
22. Suitable forms in which the prepared are given in Appendices flood protection and salt water excl
23. The information provided on and supplemented when surveys, full investigation carried out of the
Full or Survey Investigation
24. A full investigation of the wor tudinal section, site surveys and cı of specifications suitable for carry VIII, The comprehensive nature of survey work is shown in Append accuracy are insisted on, and the quality.
25. As a matter of practical conve a tank, i.e. the level up to which th as an arbitrary datum of assumed carried out with respect to this assu
26. During the field investigation special attention to the establishmen to keep an open ear for their suggse to enlist their active assistance with

WILLAGE ERRIGATION WORKS
the general features, of the irrigation work, w should be thoroughly assimilated before o one inch data is begun.
bal river basins in Ceylon are marked on ppendix XII
ematic procedure, is the collection of the data and other relevant facts regarding the the work and the scheme. The data so iminary Investigation Report (P. I. R.) on
and the preparation of the Preliminary responsible task in the development of the at only well experienced officers be entrusted ation work has an individuality of its own acquire the sense and substance of that
Preliminary Investigation Report may be [III to VI, separately for tanks, elas, minor usion schemes.
the P. I. Reports will have to be revised plans and proposals have been made and work.
k is carried out with contour survey, longi'oss sections of the bund, ela, &c. A set ing out the surveys is given in Appendix the plans to be produced as a result of the ces VIII and IX. Clarity, neatness and plans produced should be of a very high
nience, the sill level of the lowest sluice in water in the tank can be drained, is fixed value 10000. All levelling work is then med value.
, the surveying officer is expected to pay of confidence and keenness in the villagers, tions and opinions, and as far as possible,
manual work of the survey. Apart from

Page 17
DEVELOPMENT OF WILLA
this, he must interpret his specific orders the investigation to include fresh feat value in the engineer's consideration of
Foundation Exploration
27. A knowledge of sub-soil data is
depth of foundation of any structure t
the selection of the proper type, exact l; of structures thereon.
Usual methods of exploration of fou (a) Trial pits; (b) Test rods or sounding rods; (c) Driven pipes; (d) Auger borings; (e) Diamond drill borings.
Generally, at village irrigation works, if the foundations are explored by tri to any site survey work. It is advisa accommodate the working labour. T the foundation material in its own nata Procedure is costly but information gai
Tank Capacity
28. Granted access, it is not a very d skeleton contour survey of a tank bed to plot the contours, compute their a capacity by the prismoidal or other fo is given in Appendix X. Access, how may be full, or partly full, when the inv over, reliable information as to the stor before its investigation is undertaken. would be invaluable. An empirical for
V == 0
where W is the capacity in acre-feet of th spread area in acres at that depth. Th mation, though it is not logically appli It will be noted, however, that withou be estimated, and this is not an easy t full to depth D. The factor A is, of certain other variables), and our obje formula, and to express V in terms of th

ERRIGATION WORKS 15
with intelligence and be ready to extend res that strike him as likely to be of the project.
invaluable in deciding the nature and ) be erected. This knowledge enables y out and economy in the construction
dation are by :-
structures, &c., it would be sufficient il pits. This is an invaluable adjunct ble to have the pits wide enough to tial pits expose to visual examination ural setting and position in the ground ned is complete.
ifficult or expensive matter to make a during the course of the investigation, reas by planimeter, and calculate the rmula. An example of the calculation ever, is not always feasible, as the tank estigation is being carried out. Moreage capacity of a tank may be required For this purpose a reliable formula mula in frequent use is the following :-
4AD
e tank at depth D feet, and A the water : formula has its uses as a first approxiCable to any Volume save a paraboloid. a contour survey the factor A has to ning to do accurately even if the tank is course, a function of D (as well as of ct is to eliminate this factor from the e simple independent D. If it could be

Page 18
16 DEVELOPMENT OF V
°volved, a simple exponential formu but, on account of the other varia derive quite so simple an expressic what characteristics of the tank thes The depth D is the most obvious, b must have their effect on the cal characteristics of tank basins may as all natural basins were to some action of water. If this is so, the g the original determinant of all the c
29. An exponential formula of th concise way to record the capacity engineers would prefer to have a plotted on logarithmic paper as th were plotted on squared paper. to be calculated, and can be produc greater degree of accuracy.

LAGE RRGATON WORKS
la of the type : W = cD would be ideal, bles concerned, it may not be possible to n. We cannot as yet say definitely from ; other independent variables may originate. ut the length, width, and shape of the basin pacity. It seems probable that all these
be connected with the catchment areas, degree, formed in prehistoric ages by the ological formation of the valley is possibly ther characteristics.
is type, if applicable, is clearly the most of a tank, though, for practical use, most graph. The capacity diagram is generally is gives a much straighter curve than if it t is easier to plot, requires less points' :ed to give extrapolated values with a much

Page 19
CHAP
WLLAGE T.
30. The generalised statements and chapters are applicable to village wi the detailed study and design of the large number of village works schemes
The engineer, will have with him, a complete set of survey plans. The principles enunciated earlier of scientil
Hydrology
31. Accurate knowledge of the ca meteorological data available for it, is logic characteristics of the scheme.
rainfall as the source of the Yield W There is also the sinister aspect of rail for which every irrigation work must t
32. Rainfall: The map on Plate 1gauge stations having a bearing on t to the rainfall returns in the Report the average monthly rainfall at the se of 30 years. It will be found conven
SeaSOS
(1) Sept-Feb. inclusive–The Mal (2) Mar.--Aug. inclusive-The Yal
Though the periods will not necessari to the normally specified monsoons,
closeness to permit the terms North alternatively the terms Maha and Yal
33. It may be noted that the precip average rainfall is one that may be expt out of a hundred. Hence a conclu considerations of mean rainfalls afford For the assessment of the yield from it is often advisable to ignore the rains South-West Monsoon.

TER IV
ANK DESIGN
requirements mentioned in the carlier orks in general. We now proceed to village or minor tanks which form a
8
he preliminary investigation report and ; stage is now set for him to apply the fic analysis and synthesis.
(chment area in conjunction with the required for the estimation of the hydro
First there is the beneficent aspect of hich is stored or diverted for irrigation. nfall, as the primary cause of the floods be designed to cope.
--will be useful in the selection of rain he catchment. Reference is then made on the Colombo Observatory to obtain lected rain gauge stations over a period ient to divide the rainfall year into two
na or North-East Monsoonal Season.
a or South-West Monsoonal Season.
ly conform with anything like exactitude they will generally do so with sufficient -East and South-West being applied or a may be used.
itation habits are such that the mean or acted to be exceeded only in 35 to 40 times sion relative to yield determined from s rosy picture of the irrigation potential. a dry Zone catchment in an average year all in September and the yield during the

Page 20
18 DEVELOPMENT OF WILLA
Yield
34. Having ascertained the periodic to yield available for storage has to be most difficult to assess correctly and t the yield from a catchment.
Rough and conservative estimates of seasonal rainfall in one of the two follo
(a) Strange’s yield tables for bad cato
(b) The Kalawewa and Minneriya C
Strange's yield table for bad catchm Storage Reservoir is suitable for est The Kalawewa and Minneriya curves replenishments of these two tanks. catchment is the presence of a large n about one per square mile of cathmen devoid of such development. Hence estimate of the yield for a catchment the Minneriya curve furnishes the corre without working tanks. The table c square mile as per Kalawewa, Minn bad catchment in reference to the Se may be used in determining the yield For practical purposes one is advised tank catchments possessed of one or the Minneriya curve for village tank every two or three square miles of catcl almost free of working tanks.
35. The best method however of arriv measurement of actual stream flow by are necessary for reliable estimate o only in very rare instances that strea available but valuable information car even of shorter periods.
Flood Run-off
36. Having thus arrived at the bene: of 'Yield' available from it for stora primary cause of the floods, i.e., proba fall, has to be considered.

GE IRRIGATON WORKS
tals of rainfall of the area, the average estimated. This factor of yield is the here are several methods of estimating
yield may be arrived at from the mean wing ways
hments.
urves of the Irrigation Department.
ent extracted from Strange's Indian timating yield from seasonal rainfall. are based on the known and observed
The characteristic of the Kalawewa umber of working tanks, approximately ut area whereas Minneriya catchment is : the Kalawewa curve gives plausbile with that degree of exploitation while sponding yield for a dry zone catchment on Appendix XIV gives the yield per eriya and Strange's yield curves for a asonal rainfall. These values of yield that can be expected from a catchment. to use the Kalawewa curve for village
more working tanks per square mile, catchment having one working tank in hment and Strange's curve for catchment
ing at the yield from rainfall is by direct
gaugings. Gaugings over long periods f the anticipated yield. It is however am gaugings for such long periods are be deduced from the result of gaugings
ficial aspect of rainfall, viz. the amount ge, the other aspect of rainfall-as the ble maximum flood run-off, due to rain

Page 21
DEVELOPMENT OF WILLA
Existing medium which is used as a flood run-off is Dickens' formula :-
Q= C. Mo
where Q is the flood run-off in cusecs miles. The value of the coefficient C particular case.
It has been found that a value of 645 reasonable accuracy for many low coun very commonly used. Appendix XII in value of the coefficient under different worked out for catchment areas up to values of the coefficient C is shown in A
The table also gives the values obtaine
7,000 M T v M +- 4
In using the table, it is advisable to Dickens' coefficient when dealing with sm may be a consideration for a tank with a whereas in view of the distinct improb intensity down pour in a widespread ar. gant for a 50 square mile catchmet area.
37. The Irrigation Department is enga evidence of flows based on actual reco this purpose, the Island divides into th zone catchments, the dry Zone catchme the dry zone catchments which do not that the study of this subject will very nomograph, for correct estimation of I concentration.
For the present, however, Dickens' departure, the selection of value for coe catchment area, (b) the hydrological nat
86Ca,
In the case of most village tanks hov to depict ordinary flood conditions and Whereas, schemes in the North Eastern of rainfall have been experienced, requir
38. It must be realised that the Dicken does not profess to be scientifically accur who uses it as anything more than a p

GE RRIGATION WORKS 19
point of departure, for assessing the
and M the catchment area in square has to be carefully selected for each
for the coefficient C, gave results with try or dry zone tanks and is therefore dicates necessary modifications to the conditions. A table of values of Q 100 square miles for four different ppendix XIII.
c from Inglis's formula :-
select particularly the higher values of all catchment areas. Thus, C = 2,000 catchment area of only a square mile, ability of simultaneous uniform peak ea, adoption of 2,000 may be extrava
ged in the study of flood peaks on the orded flood-history in Ceylon. For ree hydrological zones, viz. the wet ints which extend to hill country and extend to hill country. It is hoped soon result in the issue of a working maximum flood flow at any point of
formula may be used as a point of ificient C depending on-(a) extent of ure or the peak flow behaviour of the
wever, value of 645 has been presumed C = 1,000, cyclonic flood conditions. Zone of Ceylon, where high intensities e consideration with C = 2,000.
s' formula is at the best empirical and ate in structure or results. An engineer oint of departure, who fails to amend

Page 22
20 DEVELOPMENT OF VIL
its results on large catchments by co reconciliation of its results with rec is incurring a grave risk. With this w XIII is recommended as giving with th average maximum flood discharges.
ments is materially affected by their li the cover growing or constructed upo As regards shape, a catchment that is will have a large run off factor, compa which, unless the storm is travelling di prolonged and gentle. Small catchm rate of run-off as intense rainfall is impervious catchment gives a very hig ment, if saturated when a major storm Swamps, minor tanks and abandoned t or detaining a part of the flood water.
Spill Discharge
39. The flood run-off gives an estin flow into the tank. The spill has to
endangering any of the component s of spill in vogue in the Irrigation Del spill and the natural or channel spill.
depends on site conditions.
40. The discharge over a masonry spil by Francis Formula (for sharp crested Where Q = total discharge in c L = length of spill crest H = head, in feet measu
This is used for all masonry spills and However, this ignores several factors
at site is a gross length and an allowa piers and abutments-the effective d L-01 n H; where n = number of 0.1 may be decreased to 0.05 for well 1 the formula for increase in head du velocity increases the discharge as th added to the measured head. But in usually slight, though appreciable at
is little. The effective head then be
being the velocity of approach. The the computation, provides a safer sp

AGE IRRIGATION WORKS
rection for "shape and time and by orded flood discharges from the area, urning the use of the tables on Appendix i e suitable coefficient, reasonably reliable The rate of run off from large catchngth, shape and slope, by the nature of h them and by the texture of their soils. semi-circular round the discharge point "ed with a long, narrow catchment, from wn its length, the run-off is likely to be ents tend to have a higher maximum generally localised. A steep, barren, h rate of run off and a pervious catchoccurs may be regarded as impervious. anks tend to lower the rate by absorbing
hate of the maximum anticipated flood be designed to pass this flood without tructures of the tank. The two classes partment are the masonry clear overfall The selection of one or the other type
l, with clear overflow conditions is given weir) Q = 3:33 L.H.
ISCCS.
in feet.
red from crest to tank water level.
should suffice, as it is, for village tanks. -The length of spill crest as measured nce is necessary for end contractions at ischarging length of spillway becomes end contractions and the coefficient ounded ends. No provision is made in
to velocity of approach. This initial ough the equivalent velocity head were large tanks the velocity of approach is
iversion anicuts where storage capacity
V 2
comes H + ho where ho == , Vo
3.
omission however of this provision in Ilway and is therefore to be preferred.

Page 23
DEVELOPMENT OF WILL
The value of the constant 3°33 is depe broad crests the value may be lower an The sharp crest, required for value of: in the field. This had lead to the adop downstream profile, known as the OC is parabolic in shape and the downstre discharge horizontally at the toe of t masonry spill structures are shown on E
41. The natural or the channel spill a This is adopted in all situations wher are certain to erode if the velocity exceed in different types of soil are given in A XV gives the discharge over C. O. spil as also seen on Plate 3.
42. The existing practice for the desig maximum inflow (obtained by Dicken's This gives high values but further assu spill analysis diagram brings down thi has been found to be satisfactory in pra method of preparation of the spill anal inflow at the rate of 1 cusec for 12 hou
Flood Detention in Tanks
43. Flood detention in tanks is pal The part permanently detained is the tanks up to spill level. The part temp that piles up in a tank above spill lev spill (a function of the afflux thus creat first balances and then reverses the pro effect on flood run off. After cautic involved, the conclusion has been reach both in the tank under consideration tank (detention in the catchment) above safe condition.
44. Self Detention . A certain volume up the water level in the tank above provides the necessary head required causes a momentary detention of par detention has to be, therefore, allowed with spill discharge and will necessarily ln the process of equating, this deten of flow, and deducted from the gross inf

AGE RRIGATION WORKS 21
indant on the shape of the crest. For d rounded crests indicate higher values. 333 is however not practically possible tion of a section with curved crest and EE spillway, where the upper section am face is concave upwards inducing he structure. The common types of Plate 2.
ffords the most economic form of spill. e site conditions permit. These spills is a certain value. Permissible velocities ppendix XVI. The table on Appendix ls and channel spills for various heads,
in of village tank spills is to assume the Formula) at constant rate for 12 hours. mptions made in the preparation of the s value within reasonable limits. This ctice. This assumption affords an easy lysis diagram. It may be noted that an rs is approximately equal to 1 acre foot.
tly permanent and partly temporary. amount of water required to fill the orarily detained is the volume of water el, until the increasing discharge of the ed), or the decreasing inflow of floods, cess. Such detention has an equalizing us appraisal of all the considerations led that it is safe to allow for this effect,
(self detention) and in every working it of appreciable size and in a reasonably
of the flood inflow is utilized in heading the spill crest level. This heading up
for spill discharge and the piling up t of the total flood inflow. This self d for in the process of equating inflow y increase with the head above the spill. tion is converted into an equivalent rate Іоиу.

Page 24
22 DEVELOPMENT OF VIII
45. Detention in the Catchment . A becomes necessary due to such “s working tanks, situated within the ( detention would be represented by t working tank in the catchment area a from the gross inflow. This factor allowance suggested is expressed by
E is the absorptive capacity or cusecs. A, is its water spread area allowable flood lift, in feet. This a tank in the catchment which is know and the total is deducted from the g the fact that no deduction whateve safety status is not established. Suc added danger, through their liability way a mitigating factor. It will be
the increase in top water area abov and introduces an additional factor
Sometimes an approximate compu taining the full supply area of the tan foot as the maximum allowable flood of course, the safety status of the tan
Factor of Safety
46. The commonly accepted meani design of a tank is the height, or " probable maximum flood level. The of the tank's absolute safety, but it is of expressing the final relationship run-off into the tank, the discharge We have already dealt, in some de independently. The consideration o constructive stage in the process ou far more constituents to consider t are the products of the analytical a Both in their production and applic connected, and mutually reactive, a effective implement for the increase both to perform and to describe. production of the individual constiti engineer to appreciate their mutual background for the welding process, consider, would be more correctly tej

LAGE IRRIGATION WORKS
Another deduction from the gross inflow alf detention occuring in each of the atchment area. The total effect of such he sum total of “self detention in each nd this sum total has also to be deducted is however, not so easy to assess. The the formula E = A X D cusecs. Where detention effect of a tank expressed in at F. S. L. in acres and D, the maximum lowance is calculated for each certified in to be in satisfactory working condition ross run-off. Emphasis must be laid on r must be made for tanks of which the h tanks are just as likely to be sources of to breach during a flood, as to be in any noted that the suggested formula ignores spill level, as this implifies the formula of safety. -
itation for the above is arrived by ascerk from the topo maps and presuming one lift for an average village tank, provided K is assured by actual inspection.
ng of the term 'factor of safety ' in the freeboard” of the bund top above the term may not be a very accurate measure certainly a concise and perspicuous way between the engineer's estimate of the out of it, and the necessary bund level. tail, with all three of these constituents f their inter-relationship brings us to the lined in para 14. There are, of course, han those we have just mentioned. All nd dressing processes already described. ation these constituents are closely interhd the process of welding them into an of paddy cultivation is a complex one, Science has certainly contributed to the lents of the problem, and will assist the eactions. Science will also furnish the but the process itself, which we may now med an 'Art' rather than a Scienge

Page 25
DEVELOPMENT OF WILLA
Synthetic Process-Project Planning
47. The task that now confronts the
best and widest scheme of development dependent criteria (para 12) now est by any one of the several avenues that
avenue will be that suggested by the exist storage. In view of the high cost, soil
the condition of the bund of an aban Seepage through these bunds after resto. seepage and consequent failure of bunc be kept low. Cultivation needs requir of the yield from the catchment as po full supply is not generally allowed to bund before restoration. The net yield If less than the permissible storage the net yield. If in excess, an increase of the and noted for further examination lat village works is assumed to be 3 ac. ft. o. by the duty gives the maximum extent
If this is less than the potential area av for future development. If in excess th available. One more aspect that nee lands under the proposed scheme. Thi as there is an insatiable demand for lai storage to be provided and hence the fu
Flood Lift
48. Having settled the spill level or the ments and calculated the net flood run. the allowable flood lift in the tank and are settled) the next requirement is to d to be allowed. This will depend on ti of crest. The type will determine til Plate 3) and the length will be the que the unital discharge obtained from the Appendix XV. There is, of course, a and there is an infinite number of way run off, L and q both being variable.
determine the most suitable type of spill of spill. A reduction in value of Linc of bund are increased. A few trial studi ponding bund heights will give the mo: For the spil length the spill analysis gra

GE RRIGATION WORKS 23
2ngineer is to conceive and design the possible within the limits of the interblished. He can approach the task these criteria suggest. The most usua ing possibilities of the site for maximum nvestigations are not done to ascertain doned village tank before restoration. ration is not uncommon. To minimise , the head of water in the tank has to : the head to be high to store as much ssible. As a compromise the level at exceed the average top level of the of the catchment has been calculated. scheme must be modified to store the !scope of development will be suggested er. The duty of irrigation water for f storage per acre. The storage divided that can be developed under the tank. ailable, then the surplus area is left out e scheme is modified to benefit the area 'ds consideration is the demand for s will not limit the scope of the scheme hd. Agreement is thus reached on the ill supply level of the tank.
full supply level to suit storage requireoff (so far as it can be calculated until hence its approximate detention value, etermine the maximum flood lift that is he type of spill adopted and its length he discharge formula applicable (see ptient of the net run off divided by q, graph of the formula or the tables on n indefinite number of types of spills s of solving the equation L X q = net The site conditions dealt with below, and limits the range of suitable lengths reases q, hence the flood lift and height es with different spill lengths and corresst economic spill length to be adopted. ph will give the flood lift.

Page 26
24 DEVELOPMENT OF VILL
Spill Analysis Graph
49. The process of equating the floo catchment into the tank with the spil the tank is visualised very clearly on gra A type spill analysis diagram or graph on Plate 2. TheX co-ordinate represen the spill crest level in the tank watc total discharge or run off over the ful parallel to the abscissa are drawn to in ment for values of c = 645 and 1,000 for C = 850). As however some of the working tanks within the catchme the catchment is deducted and fresh detention is the amount detained in th necessary discharge. This quantity, ( referred to earlier is taken off and th run off to be spilt over. Curves of dist tried. The high flood level is given by of the nett run off curve and the select
Freeboard
50. Freeboard has already been terr is the extra, precautionary height of th
symbols generally used :-
Bund level = Spill level + flood B. L. = F.S.L. -- D - F.B.
Freeboard, like all factors of safe bund, being of earth, and liable to da of human beings, animals and vehic without constant maintenance and 1 case of village tanks, almost certainl This consideration accounts in part on the surface of water causes wav the fetch of the tank. Apart form th movement of water against the fa are liable to overtop the bund unless Here is another reason for freeboa systematically collected, and with laws, the prediction of maximum flo remain so until man can control reasons freebord must be provided has not yet reconciled the villagers t adequate level, nor convinced then appears to be wasted storage, by t spills.

RRGATION WORKS
un off or the flood inflow from the lischarge or the flood outflow from ical representation of relevant factors. a 60 foot clear overfall spill is shown the afflux head or height in feet above levels. The co-ordinate represents ength of the spillway. Straight lines cate the gross run off from the catchsometimes a third line is also drawn he run off is momentarily detained in , the total amount of the detention in orizontal lines are drawn. The “ self 2 tank itself in creating afflux head for onverted into equivalent discharge as * curved lines drawn representing nett harge for possible types of spill are now the abscissa of the point of intersection :d spill discharge curve.
ned the factor of safety of a tank. It e bund above high flood level, or in the
ift -- freeboard ;
y, is largely a factor of ignorance. A nage by the elements and by the passage 's, will not remain at the specified level pair. Portions of it may, and, in the
will be low when the flood arrives. or freeboard. Again the action of wind which are proportionate in height to erosive action of waves, and the constant of the bund earthwork–such waves Le latter is raised above the water surface. l. Lastly, with the most copious data . ry care in the application of scientific s is still a matter of estimation, and must 2 forces producing rain. For all these out the cogency of the reasons adduced he necessity of raising their bunds to an of the danger of utilizing part of what erection of temporary dams across their

Page 27
CH
WILLAGE TAN
Spill Types
51. The selection of the most appr. in the whole process of village tai has already been discussed. Spills tank in continuation of the bund. conditions are more costly. Flank cause of damage to the downstrear training bunds are constructed to le The ideal site conditions for a spill and gently sloping cross section, approach and tail. Spills commonl
(1) Channel spills, usually referre (2) Clear overfall spills-gravity (3) Clear overfalls spills-flume t
Channel Spill
52. The simplest type of village 1 is most economical and is parmissil not under any circumstance, excee of the tail channel could with-star precludes the adoption of steep tail type to cases where the slop3 of the
Clear Overfall Spill
53. Failing ideal conditions nece: at the flank, the best site for the The spill in this case will be of the will be down the patent stream.
this is usually costly. The heavy co as a last alternative. In the vast in spillor a clear overfall spill at the flat made to eliminate getaway difficulty
54. The clear overfall spill can eith The gravity is applicable to sites wh
(a) there is a more or less sudde limit of an eroded gully or be

APTER Y
NK CONSTRUCTION
opriate site and typ2 of spill is fundamental nk development. The design of the spill are generally located at the flank of the Mid-bund spills, though ideal under certain spills suffer the disadvantage of being the m toe of the tank bund. To prevent this, ad the tail water away from the tank bund. require sufficient length, a fiat longitudinal hard strata, proper elevation and clear y adotped for village tanks are :-
d to as natural spills. ype trapezoidal section.
уре.
:ank spill is an earth channel. This type ble only if velocity in the tail channel does d the limiting velocity which the materiai nd (vide Appendix XVI). This restriction slopes and therefore limits the use of this terrain is considerably flat.
ssary for the adoption of a channel spill spill is at the original main drainage line. : clear overfall typ3 and the getaway route Due however to the high structure needed st of this spill precludes its adoption except hajority of cases, either a modified channel nk is adopted and the best possible provision
f.
her be of the gravity type or the flume type.
ce -
n drop in ground level e.g. at the upstream low the crest of a neglected channel spill.

