Ground water status and its augmentation with surface storage under the julamigera tank system of Karnataka

In the prevailing weather conditions of Karnataka, the tanks are not able to meet the increasing demand for irrigation due to the erratic nature of the monsoon rains, cultivation of paddy in non-localized areas and uncontrolled operation of the conveyance and application systems. A study was conducted about Julamigera tank irrigation system, which is situated in Raichur taluk and is the part of lower reaches of Tungabhadra sub catchment in Krishna river basin. The investigation was carried for assessing existing tank and ground water usage status and to develop the optimized plans for irrigation in the command area using both tank and ground water conjunctively. Net crop water requirement and losses like seepage through bund, transit and percolation were found out to estimate the gross water requirement in each month. The CRIWAR model was used to estimate the crop water requirement of the crops grown in the Julamigera tank command area. The irrigation water requirement was found to 0.619100 M Cum (1047 mm) during rabi season. Considering the net crop water requirement and losses average monthly demand was calculated during rabi season. Depending on the availability of water in tank in each month of the year and their possible deviation in the quality over the year's alternative plans of conjunctive usage of ground water and tank water were proposed. When the available water is 100 per cent i.e., up to full tank level (FTL) then whole command area is kept under cultivation and gross demand was estimated which was found to be 693268.0 Cum and corresponding supply in positions were found to be 764191.0 Cum. When the tank water availability is 75 per cent of live storage gross demand was found to be 650119 Cum and the corresponding estimated supply was 657843 Cum. When the tank receives water about 50 per cent of its live storage, gross demand estimated which was found to be 416799.0 Cum and the corresponding estimated supply was found to be 421614 Cum.