Unit 4 Canal irrigation and command area development
- 1. Unit CANAL IRRIGATION AND COMMAND AREA DEVELOPMENT Classification of canals –Alignment of canals – Design of irrigation canals– Regime theories –Canal Head works – Canal regulators –Canal drops – Cross drainage works – Canal Outlet, Escapes –Lining and maintenance of canals – Excess irrigation and waterlogging problem –Command area – Concept, Components of CADP –On Farm Development works, Farmer’s committee –its role for water distribution and system operation – rotational irrigation system.
- 2. Classification of canals Types of Canals i.Based on usage there are two types of canals: Aqueducts Waterways ii.Based on discharge there are five types of canals: Main Canal Branch Canal Major Distributary Minor Distributary Watercourse or Field Channel iii.Based on provider canals can be classified into two types Unlined canals Lined canal iv.Based on alignment there are three canal types: Contour canal Watershed canal Side slope canal
- 3. Aqueducts Aqueduct is a significant watercourse which carries water from a source to the far distribution point. There are many versions of aqueducts. The simplest types are mostly small ditches cut into the earth. They run through underground tunnels. However, modern aqueducts use the pipeline as their path. These types of canals are used for the conveyance and delivery of water for consumption, and agricultural irrigation. Waterways Waterways are the type used for carrying ships and boats and conveying people. Waterway paths are known as a secondary by-product of our country s extensive historical waterway network, and their essential contribution to everyday life has ‟ mostly gone unrecognized. They include water features like river, canal, streams, as well as lakes, reservoirs, and docks. Related features of waterways include weirs, locks, rapid, etc. Waterways provide a safe operating environment by reflecting the local conditions. Mostly waterways are used for transformation, irrigation, headrace, trail race, penstock, spillway, etc. They cater to a wide range of boating and water activities as well as control of pests. Waterways act as refuges for terrestrial fauna species during times of drought and as corridors for dispersal. Waterway paths attract more commuting, tourism. It helps to decrease carbon footprints, reduce road congestion and improve the health of local communities
- 4. Main Canal Canals are having discharge more significant than ten cumecs are called as main canals. The main canal is also known as the arterial canal. In drainage, the main canal is the superior canal of the drainage system; it collects water from the drainage canals and conducts it to the water intake. The main canal carries discharge directly from the river. It takes off directly from the upstream side of weir head works or dam. Usually, no direct cultivation is proposed. It supplies water from a river, reservoir, or canal to irrigated lands by gravity flow. It supplies water to a branch canal. We cannot use the main canal for direct irrigation. Branch Canal Branch canals have discharge in the range of 5-10 cumecs. The branches of the main canal go in either direction at regular intervals. It offtakes from the main canal where the head discharge is not more than 14-15 cumecs. Branch canal also plays the role of feeder channel for major and minor distributaries. Branch canals do not carry out direct irrigation, but they provide direct outlets. Major Distributary Canals who offtake from the main canal or branch canal with head discharge from 0.028 to 15 cumecs are termed as significant distributaries. It takes off water from branch canals. Sometimes getting supply from the main canal, their discharge is less than branch canal. These are mostly known as irrigation channels because of their supply of water to the field directed through outlets. Minor Distributary Canals in which discharge ranged from 0.25 up to 3 cumecs are termed as minor distributors. It offtakes from a major distributary carrying discharge less than 0.25 cumecs are termed as minor distributary. Sometimes minor distributary gets supply from the branch canals. The discharge in minor distributary is less than in the major distributary. They also provide water to the courses through outlets provided along with them.
- 5. Watercourse or Field Channel The discharge in watercourses is less than 0.25 cumecs. A field channel either take off from a significant distributary or minor- it solely depends on which extent the irrigation will happen. In a few cases, it also takes off water from the branch canal for the field. Small channels which carry water from the outlet of a major or minor distributary or a branch canals to the areas to be sprayed. There are small channels for feeding water to the irrigation fields.