Page 28
26 DEVELOPMENT OF VE
(b) the average ground level is be suitable getaway conditions a
In all cases a rocky site is very d dowsntream water cushion protectic
55. The flume or chute type spill
of suitable rock foundations and t gravity type very expensive. This t level at the uppermost point is at c this can be located at any point alo
.3
Filling Breach and Bund Raising
56. The maximum water pressure bund across the breach stream. T be constructed with utmost care. I tanks, the breach filling is done unt is demarcated after laboratory test The designs and specifications are p construction, field tests are made at work as per designs and specificatio
Even in minor tanks, the filling of In these cases a core wall generall up to H. F. L. is provided at the ce. about 20% of sand. The material selected. Top soil, soil containing used.
57. Before the filling of the breach faces are cleared of all trees, shrub All roots, loose stones and rubbis material at the base is not nearly as be removed till better material is m should be allowed. Sand on the do may however be allowed to rema rock filter is provided at the toe.
to a bed width of about 2, depth 3 necessary to key the trench into bo
The clay for the puddle core wal completely dry. It should then be two previous to using, it should t When being laid each basketful sh: already laid, care being taken that of any kind is allowed to remain in core wall should proceed simultar

LLAGE RRGATION WORKS
low the designed crest level of the spill and re assured.
lesirable for a gravity type spill; otherwise on should be provided. M
is adopted in situations where the absence he deep drop render the adoption of the ype is applicable to sites where the ground rest level or higher and the slope gradual;
ng the bund.
on the tank bund is on the section of the Fhis section of the bund should therefore in the case of major tanks and large village der proper field control. The burrow area s of the samples of the material are done. repared on the basis of these tests. During
various stages to control the quality of the
S.
breaches should be done with special care. y of puddle extending from below the bed ntre. The puddle consists of stiff clay with for the breach filling should be carefully roots, peat and Swamp soils are not to be
commences the base and the two exposed S, Weeds, grass and other vegetable matter. h of all sorts should be removed. If the good as the fill to be placed it should also et with. No sandy deposits in the breach wnstream side to a width of about 1/3 base in provided it is coarse and that a graded The central core trench is then excavated and side slopes 2 on 1 or less. It is very h sides to an appreciable length.
l should be excavated and exposed till it is pulversied with rammers. About a day or be wetted and worked into a plastic mass. ill be well trodden and worked in with that no stones, bricks, roots, grass, or rubbish he puddle. The construction of the puddle eously with the raising of the rest o; the

Page 29
DEVELOPMENT OF VILLA
breach. The sides of the puddle core immediately after construction. The t compartments by short clay bunds and k should the puddle core wall be allowed
58. Before depositing earth filling, the a depth of about 3" in ordinary earth a roughen and break up surface cracks v should then be moistened and filling co should be free from stones, roots and c lumps must be broken up as the filling p The filling should be done in layers of solidated. The layers should have a s. bund, the earth being thrown down frc ensure proper bonding of the new filli should be benched to secure the filling.
Village Tank Sluice
59. A village tank sluice consists of a p water from the tank to the distributi arrangements at the upstream end and s end. The size of the pipe is determine it is required to convey. It is desirable t necessary so that the replacement of the additional lands are taken under the pipes is very small compared to the co of pipes required for sluices for various Appendix XXIV.
60. The simplest type of sluice is the v the W. T. type. The use of this type is depth. The operation of this type is vei factory. Consequently these are being common types of tank sluices now adop the hume pipe tower sluice.
The simple headwall type sluice is ado This consists of a headwall at the upstre walls. A simple cistern on the down arrangements. The sluice gate is fixed to from the top.
The hume pipe tower sluice is adopte This consists of a 3’ diameter hume pipe place of the headwall. The sluice gate is ever is mounted on the top. Access t

GE RRICATION WORKS 27
wall shall be covered over with earth op face shall be divided into several ept continuously wet. On no account o dry and crack up.
: prepared bed should be scarified to ind 8" in clay. This operation would without disturbing the foundation. It mmenced. The earth used for filling ther vegetable matter. All clods and proceeds, to ensure close consolidation. 6” to 9" thick, Wetted and well conlight slope towards the centre of the »m the sides towards the centre. To ng with the existing work, the bund
pipe running under the bund to convey on channel with suitable regulating stilling arrangements at the do wstream d by the maximum quantity of water o use bigger pipes than are theoretically sluice will not become necessary when tank. The additional cost of bigger st of the sluice. The theoretical sizes extents of irrigable lands are given in
ertical pipe sluice commonly known as limited to tanks with a low full supply y cumbersome and the type is unsatis, replaced by other types. The most ted are the simple head wall type and
opted for village tanks with low heads. am end of the pipe with suitable wing stream provides the necessary stilling the upstream headwall and is operated
d for village tanks with higher heads. placed vertically to serve as a tower in installed in the tower and the operating o the tower is by means of an R. C.

Page 30
28 DEVELOPMENT OF VIL
footbridge leading from the top of foot bridge the bund top is widened In big tanks the hume pipe tower is r raft.
Breaching Section
61. The estimated “ maximum floo maximum precipitation ever to occu floods in excess of the estimated val the frequency of such occurrence in spills capable of disposing all possibl a flood in excess of the estimated va at some weak section to afford the ad fore prudent to localise such possib site on the bund, known as Breachii in the flanks or in the periphery of minimum damage. The breaching
the remainder of the bund to be vulne surplusing capacity.
The breaching of a tank is liable down the catchment. The provision desirable precaution not only for the safety of the other tranks lower dowr not empty the tank and indeed frequ its surplusing capacity to a reasonable parent tank and of those below it.

LAGE IRRIGATION WORKS
the bund. In some cases instead of the up to the tower to afford direct access. eplaced by R. C. tower built on an R. C.
d run off may not necessarily be the r in the catchment. The occurrence of ue cannot certainly be ruled out though lay be rare. The construction of tank 2 floods is of course uneconomic. When lue occurs, the tank bund would breach ditional surplusing capacity. It is therele breaching to a selected advantageous ng Section. These sections are provided the tank where a breach will cause the section is kept lower and weakerthan rable and breach to provide the additional
to cause breaching of other tanks lower ! of suitable breaching sections is a very safety of the parent work but also for the 1. A breach at the breaching section will 2ntly does little more than supplementing degree to the greater security both of the

Page 31
CHAPTE
RRIGATION FACILTTES TO FIDE)
Irrigation Facilities
62. The ultimate object of storage or
supply of irrigation water for cultivation us to the other aspect of development
provision of irrigation facilities to lanc include the provision of not only supply cl and access facilities.
Engineering Surveys
63. The primary requirement for the engineering survey plans of the area. T area plotted to a scale of 4 chains to an intervals. In addition they show all to rock outcrops, streams, roads, buildings by the Survey Department.
Tract Plans
64. The next step is the preparation of neering survey plans. This divides the are parcels of irrigable land bounded on and on the other three sides by defin therefore comprises of a portion of the ir be irrigated as an independent sub-unit.
65. The main supply channel, which f is first traced on the contour plan genera at the commencement of the trace is the the gradient is that obtained from a pre main and subsidiary drainage lines are it should be decided which streams are to the decisions being governed by the catch tracts. What should be aimed at is th combination of several to form a fair si: thus divided into tracts each independe as possible, should be irrigated from a outlet can serve the same tract if, necess not be designed to irrigate more than on

R V
LDS UNDER VILLAGE WORKS
diversion from a village work is the in the developed lands. This takes of village irrigation works, viz., the ls under village schemes. It should nannels but also the necessary drainage
design of irrigation facilities is the hese are detailed survey plans of the inch showing form lines at 1" vertical pographical and civic features such as , &c. These surveys are carried out
the tract plan of the area on the engiarea into a number of tracts. Tracts one side by the main supply channel ite natural boundaries. Each tract rigable area which could conveniently
orms the upper boundary of the tracts lly along a falling contour. The level proposed F. S. L. of the channel and liminary design of the channel. The then picked out. At this stage be retained and which asweddumised, ment of the streams and the proposed elimination of small tracts and the zed unit. The entire irr gable area is :nt of the other. Each tract, as far separate outlet but more than one ary. A single outlet however should
tract.

Page 32
30 DEVELOPMENT OF V
Blocking out Plans
66. Preparation of B. O. PP. cons lots or blocks with the necessary i each lot. The extent of each lot is di Officer. The first step is to lay do depends upon the nature of the la are commonly met with. The flat the main channel, has field channel the contours with drainage channe extend from one channel to the ol on one bank. There is then the (off the main channel) are laid acro: distributaries running along the col side and above it a drainage channe where alternate ridges and valleys case would be to locate supply ch valleys.
67. After the channels have be channels, streams, etc. are marke widths of land strips left out of the required for the provision and pr working order. Certain channels always carry roads along them. I cart tracts or drainage channels. for various types of work is given reservations is laid down in G.O. consideration. The G.O. and the in Appendix XXV.
68. The balance area is then blo near rectangular in shape with thi shorter. The blocks should not b rotated slightly towards the lower the highest point, reaching all parts
The method of laying down chal indicates the basic principles to be modifications to above ; the funda be provided with satisfactory irrigat
Housing and Garden Lots
69. In colonisation schemes the and garden lots with necessary ac a community centre, for which a 1 purpose of health, social and othe

ILLAGE IRRGATION WORKS
sts of dividing each tract into a fumber of rigation, drainage and access facilities to etermined in consultation with the Revenue wn the supply channel to each tract; this ld to be irrigated. Three types of terrain terrain with contours almost parallel to s taking off from the main channel across ls alongside. The boundaries of the lots her as the field channel can irrigate only steep terrain. Here distributary channels is the contours with field channels off these tours. Each field channel carries alongl. The third type is the undulating terrain occur. The method of approach in this unnels on ridges and drainage channels in
en laid the required reservations for the di off. These reservations are the total blocking and represent the minimum width oper maintenance of the work in good like the main and distributary channels Field channels occur either alone or with The width of the necessary reservations in Appendix XXV. The width of stream 732. The revision of this G.O. is under
proposed amendments to the G.O. are
cked into lots. Individual lots are usually : longer side not more than 4 times the e parallel to the contours but are to be contour, to ensure water entering a lot at of the lot.
nels and blocking out as described above followed. Varying conditions necessitate hental requirement is that every lot should ion, drainage and access facilities.
highland is blocked out to provide housing ‘ess. Every 150 house lots are served by servation of 20 acres is provided, for the recreational facilities of the community.

Page 33
DEVELOPMENT OF WILLA
Township reservation of 50 acres is p lots are laid symmetrically with respect t are therefore made parallel to the r or rectangular in shape, each being acci
An example of a blocking out plan is
Irrigation Supply Channels
CLASSIFICATION
70. Irrigation supply channels are cl
(i) Main Channel: This is the prin the diversion anicut. This is ge no direct issue is made to the fiel (ii) Branch Channel. This is an offsh there will generally be no direc generally used on smaller schem tracts to feed distributaries and f (iii) Distributary Channel : This take and as a rule, supplies field ch issues through pipe outlets. (iv) Field Channels : These are chanı
to the fields.
The first two types are not generally The channel taking off from the village of distributary channel and is designed
Duty of Water
71. The relation between the area irrigation water, required as supply, is ' duty' is generally used in reference t it can be used in reference to any base Apart from the base, the place of meas duty. The quantity of water issued at quantity delivered in the fields due to c. duty in the field is less than the duty at expressed in terms of the number of a flow of 1 cusec at the head of the char quantity of water in acre feet requirea acre of land.
The value of duty varies from place t of the crop, type of cultivation, interve all contribute to the variation. Their two factors cannot be predicted with The observed duty at storage excluding

GE ERRIGATION WORKS 31
rovided at a central site. The house o the road system. The lot boundaries oads and the lots are either square 'ssible by road.
shown on Plate 4.
assified under 4 types :
cipal supply channel from the tank c. .nerally a contour channel from which d. loot from the main channel from which it issue. This type of channel is not es but is used in the case of very large ield channels. s off from a main or branch channel annels together with a few individual
nels from which direct issues are made
met with in village irrigation schemes. scheme sluice comes under the category as such.
of crop irrigated and the quantity of termed the duty of water. The term o the whole cultivation period though less than the whole cultivation period. urement should also be stated to define the head of a channel is more than the onveyance losses in the channel. Thus the channel offtake. Duty is generally cres that can be irrigated by an average nel for the whole crop period or the to be stored for the cultivation of one
o place. The nature of the soil, nature ning rainfall and the type of cultivator behaviour particularly those of the last any reasonable degree of accuracy. g evaporation and other storage losses

Page 34
32 DEVELOPMENT of v
at major tanks have been known to and 4 ac. ft. to 19 ac. ft. during 5 and 7-5 ac. ft. respectively. H works a duty of 3 ac. ft. of gross si channels under village tanks a duty and 30 acres for field channels are a
Cultivation Period
72. There are two main cultivat Maha and Yala or Munmari and The duration throughout which we S6C3SOS 36C --
(i) Maha-Munmari or Kalapol (ii) Yala-Pinmari or Sirupoham
The duration of water issue for pa there being three popular varieties all cases water issue is required for prior to sowing or transplanting. T 10 weeks after it is sown or 9 Weel the 4 and 5 month varieties the co and 18 and 15 weeks respectively.
Channel Velocities
73. Water flowing down an irrig silt. Silt is defined to be the solid suspension or in solution. At low v while high velocities cause scourt factors impair efficient distribution ( expenditure or maintenance. Irriga to have a non-silting non-scouring V in irrigation channels is still a subj of solution. Various theories have various formulae given to determin neither silts nor scours, the most 2quations. In view of the simplic now adopted in the Irrigation Depa velocity.
Kennedy's formula is most conve
V == 0•84 M. where M is the critical velocity rat from observation made on the Uppe the sandy silt of that canal as stanc

LLAGE IRRIGATION WORKS
vary from ac. ft. to 7 ac. ft. during Maha Yala, against a generally assumed duty wever for purposes of design of village orage per acre and for design of irrigation of 35 acres per cusec for main channels ssumed.
on season in vogue in this country, called Pinmari or Kalapoham and Sirupoham. ter issue is made during these cultivation
lam-October to March about 150 days. -April to August about 120 days.
ldy depends on the particular variety sown, known as 3, 4 and 5 months paddy. In
3 weeks for the preparation of the fields he 3 month paddy requires water issue for cs after it is transplanted. In the case of rresponding periods are 14 and 12 weeks
gation channel carries a certain amount of material carried by flowing water, either in elocities the silt is deposited in the channel ) the channel bed and sides. Both these of water to the fields and result in excessive tion channels should therefore be designed locity. The problem of silt transportation cet that has not yet reached a final stage
been put forward from time to time and e the critical velocity at which a channel
common being Kennedy's and Lacey's ity of application, Kennedy's formula is rtment for the determination of the critical
niently written in the form :
0.64 D. O. This equation was derived by Kennedy Bari Doab Canal, Punjab and he regarded ard, the coefficient M for that canal being

Page 35
DEVELOPMENT OF VELLA
unity. Sands coarser than standard we unity and finer sands less than unity. T in Ceylon is taken to be between 1-1 at however limited to 35 f.p.s. for large ea channels and 12 fp.s. for concrete lined
Design of Irrigation Channels
74. Irrigation channels can be designe known. The formulae commonly used If used with the same care and understa found equally reliable. On the other h be expected from them. All are base. them in practice inconsistencies corres ments are to be expected. The adopt hterefore a matter of convenience of e that the engineer who deals frequentl familiarise himself with one particula think in terms of that formula, in order have a definite meaning to him.
75. In view of the simplicity of app. Department are encouraged to use the M. for this formula are :-
That. (1) It is more readily adaptable to solu
(2) It provides a simpler solution fo
direct application of the formula.
(3) It is readily applicable to pipes a single formula, having a single co both pipes and open channels.
(4) It is used with the same coefficie
practically the same values as the usually obtain in practice.
The coefficient in Manning's formula
1486
W = -R S
•0225 -For excav,
030 -For excav, mainten
•040 -For excav:
-018 -For concr
•014 -For concr -R 1108 (6711)

E RRGATION WORKS 33
re assigned values of M greater than he value of M for irrigation channels d 1:25. The maximum velocities are rth channels, 25 fp.s. for small earth :hannels.
I by any of several channel formulae are Bazin's, Kutter's and Manning's. inding it is probable that each will be and no great degree of precision can upon experiments and in applying bonding to inconsistencies in experion of a particular formula becomes xpediency. It is however, important y with hydraulic problems should r formula. He should consistantly that a certain value of coefficient will
lication, engineers in the Irrigation anning formula. Advantages claimed
tion by tables and diagrams. r problems that are best solved by
hd makes possible the adoption of a afficient to become familiar with, for
nt as in Kutter's formula and gives Kutter formula under conditions that
is assumed as
ited channel in earth.
|ted channel in earth not under regular
ICC.
|ted channel in rock. ite lined channel without forms. ite lined channel with forms.

Page 36
34 DEVELOPMENT OF V
The velocity obtained by the 1:25 times Kennedy's critical veloc the limiting velocities given in pari
Suitable sections for distributary to 12 cusecs are shown in Append
Channel Section
76. The permissible side slopes o which they are cut. The following
(a) When excavated in ordina
(b) do. hard earth (c) do. rock (d) do. normal go
77. All channels are provided w with the depth of the excavated width allowed is given by d - 1 channels.
Channel Bund
78. Channel bunds are designed
deration the catchment drainage,
Channel bunds are provided on bo contour channels. The top width in the case of bunds which carry a width of the roadway. In the cas 2' is adopted.
The freeboard for a channel un As a rough guide the following
bunds.
1' when F. S. D. is below 2 . Do. betwet 3' Do. betwe 4' Do. Over 5

LLAGE RRIGATION WORKS
bove formula should be between 11 and y. The velocities should in no case exceed 73.
and field channels for discharges of 1 cusec K XX.
channels depend on the material through side slopes are considered suitable :-
y earth ... 1 on 1
2 on 1 4 on 1 or steeper od soil ... 2 on 1 is preferred
ith berms. The width cf the berm varies section of the channel. The usual berm for small channels and d -- 2" for large
with sufficient freeboard taking into consispillways provided and the bund material. th sides of the channel except in the case of of these bunds is usually 2 to 4 ft. except roadway when the top width is the formation e of village scheme channels a top width of
ier a village scheme is generally 1 to 1 ft. freeboards are recommended for channels
2"
n 2' and 3'
in 3' and 5'

Page 37
CHAPTE
AN (CUT DVERSION SCI IRRIGATO
79. The work our predecessors accom Elas remains an asset for modern dev Upper Uva and Sabaragamuwa there ai other than tanks in use. Though Villa themselves to extensive development, c paddy land and economic conditions their domestic importance to the villagers as that of the village tank in the Lowimportance that their improvement on st a view to improving the irrigation ame giving the cultivator more time to attent The climate in the higher altitudes is hea villages are more thickly populated. T abundant. The problem to be settled supply or storage of this natural asset.
Diversion by Temporary Amunas
80. Methods adopted by the villages
across streams or oyas at suitable places 1 were to be cultivated as paddy fields. Fl from the oya, along a channel or ela, cut i slopes, to their fields. The cultivators c consideration for gradient or best poss channels caused an enormous amount of
The amunas erected across the stream the flood season, in spite of frequent strer inly packed together. Small streams e elas created an additional amount c ause simultaneously with the breach ds of the elas were often scoured awa in which the villager has to contend, ( di cultivate more land than was ab suficient food for himself and his fam
Very insecure methods of crossin cing hollowed-out tree trunks or ser 3ches preventing the kandura water is good, as not only was the extra wate

R VII
HEMES AND VILLAGE N ELAS
plished in the construction of Village elopment. In the Central Porvince, 'e over 8,000 village irrigation works, ge Ela Schemes do not always lend lue to the small extent of potential attendant on such development, yet, immediately concerned is just as vital xountry. It is in recognition of this cientific lines is being prosecuted with :nities for existing cultivation, and to i to his other agricultural operations. lthier than in the Low-country and the he supply of water in the streams is is more the proper control than the
were to erect stick-dams or amunas high above the level of the lands which "om the stick-dam water was diverted n many cases along very steeply falling lo not always cut these elas with due bile trace, and in consequence these
work in the way of maintenance.
were invariably washed away during gthening in the form of large boulders —kanduras, dolas or aras, crossing of work and worry to the cultivators ing of the stick-dams by floods, the y. All these unfortunate occurrences lo not help or encourage him to take solutely necessary for the production ily.
g the kanduras were employed by hi-circular kitul troughs across these from entering the ela. The purpose r from the kandura kept out, but also

Page 38
36 DEVELOPMENT OF VIL
the more damaging sand and bou orbanks on which the troughs reste wider and unmanageable. The oth was to construct a heavy bund prote this means divert the kandura flow : quantities of sand and boulders, whic steep surrounding country, being de factors which led to the breaching of
Scope of Improvements
82. A typical improvement schen Scheme will necessitate the
(1) construction of a permanent stick and boulder dam, or amu
(2) introduction of proper control
of flood entry,
(3) provision of means for dealing (4) improvement of the earth worl
(5) construction of necessary m regulators, spills, under-crossir
So far as principles of hydrolog followed as in the case of village ta of the improvements present many p
The Diversion Anicut
83. The diversion is effected by a da nowadays, are generally of gravity usually constructed on rock foundati
The general layout of two typical for Willage Ela Schemes is shown on
The planks should be removed du to allow the river bed above the dan sand and debris.
The anicut wall, before joining the ånd assume a position parallel to ti long enough to allow for the insertio
Note.-For this consideration, an “Ela” from a drainage line which is often referre a natural stream, and “amuna ' refers to te

LAGE IRRIGATION WORKS
lders. Unfortunately however the sides d soon eroded and these breaches became 2r method of dealing with these crossings cted with stones at these junctions and by along the channel. This resulted in large hwere constantly brought down from the posited in the ela and these again became
the latter.
he for an up-country Anicut Diversion
masonry anicut in replacement of the una, previously used,
at the intake of the channel for exclusion
with indrawn silt in the head reach, k sections of the channel bunds,
asonry Works along the channel, e.g., gs, over-crossings, falls and outlets.
'
y are applicable, the same procedure is nks. The actual design and construction oints of engineering interest.
um or “Anicuto. The dams, asconstructed section with plank bays for desilting, and
OS.
head works for the diversion and control Plate 7.
ring the "close or non-cultivation season to be cleared of most of the accumulated
"Inlet Sluice, should turn at right angles he river flow. This parallel wall must be n of a scour-gate.
means an Irrigation Channel' distinctly separate to as Ela by the villager. A " Kandura" means mporary dams erected by villagers across streans.

