Assessment of Groundwater Potential and Irrigation Water Demand for Sustainable Utilization of Groundwater Resources on Mehoni Sub-Basin

Abstract

ater balance techniques have been extensively used to make quantitative estimates of water resources and the impact of man's activities on the hydro logic cycle. In this study, an attempt has been made to describe the methodologies to understand and assess groundwater potential and irrigation water demand of the Mehoni sub basin. The ground water is the main resource for irrigation and water supply in the study area. The approach of this research is centered on quantitative estimation of water balance component on the area and developing irrigation areas for sustainable use of the groundwater potential for irrigation. Recharge and discharge components have been quantified based on inflows, outflows and changes in the aquifer groundwater storage. Inflow to the system is groundwater recharge from precipitation by considering that the sub basin is closed. The recharge of the study area is estimated by water balance technique and each component is calculated separately. The main components used for estimation of annual recharge in this paper are annual actual evapotranspiration, surface runoff and rain fall of the study area. The actual evapotranspiration of the study area was estimated by Thornthwaite and Mather water balance model and Turc method .The study area is dry basin with no river gauging in the area. Hence estimation of surface run off in the basin was done using SCS rain fall runoff method. The irrigation water demand of the study area is estimated by CROPW A T8 software. Discharge from the system includes groundwater extraction for irrigation and water supply systems. The result of the study shows that the average total annual groundwater recharge of the area is 72.9 Min 3 and the total irrigation water demand is 8.5 l 4Mm 3 annually. The over all net ground water potential of the study area is 61.784 Mm 3. By considering the existing situation the ground water potential of the study area can irrigate up to 5000 ha with out affecting the ground water level of the study area.