- 6. Unlined Canals Unlined canals consist of beds and banks made of natural soil. They are not provided with a lining of impervious materials. It produces the growth of aquatic weed retards the flow which leads to massive maintenance cost. Unlined canals can tolerate velocities no more than 0.7 m/s because of erosion. In unlined canals, there is a danger of canal bank breakage caused by overtopping, erosion and animal burrowing. Weeds had severely slowed down the water flow of the canals, preventing up to 50% of the water from reaching the tail end of the canal. It also causes waterlogging of the adjacent net. Lined Canal Lined canals are provided with a lining of impervious materials on its bed and banks to prevent the seepage of water. The most commonly used types of padding are concrete, shotcrete, brick or burnt clay tile, boulder, concrete blocks, stone masonry, sand-cement, plastic, and compacted clay. Possible benefits of lining a canal include water conservation; no seepage of water into adjacent land or roads; reduced canal dimensions; and reduced maintenance.
- 7. Contour Canal A contour canal is an artificial canal also renowned for being dug navigable by following the contour line of the land. it traverses to avoid costly engineering works (eg: boring a tunnel through the higher ground, constructing a canal lock to change the level of the canal, building a dam over lower ground, or). Contour canals are distinguished by the meandering course. They can increase the risk of erosion if not properly established. Watershed Canal A Watershed is a secure area whose runoff drains into any water substance. The watershed canal aligns with any natural watershed (ridgeline). That's why it is also known as the ridge canal. Aligning a canal (central canal or branch canal or distributary) on the ridge ensures gravity irrigation on both sides of the canal. Water runs downhill. Watershed boundary is the divide that distinct one drainage area from another. Side Slope Canal Side slope canals are personalized at the right gradient reaching the contours. It is not on watershed or valley. It does not expropriate drainage channels.
- 8. Alignment of Canals Irrigation canals can be aligned in any of the following three ways: (i) as watershed canal or ridge canal. (ii) as contour canal ; and (iii) as side-slope canal.
- 9. Water shad Canal or Ridge Canal: The dividing ridge line between the catchment areas of two streams (drains) is called the water-shed, or the ridge. Thus. Between two major streams, there is the main watershed (ridge linc), which divides the drainage area of the two streams. Similarly, between a main stream and any of its tributary, there are subsidiary watersheds (ridge lines), dividing the drainage between the two streams on either side.
- 10. (ii)Contour Canals. The above arrangement of providing the canal along the ridge line are, however, not found economical in hill areas, since the conditions in hills are vastly different compared to those of plains. In hills, the river flows in the valley well below the watershed. Infact, the ridge line (watershed) may be hundred of metres above the river. It therefore becomes virtually impossible to take the canal on top of such a higher ridge line.
- 11. Side slope canal. A side slope canal is that which is aligned at right angles to the contours i,e, along the side slope..Since the such a canal runs parallel to the natural drainage channels, thus, avoiding construction of cross-drainage structures.
- 12. Distribution System for Canal Irrigation It has been emphasized earlier that the direct irrigation scheme using a weir or a barrage, as well as the storage irrigation scheme using a dam or a reservoir, require a network of irigation canals of different sizes and capacities. The entire network of irrigation channels is called the Canal System. (i)Main canal (ii)Branch canals (iii)Distributaries, also called major distributaries (iv)Minors, also called minor distributaries, (v) Watercourses.
- 13. (i) Main Canal (Head reach). The canal headworks are generally situated on the river flowing in a valley, and the canal should reach the ridge line in the shortest possible distance. The canal, in this reach, must, therefore, be aligned very carefully, and has to be generally excavated in deep cuttings below N.S.L. (natural surface level). Sometimes, it has to cross various drainage lines. Many a times, straight alignment has to be sacrificed and detours need to be accepted, in order to achieve a good site for cross drainage works. Main Canal (Portion below head reach.) Attempts are made to align the canal along the ridge and somewhat central to the command area. Sometimes, ridge line has to be sacrificed, to bypass towns and villages, ete., Main canal is not required to do any irrigation. (ii) Branch Canals. Branch canals are taken off from the main canal on eather side to take irrigation water to the whole tract required to be irrigated. Very little irrigation is in fact, done from the branch canals themselves, as they serve to supply water primarily the distributaries. Attempts are made to align them along subsidiary ridges. Discharge in a branch channel, is generally, more than 30 cumec. (iii) Distributaries. Smaller channels which take. off from the branch canals and distribute their supply through outlets into minors or water courses, are called distributaries. They are aligned either as ridge canals as contour canals or ascontour canals. Discharge in a distributary, is generally, less than 30 cumec. (iv) Minors. Sometimes, the country is such that the distance between the distributary outlet and the farmer's field is very long ; say more than 3 km or so. In such a case, small channels called minors, are taken off from the distributaries, so as to supply water to the cultivators at the point nearer to their fields. Dischargein a minor, is generally, less than 2.5 cumec. (v) Watercourses. These are not the government channels and belong to the cultivators. They are small channels, which are excavated and maintained by the cultivators at their own costs, to take water from the government-owned outlet points, provided in the dis-tributary or the minor.
