ESTIMATION OF WATER AVAILABILITY AND UTILIZATION IN SMALL WATERSHED OF KSHIPRA BASIN

Abstract

A tank refers to an artificial reservoir of small size. Tanks are part of an ancient tradition of harvesting and conserving water local runoff and water from streams for later use, primarily for agriculture and drinking water. Often tank is constructed across a slope to collect and store water by taking advantage of local mounds and depressions. In this study, two small watersheds, i.e. watershed of Sahibkhedi tank and Undasa tank were selected. The watershed area of Sahibkhedi tank and Undasa tank are 72.31 sq.km. and 38.04 sq.km. respectively. Due to increase in multipurpose demand, the study areas have become water deficit area. Therefore, it has become essential to assess the (i)surface water availability in the catchment area of tanks, (ii)groundwater availability in command area of tanks and (iii) various demand of water so as to plan, manage and develop the available water resources in more scientific ways for present as well as future utilization. This dissertation work has been taken up with the major objectives as: (i) to review tank irrigation practice in India and collect field data on tanks in Kshipra basin, (ii) to estimate surface runoff in monsoon period within the catchment area of selected tanks, (iii) to assess demand and utilization of available water for various purposes and (iv) to carryout water balance study of tanks. In the study, water availability in Sahibkhedi tank and Undasa tank have been estimated as 9.271 MCM and 4.49 MCM on 75% dependability level. Domestic water requirement and irrigation requirement were computed to assess the total water demand in the tank command areas. The water requirement for domestic use was 0.567 MCM and 1.417 MCM for population in command area of Sahibkhedi tank and Undasa tank respectively. The irrigation requirement has been estimated as 6.508 MCM and 4.781 MCM and groundwater potential in the study areas for future use has been estimated as 2.985 MCM and 1.572 MCM for Sahibkhedi tank and Undasa tank respectively. Water losses from tanks through evaporation and seepage have been estimated as 2.478 MCM and 0.857 MCM for Sahibkhedi tank and 1.991 MCM and 0.682 MCM for Undasa tank. Water balance study was carried out to assess water utilization and downstream releases iii during monsoon season. These values are estimated as 5.843 MCM and 3.497 MCM for Sahibkhedi tank and 2.528 MCM and 1.387 MCM for Undasa tank. The main findings of the study are: I. Runoff, estimated by Binnie's percentage method is suitable for the study area whereas Thornthwaite water balance method is useful for estimation of soil recharge and groundwater recharge. II. Inflow into the tanks on 75% dependability level is less than the design storage capacity of tanks whereas inflow into the tanks on 50% dependability level is more than live storage capacity of tanks. III. Over the years, due to construction of trenches, field bunds and village level Nistar ponds for storing water, runoff from the catchment area of the tanks do not represent the total flow in to the tanks. IV. Due to shifting of cropping pattern and development of urban area, demands of water in the study areas have been increasing. V. Groundwater potential in command area is good but falling trend of water level (POW), within the Ujjain block indicates that groundwater withdrawal is more than recharge. VI. Evaporation losses from the tanks are extremely high. VII Water is precious for the study areas. So volume of water released in downstream during monsoon season should be stored either in the same tank by increasing its capacity or at other suitable site.