Page 39
DEVELOPMENT OF VILLA
The stability of concrete dams' ci provide good guidance for the design of
The generalised formula is
which simplifies to
T2 I W H (H -- 3h
when there are no planked bays. As prevail when the value of h exceeds that consideration will be h equal to H, ever Some suitable sections from above are gi
84. A. stream diversion anicut also ob of heading up water for diversion of th provide sufficient, preferably as much a of flow. Cross sections of the stream t the vicinity would provide necessary
cause extra inundation difficulties upstre:
This aspect needs particular considera immediately upstream. The observed vision and the calculated High Flood and without planks) should be compare effected to avoid inundation of develope
85. Provision of planked bays in the operation and also provides extra wate floods can be assured. Theoretically th bays as possible appear advantageous such provision; planking operations ht and may not be done; therefore max exceed five feet. In the case of high a sill level of the planked bay. As long bays should be restricted to five feet.
to limit planking to such as could be ha
86. In the anchoring of the anicut, pro essential, even though the rocky bed ma
The Inlet Sluice Control
87. The inlet sluice consists of an o'
s actually required for the supply, thrc ine only function of preventing excessiv the channel. To effect the latter, an in opening, but no planks or gate is nec

GE IRRIGATION WORKS 37
alculations shown in Appendix XVII a suitable section for the anicut.
3h)
drowned' conditions will obviously of H, maximum value of h that needs though higher flood lifts may occur. ven in Appendix XVIII.
structs water passage, in the process e stream. It is therefore essential to s the original, water way for passage aken at a few representative places in data. Insufficient water way would
3111.
|tion where there are developed lands High Flood Level before anicut proLevel after anicut construction (with 'd and necessary alterations to design d lands.
anicut structure facilitates desilting r way if judicious unplanking during refore, provision of as many planked But practical considerations limit gher than a man's height is difficult imum height of planking should not licuts, it may be possible to raise the blanks are unwieldy, width of planked Most desirable approach is therefore hdled by an individual.
ision of mild steel dowels is absolutely y have been well scarified.
pening, somewhat larger in size than ugh a headwall or abutment and has flood water and debris from entering on-grill is placed and fixed across the essary at this point of the ela. The

Page 40
38 DEVELOPMENT OF W
abutment is set back from the anic at right angles to the anicut face, a The scour-gate planking must be r
The height of the “ Inlet Sluice foot above the calculated normal against over-topping. The open required size has the effect of all needed, therefore permitting eject in the ela as explained in the next that of the head sluice.
The Silt Reach
88. This is the most important it the ela below the “ Inlet Sluice', features of the river bed and ban dam has, of necessity, a masonry
earthen embankment would with wall has generally to be carried damage from floods cannot be don above the high flood level of the ol the river bank, and, as the rock lev the required bed level of the ela,
latter and the rock level and betw. the bank forms an ideal elongated can be collected. If no suitable 1 will have to be lined with concrete
89. A scour-gate has to be inse: junction of the latter with the
Inlet Sluice and ' Head Sluice' is the velocity of flow in the "Silt R the same level as the anicut, should Sluice. This will prevent flood v Reach, but at the same time will through the Inlet Sluice under
and consequently not enter the ela it could be divided into several pit wall by means of cut-off or profi the levels of which should again be
The Head Sluice Control
90. The Head Sluice structure is the quantity of discharge permitted nature, the sill level, size of openin

LLAGE IRREGATION WORKS
t, to allow for a scour-gate to be constructed nd as close to the 'Inlet Sluice' as possible. ade thoroughly leak-proof.
'' wall or abutment should be at least one High Flood Level over the anicut to ensure ng for this sluice being larger than the owing more water to pass than is actually on with all its silt at some suitable place paragraph. The sill level is identical with
2m in silt ejection and is the first portion of varying in length according to the Latural ks. This section of the ela just below the or concrete retaining wall as bund, as no stand the flood rush at this point. This along the channel to such a place, where e to the bund by virtue of its high elevation, ya. It has to be built on solid rock skirting el along this line is in most cases lower than the deep portion thus created between the een the retaining wall and the rock face of pit or "silt reach in which silt and sand 'ock is available on the river bank the pit or masonry.
ited in the retaining wall as close to the Head Sluice as possible. The sill of the kept at the same level in order to reduce ach'. The top of retaining wall being of slope or be stepped up to the top of Inlet later from the river backing into the "Silt allow surplus water which has been forced a flood head to spill back into the river To make the "Silt Reach more efficient with their own scour-gates in the retaining e walls constructed transversely across it, the same as the sill level of the sluices.
of primary importance in that it controls o enter the channel. Due to its controlling. , mode of closing the sluice and the height

Page 41
DEVELOPMENT OF WILLAC
of the head sluice wall, require very c The important factor in deciding the sill field to be commanded and its distanc possible to allow six inches of supply i made for losses in the gradient in the ir e.g., falls. The size of opening of the sl than for immediate requirements and scheme, subject howeve to efective con
91. The sluice must be provided with method for which, in case of village ela as one by one the planks can be lifted a case the surface water only is drawn into planks are found missing, and as the latt control of the required amount of w necessary. A lifting gate with screw ge is best adopted. This device has a great due to easy manipulation.
92. The ' Head Sluice' wall has to be prevent any overtopping by flood wate wall of the latter acts as spill at anicut Reach of flood water from an extraor overtop the Inlet Sluice wall cannot not enter the channel if the Head Sluic to a height higher than the possible high
Drainage Crossing
93. A great deal of trouble is caused irrigation channel by drainage crossing along the sloping face of steep land and is These kanduras are mostly dry during t streams in the Wet season, carrying with
In dealing with this problem, the foll (a) The kandura water is required to a
(b) The run-off from the kandura is
supply.
94. In the case of (a) the only solution t a strong retaining wall across the kand the wall will have to act as a spill with pit formed in front of the retaining wall, the actual ela bed and the scoured o depositing chamber, whiist the surplus wall into the stream. The entrance of

E IRRIGATION WORKS 39
reful consideration before adoption. level is the level of the highest paddy : from the headworks. It should be n the field; allowance should also be igation channel and at the structures, lice should necessarily be much larger rovide for possible expansion of the rol gear being feasible.
a controlled opening, the cheapest , is the ordinary lifting planked type, ccording to requirements and in every the ela. But, however, very often the er must be operated frequently for the fater, frequent replacement becomes ar that can be operated from the top er chance of being operated frequently
: built high to be quite sufficient to r in the "Silt Reach as the retaining t crest level. Entrance into the "Silt dinary high flood, which might even
economically be prevented, but will e' wall has been constructed or raised
flood level.
to the satisfactory maintenance of an gs. The channel is generally traced crossed at several points by kanduras. he dry months, but become veritable them all the silt from above.
Owing considerations predominate :-
lugment the channel supply ; not required to replenish the channel
o safeguard the channel is to construct lura on rock foundation. A part of crest at F.S.L. of the channel. The due to the difference in level between ut kandura bed, makes an ideal silt water spills back over the retaining the channel to, and its exit from, the

Page 42
40 DEVELOPMENT OF WILLA
pit must be kept to the actual design either in concrete or masonry must be made for a planked scourgate either o which any silt deposited in the pit can
95. In the case of (b) one of three me
If there is sufficient head-room bet then the channel can be carried in a tr. is not sufficient then the trough will ha discharge above and below it. Care 1 for adequate anchorage in the design, bed is high and its flow not required across the kandura bed to deal with kandura will become silted up, in con and the latter will assume the functic construct the abutment walls above th

GE IRRIGATION WORKS
!d level, for which purpose cut-of walls constructed. Provision will have to be ne or two, in the retaining wall, through be ejected.
thods could be adopted.
ween the channel and the kandura bed ough over the kandura. If the clearance lve to be replaced by a pipe allowing for must be taken in the latter case to allow
In the third case, where the kandura in the channel, a culvert has to be built the ela flow. The upstream bed of the sequence, to the top level of the culvert on of a spill but care must be taken to e H.F.L. of the kandura over the culvert.

Page 43
CHAPTE
SALT WATER EXCLU MNOR FLOOD PR
96. Land reclamation by Salt Water Protection Works are now no longer though initially most of these were deve
As these, however, originate even no marised reference to these here is not co
Salt Water Exclusion
97. The cultivation of paddy is, in ge1 of the island. Unfortunately, the flat the maritime regions of the island all all narrow fringes in the South-Western into large tracts in the Eastern and thi sources from the highland in mid-cour to reach the sea, in the form of streams
During the rainy season, due to an down the water courses, but in dry wea water travels up the water course and il soil in the flat areas saline and ruins cul high tide periods. On the other hand, not accumulate in the basins, then dis and stagnation takes place. The situat the south-west coast, a high sand bar fo Scal
The problem devolves itself into tw salt water into the basin nevertheless k for the drainage of the basin.
98. This subject does not seem to hav struction of tanks in the early days. were well established and had been dr routes for passage of boats.
The contents of the basin, when full, of a pilot channel in the sand bar at th the sand bar prevents further ingress invariably done during the interim peri the basin is insufficient to discharge, a enough to mount up an effective sand b;

R VIII
ION SCHEMES AND DTECTION WORKS
Exclusion Schemes and Minor Flood classified as village irrigation works, oped as village works.
w from the W. W. Priority Lists, suminsidered out of place.
eral, widely practised in the flat areas reas are to be found in Ceylon, near ong the sea coast. Commencing from :oastal regions, these rapidly expand e Northern areas. The natural water try meander through these fiat lands or rivers.
ple replenishment, fresh water flows ther, when such flow is depleted, sea h spreading over the tract, renders the tivation ; this is particularly so during
if sufficient head of fresh water does charge into the sea becomes difficult ion is further aggravated when, as in rms at the mouth of the outfall to the
parts; the prevention of ingress of 2eping in function an efficient scheme
e received as much attention as conEvidently some of the water courses -dged and maintained as navigational
may have been emptied by the cutting outfall. The natural reformation of of salt water. But the damage is d when the accumulated head within d the monsoonal blowing not heavy r to prevent salt water entry.

Page 44
42 DEVELOPMENT OF VIL
Considerations in the Formation of a
99. As in the case of storage tank of sufficient data is a necessary pre of a Salt Water Exclusion and Land
The report will contain, along wit
Basin and tract to be protected
Location details Name of tract and swamp to be Extent of developed area requir Extent of swamp which cannot Average level of tract Average level of swamp Extent of damage due to lack ol Extent of damage due to infiltra
Drainage
Name of main drain Sufficiency of subsidiary drains Sufficiency in size and openings
Sea outfall
Location Width and height of sand bar Approximate date when sandba Approximate date when sandba Frequency of breaching of sand Average height of basin water h.
bar Is the breaching usually initiate
water is it usually done
Hydrographic
Catchment area of basin Basin area Maximum daily rainfall Average daily rainfall High Flood Level in the basin Permissible period (in days) at damage to development in thi
100. The Survey Investigation wi necessary 16 chains to the inch S Such sheets are usually available o

LAGE IRRIGATION WORKS
S. W. E. Scheme
S and diversion of streams, the collection liminary for consideration of formulation
Reclamation Scheme.
1 other information, details of:-
drained ng drainage be drained
drainage tion of sea water.
of bridges and culverts at road crossings.
Lr usually breaches
ir re-forms
bar in ayear 2ad required for natural breaching of sand
i by manual help, if so, at what height of
ld height of flood-stay allowable, without 2 tract.
Ll be facilitated by the procurement of urvey Maps of the Survey Department. f all developed areas. Contour levelling

Page 45
DEVELOPMENT OF WILLA
has to be done and plotted on the gen chain sheets. Longitudinal sections of sary to consider improvements and regra and culverts at road crossings are requ openings for water passage. A suitab survey made, for the erection of the salt
Development
101. The construction of a battery of of the drainage water course into the s into the basin. The essential function sea water, but at the same time permit the sea. A type of one-way gates ac To avoid difficulties in writing negativ sea level datum to be 50-00 in value, or efficient function of the whole scheme di of the flap gate to the accumulating hea to be maintained free from rust, &c.
provision of movable balancing counter
To encourage free flow and to avoid within the basin and the protected area sary new drainage lines should be pr widened and re-graded for efficient disch
The formation of a sand bar at the order to prevent such re-formation of become necessary (where the outfall fac the outfall by the erection of a sea wall
Sca
Minor Flood Protection Works
102. Rivers and streams when they ri hill country sources, tend to spread ol The frequent inundation of low lying tributary streams, by flood accumulati sequential damage to agricultural purs evolution of Flood Protection Schemes. the cultivator adamant in continuing residence in the low areas because of The lower reaches of the Kelani Ganga either bank. The periodic flooding of spate, makes the soil in the basins highly
103. Essential factors that would nee protection works against minor floods in
(a) The exclusion, particularly durii floods that occur with consideral

GE RREGATION WORKS 43
eral tract plan prepared from the 16 the main drainage courses are necesding of the drains. Details of bridges red to consider the adequacy of their le site has to be selected and a site water exclusion gates.
one-way flap gates close to the outfall ea, prevents any ingress of sea water of such gates is to shut out entry to the discharge of the drainage out to opted recently is shown on Plate 5. 2 figures, it is usual to assume mean the drawings of such schemes. The
•pends on the quick and free response d of water ; the hinges have therefore Sometimes this is also helped by the weights.
stagnation of drainage, all the drains
require careful examination. Necesovided and existing drainage courses large.
outfall will choke the discharge. In the sand bar at the outfall, it may *es heavy monsoonal seas) to protect jetty or groyne of large rubble into the
ach the lowlands, after leaving their it and flatten in the coastal regions. ; tracts situated in the basins of the on in the parent river and the conuits, within the basin, has led to the In all these cases it is usual to find his agricultural practice and also his the sedimentary fertility of the soil. has several such tributary basins, on these basins, by the Kelani when in
fertile.
:d consideration in the evolution of
the river should be :-
ng the cultivation season of minor ble frequency in the parent river. It

Page 46
44 DEVELOPMENT OF
is neither feasible nor desir so frequent and are also o however be provided for ad basin, when they do occur.
(b) The incorporation of suita
reasonable promptness the basin itself and also the im gained entry into the basin and speed of discharge will river is flowing.
(c) The provision of proper int order to expedite post flood
104. Consideration of (a) above actual value of the level up to w entry; this is referred to as Prot the Minor Flood Level on the s by observation and judicious selec of the usual flood season and th that time.
Consideration (b) relates to the post-flood drainage discharge. return gates, usually hinged at th prevent ingress of river flood wa expect his lands emptied out, as immediately the flood is over ; in went down freely with the drop conditions require passage of drai a certain time lag.
105. As in Salt Water Exclusic period, when the basin can rer agricultural pursuit and practice This factor, in turn, decides the of two days has been used.
Conclusion
In the midst of large scale nati Cultivator still stands as the cou Work is his priceless possession. needs for existence.
The Village Irrigation Work irr paddy land.

WILLAGE RRGATON WORKS
able to exclude major floods, which are not f great manurial value; but means should mitting such floods safely into the protected
ble one way sluices for discharging with drainage from the internal catchment of the pounded flood waters from the river which during major flood. In both, the possibility l be determined by the stage at which the
ernal drainage within the basin or tract, in
discharge.
, necessarily requires the prior fixing of the hich the basin is to be protected from flood ection Level and should be identifiable with pot. Fixing of this level is largely decided :tion. Correct appreciation should be made le probable stage of cultivation progress at
: barrage of*emptying out' sluice gates for These are essentially “ one way ” or nonhe top, so as to permit basin discharge but ter. It is but natural for the cultivator to s rapidly as possible, of all flood water, the pre-scheme oeriod the water in the land ping of the river level whereas post-scheme nage through the one way sluices, involving
on Schemes, a correct appreciation of the main inundated in keeping with the local s, requires careful and mature assessment. number of gates to be provided. A period
onal agricultural development, the Village Intry's backbone and his Village Irrigation To him it is the provider of all material
igates over 50 per cent. of Ceylon's irrigated

Page 47
Appendix I Appendix II Appendix III Appendix IV Appendix V Appendix VI Appendix VIII Appendix VIII Appendix IX Appendix X Appendix XI Appendix XII Appendix XIII Appendix XIV Appendix XV Appendix XVI Appendix XVII Appendix XVIII Appendix XIX Appendix XX Appendix XXI Appendix XXII Appendix XXIII Appendix XXIV Appendix XXV Appendix XXVI
APP
Useful Memor
Some convent
P. I. R. for Vi
P. I. R. Villag P. R. Salt W
P. I. R. Mino
Specification f Village Tank Village Anicut Capacity Calci Catchment Air
Classification
Flood Run Of
Catchment Yi
Discharge of T Tail Channel
Stability of CC Base width of
Actual Flood
Suitable Chan
Earthwork in
Earthwork in
Discharge thr Sizes of Pipes
Reservations f
Scheme for th

ENDICES
anda ons adopted in Irrigation Practice lage Tanks : Anicut Scheme
'ater Exclusion Scheme
Food Protection Scheme Dr Survey Investigation of Village Tanks
"lans
Scheme Plans
ulations
ea of River Basins
of Catchments
f
>ld
ank Spills per foot length Velocities
oncrete Dams Piers for different Heads lift, &c. nel Sections
Channel Excavation
Channel Bunds
ough Hume Pipes for Village Tank Sluices or Streams, Channels, &c. e Improvement Village lirrigation Work.

Page 48
3.
4.
USEF
Measurements of Water :
I Cusec.
1 Ac. ft.
1 Million Cu. ft.
Cu. ft. 1 gallons of water weighs
Cu. ft. Cu. ft. sea water
Rainfal :
Inches of rainfall x 3,630 -
Inches of rinfallx2,323,200
1” run-off per hour per sq.
mile
Land Measure :
1 Perch 160 perches 1 Sq. mile
Acre To Estimate Extent of Land :
Acre
1 Perch
Power :
1 Horse Power
1 Kilowatt
Conversion of C. G. S. and F.
1 Millimetre 1 Metre
1 Cu, metre 1 Hectometre
Cu. Cu.
645
O
30 1 ac
10s
200'
16-5
550 33,C 8.8 746 O'74 34
P. S.
039 393 109 353

APPENDIX I
UL MEMORANDA
bic foot per second gallons per minute ,000 gallons per day 8 Ac. ft. per day-i.e. 2 Ac. ft. (Approx.) \c. ft. in 12 hours (Approx.) ,000 gallons-i.e. million gallons (Approx.) 356 million cubic feet.
96 Ac. ft.
4 gallons
lbs.
4 lbs.
lbs.
ft. per acre ft. per sq. mile
“33 cusecs.
cusec. per acre (Approx.)
Sq. yards re = 4,840 sq. yds. = 43,560 sq. ft. Acres = 27,878,400 sq. ft. q. chains (Gunters or Surveyors chain - 66').
x 200' (Approx.) X 1 mile (Approx.) і” х 16-5”.
ft. Ibs. per second
100 ft. Ibs. per minute. cusecs. of water falling by 1 foot (Approx.) Watts
6 Kilowatts
H.P.
Units:
37 inch : 1 inch 7 inches : 36 yards : 1 yard 14 Cu. ft.
letes
254 mm. 254 c.m. 0.914 m.

Page 49
7.
Hectare
1 Kilometre
Litre
1 Gramme 1 Kilogramme
General :
1 Long ton 1 Short ton 1 Metric ton 1 Imperial gallon 1 U. S. gallon 1 Maund 1 Cube 1 Cub. yd. 1 Square 1 Sq. yd. 1 Bushel
Measurement of Paddy :
1 Ammuram
1 Amunam
1 Marakkal 1 Ton of paddy 1 Ton of rice 1 Measure of paddy
Cultivation Seasons :
I Maha Season Kalapokam Munmari II Yala Season
Sirupokam Pimmari
APPEND.
APPENDIX I
1 Sq. Hectom 10,000 sq mit 247 Acres 1,000 metres 062 miles : ) 1 Cubic decii 1,00. с.с. 1*76 pints ; 1 022 gallons OOO22bs. : 1,000 gms. 0'000984 ton 2204 lbs.
2,240 lbs." 2,000 lbs. 1,000 kgms. 120 U.S. g. 0.833 Imp. g. 82 Ibs. 377 cu. yds. 027 cubes 11*1 sq. yds. 0'09 square 125 cu. ft.
4 Pelas 40 lahas or k. 160 seers or 1 10 bushels ( 7 bushels (B bushel (Bat 49 bushels 35 bushes 2 lbs.
October-Feb1
April-August March-July
Weights of Materials Per Cubic Feet:
Cement Earth Clay Granite
90120

[CES
-(contd.)
etre
47
rs : 1. Acre = 04 Hectare
mile = 161 kilometre
lete
gallon = 455 litres
1 lb. = 4536 gms.
: 1 ton = 1,016 kgms.
allons allons
urunis
heli Trinco District) atticaloa District) ticaloa District)
ruary
lbs. average -120 lbs. s )3 .1bs 130.سس
-180 lbs.
90 lbs. 100 lbs. 120 lbs. 165 lbs.

Page 50
48 DEVELOPMENT OF VILL
APPENDI.
Limestone Concrete
Brickwork in lime or cement mortar - Random rubble in cement mortar -
Mild Steel
River sandi
Pit sand Weight of a cube of sand Weight of a cube of metal Weight of a cubic inch of steel
Tide Levels :
Station
Colombo Trincomalee Galle
May. Ley
167 M.S. 161 M.S. 136 M.S.

AGE IRRIGATION WORKS
X -(contd.)
120-150 lbs. averages 140 lbs. 20-140 lbs. 参强 135 lbs. 100-150 lbs. 120 lbs. 30-140 lbs. 9. 140 lbs. 490 lbs. , 490 lbs. 115 lbs. , 15 lbs. 95-100 lbs, 9s 100 lbs. 5 Tons (Approx.)
65 Tons (Approx.)
0283 lbs.
el Min. Level
L. -163 M.S.L.
L. -139 M.S.L.
.MLS.L 164- .سL.

Page 51
APPEI
SOME CONVENTIONS ADOPT
R.B. and L.B. of tank bund
The Co-ordinate location of a tank -
Datum of 100'00 me
Chainage of tank bund t
Plotting of tank bund cross-sections - Plotting of spill site plans L.S.S. area
6. Scale of L.S.S.
C.SS. Contour plans Spill site plan Masonry Details s
7, B.T.L. F.S.L. H.F.L. F.S.D. M.S.L. R.L.
B.O.P. UIS. DIS
8. Natural Spill
Purana Fields

WEDIX I
ED IN TERRIGATTON PRACTICE
Section of bund on the right and left banks of
the main stream intercepted. Refers to the L. B. end of bund.
Assigned level of the sill of the lowest sluico
or lowest pointin bed. From L. B. end.
Tank side on left. Direction of flow from top to bottom. Left to right.
200' to an inch horizontal, 10' to an inch
vertical.
10' to an inch natural.
4 chains (264) to an inch.
40' to an inch.
4 or 8 to an inch.
Bund Top Level.
Full Supply Level.
High Flood Level.
Full Supply Depth.
Mean Sea Level.
Reduced Level above an assumed datum.
Elevation above M.S.L.
Blocking Out Plan.
Upstream-same side as the tank or channel.
Downstream-side opposite the upstream side.
Channel spill with offtake level at approxi
mate crest level.
Existing paddy fields before restoration of
tank (usually private).