- 14. Canal Head works Functions of Head Works. The aims and objects of the canal head works are summarized below: 1.To prevent water required for canals passing the head works at a level below that at which it can be utilized and to prevent of any flow downstream. 2.To raise the level of the supply so that it can irrigate the area more efficiently. 3.To gain command economically when the canal has to pass in expensive cutting. 4.To reduce the fluctuations of the level of the river. 5.To control the silt entry into the canal. To render the head works permanent thus ensuring the required supply into the canal and to prevent them from being affected by the vagaries of the river.
- 15. Components of Head Works. Following are the parts / components of head works. 1.Weir. 2.Under Sluices. 3.Canal Head Regulators. 4.Fish Ladder. 5.Divide Wall. 6.River Control Works.
- 16. Site Selection for Head Works. 1. side channel should be selected which is not directly subject to flood action and into which the cold weather supply can easily be diverted from the main channel. 2.The side or supply channel should lead directly to the fixed off-taking site for the excavated canal. If the canal was to take-off from the main channel, it shall need very massive and expensive works. 3.The control over the supply channel is maintained by making its bed slope after the first thousand feet or so something less than that of the main river. The site should be such that a rise of 5 to 8 feet is attained at the canal head.
- 17. Canal regulators The canal system plays a key role in regulating the irrigation water. The major components of permanent canal system are discussed below. Components of a permament canal system, i.e., (1) Main Canal, (2) Branch Canal, (3) Distribuaries, and (4) Water Courses
- 18. Canal Drop Structure A canal drop structure, also known as a grade control, sill or weir, is defined a man made structure, typically small and built on minor streams, or as part of a dam's spillway, to pass water to a lower elevation while controlling the energy and velocity of the water as it passes over. Necessity of drop / fall A drop or fall is an irrigation structure constructed across a canal to lower down its water level and destroy the surplus energy liberated from the falling water which may otherwise scour the bed and banks of the canal. We know that the canal requires a certain slope, depending upon the discharge, to overcome the frictional losses. This slope may vary from l in 4000 for a discharge of about 1.5 cumecs to about l in 8000 for a discharge of 3000 cumecs..This slope is, therefore, quite flat in comparison to the available ground şlope of an average value of 5 to 20 cm per kilometer length (i.e.,1l in 200 to 1in 50 ). Thus the ground slope in nature is always very much steeper than the design bed slope of irrigation canal, based on the silt theories, If an irrigation canal, taking off from its head, is in cutting, it will soon meet with condition when it will be entirely in embankment. If the canal is in embankment, the cost of construction and maintenance is very high and at the same time the percolation and seepage losses are excessive. Also, there is always a danger of the adjacent area being flooded if some cut or breach takes place in the canal banks. Hence, the canal should never be in high embankment. However, the divergence between the gentle bed slope of canal and the steep ground slope throws the canal in embankment after a certain distance though it started in cutting at its head. To overcome this difficulty, drops / falls are introduced at appropriate places, and the water surface of the canal is lowered. Arrangements are made to dissipate the excess energy liberated from the falling water.
- 19. Location of Drops /Falls 1. For the çanal which does not irrigate the area directly, the fall should be located from the considerations of economy in cost of excavation of the channel with regard to balancing depth and the cost of the falls itself 2. For a canal irrigating the area directly, a fall may be provided at a location where he F.S.L. outstrips the ground level, but before the bed of the canal comes into filling. 3. After the drop, the F.S.L of the canal may be below the ground level for 1/4 to ½ kilometere 4. The location of the fall may also be decided from the consideration of the possibility of combining it with a regulator or a bridge or any other masonry works. 5. A relative economy of providing large number of small falls vis small number of big falls should be worked out. 6. The provision of small number of big falls results in unbalanced earth-work, but there is always some saving in the cost of the fall structure.
