Various Pumping Tests and Methods for Evaluation of Hydraulic Properties in Fractured Hard Rock Aquifers

Abstract

Large tracts of South India are underlained by hard crystalline rock terrain (granite, gneiss, basalt, etc.). The area is also classified as semiarid to arid, generally prone to drought conditions, requiring optimal management of groundwater resources against increasing demands of water for various activities (agricultural, industrial, domestic). Estimating the hydraulic characters of water bearing layers is an essential part of groundwater studies. The most effective way of determining these characteristics is to conduct and analyse in-situ hydraulic tests. One of the early records of pumping tests on a large scale in India was done by (1978). The study indicates that well losses comprise a significant portion of the total drawdown in a number of low- and high-yielding wells. (1988) observed that the transmissivity values (T) obtained by slug-tests are more than pump test values for low T values, and that they vary from negligible up to a factor of about three for higher T values. (1996), from hydrological tests on dug wells in the crystalline rocks, estimated a range of T values from 26.5 to 56.36 m²/d, for the weathered zone based on interpretation made by Papodopulos and Cooper method (Papadopulos and Cooper, 1967). (1997), from a study in Karnataka, postulates that the yield fluctuation in the pre- and post-monsoon periods is largely dependent on recharge that is restricted to about 60 m depth.