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Sustainable Irrigation For Doubling Water Productivity In Chillewadi Medium Project Of India

Congress: 2015


Agriculture is the mainstay of the Indian economy, almost three quarters of the country's working population are engaged in agriculture and about half of the gross national product is generated by agricultural production. In India rains are received for about 40 to 100 days during June to September. Rainfall distribution is uneven with respect to time as well as space and frequently erratic during these four months. The mismatch of rainfall and crop-water requirements is quite common. A large part of the country is arid and semiarid as rainfall is not sufficient to ensure even a single crop. Thus irrigation is an inseparable part of the welfare of Indian agriculture. In the arid and semiarid plains of the perennial rivers of the north like the Ganges and the Indus, flood flows are diverted through inundation canals for irrigation, while in the rain-challenged south; water has to be stored in large tanks for domestic and agricultural use. Irrigation development in India gained momentum after Independence in year 1947. In spite of substantial growth in irrigated agriculture and consequent agricultural productivity over the years, irrigation systems in India are still facing many problems. On most command areas served by a canal, water is poorly distributed over area and time. The on-farm irrigation practice prevailing in the country results in wastage of water leading to low irrigation efficiency. Government has not made any change in mode of supply of water to farms from canals, farmers still irrigate by flooding or channeling water through parallel furrows. The overall water use efficiency seldom exceeds 40 percent in canal based system. Chillewadi canal system redesigned as pipe line system a new approach. Dam-based canal irrigation, with conventional methods of water application to farms is an obsolete, wasteful. It must be replaced by sprinkler and drip irrigation, distributed through pipes. This approach has enabled Israel to irrigate the desert and also practiced in many advanced countries. Retrofitting canal systems by buried pipeline networks has also been extensively practiced as part of the modernization of irrigation systems in advanced countries several decades earlier. Though subsurface methods of irrigation methods are adopted to increase on form water efficiency the conventional method of canal system has not changed yet, thus forcing farmers to adopt irrigation practices of poor efficiency. Piped irrigation system can enable India to double irrigated area with existing water resources, escaping water scarcity in minor and medium irrigation projects .The present canal systems farmers do not have choice of crops but to adopt crops that meets the system requirement, wholly dependent on irrigation schedule decided at canal headquarters. Today farmers want to diversify into a wide diversity of crops, and for this they need water on demand. This is why they have gone in a huge way for tube well irrigation. There is urgent need to shift from the canal-based irrigation to pipe-based irrigation operation and maintenance requirements for the open canal include weed clearing and cleaning, and replacement or repair of water measurement structures are avoided. Also the land holdings of individual farmers are becoming smaller over generations, also cost of lands is increasing alarmingly, and there is strong opposition for open canal. Chillewadi medium irrigation scheme, the complete water conduit system from reservoir up to farms is underground, farmers land is not required. The farms in command area are irrigated by pressurized system and water can be supplied on demand. The farmers on non command area are also supplied water at intermittent storage tanks .They have to pump water from these tanks .The overall water use efficiency is doubled and the farmers are supplied water on demand and they adopt to drip and sprinkler irrigation system and grow crops of individual choice. Results and discussions. Excess irrigation to farms from open canals and conventional parallel furrow, flooding method of water application to farms rendered lands less fertile and rate of food production per hectare is diminishing. Chilhewadi open canal system was designed with irrigation efficiency of 48.75 percent. The new design concept deviating from conventional contour canal system the irrigation efficiency has increased more than 80 percent due to pipe system. In plain topography, contour canal system is extensively accepted system to irrigate land. However in hilly terrain, such canal system is expensive. The performance of canal in steep side long hilly terrain is poor, due to high banks & difficulty in execution of good quality bank work. The lined canals in hilly terrain do not function properly due to unequal settlement of bank work. Sometimes the leakages from such banks are frequent also uncontrollable ending in failure of complete scheme. To avoid such instances in hilly terrain, the pipe distribution system is a better alternative. Unlike contour canal, the underground pipeline follows the undulating ground profile requiring no culverts & bridges expect pipe aqueducts @ deep valleys. Though the cost of closed conduit is slightly higher than lined canal, repair & maintenance costs are negligible. Increased irrigation efficiency, acceptance of advanced irrigation practices by farmers for increased water productivity, speed of execution of scheme overcome enhanced cost of closed conduit system. The advantages of underground pipe system not only over weigh the initial high cost of construction, also alleviate the risk of water logging and salinization with added advantage of increased reliability of water distribution. Higher irrigation efficiency combined with almost maintenance free system will satisfy timely demand of water for crops. Constant discharge outlet valves will ensure equitable distribution of water .Volumetric supply will increase awareness amongst the farmers to utilise the water efficiently to maximise their agricultural production. Also awareness among the farmers towards adaptation of advanced irrigation methods like drips will increase their agricultural productivity rather than conventional irrigation methods. During last three decades efforts are made to increase field application efficiency by adopting sprinkler and drip irrigation systems. However canal water irrigation scheme does not promote the farmers to adopt advanced field application methods, on the contrary farmers have a tendency to go for flooding method of irrigation having least irrigation efficiency. Conclusions In small and medium irrigation schemes a pipe canal system coupled with advanced methods of application to farms has increased the overall efficiency of the scheme beyond 90 percent. So the policy makers and irrigation engineers in developing countries like India have to shift their thinking process from conventional canal system to underground pipe line system so that farmers can easily adopt to advanced irrigation methods with assured water supply on large scale. References - 1 Second revised project report of Kukadi Project Govt. of Maharashtra. (Volume- 3) 2 White Book (volume 1 Nov 2012) Publication by Govt. of Maharashtra 3 Simulation study by Central Design Organization Govt. of Maharashtra 4 Indian Standards, Code of practice for design of Tunnels carrying water (IS 4880 Part-1 & Part-II-1976) 5 Open - channel hydraulics by Ven-Te-Chow

2011 IWRA - International Water Resources Association - - Admin