- 20. Types of canal Falls 1) Ogee falls 2) Rapid falls and 3) Stepped falls. 4) Notch falls, 5) Vertical falls and 6) Glacis type falls were developed
- 21. Ogee fall
- 22. Rapid fall
- 23. Stepped fall
- 24. Notch fall
- 26. Glacis type fall
- 27. Cross Drainage Works (1) By passing the canal belöw the drainage. This máy be accomplished either through (i) a super-passage (ii) canal syphon generally called a syphon (2)By passing the canal over the drainage. This may be accomplished either through (i) an aqueduct; (ii) syphon-aqueduct (3) By passing the drain through the canal,so that the canal water and drainage water are allowed to intermingle with each other. This may be accomplished through (i) a level crossing (ii) inlets and outlets.
- 28. canal syphon and A super-passage
- 30. A level crossing and Inlet, Outlet
- 31. Selection of a Suitable Type of Cross-Drainage Work • Suitable canal alignment. • Nature of available foundation. • Suitability of soil for embankment. • Position of water table and availability of dewatering equipment • Permissible head loss in canal,. • Availability of funds.
- 32. Canal Outlet A canal outlet or a module is a small structure built at the head of the water course so as to connect it with a minor or a distributary channel. It acts as a connecting link between the system manager and the farmers. Types of Canal / Irrigation Outlet: (1) Non-Modular Irrigation Outlet (1) Pipe Outlet (2) Modular Irrigation Outlets and (3) Semi-Modular Outlets.
- 39. Gibb’s module:
- 42. Lining and maintenance of canals Objective of Canal Lining 1. To save water (reduce seepage). 2. To stabilize channel bed and banks (reduce erosion) 3. To avoid piping through and under channel banks 4. To decrease hydraulic roughness (flow resistance) 5. To promote movement, rather than deposition, of sediments 6. To control weed growth 7. To avoid waterlogging of adjacent land 8. To decrease maintenance costs and facilitate cleaning 9. To reduce excavation costs (when extant material is unsuitable) 10. To reduce movement of contaminated groundwater.
- 43. Types of Lining Earthen Lining Portland Concrete Lining Plastic and Rubber Lining Exposed and Buried Membranes Lining Fly Ash lining
- 44. Earthen lining Earthen lining usually require significant over excavation, and transport of suitable material( in large volumes ) from another side Many earthen linings are 2-3 feet thick ; “thin” lining are 6-12 inches thick Clay lining are crack after only a few cycles of wetting and drying ,causing increased seepage losses . Bentonite clay swells considerably when wet, but cracks may not completely seal after the canal has been dried, then filled with water again Bentonite is a special kind of clay, usually made up of decomposed volcanic ash and containing a high percentage of colloidal particale (less than 0.000 cm in diameter. High –swell Bentonite may swell 8 to 20 times in volume when wetted; other types may swell less than 8 times in volumes Repeated drying-wetting cycles can cause loss of lining density, loss of stability. and progressive deterioration of the lining Other than Bentonite, clay linings may be of montmorillonite; or montmorillonite chlorite Some clay linings have been treated with lime to stabilize the material. The addition of lime to expansive soils (e.g. Bentonite) improves workability and increases structural strength
- 45. Portland Concrete Lining Small concrete-lined canals are usually non-reinforced. Steel reinforcement (rebar or steel mesh) is also not commonly used on large canals anymore unless there are compelling structural reasons The elimination of steel reinforcement from concrete canal linings save to 15% of the total coast(USBR1963) During the past several years it has become popular to install concrete small canals at the same time as final excavation and finishing, often using control the alignment and longitudinal slope Reinforced concrete can contain rebar and or wire mesh. Reinforcement usually for structural reasons, but also to control cracking of the lining Concrete panel joints may have rubber strips to prevent seepage Some “Underwater” concrete lining operation have been performed in recent years on full canals (so as not to deliver operations) Careful shaping finishing, of the native soil is an important step in the preparation for concrete lining simply because it can greatly reduce the require volume of concrete (significantly lowering the cost significantly lowering the cost) Weep holes or flap valves are Often installed in cut sections of a concrete-lined canal to relieve back pressures which can cause failure of the lining Flap valves may be installed both in side slopes and in the canal bed Some concrete-lined canals have (measured) high seepage loss rates, particular tjin"fill" sections Of canal, and in soils with high permeability (usually sandy soil) but seepage rates are rarely measured; they are "assumed" based on tables in books British researcher report that their investigation show that 0.01% of the area of a concrete canal lining is cracked (0.01% are cracks) , the average seepage rate may be the same as that of an unlined canal Soil mixed with portland cement, especially sandy soil, can be an acceptable cost saving approach to canal lining