Page 52
AF
PRELMINARY INVESTIGATO
Date o .............................. o s o e e e a ao
Name of Work : .................................
Village : ....... LLL0LCSLLLSLLLLLSLLLLL0SLLLS0LSLLLSLSLLL 0LCLLLSLLLSLLLLLLSL 0LLLL0LL000LL
Pattu : .............................................
D. R. O's Division ............... O as e un o 9 de e o 8 se «o o a O e
Information supplied by:
2.
3.
4.
S.
Means of Access :
Topo tracing, showing means of access, bund, spills, sluices, &c., landto benefit and proposed main channels.
Tank
Bund : Massive, normal weak, overgr
Length : Max. he
Top width: Side slo Details of big breaches, number, width
Sluices: Type Size
1. ...................... 8 498889888«. O g 4 + 8 B
2. ........................ sessoossos ossos s

PENDIX III
REPORT FOR WILLAGE TANKS
Name of Officer Reporting : .....................
Co-ordinates ......... LLLLLLLLLLYLLLLL0LLLLLLLLLLLLLL se e O Y
Electoral District ......................... e
Province : .......................................... o
Components
W
ight : Good
)eS : Normal
and overall depth Poor
Sill Level Conditions
0CL0L0YLSLS SLLLLLLLYLLLLLLYLLLLL0LLLLYC000LL L LLLLLS SLLLLLLLLLLLLLLL0LLCLLL LLLLLL 0 W 40 000 (?

Page 53
APPE
APPENDIX
6. Spills :
L.
Length
Nature
Condition
Spill water
Ge
7. Number and attitude of Shareholders :
9.
10.
11.
Do shareholders resi
Total number of persons resident at tank.
Does the community depend in whole or
If so, state number of persons thus depen
Materials : Metal on spots......... mils, a on spot......... mils. away. Pluddle clay carry.
Details of usual cultivation and sufficiency
What depth of water remains in tank aft.
Is this because fields are higher than tank
Approximate distance of fields from tank
Supply, Capacit
Catchment Area : and......... abandoned tanks
Description of Catchment-(vegetation-s
Total Capacity of Working Tanks in Catc.
Approx. Depth of Tank Approx. Capacity of tank.

DCES 51
III-(contd.)
le at tank ?
in part on the tank for their livelihood 2
dent :
way. Sand on spots......... mls. away. Turf on spot......... mls, away. Earth ........ ft.
of water :
»r sluice or bund cut ceases to function 2
bed
bed
y and Command
sq. miles with............ working
оре, &с.)
ment
feet ас, ft.

Page 54
S2 DEVELOFMENT OF VE
APPENDI, 4. Rainfall
Highest daily fall ins. on
Month A B C
September st a
October e
November
December
Januагу e
February 8 N. E. Monsoon
Total ..
March
April O
May O O
Juno
July P
August 曾 修 S. W. Monsoon
Total ..
15. Probable Command :
16. Spilling History :
R. B. Spills. Spills times per year
or Total duration in days Breach. Average depth over crest
Length of Spill Clear overfall or natural
L. B. Spill. Spills times per year
or Total duration in days Breach. Average depth over crest Length of Spill Clear overfall or natural

LAGE IRRIGATION WORKS
III-(contd.)
Yield
Minneriya Curve
used Nachchaduwa
N.E.M.
S.W.M.
Supply other than from Catchment :-
Description
N.E.M. Ac. ft.
S.W.M. Ac. ft.
Normal year Wet year Dry year

Page 55
17.
18,
19.
21.
APPENT
APPENDIX I,
rrigable Area under the Scheme
Acreage Cultivated
Acreage Abandoned W 4N
Additional Acreage Available
Acreage of fields in tank submerged at prese Acreage of fields or private lands abut on F.
Details of area that will be submerged if tan
Flood ru)
Flood History H.F.L. feet above Cause of H.F.L.
Did tank breach 2
Did bund overtop ? Damage caused by H.F.L. Damage caused by normal F.L.
Flood discharge calculated C as 645, 7.- Estimated Q
from observed flood level Q =
Additional information (if any). Remarks cultivators ask for :
:
Catchment Development-Effect of the p1 the degree to which it will limit future uti of which the tanks own catchment is only a
26. Proposals :
B.T.L. .............. ... Bund top width .............
FS.L. ................, H.F.L. .................
State whe ” Utail chann
No. of sluices with sill levels ...............
Length of spill..................
Useful storage ........... ....... AC. ft.
Maha................ proposed cultivation {
U Yala ••••••••••••••••••

(CES 53
-(contd.)
Crown...... .........Acres
Maha.................Acres
O Yala...................Acres
Maha................Acres
O Yala..................Acres
Private...............Асres
Crown....... ........Acres
(nt F.S.L., ...............Acres
S.L. contour . . e es e e o vp ) ) a as 4 e 9 sAcres
k is restored or improved ....... ........Acres
off
F.S.L., Date :
How frequently 2
350, 1,000, 2,000
re urgency, &c., and description of what
oposed restoration on existing works, and lisation of the water resources of the basin
part.
... ; us slope......... ; diss slope....... e et e o a use
Free Board ...................
her C. O. or natural, and if natural, give
gradient.
, Ac. at duty 3 ac. ft/acro.
Ac. at duty 5 ac, ft/acre

Page 56
54
DEVELOPMENT
AF
27. Estimate for Construction'
9.
10.
11.
Mls. preparation of access
Ac. Jungle clearing of bur
Cu. E/work in bund raisin
Cu. Puddle clay in core wa
Sq. turfing D/S slope of bus
Sq. Rubble/concrete slab pr
Item allow for clear overfall
Cu. excavation in natural sp
No. sluices size type
tem allow Bund level Block
Sq. Temporary sheds/semi p{
12. Item Allow Pay of overse
0 - 0
LLLLLLLLSLL0SLLLLLLSLLLL0LLLSLLLSLLLL LLLL S months, &c.
13. Item Allow L. T. and contin
14. Allow for Irrigation Facilitie
Strike out unnecessary items and ad
Date :

F WLLAGE, RRGATION WORKS
ENDIX III-(contd.)
All inclusive
ack/service road to work sites
LL L0L00L0 SLL LLLL LSLLLLLLLL 00LS 0 S0SLSS
spill sites, breaches, camp area, &c.
transport feet
, transport mls.
, transport mls.
tection to us face of bund
skin type masonry spill
ll and tail channel
s, sign boards, guage posts, &c.
brmanent quarters
ers......months, watchers
encies
Head works
to............AC. Gè.........Is
Total Cost
any others that may be required.
a a
A us is a e s p a os
SS0S S SLLLL0LLLLL0LLLSLLLLLLLL 0LSL00SLLL
A a a so see age
O P B Q IQ KO S K Q ( a ) ( )
we do so sa e s a see
a o e o so e o so a e a so a as
A · · · · · · · · 0 8
0S SLLS0L0LLLL0LLLL0LLLSLLLLLLLS e o B
O. O. 4 d 8 so )
Y - 8 du 8 o Ao P o 0. e
p a so o e ab eo a s o as o as e no e e as e
pamamamamama
e se e as e a se e o e a e a e a
LS SLLLS S0LLL LSLLL LLCCLLLCS0LL0SCLLLLSLLSCCSSSLS0LS
Signature and Designation of Reporting Officer.

Page 57
APPENDI
PRELMINARY INVESTIGATION REPOR
1.
2.
3.
Date .............. • • • • • • • • • • • • • • • • • • • Name of O
Name of work....................................
Co-ordinates ............... LLLLLCLLLLLLLLCL000L0LLL0L00CL0LL LL 0L0L 0L0
Village .............................. Electoral D
Pattu...................................... Provin
D. R.O's Division .............. a e a sess so
Information supplied by :
Means of Access :
Topo tracing of Head Works, including c whether Crown or Private land :
Description of
Head Works-Detail description and sketch
Sluices : Nos. Type
(1) e o a se e se a e e a s s s s e s e
(2) a O e O O O O O ) » D O e es e 4G g g Pl
Possible alternate size for Head Works :
(a) Upstream :
(b) Downstream :
Detail description of Channel System
(a) Length of channels
(b) Approximate dimensions . .
(c) Gradients .. e
(d) Cross drainage works s o
(e) Other structures a o

IV
T FOR WLLAGE ANCUT SCHEME
fficer Reporting....................
Priority List No. .................
8 8 8 8 8 0
is 8 d ( )
Q) 4b, 40 Q Y 8 is
8 is 8
hannel system and lands benefited stating
Scheme
'ed cross sections of stream.
Size Sill Level
» ( ; a o e ses.
LLL0LLLS S S SLLLLLLLYLLLLL YLLLLLLLLLLYYYY0LL00LLL0LSS SSL0L0YCL0LLY
8 - 8 88 a 8 as so st
8 8 & 9 s Od Yi () ) Y a As 8
( e a 8 s 0 & 8 8
e o a se se o se es se se se geo es es se o «
Y SLLS SSL0L00 000L LLL 0LL Y C0LLLLL0LLLLL00
g ) es es e is a se a 6 y 8 a
& 4 a s sep
R.B.
O p O s. s p ess
so 8
s se As a a e s : 3

Page 58
S6
10.
11.
12.
13.
14.
15.
16.
17.
18.
19,
20.
21.
DEVELOPMENT OF '
APPENI
Distance from head works of highes
Existing Anicut AmunaBemma :
Nature :
Height :
Date first constructed : No. of times washed or damaged pe Annual labour required for repairs :
No. and attitude of shareholders :
Do shareholders reside in the neighb
Total No. of people resident :
Does the community depend in who If so, state No. of persons thus diape
Cultivation date
(a) Usual cultivation and results : (b) Sufficiency of water : (c) Total irrigable area under the
(1) Ph
(2) C
(d) Acreage cultivated : (1) M
(2) Y
(e) Acreage abandoned : (1) P.
(2) C
Materials
(a) Stones suitable for dressed sto
(b) Metal at spot!............ . . . . . . .
(c) Sand at spots......... ......... mi
(d) Turf at spots.................. mi
Suppl
Catchment area .................. Sq. Im
tanks or Anicuts or Amunas.
Description of catchment (Vegetatio
Total capacity of working tanks (if a

WLLAGE RRGATON WORKS
DIX IV-(contd.)
t paddy field benefited :
General
Length :
r year :
pourhood ?
le or in part on the scheme for their livelihood
ndant :
scheme:
rivate sigs e s a acces
OW 8 8 is ........acces
alla Y SSYSSS SS SS LLLLLGLLLGLLLLLLL 0LLLLLSLLLLLLLLL0LLLLLLLLL0L acces
rivate LL LS S S0LLLLLL0LL0LT LL LLLLLL LLLLLL q q 3GséS
OW 0S SYS S S0YLLLSLLL LL0YLLLLLLLL LLLLLL acces
the masonry at spots........... .......miles away
illes away
les away
es away
y and Command
iles with .................. working .................. pan
n, slopes, &c.) :
iny) in water shed :

Page 59
APPEN
APPENDA
2. Description of other diversion schemes acr
(a) Situation : (b) Command : (c) Cultivation system :
23. Any modification necessary in the cultivat of other diversion schemes higher up :
24. Rainfall
(a) Highest rainfall ....... ...ins on ........
Average monthly rainfall recorded :
A...... ............niles away
B..................miles away
C.............. ....miles away
Months
N. E. Monsoon
September
October 锦 惨
November
December 崇 够
January
February ( 0.
Total ..
S. W. Monsoon
March
April
May 8
June 缘 ●
July
August
Septembero
Total 8
This month should be deleted from one oft monsoon for that particular station.

DICES 57
V-{ucatd.)
oss the strean :
tion system under this work due to presence
at soooooooooooo
0LLLLL0LLLLYYLYYYYL0YYS S S SYLYYSLSLzLLLL L0L0LLY LLLLLLYLLLLS SYYLLLYYLYYLLLLL YLLLLL
sts w 8 AP
SLLLL0LLLLSL YLLLYYYLLLYYYLLLL S SLSLL0LLLL 0LLLLLLLYLLLLLLYS SYL YLLLYLLLLLLL0 0L0LY0
L LLLLLLLL00LLLLLLLY 0LLLL LS S SLSLLLL L0 0LL0L LL0L LLLLLY LLL YS S SYYLLLL LLL 0 LL LL 0LL0 LLLLLLLLY0LL
* * * *«> 8 : Me Ke g 8 is .
0 8 × 8
晚年 8 w
88 峰曙嫁 旷
LLL L0YLLLLLL0LLLLL0YS S SLLLLLLL0 LLLLLLLLY LLLLLLYLLLLLLLS S LLL0LLLLL0L0LLLLY0LLYLLL
LLL Y LL0LLCLLCLLLYYY 0LLLL LS S S LLLLLLLLzYLLLLLYLLLLYYLLLL 0LS S SLLLLLLLLLLLLL0L LLLLL LL
LLLK LLL LLL LLLLLGLLSGG LLLL0LLLLS S SY LLLLLL0SL0L L LL LLLLLLLL0L YYS S S 0LY0LYYLLLLLLL LSLLLL LL
;he periods in accordance with duration of the

Page 60
S8
25.
26.
27.
28.
30.
31.
DEVELOPMENT OF V1
APPENIE
Rum Off :
N. E. Monsoon Yield........... 80 (h
S. W. Monsoon Yield.................
(a) Is the stream perennial 2
If riot what is the duration off
(b) Is the supply augmented by spr
If so give details.
(c) Supply other than from catchm
Description :
N. E. Monsoon Yield...... a 0 80 pes
S. W. Monsoon Yield..................
.٫۰ F.
Flood History
(a) Observed H. F. L. (b) Cause of H. F. L. (c) Did anicut damage 2 (d) Did flank bund overtop ? (e) Damage caused by H. F. L. (f) Damage caused by normal F. L. (g) Area submerged by H. F. L. (h) Area submerged by normal H.
Flood discharge calculated :
C = 645, 850, 1,000, 1,500, 2. Q =
Is anicut/Amuna/Bemma crest level sa Additional information (ifany) re urg
wators ask for :
Catchment Development
Effect of the proposed restoration ( limit future utilisation of the wate of this anicut is only a part :
Anicut/Bemma/Amuna
Crest Level :
Length :
Type :
No. of openings, if any, and whethe any, with length, level and top widt
Head Sluice Type
LSLSLLL L LLLLLLLL 0LLLLLSLLL CLLLLLLLSLLLSLLLL SLSL0LLLL0LLLSLLSSLLS LLS 0 0LLLLLLL LL LLL
e O O O S O S O Qga po p O O O A a e O a o or e o se so sess a

LLAGE IRRIGATION WORKS
IX IVY-(contd.)
............acre feet
......... acre feet
OW
ing ?
ent:
· ·· · · · · · · · ..acre feet
O ..acre feet
ood run of
F. L.
,000
tisfactory, too high or too low 2
ency of work and description of what the culti
in existing works, and the degree to which it will resources of the basin of which the catchment
Proposals
r planked or screw operated. Flank Bunds, if h, side slopes, &c.
Size Si Level
no O do b ) SO OD OKO 60 49 43 o 3 o 9 a O UN O 0. o es a es O es e
pea e soooooopeposes so o a so . 0 s swoo e a e s s pe D e o

Page 61
APPENDC
APPENDIX I
32. Channel system
Length of channel : Approximate dimensions : Gradient :
Cross drainage works necessary : Other structures necessary :
Proposed cultivation . Maha ap D
Yala
33. Recommendation :
34. Estimated Cost
Cost of Anicut .. e.
Cost of Channel .. A
Cost of Structures •
Dae .......... o e () o e is a 8 o s 88 x) o a se 3) {9 *) ) * R M 86 8 8 8 & 9 & 8) 86 y

59
's-contd.)
Crown
X y y 8 y 9 8 . . . . . . . . 够姆 够够沸 ●崇
8 8 0 - 0 8 ses 9 * g ) 9. * g ) e is o
X s8 a es se a 9 a 8 8 8
e see } e le ' ' •';
YLL 0LS S SLL0LL0L0YLL0LL00LLLLLLLYLLLLLYLLYYLLLL
8 a
Y zS S S LLLLLL L0LLLLLLLLLSLSLLLLLSLLLLLSLY0Y 8
Total . .
LLLLLLLLS LLLLLLL 0LL 0 00LL LL LLLLL LLL0LLL 0LL LLLLLLLL0 0LLLL 0LL0 zLL 0LLLL LLYY er se e y e g is e o 8 * *
Signature and Designations
of Reporting Officer.

Page 62
1.
3
4.
5
*
6.
APP
PRELMINARY INVESTIGAT
EXCLUS
Date ........ • • • • • • • • • • • • • • • • • • • • • • Name of
Name of work ...................... . . . . . . Co-ordinates ...................... o obsessee one e
Villago ............................... ........E.
Pattu ...... S 0LLLLL LLLCLLS LLLLLL0 0S LSLLLLLS0LLLLS0L LLLLLS ..... Pro
D. R. O's Division ..........................
Information supplied by :
Means of Access :
Topo tracing showing the lands affected
and channel systems, lands benefited
Description of Scheme
(a) Does salt water enter the land due
Give the High Tide Level and the
distance from the sea. or
(b) Does the salt water enter the fields
with a sand bar 2
If so give the maximum height of t
During what months does the sa
breach it 2
Is the site at the mouth of the rive not are there better alternate site
(c) Show on a sketch plan the followin
(a) Catchment of the basin affect (b) All the drainage channels an (c) Individual catchments of eac (d) Suitable traces for salt water (e) Probable trace for deviation ( (f) Site for Sea Outlet Structures (g) Sites for Spills, if necessary.
(h) Area affected by salt water.
(i) Cross sections of all the drair
(d) What extent of land is annually aff
7. Drainage Channels–Give a detail des
area, flood heights together with sket
Annex sketch plan.

NDIX V
ON REPORT FOR SALT WATER ON SCHEME
riority List No. ...............
to be a
ectoral District ....................... 0 p. 8 et 8 848 s 9 0 h à 8 0 008 净
vince ................................ aw pees be see e eo e a b e o e os se
a d
by the intrusion of Salt Water, existing drainage stating whether Crown or Private land,
to fluctuation in tide levels 2
Low Tide Level at the point considered and its
whenever themouth of the river is blocked open
he salt water level entering the fields, ld bar form and how often do the Cultivators
r suitable for a salt water exclusion structure, if
g information'.
ed by salt water entry.
other features.
of the drainage channels.
2xclusion bunds.
hannels to the sea if necessary.
age streams from the scheme.
cted by intrusion of sea water.
:ription of the streams showing the catchment ches of cross section of each stream.

Page 63
8.
9,
10.
11.
12.
13.
14.
APPENDI
APPENDIX V,
Genera
Number and attitude of the shareholders.
Do shareholders reside in the neighbourhoo
Total number of people resident,
Does the community depend in whole or in
If so, state number of persons thus dependa
Cultivatisin Date
(a) Usual cultivation and results. (b) Source of supply of water and the suffici (c) Total cultivated area under the scheme,
(d) Acreage cultivated.
1. Maha .....................
2. Yala ........................
(e) Acreage abandoned.
1. Private......................
2. Crown ...... 8 8 3 8 88 88 8 8 8 8 8 8 8
Raimfa
(a) Highest rainfall......... AB 0 B 8 69 tib ** O`8k V O K y - 40 4) X 0 0 4 a «0 t
A ....................... exo se o a la a se a
B.................... * * * 8 4) { K} ) ) * * * oo o
C.................. X) op 0 & 0 & 0 w8 0 & 0 & 2 & 0 &
Months
N. E. Monsoon A.
September 8 as 8 A . 8
October 岭 娜 8 A 80 e 8.2 es se se
November .. Y LLS S S LLLLLLLL LLLL LSL LLLLLYLLSLLLYLL
December a 6 y es a se a se e es e
January y a se es o se s a «s s
February 3 K). X 8 a 4 w
Total ...

CES 6
-(contd.)
part on the scheme for their livelihood 2
ht.
ency of water.
0 aCes
... ....aCTS
... ......acres
.........acces
0 acres
...aCS
...ins, on ...........................at............
.............. miles Sway
............. miles away
............. miles away
B C
S SSLLSLSLLSLSLLSLLLL S S LLLLSLLLLLLLL L LLLSLLLLLLLL LL 0 LLLL LSLLLLLLSLLLLLL SLLLLLLLL LL LLL LLLLL LCLLLLLCLL0LL0LSLLSLL00
L0LLCLLLLLLLLS S LL LLLLLL L0L0LLSL0LLLLLLLLLSLLSLLLSLLLLLLSS SLLLLLLL0L0SLLL0LLLLL o O
0LCCCCCCLLLLG S S LLLL SLLLLLLLL LLLLLLLL LLLLLLLLSL LLLLS LLLLLSLLLL S SSSS SY0LLLYLLLSLYLLLL 0LLLSLL SLCLLSCC0LLCL0
S0CL0CLLCCCL S SLL0LL0 L0SSSLLSLLLLL0SLLLS0SLLLS a a a s p e a go a e as a un e a a a a a 0 e
S0CLSLLLLL0000LLLLLL SLLLL0LLLLL 0SL0LLLSLLSLL LS SLL S SLLLLSLSLLLLLSLLLLL A S LLLLL LL LLL LLLL0LL LLL LLLLLLLLS 8

Page 64
62
15.
16.
17.
18.
19,
DEVELOPMENT OF VIL
APPENDI S. W. Monsoon
March 8 a s a
April 9 y 6 es e Y a
May è o W 8 a v se as
June
U 0 - 8
July é «» e se a e
August
y a se
Yield -----ܚ
N.E. Monsoon Yield.................. 8CTo !
S.W. Monsoon Yield................. a
Food Rum Off
Flood history
(a) Observed H.F.L. (b) Cause of H.F.L. (c) Damage caused by H. F. L. (d) Damage caused by normal F. L. (c) Area submerged by H. F. L. (f) Area submerged by normal F.L.
Flood Discharge Calculated C = 645, 1,000, 1,500 Q = Additional Information (if any) re urgency Catchment Development-Effect of the which it will limit future utilisation of t catchment of this scheme is only a part, Brief Description of Proposals Recommendation
Forecast of Estimated Cost
Acres Clearing along bund trace Cubes E/W in forming bund Sqrs. Turfing bund No. Structures
No. Outlet sluices No. Other Structures Item For supervision * 影
Item For Contingencies e e
Date:....... •••••••••••••••••••••• 9 & 8 de sees

AGE IRRIGATION WORKS
ʼ V4—(contd.)
a s 0 - 0 e o Ao e U U 8 LLSL LLLLL SLLLLLL0 0LLLLLL0SLLLLLLSLL LSLLS LSLL 0 LL
SLLLLLLLLLLS SL0LLLLLLL LL 0SLLSLLSLL LLLLSLLLLLL a v P KO S O
LLLLLL LLLLLL SLLLLLLL0LLLLLLL LSLSLSL LLLLL SL0LLLSSL 0SLLL SSL C LSL S LSLLLS0LLLLLL CSL0L0LL
SCCCC0L0LLC0 S SLLLLLLL0L0 LLL0L LL0LL L LLL0LS S SL 00LL 0S0LL LL0LLLLLY LLLLLLLCLL LLLLLL
SSSLLLLL 0LSLLS SS0SL0SLLSLLSL 0SL LLLLLLLSL SLLLLL 0S0L 0LL SL S0L SS L SS 0SL S L SL00 0L SLLLL LL
SL0 0C CLL CCLLLS SS0SL CLLL LLL 0LLSLSLLLL 0LLL LSLS 8 8 8
mബയ
LSMSMSSLLLSS SSLSLSS анымы жанымдык
feet
of work and what the cultivators ask for.
proposals on existing works and the extent to he water resources of the basin of which the
All Inclusive
0
a es
O a
e. to
0 O e e
O O
O O.
Total O
Signature and Designation of Reporting Officer.

