ABSTRACT
ABSTRACT: The Kallugotla watershed in Kurnool district of Andhra Pradesh, located in semi arid region, experiences scarcity of water for drinking and irrigation. The watershed (25 km2) covered by limestone-quartzite terrain of Upper Precambrian age. The area receives an average annual rainfall of 550mm. Integrated geohydrological investigations comprising resistivity surveys, hydrogeological surveys, bore hole pumping tests and natural recharge studies were carried out in the watershed for selection and design of artificial recharge strategies for sustaining the yield of irrigation wells. Based on the investigations, few watershed specific artificial recharge strategies were suggested and implemented in this watershed. Natural recharge rate due to combined effect of rainfall and applied irrigation was measured at 6 sites in the watershed area during 2000 monsoon using tritium tracer technique. The result indicates average recharge of 105 mm for the seasonal rainfall of 585 mm and irrigation input of 377 mm. The natural recharge and water level fluctuation data obtained in this watershed with the recharge measurements made in the adjacent watershed was used for estimating natural recharge due to rainfall and return flow due to applied irrigation independently. Dye and chemical tracers were used in tracer experiments for delineating flow pathways during the time of groundwater recharge through the artificial recharge structures. The tracer data obtained was used for determining the influencing zone and beneficiary wells due to artificial recharge structures. The tracer studies indicated that the recharge occurs along the gently dipping joint planes.