- 46. Plastic and Rubber Lining • Plastic linings are also referred to as "geomembranes" or "flexible membrane linings • Plastic canal linings have been in use for approximately 40 years • Plastic and rubber linings are covered with soil, and Yicks, or other material for • Plastic lining are typically 10 20 mil (0.010 to 0.020 inches, or 0.25 to 0.5 mm)- thicker membranes are usually recommendable because of increased durability,and because the overall installation cost only increase by about 15% for a doubling in thickness • The USBR previously used 10 mil plastic linings, later changed most specifications to 20 mil linings • Plastic linings of as low as 8 mil (PE), and up to 100 mil have been used in canals retention ponds • Low density polyethylene (LDPE) is made of nearly the same material as common trash bags (such as "Hefty" and 'Glad" brands), but these trash bags have a thickness of only I.5 -2 mils • Plastic canal linings are manufactured in rolls, 5 to 7 ft in width. then seamed together in a factory or shop to create sheets or panels of up to 100 ft (or more) in width • Rubber membrane linings can have a thickness ranging from 20 to 60 mil • Flexible plastic and synthetic rubber linings are susceptible to damage (punctures, tears) both during after instalation • Flatter than normal side slopes (say 3: I ) are sometimes preferred with plastic linings to help prevent the possible migration of the lining down the slope, and to help prevent uncovering of the lining by downward movement of soil • correctly installed plastic and synthetic rubber linings are completely impervious, provided they have not been damaged. and provided that the flow level in the channel does not exceed the height of the lining
- 47. • plastic liners will "age" and lose plasticizer, causing a loss of flexibility and greater potential for damage. Increased plasticizer during fabrication has been shown to be effective in this regard plas-ti-ciz-er (plas „tuh s/e zuhr) n. a group of substances that are used in plastics to impart viscosity, flexibility, softness, or other properties to the finished product • Some canals in central Utah have had plastic linings for more than 30 years, and most of it is still in good condition (measured seepage is essentially zero in the lined sections, but some evidence of puncture/tearing has been found) • Plastic lining material is sometimes used to retrofit existing concrete-lined canals after the concrete lining canal fails and or continued maintenance is considered infeasible • In the former Soviet Union, thin PE lining has been placed under precast slabs of concrete lining in some canals • In India, some canals have been lined with plastic (PE) on the bottom, and bricks or tiles on the side slopes • Polyethylene (PE) is the lowest cost geomembrane material, PVC is next lowest. Some newer materials such as polyolefin are more expensive
- 48. Exposed and Buried Membranes Lining • Exposed membrane linings have been tried, but tend to deteriorate quickly for various reasons • Exposed membrane kinings have recently been installed in some full (operating canals) • Buried membrane lining should have a cover layer of soil of approximately 1/12of the water depth ,plus 10 inches • Some vegetation can penetrate these types of lining(asphatlic too), so sometimes soil sterilant is applied to the soil on the banks and bed before lining
- 49. Fly Ash lining Fly ash is a fine dust particulate material (roughly the size of silt) produced by coal-burning powerplants, usually in the form of glassy spheres Fly ash contains mostly SiO2 (Silicon dioxide), Al2O3 (aluminium oxide) and Fe2O3 (iron oxide) Fly ash is often mixed with soil to form canal linings,the mixture being more dense and less permeable than soil alone Fly ash is sometimes mixed with both soil and Portland cement
- 50. Excess irrigation and water logging problems Water logging Waterlogging occurs when the soil is saturated with water. The agricultural land becomes waterlogged when the soil pores within the root zone of the crops get saturated and the normal conditions circulation of air is cutoff. The waterlogging affects the productivity of the land and leads to a reduction in the crop yield. Waterlogging generally occurs because of over-irrigation, high water table and the poor water management. Due to the presence of water at or near the land surface, evaporation takes place continuously. Because of evaporation, there is a continuous upward flow of water from the water table if it is high because of the capillary action. Water brings salts with it and when the water evaporates, these salts get accumulated on the surface. These salts affect the fertility of the soil, and the soil may become alkaline. Waterlogging can be prevented to a large extent by providing an effective drainage system.
