Impact of Vertical Geological Structure and Water Table Depletion on Indian Crystalline Aquifers

Abstract : Book cover Engineering Geology for Society and Territory - Volume 3 pp 583–587Cite as Impact of Vertical Geological Structure and Water Table Depletion on Indian Crystalline Aquifers A. Boisson, J. C. Maréchal, J. Perrin, B. Dewandel & S. Ahmed Conference paper First Online: 22 August 2014 1806 Accesses Abstract India is the first country in the world for groundwater exploitation. The large global pumping rate has induced in numerous regions a strong water table depletion and various over-exploitation situations especially in crystalline aquifer areas. Long time monitoring as well as various specific research projects have been conducted on three sites: Maheshwaram, Gajwel and EHP Choutuppal located in Andhra Pradesh India. They allow a comprehensive inventory of the situation and predicting the impacts of the growing pressure on Indian aquifers. Studies show that in crystalline rocks the hydrodynamics is controlled by the weathering profile: groundwater flow dominantly occurs in a shallow higher-permeability zone that overlies a deeper lower-permeability zone hosting little flow. Continuously decreasing water levels produce drastic changes for groundwater management especially when geological structures lead to water level thresholds. Impact is visible on water availability which may not sustain current agriculture practices and create more inequity between farmers regarding water accessibility. Concerning water quality, impacts are also important with a trend to enhance salinization and fluoride release in the aquifer. Moreover this depletion of water table will reduce the adaptation capacity and consequently, solutions like managed aquifer recharge will become less efficient due to enhanced water storage in the unsaturated zone. Finally, energy demand should rise to compensate lower yields and larger water lift.