Page 65
1.
8.
O,
11.
APPEND
PRELMINARY INVESTIGATION
PROTECTO
Date .................. Name of Officer Repor
Name of work.................. Priority List
Co-ordinates ..................
Village .................. Electoral District
Pattu .................. Province ...............
D. R. O's Division ........... one
Information supplied by :
Means of Access :
Topo tracing showing the lands affected
private lands.
The following information should be given (a) Number of times the lands are floode
(b) Brief description of the major and m occur, and the period of flooding.
(c) Catchment of the river.
(d) Description of the catchment (Vegeta
(e) What is the depth of water in the are
(1) A major flood. (2) Aminor flood.
Description o
Show on a sketch plan
(a) Depth of inundation of land by a mi (b) All the drainage lines within the basi (c) Low places along the bank of the rive (d) Catchment areas of all drainage outle
Give the H.F.L. and M.F.L. of the river
(a) Upstream of the Scheme. (b) At the Scheme. (c) Downstream of the Scheme.
Will any private property, house or industr the proposals If so, give details.
Are there any ilands depending on flood wat purpose. Give the extent so depending.
To what depth of water from the river shou

IXY VTI
REPORT FOR MNOR FLOOD N SCHEME
ting ..................
No. ..................
by minor floods stating whether COW. Ot
مـــ2
:d during the year. inor floods giving the months in which they
tion, slopes, &c.). a affected by
f Scheme
nor flood and the area affected.
In with cross sections of each stream. irthrough which flood waters enter the basin.
yts. W
y along the banks of the river be affected by
er of the river for cultivation cr for any other
ld the basin be protected from flooding.

Page 66
64 DEVELOPMENT OF
APPEN
12. Number and attitude of shareholdel
13. Do shareholders reside in the neigh
14. Total number of people resident.
15. Does the community depend in whic
16. If so, state number of persons thus
17. Cultivation date :
(a) Usual cultivation and results. (b) Sufficiency of water. (c) Total irrigable area under the
(1) Private....... 8 8 Q O« 0 y 8 de ac
(2) Crown .................. 3C
(d) Acreage cultivated Maha .....
Yala .......
(e) Acreage abandoned
(1) Private .....................
(2) Crown......... .....acces
18. Rainfall
(a) Highest rainfall............ins. C
miles awa............................مA
B..................miles awa
C........... ........miles awa
Months
N. E. Monsoon
September
October
November
December
January
February
Total

ILLAGE RRGATION WORKS
DIX VT-(contd.)
ourhood ?
le or in part on the scheme for their livelihood
lependant.
Scheme.
.......acres
e. ...aCICS
n . . . . . . . . . . .at... . . . . . . .

Page 67
APPEND.
APPENDIX /
S.W. Monsoon
19.
20.
21.
24.
2S.
March
April
May
June
July
August
Total
Yield
N.E. Monsoon Yield.................. acre fee
S.W. Monsoon Yield............... ...acre fek
Food run off
Flood history
(a) Observed H.F.L. (b) Cause of H.F.L. (c) Damage caused by H.F.L. (d) Damage caused by normal F.L. (e) Area submerged by H.F.L. (f) Area submerged by normal H.F.L.
Flood Discharge Calculated
C = 645, 1,000 1,500
Q జ=
Additional information (if any) re urgency vators ask for.
Catchment Development-Effect of the pro which it will limit future utilisation of the catchment of this scheme is a part.
Brief Description of Proposals
Recommendation
4-H 1103 (671)

o ab eo up LL L00SLLLSLCLLLLLSLS L0L LL0LL0LLL0S CS LLLLLL
LLLLLL SLLL LLL0 LL0LL L S SLLLLLLSLL LLSLL LSLLS s ss e o so a a e s 8
ess LL LLL LLLS LLLLLLLLSLSL SLL LSLL0 LLLLLSLLLLLLSS LL LLL LLLLLL
o O. LLSLLLL0LLLSLLLS LSLLLSL LSLS S L0L LLL LSLLSLLLLLSLLLSS v 4 8
LSLLLSL LSL LSL LSL LSLLSL L S S SLLS L L LLLLL LLLLLL Q QO O O 8 «e 40 a0 «O «O Q 0 u 8
a e i u as LLLLLL L LL LSLSLSS LLLLLSLLLLLSLS S S LL LLL LLLL LLLL LL0LLLSLLL L wo
of work and description of what th
posal on existing works, and the degre water resources of the basin of which
65

Page 68
66 DEVELOPMENT OF V
APPENI
26. Estimated Cost
Acres clearing for bund traces Cubes E/W in forming bund Sqrs. Turfing slopes of bund No. Outlet Sluices No. Other Structures Item For Supervivision Item For Acquisition, &c. Item For contingencies
Date : . . . . . . . . . . .

FILLAGE, RRGAON WORKS
DIX VI-(contd.)
All Inclusive
Total 始
Signature and Designation
of Reporting Officer.

Page 69
1.
2.
APPEND
SPECIFICATION FOR SURVEY INVE
The survey shall consist of 4 parts :-
Part - Tank bund surveys to determin quantity of earthwork necessar
Part II-Tank bed contour surveys to vations (2) the flowage damage
Part III-Breach sitesurveys to determine (2) the quantity of earthwork and other unsuitable materials
Part IV-Spill site surveys to determine t
Unless otherwise specified, all levels shall
of the lowest point of the bed shall be 10000 R.
1.
Part-Tank Bund Surveys :
The axis of the bund shall be the centre side till the ground level is about 5' above 1
The bund axis with the left bank end as the pegs at 100' intervals and at points of chang the surrounding ground level and shall shot
A traverse survey of the bund axis shall be such as rock outcrops, streams, roads, h. on either side of the axis shall be surveyed
Two bench marks of standard constructio) of the axis and their position and values sh
Spot heights along the axis and along the u at 100' intervals (at each chainage point) o breaches or other topographical features.
Spot levels along cross lines at each chain closer or bring out the true profile of the either side of the toe. Additional cross sec in existing bund profile.
A flat plan and longitudinal section of the plotted to the following scales :-
Flat plan a ... 2 Longitudinal section .. ... 2
Cross section
The flat plan and longitudinal section sha shall occupy the upper portion of the sh portion.

Y VIII
STIGATION OF WILLAGE TANKS
e (1) the alignment of the bund and (2) the y for improvements to bund.
determine (1) the capacity at different elle
2 (1) the alignment of the bund at the breach in breach filling (3) the quantity of silt to be removed.
he most suitable alignment and type of spill.
be to an assumed datum, the assumed level L.
ine of the existing bund extended on either he average top level of the existing bund.
zero point shall be marked by sawn wooden e of direction, the pegs shall project 3 above w the chainage number.
made. All topographical and civic features ouses, private lands, &c, falling within 66 by offset lines and shown on the plans.
n shall be established one at each extremity all be shown on the plans.
pstream and downstream toes shall be taken r closer to indicate gullies, stream crossings
age point shall be taken at 10 intervais or bund. These levels shall extend to 10' on tions shall be taken to show marked change
axis and cross sections of the bund shall be
00' to an inch.
00' to an inch horizontal and
10' to an inch vertical
10' to an inch natural.
ll be drawn on the same sheet. The plan
•et and the longitudinal section the lower

Page 70
68
10.
1.
DEVELOPMENT OF VIL
APPENDIX
The flat plan shall show in addition to features within the area surveyed, the c the cross sections.
The longitudinal section of the axis sh downstream toe.
Part II-Tank Bed Surveys :-
Using the bund axis as the base line, cros intervals,
Spot levels along these cross lines shall contours to be correctly drawn. Mark
clearly indicated by the spot levels along and levelled.
The spot levels along the cross lines sha above the average top level of the existi
All civic features such as roads, houses the area shall be surveyed and shown o; shall be surveyed, levelled and shown on
The plan shall be plotted to a scale of axis, the spot heights, the topographi contour lines at 1 vertical intervals shal
Part-Breach Site Surveys :
Using the bund axis as the base line cr from the L. B. end of the breach and e extend to 80' on either side of the basel
Spot levels shall be taken along the cros undulations.
All topographical features such as rocl shall be surveyed, levelled and shown of
The plans shall be drawn to a scale of 4 the chainage, the spot levels and the top
Each breach site shall have a separate p
Trial pits shall be excavated along the on either side of it to estimate the qual removed and to ascertain the suitability commenced. The pits shall be excav location shall preferably be staggered. to site conditions.
The location of the trial pits and the reg on the site plan.

GE RRIGATION WORKS
VII-(Contd.)
the bund axis, all the topographical and civic inage number of the trace and the location of
tl also show in dotted lines the upstream and
lines shall be taken into the tank bed at 4 chain
e taken at 100' intervals or closer to enable the d variations in the topography that will not be the cross lines shall be surveyed by offset lines
ll be continued till the ground level is about 4 1g bund.
private lands, cultivations, &c. coming within h the plans. Rock outcrops and main streams the plans.
4 chains to an inch and shall show the bund c and civic features. From the spot heights l be drawn.
ss lines shall be taken at 40' intervals starting
nding at the R. B. end. The cross lines shall
e
; lines at 20' intervals or closer to show marked
outcrops, streams &c. falling within the area the plans.
' to an inch and shall show the bund axis with graphical features. 谈
.
und axis and along two parallel axis 10’-20' ity of silt and other unsuitable materials to be of the base on which the breach filling can be ed to 2' below the probable base and their he number of pits shall be determined according
ced levels of the different strata shall be shown

Page 71
APPENDI(
APPENDIX VII
Part IV-Spill Site Surveys :
The spill axis shown on the plan shall be es extremities shall be marked by sawn wooder ground level. This axis shall be tied to the t
With this axis as the base line, the area sho lines at 40' intervals and, spot height at 20' lations, shall be taken.
All rock outcrops, cavities, streams, private and levels shall be surveyed in.
One permanent bench mark of the standar extremity of the spill axis.
The plan shall be drawn to a scale of 40' to an in, the bearing of spill axis to bund axis, the shall be shown on the plan.
Trial pits shall be taken along the spill axi either side of it to verify the suitability of th pits shall be 5' or less if suitable foundation met with earlier. The location of the pits a The number of pits shall be determined accor
A few trial pits along the tail channel shall of the tail channel bed.
The location of the pits and the reduced lev pits are excavated shall be shown on the site

ES 69
-(contd.)
tablished on the ground at site. The two pegs projecting 3" above the surrounding und axis.
wn on the plan shall be covered by cross intervals or closer to show marked undu
lands, &c. together with their boundaries
d construction shall be established at one
inch. All spot levels and features surveyed position and value of the bench mark, &c.
s and along two parallel axis 5'-10' on he foundation materials. The depth of the for the type of structure contemplated is long the axis shall preferably be staggered. ding to site conditions.
be taken to determine the type of material
ls of the different strata through which the plans.

Page 72
... D. Works Order
Plans of Village Tank Improvement Sc drawing paper in accordance with the fo concerned, the plans will be inked in a the Divisional system in vogue) and s tration number in the report and corres
2. The following data will always necessary in any particular case :-
(1) General Plan, 4 chains to one inch streams. Bed contours to be s existing spills to be shown.
(2) Bund : Longitudinal Section, 100
of top (full line) and toe (dotted from left bank. end of bund to breaches, ed., to be shown.
(3) Bund : Cross Sections, 10 feet to
(4) Spill Sites, 40 feet to one inch de
spill sites.
(5) Existing Spills, large scale detail of existing spills and of their app Masonry Details, 4 feet to one inc
(6) Catchment Area, one mile to one
(7) Diagrams : the following diagran
(a) Capacity Diagram, on logarit, (b) Spill Discharges, total discha (c) Monthly Rainfall, inches fall
3. All permanent features are to be bund profile should be washed in ligh blue.
4. The datum of all levels on the t lowest sluice. Care must be taken to

APPENDIXY VIII
AGE TANK PLANS
See para. 24)
hemes shall be prepared on D. E. or Imp. sheets o' blowing instructions. After approval by the D. I. E. nd coloured, and each sheet will be registered (unde. ubsequently be referred to exclusively by that regispondence.
be given, with such further information as may be
l, of bed, bund, spills, adjacent fields, roads, railways, shown, and areas computed. Getaway route from
feet to one inch, horizontal 10 feet to one inch, vertical, line) of bund. This section must always be plotted right. Position and data of spills, sluices, former
one inch, natural scale. stailed, contoured site-plans of present and potential
ed plans, elevations, longitudinal and cross sections roach and tail channels. h.
inch outline of catchment showing tanks included. ls should be plotted or pasted on the Plans :
hmic paper. rge as ordinates, flood lift as abscissae. per month on base of months ;
inked in black contours are to be inked in orange burnt sienna tank area should be clearly washed in
unk shall be 100'00, the assigned level of the sill of the specify precisely where and how this level was taken.

Page 73
APPENDI
WLLAGE ANCUT S
D. Works Order
Plans of Village Ela Improvement Schemes sha drawing paper in accordance with the following concerned, the plans will be inked in and colour the Divisional system in vogue) and subsequentl number in the report and correspondence.
2. тhe following data, inter alia as circumstalı
(1) Head Works, large scale, 40, 20', 10' to o sections, 10 feet to one inch natural, with r.
(2) Parent Stream, 200 feet and 10 feet to on
below selected site.
(3) Ela, (a) 100 feet (or 200 feet) and 10 feet to
(bed and bank) and extension trace.
(b) 10 feet to one inch natural cross sec
(4) Masonry Works, 4 feet to one inch detail.
masonry structures.
(5) Silt Control, large scale details of head reak
of silt and flood control measures.
(6) Diagrams, the following should be given w.
(a) Monthly rainfall. (b) Dischange over anicut for various heads, (c) Discharge through head sluice for variou 3. All permanent features should be inked in heatly as possible.
4. The datum of all levels should be the final ( should be assigned to this datum.

Y IX
CHEME PLANS
be prepared on D.E. or Imp. sheets of instructions. After approval by the D.I.E. ed, and each sheet will be registered (under referred to exclusively by that registration
ices require, will be given :-
ne inch plans of site or proposed site; cross corded High Flood Level (H.F.L.) marked. e inch longitudinal sections from above to
one inch longitudinal section of existing ela
tions of ela and trace.
s (plan elevation and sections) of existing
ch showing existing potawas, &c. for design
hen it is possible to include them.
is heads and openings.
and the plans coloured and completed as
rest level of the anicut and the value 10000

Page 74
CAPAC
(See
. D. Note
1. The bed of the tank up to proba contour surveyed; the levels are taken { point on the bund up the main arms oft
2. The contours are plotted at 1 foot and the total area embraced by each and
3. Either, or both of the following fo (a) if the number of areas is odd :-
AD Ao -- 4A E す -- 2An.
(b) if the number of areas is even :-
V= AD )Aم -- A -- A
2
AD is the vertical interval between
4. An example of the calculation, whic form, is given for GALKADALA TANK Plan WD/D 2-1.

ΡΡΕΝΙΟΙΧ Χ
Y CALCULATION
para. 28 et seq.)
ble F.S.L. at least, and preferably up to H.F.L., is ther on a grid or on lines radiating from a central he tank.
vertical intervals above datum (sill of lowest sluice) the bund is computed.
mulae are used to compute capacity :-
L十2A2十4A3十...
2 -- 4An-1. --An
十... -- An-1 十 An ا
2
COntOUTS.
h, for convenience, should always be done in tabular , F/23 (2:25x 1:87), the areas being obtained from

Page 75
APPEND
APPENDIX
Odd numbers of
Contour Area Acres
factor Product
97 15 1 15 98 4-95 4 198
99 8 1. 8
2 29.3
8
100 13-6 4 544
101 22-4 1 22-4
2 114 224
102 322 4. 1288
103 40 40
305-3
The calculated capacities are then plotted on and an exponential formula, or formulae, derive
N.B.-In view of the uniformity of the logari by making D = 2 feet, or even more for higher of computing areas and of the capacity calculatic

yb
CES 73
----(contd.)
Areas Even numbers
of Areas Capacity A D acre feet
factor Product 3
.75 s 2.47 1- 3-22
2-47 3:22
1. 8 9-8
盐 6-8 1. 20-49
6-8 20-49
224
38-0
16.1
65.79 65.79 16:1
101.8
and so on
the special logarithmic paper provided,
hmic plot, ample accuracy can be secured 'alues of D, and this will reduce the labour
...

Page 76
CATCHMENT
No. of Drainage Name Are Basin Sq. .
Kelani Ganga Bolgoda Ganga Kalu. Ganga 1. Bentota Ganga Madu Ganga and Randombe
Lake 6. Madampe Lake 7. Telwatte Ganga and Hik
kaduwa Ganga 8. Ratgama Lake 9. Gin Ganga 10. Koggala Lake 11. Polwatte Ganga 12. Nilwala Ganga 13. Sinimodera Oya 14. Kirama Oya 15. Rekawa Oya 2 16. Urubokka Oya 17. Kachigal Ara 18. Walawe Ganga 19. Karagan Oya 2 20. Malala Oya 21. Embilikala Oya 22. Kirindi Oya 23. Bambawe Ara 24. Mahasiliwa Oya 25. Butawa Oya 26. Menik Ganga 27. Katupilla Ara 28. Kurunda Ara 29. Nabadagas Ara 30. Karambe Ara 31. Kumbukkan Oya 32. Bagura Oya 33. Girikola Oya 34. Helawa Ara 35. Willa Oya 36. Heda Oya 37. Karanda Oya, Kirimeti Ara 38. Aymena Ara

PPENDIY XI
AREA OF RIVER BASNS
ide Plate No. 1)
No. of a in Drainage Name Area in Mile Basin Sq. Mile
885 39. Tandiadi Aru 8-6 146 40. Kangikadichi Ara 22 050 41. Rufus Kulam 13S 243 42. Pannel Oya 72 43. Ambalam Oya 45 23 44. Gall Oya 700 35 45. Andella Oya Nauakiri Aru 204
46. Tumpankeni Tank 15 20 47. Manakada Aru 45 4. 48. Mandipattu Aru 39 370 49. Pathanthodaphue Aru 39 25 50. Vett Aru 10 91 51. Magalavatavan Aru, Unichai 135 375 52. Mundeni Aru 500 15 53. Miyangoda. Ela 88 87 54. Maduru Oya 6O2. 9-5 55. Pulliyanrota Aru 203 136 56. Kirimechchi Odai 3
86 57. Bodigoda Aru 64 954, 58. Mandan Aru 5 25 59. Makarachch Aru 14.S. 156 60. Mahaweli Ganga 4034 23 61. Kantalai Basin and Per Aru 174 455 62. Pan Oya 56 31 63. Palampotta Aru 27 5 64. Pankulam Aru 147 15 65. Kunchikumban Aru 80 497 66. Pulakutti Aru 8 35 67. Yan Oya 594 51 68. Mee Oya 35 42 69. Ma Oya 400 42 70. Churiyan Aru 29 476 71. Chavar Aru 12 36 72. Paladi Aru 24 6 73. Nay Aru 73 20 74. Kodalikalu Aru 29 89 75. Per Aru 146 236 76. Pali Aru 33 165 77. Maruthapilly Aru 16 2O 78. Therauil Aru 3S

Page 77
81. 82. 83.
8S. 86. 87.
89.
91.
Piramenthal Aru Netheli Aru Kanakarayan Aru Kalakalappu Aru Akkarayan Aru Mandekal Aru Pallavarayankadu Aru Pali Aru Chappi Aru, Punadi Aru Parangi Aru
Nay Aru
Aruvi Aru
Kal Aru Modaragama Aru
APPEND
APPENDIX XI
32 93, 47 94. 350 95. 22 96 75 97 116 98 62. 99 176 100 26 101 325 102 219 103, 1268 82 364

CES
-(contd.)
, Kala Oya . Moongil Aru . Mi Oya , Madurankuli Aru . Kalagamune Oya . Rathambala Oya . Deduru Oya . Karambala Oya
Ramal Oya . Maha Oya
Attanagalla Oya
75
1064 17 675
59
1022 230
S90 284
22,9484

Page 78
CLASSIFIC
(
For Dicken's Formula, Q = CM°-75
Description of Catchmer
Flat, sandy plains Flat, sandy soils of paddy fields Gentle slopes and absorbent soil Undulating, hard clay soil . . Undulating, impervious, within h Mountainous and rocky
Note.-If 1 inch ofrainfall per hourr
of discharge will be 1 cusec. Similarly dischage of 640 cusecs. This will sugges

PPENDIX XII
ATION OF CATCHMENTS
See para 36)
ClSCC
t Suggested C
200 to 400
500
645
800 to 1,000 ills u o ... 1,000 to 1,200 1,400 to 2,000
uns off 1 acre of surface in the same period, the rate 1 inch of rainfall per hour from 1 square mile gives t the physical significance of the above co-efficients.