- 51. Causes of waterlogging • Over-Irrigation • Inadequate surface drainage • Obstruction of natural surface drainage • Obliteration of a natural drainage • Obstruction of natural subsurface drainage • Impervious top layer • Seepage from canals • Construction of a reservoir • Defective methods of cultivation • Defective irrigation practice
- 52. Effects of waterlogging • Reduction in growth of plants • Difficulty in cultivation • Accumulation of salts • Weed growth • Increase in plant diseases Increase in plant diseases • Lowering of soil temperature • Increase in incidence of malaria
- 53. Measures for prevention of waterlogging 1. Limiting the intensity of irrigation 2. Providing a drainage system 3. Lining the canal section 4. By lowering the FSL of the canal 5. Improving the natural drainage of the area 6. Provision of intercepting drains 7. Increasing outflow from the groundwater reservoir 8. Changing the crop pattern 9. Prevention of seepage from reservoir 10. Changing the assessment method 11. Adopting better methods of application of water 12. Educating the cultivators to use water economically
- 54. Main Elements of Regulators The water area of vents (S*dw) The bridge The piers between the regulator vents The abutments The floor The gates
- 55. Classifications of Regulators. i. According to purpose: Regulation of Discharge Regulation of Water slopes (and velocity) Measurement of Discharge "Q" Division or Diversion of Discharge Change in bed slope ii. According to location Head Regulator Intermediate Regulator Escape Regulator Diversion Regulator iii. According to Material (Type of Construction) 1- Masonry Arch Regulator 2- Mixed Type Regulator (masonry + RC) 3- RC Regulator
- 56. Principles of Design i) Hydraulic Design To get the area of water way Discharge is considered for fully opened Reguator Determination of heading up Check the velocity through regulator vents ii) Floor design To determine the floor length To cover the floor length by regulator floor To check the percolation length To determine the floor thickness To make adequate precautions against undesired percolation iii) Structural Design To determine the dimensions and check the stability of the structural elements Which are: Piers: Abutments; wing walls Roadway (bridge); gates Cranes and lifting devices
- 57. Types of regulators in canals Still pond regulation Silt control devices Open flow regulation
- 58. Still pond regulation Canal draws water from still pond Water in excess of canal requirements is not allowed to escape under the sluice gates. Velocity of water in the pocket is very much reduced; silt is deposited in the pocket When the silt has a level about 1/2 to l m below the crest level of Head Regulator, supply in the canal is shut off and sluice gates are opened to scour the deposited silt.
- 59. Silt control devices Providing a divide wall to: Create a trap or pocket. Create scouring capacity of under sluices By concentrating the currents towards them Paving the bottom the approach channels to reduce disturbance because due to disturbance sediment remains in suspension
- 60. Open flow regulation i. Sluice gates are opened and allow excess of the canal requirement ii. Top water passes into the canal iii. Bottom water maintain certain velocity in the pocket to keep the silt to remain in suspention iv. Canal is not closed for scouring the silt.
- 61. Installing silt excluders Making entry of clear top water by: Providing raised sill in the canal Lower sill lever of scouring sluices Wide head regulator reduces velocity of water at intake Smooth entry to avoid unsteady flow Handling careful the regulation of weir Disturbance is kept at minimum in weirs
- 62. Advantages of Regulators to weirs 1. Regulator may be fully opened at flood time giving enough waterway area to avoid excess heading up 2. both US & DS wáter levels are controlled minimiże silting at US
- 63. Farmer’s committee –its role for water distribution and system operation – rotational irrigation system Farmer’s committee: Success of canal irrigation depends on the response of the farmer, both as an individual and as a member of the group benefited by the outlet. The irrigation facilities should be designed with a view to meet his requirements, particularly in respect of land forming. Active participation of the farmer at the stage of design should therefore be encouraged. This will also help in building up of an atmosphere of common purpose and thereby in the unification of the beneficiaries into a homogeneous group. The Govt. of Maharashtra in Irrigation Dept. has taken a decision to promote and expedite the formation of WUA s, so that all the created potential under various projects is taken over ‟ by Water Users Associations. The Govt. is also promulgating separate Act for farmers ‟ ‟ management in Irrigation system. Hence, it would be necessary to revamp the approach, if necessary, in accordance with the provisions and procedures laid down by the Govt. from time to time.
