INFLUENCE OF CONSERVATION MEASURES ON GROUNDWATER REGIME IN A SEMIARID TRACT OF SOUTH-INDIA

A study was conducted in peninsular India in a predominantly agricultu ral watershed treated with soil and water conservation measures such a s diversion drains and staggered contour trenches in nonarable land, t erraces of trapezoidal cross section with graded channel on the upstre am side (locally termed as graded bund) and stone checks in arable lan ds and rockfill dams, archweir and nala bund (a local term used for ea rthen embankment across the drainage channel) across the gully. Hydrol ogical analysis has revealed that integrated management of land and wa ter resources has consistently improved the groundwater regime. Surfac e runoff from the treated forest and agricultural catchment were only 27.4 and 57.4% of the untreated agricultural catchment, reflecting in high infiltration of rain water due to enhanced opportunity time. Cons equently, water levels in the open wells rose by 0.5 to 1.0 m, thereby increasing the area irrigated by the wells by 172% when compared to t he preproject period, which in turn improved crop yields by 70%. Hypso metric analysis indicated that water surface levels do not follow the trend of land surface levels due to the nature of the underground geol ogical formation.