Page 79
APPEN
FLOOD
(See
Catchment ( in Sq. Mils. Discharge Q=CM
8.Cae 645 مینی=C
0 1 8 . 115 . . 155 O2 195 . . 255 O3 d 8 265 . . 350 04 w 330 . . 42S O-5 38S .. 510 O-6 435 . . 575 0.7 495 . . 655 08 0. S50 . . 725 09 8 595 . . 785
•O 645 850 101 690 95. s2 740 975 1.3 785 1,035 14 825 ... 1,095 15 875 ... 1,155 1 •6 920 . 1,215 1.7 965 ... 1,270
•8 1,005 1,325 19 1,050 . 1,380 20 1,085 1,430 22 1,165 1,540 24 1,250 . 1,640 26 1,325 1,740 28 1,400 . 1,845 3.0 1,470 1940 32 1,545 2,035 34 1,620 2,125 36 1,685 . . 2,220 38 1,755 2,310 40 1,825 2,405 4-2 1,892 2,490 44 1960 . 2,580 46 2,025 2,670 4-8 2,095 2,755 5-0 2,155 2,840 52 2,225 2,925 S4 2,290 . 3,010 5•6 2,350 . 3.090

DIX XIII
RUN OFF
bara 36)
Inglis )-75 Q = 7000M
(Dickens) in Cusecs - -- JM --4 50 C= 1,000 C=2,000
178 ; 356 . . 346 300 . . 600 . . . 684 405 . . 810 ... 1,014 503 .. 1,006 .. 1,336 594 .. 1,188 . . * 1,652 682 .. 1,364 .. 1959 ... 765 .. 1,560 . . . 2,260 O de 846 .. 1,692 .. 2,559 924 .. 1,848 . . . 2,850 1,000 . . 2,000 .. 3,132 1,073 . . 2,146 .. 3,410 1,147 . . 2,294 . . 3,685 1,217 . . 2,434 ... , 3,955 1,287 ... 2,574 .. 4,221 1,355 . . 2,710 .. 4,478 1,423 . . 2,846 .. 4,735 1,489 ... 2,978 .. 4,982 1,553 ... 3,106 .. 5,230 1,618 ... 3,236 .. 5,478 1,682 ... 3,364 .. 5,720 1,808 ... 3,612 .. 6,185 1928 ... 3,856 .. 6,640 2,047 .. 4,094 .. 7,080 2,165 .. 4,330 .. 7,515 2,279 .. 4,558 .. 7,935 2,392 .. 47,84. .. 8,352 2,503 .. 5,006 .. 8,750 2,613 .. 5,226 . . 9,138 2,721 .. 5,442 . . 9,532 2,828 .. 5,656 . . 9,900 2,934 .. 5,868 ... 10,270 ... 3,038 .. 6,076 ... 10,620 ... 3,142 .. 6,285 ... 10,990 3,243 .. 6,486 ... 11,330 3,344 .. 6,688 . . . 1 1,670 3,443 .. 6,886 . . 12,010 3,542 .. 7,084 ... 12,340 3,640 .. 7,280 ... 12,660
3,737 .. 7,474 ... 12,980

Page 80
78
DEVELOPMENT OF V.
APPEND,
LOXO
(Se
Catchment
Cs- 645 C=8
6-0 ... 2,475 ... 3,2 62 • • 23,3 • • (540و 64 ... 2,600 ... 3,4 6-6 ... 2,660 3,5 6-8 2,720 3,5 7-0 2,775 3,6 72 o 2,840 ... 3,7 7-4 O 2,900 ... 3,8 7-6 2,950 ... 38 7-8 ... 3,015 ... 39 8-0 ... 3,070 .. 40 82 3,125 .. 4, 84 o 3,180 4, 8-6 . 3,235 42 8-8 3,295 . . 4,3 90 ... 3,355 44 9:2 ... 3,405 44 9-4 O 3,465 .. 4 9-6 ... 3,515 . 4t 9-8 . 3,570 . 4. 10-0 . 3,625 . 4, 1025 . 3,695 . . 4, 10.5 3,760 .. 4 1075 3,830 .. 5,0 11-0 3,895 .. 5, 11:25 3,965 . 5, 15 4,020 5, 1175 4,095 .. 5, 12-0 4,160 5, 1225 4,220 5, 1250 4,290 5, 1275 4,355 5, 13-0 4,420 5, 13.25 4,480 .. 5 135 4,540 . 5, 13-75 4,605 ... 6, 14-0 4,670 . 6, 1425 4,730 . 6, 14.5 4,790 .. 6 14 ̆ገ5 4,855 . 6, 150 4,915 .. 6, 15ን5 4,980 . 6,

LLAGE, RRGAON WORKS
IX XIII--(contd.)
D RUN ORF
e para 36)
Inglis 0.75 Q = 7000M C (Dickens) in Cusecs attoo
Кемых
50 Cs1,000 C=2,000 IM-4
50 . . 3834 . . 7,668 . . 13:290 40 ... 3,929 .. 7,858 ... 13,610 25 .. 4,024 ... 8,048 ... 13,900 00 . . 4,117 . . 8,234 ... 14,210 80 .. 4210 .. 8420 ... 14,490 55 .. 4,303 .. 8,606 ... 14,780 40 .. 4,394 ... 8,788 ... 15,070 15 .. 4487 .. 8,973 ... 15,340 95 .. 4,578 ... 9,156 ... 15,630 70 .. 4,668 ... 9,336 ... 15,900 45 .. 4,756 ... 9,512 ... 16,190 20 .. 4,844 ... 9,688 ... 16450 95 . . 4934 ... 9,868 ... 16,710 75 .. 5,022 ... 10,044 ... 16.980 40 .. 5,110 ... 10,220 ... 17240 20 .. 5,196 ... 10,392 ... 17,480 190 .. 5,282 ... 10564 ... 17,750 560 .. 5,368 ... 10,736 ... 17,990 535 .. 5,454 ... 10908 ... 18,240 '05 .. 5,539 ... 11,078 ... 18,470 75 .. 5,623 ... 11,246 ... 17,730 365 .. 5,728 ... 11456 ... 19,010 55 .. 5,833 ... 11,666 ... 19,300 )40 .. 5,937 ... 11,874 ... 19,600 30 .. 6,040 ... 12,080 ... 19,880 215 .. 6,142 ... 12,284 ... 20,160 290 .. 6,244 ... 12,488 ... 20,440
585 .. 6,374 ... 12,694 ... 20,720 80 .. 6,448 ... 12,896 . . 21,000 560 . . 6,548 ... 13,096 . . 21,256
550 .. 6,648 . . 13,296 . . 21,525 730 . . 6,748 ... 13,496 . . 21,805
320 .. 6,847 ... 13,694 .. 22,057 00 .. 6,945 ... 13,890 ... 22,316 395 .. 7,042 ... 14,084 ... 22,582 )70 .. 7,140 ... 14,280 ... 22,834 150 .. 7,237 ... 14,474 .. 23,100 230 .. 7,334 ... 14,668 ... 23,345 515 .. 7430 ... 14,860 . . 23,604 395 .. 7,526 ... 15,052 .. 23,835 75 .. 7,622 ... 15,244 . . 24,087
560 .. 7,716 ... 15,432 ... 24,318

Page 81
APPE
APPENDIX
FLOOD
(See p.
Catchment C in Sq. Mls. Discharge Q=CM
C= 645 Cs 850
155 .. 5,040 .. 6,640 15.75 .. 5,100 .. 6,720 16-0 .. 5,160 .. 6,800 16:25 .. 5,220 .. 6,880 165 .. 5,285 .. 6,955 16.75 .. 5,345 .. 7,040 17-0 .. 5,400 .. 7,115 17-25 .. 5,460 .. 7,200 17.5 .. 5,520 .. 7,275 17.75 .. 5,575 .. 7,355 18-0 .. 5,635 .. 7,430 18-25 .. 5,700 .. 7,510 18-50 .. 5,755 .. 7,580 18-57 .. 5,815 .. 7,665 19-0 .. 5,870 .. 7,735 1925 .. 5,935 .. 7,815 19-50 .. 5,985 .. 7,885 1975 .. 6,050 .. 7965 20-0 .. 6,100 .. 8,040 20:50 .. 6,220 .. 8,195 21.0 .. 6,325 .. 8,340 2150 .. 6,435 .. 8,485 22-0 .. 6,550 .. 8,635 22:50 .. 6,660 .. 8,780 23-0 .. 6,770 .. 8,925 23.50 .. 6,875 ... 9,070 24-0 .. 6,990 ... 9,215 24-5 .. 7,095 ... 9,360 25-0 .. 7,210 . . 9,500 25-5 .. 7,310 ... 9,645 260 .. 7,425 . . 9,785 26.50 .. 7,520 ... 9,925 27-0 .. 7,635 ... 10,065 27.50 .. 7,735 ... 10,200 280 .. 7,850 ... 10,345 28-50 .. 7,950 ... 10,480 290 .. 8,065 ... 10,625 29-50 .. 8,170 ... 10,760 30-0 .. 8,270 ... 10,895 310 .. 8,475 ... 11,170 32-0 .. 8,675 ... 11435
330 . 8,880 ... 11,705

DCES
III-(contd.)
UN OFF
yra 36)
Inglis 75 Q = 7000M
(Dickens) in Cusecs
C= 1,000 C=2,000 IM-4
7,812 ... 15,624 .. 24,577 7,906 ... 15,812 . . 24,806 8,000 ... 16,000 .. 25,046 8,095 ... 16,190 .. 25,277 8,190 ... 16,380 .. 25,508 8,280 ... 16,560 ... 25,739 8,372 ... 16,744. .. 25,956 8,465 ... 16,930 . . 26,194 8,556 ... 17,112 .. 26,397 8,648 ... 17,296 . . 26,621 ... 8,740 ... 17,480 .. 26,866 ... 8,830 ... 17,660 .. 27,076 8,922 ... 17,844 .. 27,300 9,012 ... 18,024 ... 27,510 9,100 ... 18,200 .. 27,713 9,190 ... 18,380 ... 27,825 9,280 ... 18,560 . . 28,140 9,370 ... 18,740 . . 28,364 9,460 ... 18,920 . . 28,574 9,635 ... 19,270 . . 28,980 9,810 ... 19,620 .. 29,400 9,984 ... 19,968 .. 29,785 ... 10,160 . . 20,320 .. 30,198 , . 10,330 . . 20,660 ... 30,583 ... 10,510 ... 21,020 ... 30,996 10,680 .. 21,360 .. 31,367 10,840 .. 21,680 ... 31,766 ... 11,010 .. 22,020 ... 32,116 , 11,180 ... 22,360 ... 32,480 11,340 ... 22,680 ... 32,865 11,510 .. 23,020 ... 33,215 11,680 .. 23,360 ... 33,565 11,850 .. 23,700 ... 33,950 12,000 . . 24,000 ... 34,300 12,170 . . 24,340 ... 34,650 12,330 . . 24,660 .. 35,000 12,500 .. 25,000 .. 35,350 12,660 .. 25,320 .. 35,665 12,820 .. 25,640 ... 36,015 13,140 . . 26,280 ... 36,680 13,450 .. 26,900 . . 37,331
13,770 .. 27,540 ... 37,975

Page 82
80
DEVELOPMENT OF WI
APPENDI
FLOOD
(See
Catchment
in Sq. Mls. Discharge Q=CM
C= 645 C=85
34-0 9,080 1197 350 9,280 12,231 36-0 9,482 1249. 37-0 9,680 12,75 380 9,870 13,00 39-0 10,070 1327 400 10,270 13,52. 410 10,460 13,79. 42•0 10,650 14,02. 43-0 10,840 1428 440 11,025 14,54 45-0 11,220 14.79 46-0 11,400 15,02. 47-0 11,580 15,27 48-0 11,750 ... 15,49 490 11,950 ... 15,75 50-0 12,130 15,98 52-0 ... 12,510 1648 54-0 ... 12,850 1692 56-0 13,225 1743 58-0 13,550 17,85 60-0 13,920 18,35 62-0 4,260 18,79 64-0 14,580 1921 66-0 14,930 19,68 680 15,260 20, 10 700 15,610 20,58 72-0 15,930 2100 74-0 16,270 21,43 76-0 16,610 21,90 78-0 16,930 22,30 800 17,220 22,70 82-0 17,550 23,12 84-0 17,900 23,55 86-0 18,225 2401 88-0 18,550 24,45 90-0 18,840 24,82 92.0 19,160 25,25 940 19,490 25,68 96-0 19,800 26,1 98-0 20,100 26,48 100-0 20,450
26,9.

LLAGE IRRIGATION WORKS
XIII--(contd.)
RUN OFF
para 36)
Inglis 0.75 Q = 7000M
(Dickens) in Cusecs
O C= 1,000 C=2,000 /M-4
) 14,080 . . 28,160 ... 38,626 ) 14,390 .. 28,780 .. 39,214 5 14,700 . . 29,400 ... 39,844 ) 15,000 .. 30,000 . . 40,460 ) 15,300 .. 30,600 . . 41,055 ) 15,610 ... 3,220 .. 41,608 5 15,920 .. 31,840 .. 42,196 ) 16,220 .. 32,440 .. 42,770 ) 16,500 ... 33,000 . . 43,365 D 16,800 ... 33,600 . . 43,890 ) 17,100 .. 34,200 .. 44,450 17,390 ... 34,780 .. 45,010 O 17,670 .. 35,340 .. 45,535 O 17,960 .. 35,920 .. 46,088 O 18,220 ... 36,440 . . 46,602 O 18,500 . . 37,000 . . 47,110 O ... 18,800 .. 37,600 . . 47,635 O ... 19,390 ... 38,780 .. 48,650 0 ... 19,920 ... 39,840 . . 49,595 O ... 20,500 .. 41,000 .. 50,610 O 21,000 . . 42,000 .. 51,555 O 21,580 .. 43,160 .. 52,500 O 22,100 .. 44,200 .. 53,455 O 22,600 .. 45,200 .. 54,355 O 23,150 .. 46,300 .. 55,230 O 23,650 . . 47,300 .. 56,070 ) .. 24,200 .. 48,400 .. 56,945 0 . . 24,700 . . 49,400 .. 57,785 0 .. 25,220 .. 50,440 .. 58,660 O .. 25,750 .. 51,500 .. 59,500 O .. 26,250 .. 52,500 . . 60,326 O 26,700 .. 53,400 .. 61,110 O 27,200 .. 54,400 .. 61,915 O 27,750 .. 55,500 .. 62,685 0 . . 28,250 .. 56,500 .. 63,455 O ... 28,750 . . 57,500 .. 64,225 0 .. 29,200 .. 58,400 .. 64,995 ) .. 29,700 .. 59,400 .. 65,730 O ... 30,200 .. 60,400 .. 66,465 O .. 30,700 .. 61,400 .. 67,200 O .. 31,150 .. 62,300 .. 67,935 0 .. 31,700 .. 63,400 .. 68,635

Page 83
APPE
CATCH
(Se
Yield p
Monsoonal Strange's Rainfall in Catchm Inches Curv
30 210 31 226 32 243 33 260 34 279 35 - 298 36 37 37 - 336 38 358 39 - - 379 40 - 400 4. - 422 42 446 43 o 469 44 493 45 517 46 - 543 47 568 48 - 595 49 622
50 651

NDIX XIV
MENT YIELD
e para 34)
er Square Mile in Acre Feet
Bad ent Kalawewa Minneriya
Catchment Catchment
119 a 14S 130 s up 159 43 173 158 188 175 ... 204 90 8 220 209 239 230 as 259 250 s s 280 279 Q 9 301 302 o e 328 334 * 惨 352 366 - O 380 400 e e 408 440 436 474. 46S 524 O 483 575 0 525 625 O 562 680 590
745 8 620

Page 84
DEVELOPMENT OF WILL
82
q}ầuəT şooq Jad sȚIĻds Yue L go assueųɔsỊCI
AY XICINŢddy
#0.1 8Z-Z |8ŷ-I SS-i 9-0 £I-I 8J • I 9-0 osɔɔsno us†y8-0 †ሃብ) uəaț8 sỊ ɔ8reqɔsỊCI0€-0 Z-0
Ø A | Ở A | Ở A | Ø A | Ø A | Ô A | Ô A | Ô 4ɔɔŋH 1ņof ‘sfuq syawutəy000‘Z/I00ç‘I/I000‘I/I00Ç/IƐƐƐ/I0çZ/I00Z/Ioos/1 |×ooY -134O poəH
-‘O‘O apə1ɔ
JINGIIGIVXTMO TGINN WHO TI ÞJ.-TTIAS TÝMOLYN. (§ øges, puse Oso ered ɔɔS)

E RRIGATION WORKS
og øges, uo səAunɔ ɔų) uogų go peə, əlɛ sənţea osəq L
0I-9 98-9
89ኀ7 Z0ኀን
0ț7-9 98-Z 09-Z L0-Z Ş8-I Zįžo į
ZO. I
Zɛ-Z 0Z-Z ZI-Z S0-? £6'. I
08. I 99. I 09-I 寸 £ €. I 8! ·s
0. I
09-L 8L-9 Z6-9 09-9 ŞI •9 Stፖ•†”
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ŞI • I
89-Z 09-Z Zsy-Z Ş8-Z OZ-Z
Ş0-Z 68- I 01 - { [9• I ŹŞ• I 9€. Į
ŞI • !
OL-8 08-1. Ç8-9
S6-9 0Z-9
0}ን•†7 99-8 86・Z 99-Z 98-Z 28. I
! €. I
ZZ-9 €0.9) Ș6-Z 88-7 OL-Z
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0Z-0I 0Z-6 00-8 09•L Ş0-L 90-9
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09. I
II. I
ZZ-# Z0-ț7 08-9 OL-£ 09-9 88-9
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08. I 8寸...
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#6. I
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08寸 Z§-s
0ሯ•†7 06-£ 99.9 89-8 0Z-8 Ş8-Z
Sነ•ሯ ᎤᎵᏁᏃ
00-£I 09. I I 01-01 09-6 00-6 SL·L
09-9
7ቆን• 1I
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89-Z
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09.ol.
0Z-9 0ዚኀ7 0ሯነ IZ-9
8£-Z
cae - †
90-l Ş8.9 99.9 8Z-9
8ɛ-ɛ
••• •
06-9 I 09寺 08-ZI 00-ZI Oy. I I 00-01
OL-8 Zț7•L 0L-9 ŞI •9 0፤•ነ
寸0E
•• •
0€-LI 09-9 I 96-9. I 91.9 || 8£-ZŁ 18-0!
?ሪፖ•6
#L-9 ZI-9 ZS-9 8E寺
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0-1

Page 85
APPENDC
0S-ZZ 01-61 OZ.9† 09•$s 00° II Ş8-8
09-1
00•ነ 寸LE 09-8 ŞZoo. 00-£ ZL-Z 9い・ペ
0ሯ-ነC 00-sz 00-81 06寸 01-Zi 08-6
0ነ•8
0いき ÇZ-ș 00-ን OL-£ 0寸E 01 -8 16-Z
0s-80 0ó•ክነC 06:00 00-LI 01ኀ”፤ 0Z-I I
0ክ•§ 0・い 01-? ኗን•ኀ” ZI-? 8Leo
OZ-?, 00-9 00-0, Z9-9 09-9 I ZI-9 Os •9 I OL·ț7 0£. Il sỹ-y
0ɛ-Z, 099 0ç-8I ZI -9 06ኀ7፤ 09•S 08-ZI 8Z-9
06-61 00-Le- → •-,* 00,9; 07.9 100-L1 00’l, 06-ÇI 00.9 109-wi 09-9
ș6-8ț» 96-Zț7 £Z-L€. 6L-49 #9.92 18. IZ 90-6į
0-9 9-9 0-9 い* 0ኀነ Soo ペ・

83

Page 86
TAL (
The following mean velocities are st through the different materials specif
Class af Soil
Fine Sandi Coarse Sand
Loam Compact Clay Gravel, loose Gravel, compact Shingle Boulders, 6" to 8" Boulders 12" to 18
The scouring effect of water varies channel in coarse sand may begin to while a channel in the same material w

PPENDI Y XVI
LANNEL VELOCITES (See para 41)
gested as the maxima to be allowed in tail channels
Limiting Velocity feet per second
to 1-5
15 to 2 25 to 35
4.
4.
5 7 10
to S
to 10
to 7 to 12 to 20
with the hydraulic radius (R) of the stream. Thus a cour under a velocity of 175 ft, per sec. if R is 1 ft. ith R 5 ft. will stand velocities of 3 ft per sec.

Page 87
APPENVIDI
STABILITY OF CC
(See para
The following formula, evolved by Mr. Kennec of great value, enables the dimensions of a trapé pressure, to be calculated directly, without any of stability diagrams, or even to calculate the hy
Generalized
2. The wall is presumed to be of concrete, and face upstream.
The generalized formula, applicable in all cas
b - 中 (H+3n),
瓦了百
wherein,
T is the crest width in feet.
B the width of base in feet (not used in the H the height of wall in feet.
h the afflux, if any, above the crest, in feet, b the width, in feet, of a planked bay, if at l the width of pier or solid wall between b () the weight of one cubic foot of water, i.e p the weight of one cubic foot of the conc k the ratio of bottom width, B, to top wid N a derivative of k, namely: N = k + k,
The following additional symbols are used :- Wto represent the weight of a transverse se D the total depth of water upstream in feet
P the resultant hydrostatic pressure on a
in lbs. per foot run.
p the height of the line of action of Pabov
m the distance, in feet, along the base of the downstream boundary of the middle th
Bo the width of base of a wall of triangula
stability as the trapezoidal wall.
Nature of
3. In order to facilitate the following explanat
I
terms to the right of N by a symbol. For reaso.
b + co
- 1 - H (H -- 3h) = B........... p (H -- 3h) o
and this symbol will be used. It will be under remain constant in any particular case specified

YVII
NCRETE DAMS
83) ly many years ago, and has frequently found Zoidal concrete wall, subjected to hydrostatic necessity to use the trial-and-error method 'drostatic pressure.
Formula
must be trapezoidal in section with the vertical
es, is as under :—
LL LLL LLL LLSS S SLLS S LS S S LSS S LLSS SSL SSS S LSS C C 00 LC S LLLC LL C L0L S LSS LSL S S S S S SLS LS S LS LS 0 SSS C L0 LL LLL LS L LSSL LS S (1)
formula).
ly.
lays, in feet. 2, 62.5 lbs.
rete in lbs.
th T, i.e., B= kT.
- I.
:ction of the wall, one foot thick, in lbs.
one foot wide transverse section of the wall,
'e the base, feet.
wall between the line of action of W and the ird of the base.
r section that will support P with the same
Formula
ion it will be convenient if we replace all the
ls which will be explained later these terms:-
SC C S S S S S S SL S LS LS LS SLS S S SL S L LL S L S S S S S S S S S S S S L0L SL SLS S LS LS LS S S (2)
tood that B, represents all the factors which

Page 88
86 DEVELOPMENT OF V
APPEND
The generalized formula is now reduced
= -- R T = B;
O N =
and it will be apparent that it is indeterm possible, as both T and N are independ condition, namely that the section selected
Most Eco 4. For reasons which will be explained bel would be a triangle, (the limiting case of a mical, a rectangle (k = I). Practicaul cor triangular wall, but economy requires that t as closely as possible, or, in other words, admissible. The derivative N will increase N, and the bottom width B with k.
Use o 5. In any given case, then, the most conver product of the "fixed' terms represented by value of T, and to solve the equation for quadratic, or, preferably, from a graph of th
The formula gives dimensions of a wall th
of action of the resultant of the weight W a at the downstream boundary of the middl denominator of either of the constituent term balanced increase in B, or in both B and 'safer' wall, i.e., will push the intersection c further upstream "into the middle third. stability of the wall at all.
The reason for mentioning this fact is that i
of the net trapezoidal section to the design
provided there is no encroachment on the net in Talone.
Examp 6. The following example will explain the p
Required the most economical section of height 5' afflux 2", no back pressure; we
9 62.5 -- "-"-" B 130 5(5 -- 6)
R
4.
594 sq. ft
I
Ta
Ex
N
... 5

AGE RRGATION WORKS
XVII-(Contd.)
the form :-
te, i.e., that an infinite number of solutions is ly variable. We, therefore, impose a second all give the most economical wall possible.
mical Section
w, the most economical section of wall possible apezium with (T = o, k = oo )--theleast econoiderations preclude the adoption of a pure, e section adopted shall be approximate thereto, at the top width T shall be made as small as inversely as T; the ratio k will increase with
Formula
ient way of using the formula is to evaluate the B and then to select the smallest admissible ... k is derived from N, either by solving the : function.
at will be precisely stable, i.e., in which the line nd the pressure P will intersect the base exactly e third. Any increase that is effected in the s of B. after T has been calculated, or any unT, over the calculated minima, will result in a f the line of action of the resultant and the base An increase in T alone may not increase the
enables one to apply, in practice, the principles f a "stepped' section, e.g., of masonry wall rapezoidal section, and no unbalanced increase,
of Use ctical use of the formula :-
ll for an anicut with 5' wide bays at 9' centres : ht of concrete 130 lbs. per cub.ft.