- 64. Role of water distribution system operation: The water distribution network is the term for the portion of a water distribution system up to the service points of bulk water consumers or demand nodes where many consumers are lumped together. The World Health Organization (WHO) uses the term water transmission system for a network of pipes, generally in a tree-like structure, that is used to convey water from water treatment plants to service reservoirs, and uses the term water distribution system for a network of pipes that generally has a loop structure to supply water from the service reservoirs and balancing reservoirs to consumers. Pipelines laid within public right of way called water mains are used to transport water within a distribution system. Large diameter water mains called primary feeders are used to connect between water treatment plants and service areas. Secondary feeders are connected between primary feeders and distributors. Distributors are water mains that are located near the water users, which also supply water to individual fire hydrants. A service line is a small diameter pipe used to connect from a water main through a small tap to a water meter at user's location. There is a service valve (also known as curb stop) on the service line located near street curb to shut off water to the user's location.
- 65. • Underground storage reservoir or covered finished water reservoir • Uncovered finished water reservoir • Surface reservoir (also known as ground storage tank and ground storage reservoir) • Water tower (also known as elevated surface reservoir • Standpipe • Sump
- 66. Rotational irrigation system In India due to uncertain and uneven rainfall it is necessary to irrigate agricultural land by some artificial means like construction of dams, canals, weirs etc. Right from the first five-year plan till the end of twelfth five year plan the capital investment on irrigation works in an ever-increasing scale. The number of projects taken up for construction is also increasing and at present there is quiet large number of projects under construction with some already completed and commissioned. A number of committee commission institute have been appointed by the Government from time to time to investigate the cause of underutilization the irrigation potential and suggest remedial measures for improved utilization i.e. it is felt necessary to develop the irrigation management using certain inputs such as crop - water requirement in association with soil. It is also necessary to have farmers participation. The growing problems of poor utilization of irrigation have felt ‟ heavily by the planners and policy makers in the country. There is a wide scope for improvement out duties of water allowance are extremely high the water table starts building up in the command areas, there is water logging reliability of water or satisfaction to a large number of far mers only those located favorably in the canal system, mostly at the head reaches get supplies and they over use it. There are large number of farmers who do not get sufficient water. The problems at the main system level are water allocation pattern and the overall project management and at the tertiary (outlet) level, it is mainly the problem of water distribution at outlet level are more serious than at the main system level. In pursuit of the simplex nature of various problems, it is important to study the performance of the project, both at the main system and tertiary levels mainly to identify the operating constructions. This will help in improving the performance of existing project as well as the problems can be taken care of while planning the new projects.
- 67. Canal Rotation Program: For outlet operation schedule data in this format used to be compiled from format number 2 , schedule of dates can be worked out by planning sequence of outlets as designed in operation plan . Competence in arranging opening and closing of outlets influence and enhances conveyance efficiency. Any change in operation may be necessary due to - • Rains in the parts of command. • Incapacity for farmers to follow the schedule due to unforeseen reasons. Such situation is to be met by consulting WUA s by keeping continuous dialogue with WUA till completion of rotation . ‟
- 68. Chak Rotation program for each chak/ rotation : The main intention of this format is to estimate more time for each beneficiaries at farm gate connection factor is decided in field channel observation at travel time and losses. These factors are to be updated at dates analogous seasonal data. Time sharing within this flow period for each farm is done in this format will be useful to canal inspector of each beneficiaries within the chak can be calculated by WUA in consultation with canal inspector without changing outlet opening and closing schedule. Farm data table for each chak/ rotation: This format completion of base data about crop and crop areas. Water depth will be as per MAD curve and will change as per crop, rotation number, soil type and depth etc. This will have to be ascertained for every rotation. FAE is presently based on observation i.e. ratio of water required by crop and water delivered at farm. This ratio is to be updated as per field observations