Results of Pumping Tests in Crystalline‐Rock Aquifersa

Abstract

ABSTRACTThe Evangelical Lutheran Church (E.L.C.) Water Development Project, headquartered in Betul, Madhya Pradesh, India, has been involved since 1971 in developing ground‐water supplies in the Satpura Hill Region of Central India. To date, over 400 wells have been drilled in crystalline rocks and more than 100 of these wells have been pump‐tested to determine aquifer hydrologic characteristics.Crystalline rocks crop out in roughly 20 percent of the Satpura Hill Region and the main rock types are granite, gneiss, and schist. The crystalline‐rock country is gently undulating and ground‐water flow systems are of the local type being limited to small drainage basins of a few square miles in area.The controlled testing and detailed analysis of over 100 pumping tests provided an excellent opportunity to evaluate the applicability of standard analytical models for the analysis of pumping tests in crystalline‐rock aquifers.Step‐test data were analyzed by Rorabaugh's (1953) method and by a graphical method. The results indicate that well losses are significant in a number of wells tested and appear to be related to non‐Darcian flow in the aquifer adjacent to a pumped well.Constant‐rate pumping tests were used to determine aquifer transmissivity. Time‐drawdown data were analyzed by the Cooper‐Jacob (1946) approximation to the Theis (1935) equation and recovery data were analyzed by the residual drawdown method. Aquifer transmissivity ranged over two orders of magnitude from 102 to 104 gpd/ft (1.24 to 1.24 × 102 m2/day). Pumping‐test results often enabled the prediction of aquifer conditions, such as limited aquifers, recharge and leakage boundaries, and aquifer dewatering.