Page 89
APPEN
APPENDIX X
The necessity to provide for 3" plank groov making T = 1-563.
'. N - - 382
s 1563
and by solution of the quadratic :
0 =یی= 2-39 -س- k2 -+- k r preferably from a graph, we find k = 58.
B = kT = 7·25 ft.
Cross-sectional area A = B + T
= 21:25 sq. ft. and economy index (see below) = 90°5%.
Econom 7. lf we give the cross-sectional area of the t the relative economy of trapezoidal walls w percentages of this maximum. In general tern
Economy Index =
Solving the above example for various value
Τ2 - f X 59-4
K N ર્સિ
1 1 7.7
15 2.75 4-65
2 5 3:44
3 11 2-32
4. 19 1.77
5 29 143
8 7 0.95
10 109 0.738
OO CXO O
* from first
Note.--It is hardly necessary to mention tha a practical example and has only been done in This table indicates the rapid fall in econom and points to the desirability in every case of ma

DCES 87
VII-(Contd.)
es requires a minimum top width, T, of 1-3*
y Index
riangular wall an "economy index' of 100%, 'ith varying values of k can be expressed as
S.
100 VN k -- I s of k gives the following:
Economy B A Index feet Sq. feet per cent.
7.7 38.5 50
6.975 29.06 66
6-88 25.80 75
6.96 23-20 83
7-08 22-125 87
7.15 21-45 90
7.32 20-58 93.5
7.38 20:29 95
7.71料 1925 00
principles
it this elaborate procedure is not necessary in this case for explanatory purposes.
which accompanies a reduction of the k ratio king Tas small as possible,

Page 90
88 DEVELOPMENT OF Vl
4PPENVIDI.
Th
8. To save the labour of calculating the foot, the following table may be used, or a
P 125 130
ل na 5 48
Values of N and - N
9. The value of k for any value of N οι,
(i) by solution of the quadratic Or (ii) from a table of the function Ο (iii) by a graph.
It will be found worth while to adopt metho tions to make. The use of logarithmic paper plot of N becomes asymptotic to the straigh N = 1-325 k", which is drawn by joining k = 2 the plot is a gentle curve to N = 1 at
Walls with
10. The ordinary anicut and "planked piers or lengths of solid wall between. In the flood occurs. In practice, it is necessary to planks all being in. In this event the hydros' added to the direct pressure on the interveni
-- 1
b Total unital pressure = ... P.
b If the wall is solid, b = o and? = , sc
term can be included, without further qualific
Note.- The presumption of planks left i wall. If downstream conditions are such t the pressure moment, Pp, and the generaliz solution is obtained by direct use of the cons

GE RRGATION WORKS
YVII-(Contd.)
Term
io () : p, i.e., 62: weight of concrete per cubic aph may be plotted.
140 14s 150 lbs scub.f.
6 445 43 417
is obtained :
equation N see k-k- 1.
d (iii) even if one has only a few stability calculais recommended as, for all values of k > 2, the It line represented by the exponential equation
N = 5 at k = 2, to N = 109 at k = 10. Below k = I.
Planked Bays
'ill' consists of a series of planked bays with y, the bays should be open when the maximum rovide stability in the not unlikely event of the tic pressure on the planked bays will have to be
masonry, or, in symbols :-
le
on, in the generalized equation (1).
may result in an excessively heavy section of there will be appreciable back pressure on The allowance will result in a modification of ormula will no longer apply. In this case a ent formulae (5), (6) and (7) in para II.

Page 91
APPEND
APPENDIX XV
Derivation of F.
11. The formula is derived from an interesti namely that :
Β T e B - T -- - - m = ( 十 B -- T
or, in the symbols adopted, that :
T T m = . (- , ko -- k -) = . N. --...,
k -- -- 1) = k -- I
Now, in the same symbols :
W= k (k + 1) TH#2..............................
The product, Wim, is the moment of Wabout
and combining equations (3) and (4) :-
彰
Wm = i NT* Hç ..................................
For equilibrium the moments of W and P abol
i.e., Wm. == PየSC LL CS 0 C C S C SL S SL C L CL L L LS S SL S SL S SSLS S LLL LL LL LLL S LS S S SLSL S LS SL L0L 0
The unital hydrostatic pressure P per foot run
P = u, H (H -+- 2h).
While e =
H H -- 3h. 3 H + 2h.
.". Pp = co Ho (H + 3h).......................,
Note.-Equation (7) covers all cases where the
If it were ever necessary to design a wall that wo
Ds tution of H for the term H (H + 3h) would ena
Combining equations (5), (6) and (7) (and . explained in para. 10) we derive the generalized s
1 b -+- 1 Ꮳo as ... --. -. H. (H -- 3h).......... T"=ミ 1 p (H -- 3h)
B
d
12. The stability of a pure, triangular wall, wh our variable trapezium, cannot be calculated by

CES 89
T td.)
ormula
ng geometrical property of a trapezium,
歌
8 + v is τα (3)
C C C L C L L S S L SLS S S S S S S S S S S S S SS S LL SS S S S S S SS S S SS S S S S S S S S S S S S S SSS SSS (4)
the downstream edge of the middle third,
Y C0L 0LS0L L LL 0 0L S0 S SLLLL S0S S L S L S S S S S SLLSL SLS S S SS S S S S S L S S S SLSS SS SSLL LS SS S S S S S S S SS S S S S S (S)
ut this point must be the same,
- ................................(6)
of a solid wall is, in generalized terms :
LL LL 0 LLLL 0L L L LLSL LLL 0SL0L 0L 0L J LS L LLLL L LL LLL LLL LL 0L LL S LSL 0LL LL L LLLS LSLL LS LSLS S LSLL LL 00S0LL LS SS (7)
lepth D is not less than H, the height of wall.
uld be 'just stable' with D C H the substi
ble formula (1) to be used.
inserting the term for planked bay types, Lability equation
a s» a 8 « A a «» « «x το α)
ich may be regarded as the limiting case of formula (1) as T is zero and k, and N, oC

Page 92
90 DEVELOPMENT OF V.
APPENVID,
From first principles, however, and fro a wall :
Wm = Pp.
i в. н е. - # o) H* (H + 3h) . !
6
whence
b -- B - i. 9. H (H -- 3h).
b 1 p
which is the value already assumed for B1 of the symbol in equation (2) will now be a
Furthe
13. The following development may be of suggested as likely to be more useful, in p in the way suggested. The logarithmic gra at K = 2 to the straight line represented by
N = 1-325 kl.915 (if k > 2).
We thus have:
2 2 -- B.
ar (if k > 2).
0-869B T = -o (if k > 2)........... . . . . . . . .
0•869 Bk . and B = kT = Goa (if k > 2)
B = 0۰869 B k۰048 (if k > 2).............
Applying formula (9) to the example give
B = 0-869 k-01859.4
Suppose k = 2, then
log B = log 0869 -- 043 log 2 -- log and B = 688 feet (clf tabulated result)
There is no reason why formula (8) or (9) sh k > 2, if it is desired to use a formula that one would not use both formulae (8) and (9) other can be derived much more simply fron
However, as already recommended formu simplified by the use of curves,

LAGE RREGATION WORKS
Y XVII-(contd.)
the equation of moments (6), we have, for such
十
-
LL SSL SL SL SLS S LL SL 0L S LSL S S S S S S C S S S SL L SL S 0L L S S S L SLL SLLL L S S S S S S S L S LSLLLLLLLL(2)
egarded as a mere symbol. The full significance ppreciated.
Development
mathematical interest, though its results are not ractice, than the use of the generalized formula ph of the function k + k - I becomes asymptotic
the exponential equation.
0L L S LSLLL 0S SSL SSL qq LLLL LSL S LS SS S SS SSL S S S0 LSL LS SL S SL qLS S 0 SLL SLSL S S S S S S SLL L SL S 0LSL S LSL0L LL (8)
SLLL SL S S S S C C SL S S L S SL S SL S S S LS SLS S S S S S S S SS S S S S LS CL LS S SL S LS LS S SL S S LLLL S S S S S SL (9)
n above we have
594
ould not be used instead of formula (1), provided can be solved entirely by logarithms. Naturally in any one case, as, having calculated T or B, the In the basic ratio B = kT.
lae, such as are used in this case, are infinitely

Page 93
APPENDICES
yい。ド制魔苟- -
„9-,9 = qos=ミ
„9-; = q
| .9-, i = 1 ojosa jo usapļAA
passassau əunssəjd someouueɔŋSUAAOCH
ajono uod qi oyi se uołoɔgɔɲɔuoɔ yo sų313AA
(ç8 ered��S) speəH yuələgłCI joj soldjo sumpsAA əseo
III.Ax XIGINAddV
Lo- » = 1 suoja jo qapso do L
• Keq ġo qapỊAA = %
·ąsowo ɔaoqe JəŋɛAA JOųądəCI = {
· Joya jo qqssa H = H
“I

9
e t
s vry vo ~ oso com
sz.8i
ŞL-91 SZ-9 i Stool ÇZ-Zł ŞL-01 9-6
ŞL-9] Şz-9 l SL·& 1 SZ-Z]
0一
0-8
co s „C)
0-9 l SL·ol ÇZ-Z1 ŞL-01 い6 0-8 SL-9 いい
ÇZ-$ ! §-s i ŞZ-01
Sl·l. SZ9 いべい いべ*
S-Li SL-9 l い等I Çool SL-i s 9-0! 0・3 SoL
ÇZ-9! ŞL-sys
ŞZoo i
0-7 s
9-01 SZ-6 Sl·l.
999
い等 SZ-£į SL· l l 9-01 0-6 Sl·l. い・9 S-Ś
9-Zs ŞZ-į į SL·6 SL·8
97-9 SZ-9 0•ክ”
ŞL-9{ い・いl SZ-sos SL-ZI Ş• ! ! Ꭴ•Ꮕ1 SL·8 SZTML
9-Sl ÇZ-ț7ł SL-Zł §-s I. ÇZ-0! 0-6 S“L ÇZ-9
Ꮕ•ᎭᎳ いz sz-11 ' Ꮕ•0Ꭰ SL-8 いト 92-9 SZ·S
SZ, Zs SL-0!

Page 94
DEVELOPMENT OF
92
92-60-891-9Ꮎ•ᏕSAL-8いトŞ•9Sloț7SZ-8SZ-L0-9$寺 Sol.Ç-9SZ-90-șSZ-192-90-9SL-80-10-9SAL-ț»S-€. £ZH0£ZH0£ZIo = ự „0-,S = q„9-,v = q„0-,ỳ = q 0- i = 1 ‘Jəld jo uspłAA„6+, Z = L “Jəld Jo qypįAA do L -II (oppuoo)–III.AX Yng Ngadsy

VILLAGE IRRIGATION WORKS
in vo rs oo a
SZ-81 い・9 SZ-ŞI 9-8. I 0•ሯI SŁ-0!
Ş-9 I 9%-9 s SL-£I SZ-Zs SŁ-0 i
S-6
0-9 I
S-€I
0-ZI SL-0! 92-6
SL-ZI Şo II
SZ-0s 0-6 S·l
0• LI SŁ•9 I 0•ክ”! SŁ•ZI 9- I ! ÇZ-0s
SL-9, I 0-†ን! Ꭴ-Ꮛ Ꭰ S-II SZ-01
0-ZH 0· I I SL-6
0-91 SZ-SH SALTMEI So? I SZ- I ! 0-0I
SZ-9 I SAL-8 i 9-ZI ÇZ-i i 0-0 || ŞL-8
9 -8 || SZ-ZI
0-IH SL-6
SZ-L
S-II 9-0I い-3 9:2-8 0-1 い・い

Page 95
APPENDI
APPENDIX XV
III. Continuous gravity section-Top width = 1.
-DEPTH O. E.
O 1.
3 20 25 4. 25 3-0 5 3-0 3.75 6 35 45
7 4.25 5-0 8 4-75 5.5 9 55 65 10 6-0 7.0

ES
II-(contd.)
6
ER CREST"
2 3
3-0 35 3.75 4.25 45 5-0 S25 5.75
5.75 65 65 7.25 7.25 7.75
7.75 85
93

Page 96
APPEN
ACTUAL FL
(See paras
As mentioned in the paras referred to above presentation usually adopted, in the process c and in deriving the high flood level expected
A word of caution must however be mer derived from the spill analysis graph, howev sactually be reached : this is because the rate value at commencement of spilling, attains its period; so that at any stage during the 12 h than the computed rate until the full value of pile up in the tank raising the water level abo in the value of the flood lift, the maximum of very often gets accommodated in the Free B reserve, it would be preferable practice, howe spill length by ten to twenty percent before fi

IX, XIX
OD LIFFT &c.
2 and 49)
the spill analysis diagram or graph is the redesigning the components of the Village Tank be reached for the spill length selected.
ioned. The value of the high flood level so br falls short of the high flood level that will if discharge over the spill, beginning with zero computed value only at the end of the 12 hour ur duration the actual rate of discharge is less lood lift is reached. The balance will therefore e the designed high flood level. Such inflation which may amount to as much as 25 per cent, oard provision. Without touching this useful er to increase, as a working rule, the designed hal adoption.

Page 97
APPEN
SUTABLE CHANNEL
(See par
D-Channel Sections of capacity 1-12 cusec
Discharge Bed F.S.D. Area
Q width d A.
b
1-0 ... •2S ... 0-65 ... 124 1.25 . . 125 ... 0-75 . . 150 150 ... 1-25 ... 08 ... 167 2-0 ... 150 ... 0-90 .. 216 2.5 ... 1-75 ... 0-95 ... 256 30 ... 2:00 ... 100 ... 3-00 3.5 ... 250 ... 100 ... 350 4-0 ... 2፡75 ... 1-03 ... 3"89 4-5 ... 2-75 ... 110 .. 423
S-O ... 3-00 ... 1-12 . . 4.62 5-5 ... 300 . . 19 . . 497 6-0 ... 3-00 . . 123 .. 520 65 ... 325 . . 125 .. 562
7-0 ... 325 ... 130 .. 5.91 7.5 ... 350 ... 1:30 . . 624 8-0 ... 350 ... 135 . . 655 8S 350 ... 140 6'86
90 ... 375 ... 140 . . 720 95 . . 4:00 . . 1-40 . . 7-56 100 . . 400 ... 144 .. 7.82 11-0 ... 425 ... 147 .. 841
12ሇ) .. 4*50 ... 1•49 .. 8-95

DIX XX
SECTIONS FOR USE
a 75)
s for Mannings n = 0225-Side Slopes 1/1.
Kennedy's
Bed Velocity Critical
Slope V Velocity
S Vo V/Vo
. .0005 . . 0-80 0-64 1.25 . .0005 ... 0-85 0-70 1.21 . .0005 ... 0-89 0-73 121 . .0005 . . 0.96 0-78 1:23 . .0005 ... 101 0-8 1:24 . .00045 ... 101 0.84 1-20 ... -0004. ... 101 0.84 120
•0004 ... 103 0-85 . . 121
•0004 ... 1-06 0-89 1s20
. .0004 ... 109 0-90 1-21 ... •0004 ... 112 0.93 •20 ... 0004 ... 115 0.96 1-20 0004 ... 116 0-97 120
... 0004 ... 119 100 ... 119 0004 ... 120 100 . . 120 ... 0004. . . 122 O2 1-20 . -0004 - . 1:24 104. . . 120
... 0004 ... 126 104. ... 1-21 ... 0004. . . 127 1-04 • • 1*22 ... 0004 ... 1-28 1-06 ... 1-21 0004: ... 1-31 1-07 1-24 0004: ... 134 1-08 • • 1-24

Page 98
DEVELOPMENT OF V
96
9-08, 9oz S-Z voz coz I. z o.z. 6.18. I 9-1 s-1 yi C-1 1.1 0.16-09-0
寸-0© I-Z 0-Z 6 I 8-I L-I 9. I ç. I No.1os Zos I-I 0-1 6-0 3-0 1-0.寸0
£•09. I S-I S-I V-1 ç-i z-1 z. I 1.10-1 6-0 6-0 8-0 1-0 9-0 9.0 çoƐ-0
Z-0I-I 0-1 0-1 6-0 6-0 8-0 3-0 1-01,0 9,0 9,0 90 s-0 * 0 +-0 g.gZ-0
I-0いる い0 い0 い0 *0 *0 yo to€:0 €0 £-0 £-0 zo zo zo zo.I-0 40°,S „6°, o „9-, o „ɛ-o „0“, o „6-,ɛ „9-,ɛ „ɛ-ɛ„0”,ɛ 26-Áz „9-,z „ɛ-,z „0-,z ,6-,I29-, I „£-, I
GTGI
tɔɔfɔuombs us uouoas fo pəay 24,3sonība pəlpinqtal-fəuupųɔ so ựipsa pag
so I SEIdOTS ĢICIIS—NOILVAVOxã TENNYHO NIXTHOAA HÄILYIVCI
„Soz oo , I-0 sisidə(I—,0-,ç ou „g-, I sųısa pag
IXX XIGINGIẢIV

LAGE IRRIGATION WORKS
0ኀን፤ Ꭼ•£Ꭰ £-ZI #-II 9-0!
9-os 9-ZI 8. II 0· I I Z-Os
ክሙ6 9-8 6-L Z-L #-9
0-£I Z-ZI #7. I I 9-0I
0-6 £-8 9•L 6-9 Z9
Ç-ZI L•II 6-0 { I-OI
[•9.
0-IH £.0s 9-6
Z-8
0•ነ S-€. I-8 9-Z Z-Z
£-£
9-Z I-Z L-I
0-£ 9-Z £-Z 6- I
8:Z †7•ሯ I-Z Łos
£-Z 6-1 L•I †ፖ•I
0. I 6-0 8-0 L-0

Page 99
APPE
6-8Z L·LZ 9.9Z Ş-SZ €-ÞZ
ɛ-ɛZ Z-ZZ Z. IZ Į-0, I-61
I-8I Z-LI Z-9I £-ŞI ነኀን፤
ț7-9 Z £ኀ”C £-8? £-ZZ Z. IZ
€-0Z £.6s f7.8's ț7·LÍ 9-91
9.ÇI 8寸T 6•£Ꭰ H-EI €-Zs
9ኀንሽሪ S-97 9-ZZ Ş· IZ †ነ-0ሯ
Ş-6I 9-8I L·Ls 8-9 I 6-9 I
0-9I ፭•†ን፤ ț7-8I 9-ZI 8-II
9-ÉZ 9-ZZ 9. IZ L-0% L-6s.
8-8I 8-LI 0-LI I.9I Z-ŞI
ክነ•ክI 9-os 8-ZI 0•ሯI £-II
8-ZZ 8. IZ 8-02 6-6 I 6-81
0-8I s ·LÍ £-91 寸いT 9-ț7I
8-9 I 0•£Ꮴ Z-ZI Ş-II L-01
0. IZ 1-0, I-OZ Z-6I Z-6Į 9-8I 9-8 i 9-LI #7-LI 9.9s
9-9 I 8-9 s L-ŞI 6-7 I 6•ክ”I ፭•ቱ7[ I-ț71 #7.gI £-$s 9-ZI
Ç-Zs 6-II 8. Į Į Z-I I 0-II Ş-01 †7-0፤ 8-6 ミ・3 Z3
S-LI L-91 6-ŞI [•9 s 8ኀን፤
Ç-8 s 8-ZI I-ZH ț7. Is L-01
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9-9 時・g €-9 Z-8 1-8.
0-9 62 8:Z L-Z 9-Z
い・Z 寸Z £-Z Z-Z I-Z
5-H 1103 (671)

97
DCES
0-09 S・8寸 s·to 9い等 Z.łysz
8-ሯነ #. Iso 00寸 L·88 £·lo
0.98 Lኀ76 9-88 (Z-Zɛ በ• Iዩ‛
8.8寸 £·Lț7 6•9Ꮠ7 寸寸寸 0-9#7
9.1寸 E-0寸 6-8€. 9-18 £-9€.
0-98 8-99 9-Zɛ €. Io I•በድ
S-Lț7 I.97
£- 61寸
Ç-07 Z-6€. 6-Lo 9-9€. £•ᏚᏕ;
0-ነ£ 8. Zo 9. Is 寸08 ፳Z•ßረ
£-9#7 8寸寸 Ꮥ•£Ꮴ I-Z#7 L-0,7
*3g I-88 8-9€. 9-S$ ፭•ነ£
0-£8 8.18 9. IS #7-6Z ç’.87
0•ኗw 9.{#7 £-Zț7 60寸 9-6€.
£-8€. 0-L9 L-SE 9-ț7€. z-£8
0-Z8 8-0£ 9-08 Ş-82 ły. / Z
88寸 W•ሯን I-Iț7 L-6€. ቀ”•8£
I-18 6-99 9.478 寸EE Z-Z9
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£-Iț7 6-68 L-88 寸LE I-99
6*g L-£ɛ Ç-Z£ £• [8 I-0£
0-6Z 6·LZ 8-9Z L-SZ 1.ły?
Lolo Solo Z-98 0-98
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0-8Z 6-9 Z 6-9% 8寸Z §.ęZ
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S-L€. €.9€. {-98 6-88 L-Z€
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ɛ-99 0-98 6-88 L-Z€ §-s £
寸08 £-6Z Z-8Z I • LZ 0-92
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*** 『
9-Z£ †7.18 €-0£ Z-6Z I-8Z
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£-18 I-08 I-6Z 0・86 6-9Z
6-SZ 6-f7Z 6-87 6-ZIZ 6-sz
0. IZ I-OZ Z-6s £-81
c. # s
Q.Ç

Page 100
EARTHWORK IN CH
T H'
1'-67 2.0'
0-1 0-2 0-2 0-2 04 0.5 03 06 0-8 O-4 0-9 1 - 1 05 1. 14 0•6 15 1-8 0.7 1-8 22 0-8 2-2. 2-6 0.9 2-6 3-0 1-0 3-0 3.5 11 35 40 12 40 4-6 13. 45 5.2 14 5-1 5-8 1-5 Si6 6-4 1-6 63 7.1 1.7 6.9 7-8 18 7.6 85 19 83 9-2 2-0 9-0 10-0 21 9-8 10-8 22 101 11.7 23 11e4 12-6 24 12.3 13-6 25 13-1 14-4 26 141 154 27 150 164 2-8 160 17.4
29 17.0 18-4 30 18-0 19.5 31 19.1 20-6 3.2 20-2 21-8

[PPENDIX XXII
ANNEL BUNDS-SIDE SLOPES 1 : 1
p Width of Bund
H' 2.6 37-0" 37-6" 4-0°
03 03 0-4 04 Ꭴ• 1 0-6 0.7 0-8 0-9 0-2 0.9 11 1-2 1.e4 0-3 1-3 •5 1.7 19 04 1-6 1-9 2-1 24 0-5 21 2-4 2.7 3-0 O-6 25 2.9 3-2 3-6 0-7 3-0 3-4 3-8 4-2 08 35 3-9 4-4 4-8 0-9 4-0 45 5-O 55 10 4-6 5-1 5.7 6-2 o1 5.2 5-8 64 70 12 5-8 65 7.1 7.8 13 65 7.2 7.9 86 14 7.1 7.9 86 94 15 7-9 8-7 9-5 103 16 8-6 9-5 103 1-2 1.7 9-4 10-3 11-2 12- 1-8 10-2 112 121 13-0 19 11-0 12-0 13-0 14-0 2-0 119 29 14-0 15-0 212-8 13.9 150 16-1 2-2 13.7 14.9 160 17.2 23 14-7 15.9 17.1 18-3 2-4 15-6 16.9 181 19-4, 25 16.7 18O 19.3 20•6 2・6 17.7 19.1 20-4 218 27 18-8 20-2 216 230 2-8 19.9 21-3 22.8 242 29 21-0 225 24.0 25-5 3-0 22.2 23.7 25.3 26-3 31 234 250 26-6 28-2 32

Page 101
APPENDICE
APPENDIX XXIII
3e3
3-4
35
3-6
3.7
3-8
3.9
4-0
4
4-2
4-3
44
4-5
46
4-7
4-8
4-9
5-0
213
22-5
236
24-9
261
27.4
28.7
300
31-4
32.8
34-2
35.7
37.1
38.7
40-2
418
43-8
45-0
23-0
24-2
25-4
26.7
280
29.3
30-6
32-0
33-4
34.9
36-4
37.9
39-4
4-0
42-9
442
45-8
47.5
24-6
25.9
27.
285
29.8
31.2
326
34-0
35.5
37-0
38.5
401
41-6
43.3
44-9
466
48-3
50-0

99
-(contd.)
26-3 27.9 29.6 3.3
27-6 29.3 31-0 3-4
289 30-6 32-4 3.5
303 32-1 33.9 3-6
31.7 33.5 35-4 3.7
33.1 35-0 36.9 3-8
34-5 36-5 38-4 39
360 38-0 400 4-O
37.5 39-6 41-6 4-1
39.1 412 43.3 4-2
40-7 42.8 45-0 43
42-3 445 46.7 4-4
43.9 461 48-4 4-5
45-6 47.9 50-2 4-6
473 49-6 52-0 4-7
49-0 514 53.8 4.8
50-7 53-2 55.6 4-9
52.5 55-0 57.5 5-0

Page 102
4ه
Disch
DIS
Size of Pipe 4.
Length of Pipe 6′′ 12′′ 18′
0.1 0-209 0፡207 0-204 0-2 0.296 0.292 0288 0፡3 0-362 0፡358 0-354 04 0-419 0.414 0.407 0.5 0-468 0462 0.45S
0-6 0 513 0.506 0.499 0.7 0.550 0-546 0-540 0-8 0-594 Ꭴ-585 0-576 09 0-630 0-620 0-60 10 0.662 0654 0645
1. 12 13 14 1S
16 1.7 18 19

PENDIX XXIII
e Through Hune Pipes
HARGE IN CUISECS
6
24
307 367
6
127
187
24'
30’
367.
)-201
O-284 0.348 ኴ-401 Ս-450
0.492 O-532 0•568 0-602 06.35
0-198 0.97
0-280 0-277 0.343 0339 0.398 0-391 0.442 0436
0486 0-479 0.524 0517 0.560 0-553 0594 0-585 0-626 0619
0.43
0-60 0-74 0-86 0.92
110 128
16S 1.83
0-55 0.68 0.78 0-88
0-96
10
117 123
05 0-62 0.72 08
088
102
108 14
0.58 0.67 0.76
0-82 0-89 0-95
0. 106
0-55
07
0.78 0.84 0-90 09S 00
O-52 06 0.68
0-74 0-80 0-86 0.91 0.96

Page 103
APPEN
APPENDIX X
Discharge Throu
DISCHARGE
9"
6' 12" 87 24' 30’ 36 42 487
1-0 00
43 1.35 129 122 1.17 1.12 109 -0. 176 16S 58 1-50. 42 1.38 132 1.28 2.02 192 182 1.72 -66 1:59 52 148 226 2.15 2.03 -92 1-85 78 1.71 16
2・48 2・35 2・22 2・11 2・02 1・94 1・88 1・8C 2-68 2-50 2.40 2.29 2.20 2-10 2.02 .9 2.86 27 2.56 2.44 2.33 2-24 2.18 21C 303 2.98 2.72 2-60 2.48 239 2-30 2-22 3-19 3-08 2-89 2.73 2-60 250 2-42. 2.35
30 288 2.73 262 2.53 2-46 300 2-88 2.76 2.62 2-57 300 2-88 2.76 2.68 2.98 2-88 2.78 308 298 2-88
306 2.97

DICES 101
XIII--(contd.)
gh Hunne Pipeg
IN CUSECS
2^
6 12 18 24' 307 36' 427
1-84
; 2.60 2.48 2.38 2-30 2.25 2.15 210 : 321 3・03 2・92 2・80 2.73 2・60 2・58 368 350 338 325 3.5 2.98 2.9S 4-1 391 3-7s 3-62 350 335 330
450 430 410 3.98 3-85. 3-6S 360 4-86 4-63 4-45 4-30 4-15 3.95 3.90 | 5•20 4•96 4•70 4፡60 4-45 4•20 4•18 5.50 5.25 5-05 4.88 4.70 4-50 445 5-81 S-52 532 S15 S.00 472 468
, 610 S-80 556 5.38 S-20 49S 4.90 6-3S 6-02 5-82 5-60 5-45 518 S.O. 6.61 6-25 6-05 5-85 5.65 5.38 5.30 687 6-50 628 6-0S 585 555 5-50 7.10 6-78 6.50 625 6.10 5.75 5-70
7.36 7.00 6.70 645 6:30 5.95 5.90 7-58 7.20 690 6-65 6-45 610 6-0S 7•80 7-40 7•10 6-85 6-65 6፡30 6-25 8-02 7.60 7.30 7.10 6-80 6-50 6-40 822 7-80 7.50 7-20 7.00 6-70 6-60

Page 104
DEVELOPMENT OF VI)
102
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,8ỷ „Oț¢„Zɛ„țz,91,8/8寸„Off „ZE,$ጎሪ,9||,8,8;„Ży,9€.„0£,#2,8||„ZI,9adias fo quầuəT
„ț%„8sきい„ us oppg
soəsno un 23.apųɔspa.
ɔdţa so azys
(podoo)-IIIxx xia Nagay

LAGE IRRIGATION WORKS
08-62 06.8% 00,8% SZ-sz 09.9%
SŁ·SZ 09•$ሯ 00-†ሯ 00•£Kሪ 09. Zo
00. IZ 06-61 08.81 0Ş·ls
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08. iz oz. iz 09-61 0Ż-8I
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Osz-ZZ 09. IZ 00-07 09-81
0£. Zo 99. Iso
00.19 .
00-09 006ペ 00-8Z 00-LZ 00,97 00,92 00•ነ፭
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06-0! §§-01 09-0! 00-01 OL-6 0ቀ•6 01 -6 08-8 Off-8 S0-8
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09.8 0Z-8
06- L 09·l, 00:s. 09-9
Off-sis 0I-II 08-01 09-0! 01-01 06.6 09-6 0,-6 06-8 09.8
01-8 OL·L 0Z-L 08-9
08- 1 ! 09-3 i 01 - † 1 08-0! 09-0! 01-04 08-6 0;~6 01-6 OL-8
0€.8 €)6·l. 09- L 00-l.
0; -zs 08. i s 0$. s I 0Z-I I 03.01 0寸0 0ł ogł 08-6
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09-8 04-8 0l-L 0&-L
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S?-6
$8.8 $$-8 03い ᏕfᎩ•Ꮣ
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§ 1-6 0,1-8 0Z-8 $9's.
O-Z 6. No 8. s Lo s 9 i め・ 建筑 €. No z. ! } · { (); } (, į;
&{}
39 N (WH

Page 105
APPENDIX XXIV
(See para 59)
SZES OF PEPES FOR VLLAGE SC
Irrigable Area
Up to 75 Acres
76-150
151-225
226-300 301-450
pipes are designed to give the required discharge a

HEME SLUCES
Minimum dia.
of Pipe inches
9
12
15 18
24
t a minimum water level of 2 ft. in

Page 106
محمد
RESERVATIONS F
I. Reservations in Terms of G. O. 732
Minor streams, i.e., streams between 1 Streams below 10' in breadth may
minor streams' where such action judicious Medium streams, i.e., between 15'-50 Major streams, i.e., over 50'
Tank Bund
II. Proposed Amendment
Streams
Drainage channel Field channel or cart track Field channel and cart track Distributary channel and cart trak or Main channel and road Main road through highland allotmen Subsidiary roads through highland all

PPENDIX. XXV
DR STREAMS, CHANNELS, &c.
(See para 67)
0'-15' in breadth
be classed as is considered
road
tS
OtmentS
1 chain (66) on either side 2 chains on either side 3 chains on either side
15 h from the centre line where his
the height of the bund
1 times bed width on either side 11' or 22'
22'
33'
66
99' or 132'
66 -
33'

Page 107
APPENDIX
(See para |
CHEME FOR THE IMPROVEMENT O
The Irrigation Ordinance
SCHEME
1. Name and description of work 2. Extent and nature of lands irr
Private lands : Crown lands :
3. Terms agreed upon(1) The construction of the follow
up to the estimated cost of by the Government.
(2) In consideration of the aforesai ative ment, the proprietors on their part u earthwork in accordance with the spe tion Engineer and to the satisfaction Government Agent, and for this purp
(a) to clear
cubes of earthwork, in respect aforesaid irrigation work; (b) to contribute the necessary lat in commutation of such labo June, 30, of the year in which s for each acre of jungl of earthwork, for the clearing or (c) to clear all the specified jungle and to complete all earthwork
Bond (2) In consideration of the aforesai
bernative ment, the proprietors on their part u earthworks in accordance with the Irrigation Engineer and to the satisfact Government Agent, and for this pl. accept for such labour payment at t acre of jungle and of earthwork, so cleared or completed.
rd (2) In consideration of the aforesai ernative ment, the proprietors on their partu
of work free of all charges, namely, and the following items of work for w
a day, namely, all such work being in accordance with
Irrigation Engineer and to the satisfact Government Agent.

XXVI
5)
F MNOR RRIGATION WORKS
, No. 32 of 1946
igable under the Scheme :-
Acres approximately Acres approximately
ing items of the necessary work, namely,
is undertaken
ld undertaking on the part of the Governindertake to clear jungle and to complete :cifications issued by the Divisional Irrigaof the Government Agent or Assistant ose each of the proprietors agrees
cres of jungle and to complete : of each acre owned by him under the
»our in person, free of all charges ; or ur, to contribute money, on or before uch labour is due at the rate of
e and of for each cube the completion of which he is liable; and within months
within months.
i undertaking on the part of the Governindertake to clear jungle and to complete specifications issued by the Divisional ion of the Government Agent or Assistant rpoe each of the proprietors agrees to he rate of for each
for each cube of
undertaking on the part of the Governldertake to complete the following items
ages at the rate of
the specifications issued by the Divisional on of the Government Agent or Assistant

Page 108
106 DEVELOPMENT
APP,
(3) The proprietors or a sum of settlement of the cost, items of work aforesai per annum for a peri completion of the irrig гераіd.
(4) The proprietors work, all labour requir
(5) The proprietors of any of them in contri the Government Agent to be performed by any prescribed in Part VII,
THE RRIGATION ORDINANC
It is hereby notified that I, . . . . . .
Assistant Government AgentlGover
District in the . . . . . . . . . . . . . . . . . . . by virtue of powers vested in me by S 1946, approved the resolution set out
The Kachcheri,
LS L LC S0LSS S S S SSLSS S 0LS S 0LS SSLL 0 S SLS S S0SL SSSL S S0 S SSS S S SY SSSSSSS S L0 SS 195
“This meeting of proprietors withi.
*
S LS LS SS0 SSS SS S0 SS S0 S 0S SLS SLSLS S SSS S L SSL S L S S S S L0 SSL S0L SS in the . . . . . . .
S S SqS SS SS SSLSSS SS SS SSLS SS S SS S SL S SL SS SS0L S SSSLSSS SS SSL S LS S S S S LSL S SLSL SLLLL S S SS SSL SSL SSL SS qSS S SS SS SSL SSL SSS 00 SS S00LLS S
Irrigation work prepared under Part W

F VILLAGE IRRIGATION WORKS
NDIX. XXVI. —(contd.)
rther agree to repay to the Government the actual cost,
in full ncurred by the Government in the construction of the by a construction rate of per acre d of years from the date of
tion work or until the said cost or sum has been fully
1rther agree to contribute, after the completion of the d for its maintenance and repair, free of all charges.
Irther agree that in the event of any default on the part puting any uncommutable labour due under this scheme, or Assistant Government Agent may cause such labour other person and recover the cost thereof in the manner if the Ordinance.
, No. 32 OF 1946
lment Agent, of the . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
S SSLSCSS00LSS0L S LL S SSSSLS S0L S 0L SS SS 00 S 0LSS SS0LSSS S0 S SS SS SS SSL S S 0 SL SL SL S SS S SS0SS S LSLS C S L SL S LSL S LS0 S SC SS0LSSS 0L Province, have ection 15(1)(a) of the Irrigation Ordinance, No. 32 of in the Schedule hereto.
Assistant Government Agent|Government Agent.
SCHEDULE
Resolution
the irrigable area of the . . . . . . . . . . . . . . . . . . . . . . . . . .
S LLL S 0S S LSL S S L S LS S S L S L LS S LSL S LSL S S LSL S L LS S L S LSL LSL S LSL LS LSL S S LSL S S S S District,
. . . . Province, approve the scheme relating to that of the Irrigation Ordinance, No. 32 of 1946.'

Page 109
Plate 1
Plate 2
Pate 3
Plate 4
Plate 5
Plate 6
Plate 7 ..
Plate 8
P
Rain Gauge Stations and Catc Type Spill Structures Discharge of Tank Spills Blocking out Plan of Lands ur Channel Structure and S. W. l Type Designs of Village Tank Type Layout of Anicut Headw Spill Analysis Diagram

ATES
hment Basins of Ceylon
der an Irrigation work 3. Flap Gate Sluices
orks for Diversion of Streams

Page 110


Page 111


Page 112


Page 113


Page 114


Page 115
  

Page 116
CLEAR OVERFALL
GRAVITY TRAPEZOIDAL SECTION
- جهة مثل ـ ـ ـ حلاو-106
4 2 O 4.
د : " Clits too
S0SeYSuSuiL SYAA AL0AYSYLYSASA A A A AAASAAAASSSAS S S SA S AS ---- ------ --قیق -----۔ V/ トーーーーで、zーーーーーーー
ELενATION"
CHANNEL SPILL WITH MA FOR SCOUR PR (
..T.L. 109.0
石千寺 4ك 4-et
-a. 1ல் CAST tos-2. ' -
gest-essesses E. ・ーーーーー: ۔۔۔۔۔۔۔۔۔۔۔۔۔۔۔۔ ۔tگن-ف--ن! AA Lq AALAA AAAASLSAS HeLLJJSHSH A Aq A AAS AAAS
F
ELEVATION
 
 
 

- |
SONRY STRUCTURE
)TEOTION

Page 117
CLEAR OVERFALL O. -3 · · كسكسكسيجيص
tiG PLAlN CONCRT 霞 gung
CLEAR OVERFALL
Segon مهوه 4 Le تدفع
PRO POSED A.V. e. 84•68
 
 

SEE CREST SPILL PLATE2
are
... o.o
h.l.038
F.S. 100 go
དེ། བ་ཁང་གི་ ד -ע
-- WL 49 2 co gf
vJVV VEV vervJ TV LVTY tv -
Sgd. S. Arumugam
WLLAGE RRIGATION WORKS
TYPE SPL STRUCTURES
Printed by Survey Dept., Ceyr, 'une 1967
=

Page 118
DISCHARGE OF
『電
CLEAR OWERFLL TYPE
트
i
I
트
Mill "E" I r I lull Type Spills o Cr
'os =昭 ନ୍ଯ
* . Flood Lift H or D چي خي چي خيل چې خو مخي چي
ܕ: ܕܕ̄ ܕ ܨܬܝܼܖ ܕ̄ ܕ̄ ܕ̄ .̄*
TAIL CHI PHEL BLE
Dr El ir-r Girl Errici, rimi
 
 
 
 

Pltē
目 TANKSPLS.
CHANNELI TYPE ||||||||||||||||
LLI
fing the Dischorggs ate. Of Chann gli "es length of 00' was assumed
트 E T S s II a.
FEET ABOVE CREST
First tary - I - Irri Lyari
*H r - -
i Cue

Page 119
f7 HCI MoRA TIMạ&R PuNG. 7
i
fick fogo
iš THICKSTOF PLANKS ! I Fg >سلس
TYPE NOTO
ఈర
t
KCHANM
ཕཁམས་བརྫངས་པ་ SðlaðdNTL - 32
S.
se
d
F. s. L. IN 'CHANI
S
びエリエ S ಜಜ್ಬ 1 - ο
لـ
s Aa PsYesawa é rulew
ls on
t
YW
-CANN
. ” ہم و بحی۔ -$ ق م
PL A N
PT. 2 o at:
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

邀 de aspans Atë - SERSF -
-1-
RVER SOE 〉།། نئے۔
S was or as iiiii Toep met चैन्म SECC. As - SSSSSS ۔۔۔۔
т —
ق
Ay
is -o-
CH FALLS 口一“一
LSS LLSS SLLSS S SSS S SLSS SLSS S LSLS SSS SS S - - - - - - - - അൽ
-- i. d 1 - - - - ف - عــ - - - - - --- ہے -- -۔ -- -۔ ۔ ۔ ۔--ا
UPSTREAM ESE AO
ᏱᏨ*

Page 120
TYPE 469 a 12" DIA CONT
are allow
FOR CHAN
RoA
+ - - مقاله - ۳
eers
--66p-44A/g7 a
PLAN
s 暴荒
TYPE CASC
 
 

OLLED PPE-OUTLETS ELS
下蓋ー
寛 择一 获碎法 平 AAPA
سمتیہ-iمنہم۔
-مةؤح5م.
assa
: '' és
. . . ゴミ。 D-6-0-p
—
5.
ADE FALLS
9 --
حمراقبة وإمسة 4 سم
TN
م- سه -ا
al
鲨 -
牡二齿-j حمو4حس
s
SECTION A-8
Agoya

Page 121
тоwғ8 杀 * دب
ピー %-c bUND OP Éi. 29 , 5 6
cالہ ہم۔
イ
صبہ || | :
3 FT. p.A. iri ez. C.C. H. UMe PJ PES.
PP2 CQ93Re WyAL
مـسـ، ــ ..- بــ - - - - ــ .3 . . -م -...، سم، سسسسسسسسجيمسلم
o lo: TIM DE R Foor ek i DSE ‘l
2. Po 3radne : kJ:
-sTEL coNRo. GATE 2 DA. R.c.c. HuME
ہے جچحت ہیلملل
-ਗa
O N G T UDNA
۔۔۔۔
==#=جلا! کسrgدstop G
t see t support T Fs Top coverigo, shows sir". " t ?-്
双エ SLLEDHSiiSSi i SSSSSS MSrursus
 
 
 
 
 
 
 
 
 
 
 
 
 
 
 

TYPE DESIGNS OF VILLAGE TANK S
4. 4 8 2.
S C A LE op FgET.
9" bA, R.C.C. - UMA PPS
SEC T ON
تت-ک"--موسسسسسسس-------------------
ത്ത-ml-l.- ki-m
9. A. R. C. C. 4 uwma Pn Pales
---، س--س--سسسسسسسسسسسسسسسسسسسسسسسسM ゞ一ー PU Djo. S CORE wAtt.
. --.-س--سس----سسسسسسسسسسسسسسسسسس-----سسM
ത്ത- HUME PPE TOWER SLUCE
132 G"
CONC- पिट्र |Y s R 业
طلسي.
;
C
| 1e" :
k
کے --- تـ لم۔ ------- ہے ’ممبر ہے --- JiàF --۔ لی۔ SEC T ON ! بمب 2 مم -ri- RusBLE PAYNG N cat/-5
اعدہ 三 ہے Myrnum- Hشمل ہے -- : 考
- にメ。「冒空富 عاء ; 限 የ མཁས་པས་ཁམས་ 80 تھا !کہہ کہ حیہ° -구
--- 4: . له سر المتكساس سى *
P- o: . 오 : |- H 1 ܐܘ
TN r- l, w حسسسس مح
E-'S S -حسعصمسميN velkýRT 2 그 노출분른 * Illililllls
ତ! 5 Russ. PAVN* -سسسته سمتحسیستمحو
- N 双妖AA密限官。 یہ ۶ إبيس- 5 سهحساس سرمه "ژ۵ - ... م. . . بیبیسیس-"I00 - س-سسسس
ToweR SLice

Page 122
UCES
barop
áол. м3, ығыз ペFögrö露隊2露
ed&jKiMigğ ÄRR "V E. 150
ë. • O AWAK. WATER Eve 2 -سیسیجیتی-سیاست .
了AN K Si:OOW' *OR REMOVAela aggl
Soloé 妒麓R雷、 爱岛瑟登
-
. . . - - . : a , JULIKSOM KOS .لا. وو اعلن Jಲ ಫಿಸಿ بح۔ صدیو مسیح --- ” o:7 --سم LONGITUDNAL SECTION
g -e-
BH
PLUG SUiCE
is-o" -
FÖçof egić
so
翌选。4谢·莎 MA్కడా -است چتیسی است.
A R K. ows to grea. . ふ Sæll. C. íNs =Frr F. s *
Roa ESPAS)
f ఆP
PA
SLUCE WITH
 
 
 
 
 
 
 
 
 
 
 
 
 
 

PAE 6,
ÀAA3, Wolfo &ool, ള്ളത്ത
፩” |- Ocorro
M 萨及 kడి * Pia y saik
ozoa, Ps
LONG: SECTION
VERTICAL P1PE St-JiCE
ਅ-ਭੀ *E দুঃ evSSLE FAvada
S. K «Ak. -
皇、
SECTION
Sgd S. Arumugon
FNG GATE
Printed by Survey Dept., Ceylon June 887.

Page 123
T旨
YMAL
甲A55窦纪烃。L容
N SLUCE W ANC CSS SO
NLST S. Sl- co.o
SCARAFY Kock) Fics
SE C T ON - XX
i
X SE O 25 NL: SCS FORPo ○ K e
/ sil ato * Oہے a also イ
f . V V g*/ c一イ
s শ্ৰৱকেত -ూ اسسسسسسسة حجه ܒܹܠܔ SN س؟ 燕 i  ̄ܐ<ܐ>> N--س میں مکرر
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سمس * جبر
- "శ్రి a Te PS ーニニ 業#リエ旋7/ー
r FA G G
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人 人 • է:NIKe ፩ * 人人 ! . . ; ty ஃ ~1 YA / لم لم نه به ده ° ۔ ?ه as porce s R A. /
 
 
 
 
 
 
 
 
 
 
 
 
 
 

R.B. SLuţCa 3Are TYPE LAYOUT OF AN DIVERSION OF
r292 and
لس۔۔۔۔۔ NET SLUCI: SLL. EL CO.ó
2uE3BLE N CAT. 已/ ONC: Toe WAL.
酥 哥多哥芬
Alé’LoNe M.-S. do WELS AT 2'crs... + (St Alessa Rosd)
2
2
A محر
U.. où H BA0 Sluice sill do-d
W
tak conc LNN6
\\
hiëA9'WAll Wellu A8CVE MSGH FLOOD LEYL Ao WALL ܓ--ܔܠ
contko-GATP2. Above ..f.
下ートミ。 -h۹۰F ماY NIC- SL-or - - - ELIO-52 SLUCE SL iO /イマト KWA 99.O τν りルノ TOIA ONG AMS’S
ノ_夕 dapWEl Sar 2” ,SLT REACH  ̄ܐ -ܒ ܢ
3Ed 98k KscAR FY Kock
ァー* 刊AC伴
イ ހިހި/ సcurcRITE ހަހަލޮހޮހީ
حس ن
63'TK Planks YMT I FPNG co
e哆
SeRSTAFF YF-SIF voor
4 S 7 :
м.s powвlsдs tмAЖ“
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R o u N D (AèÖWE H. F. L. ) SECTION-BB
l 1O3•25 1 Nyle2T
ø"TAK: coNc. LINING
SCOUR GATE
PANKS

Page 124
HEADWORKS FOR
L.8 H0. SLulc2 GATE K. 2. d. S.
LING 100 LiptNG
i
CONC. PA65
crest
es
AN
-
፥+
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ALYSIS DIAGRAM
PLATE 8.
CUSEGS
MENT DETENTION
300 CUSECS
CUSE9
YCLoNic F.B. 222
NORMAL F. B. ತ54
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Page 126

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