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Environmental impacts of groundwater intensification in India Sunderrajan Krishnan Trishikhi Raychoudhary Chaitali Purohit Ankit Patel Definition of problem Any disturbance from the natural regime of groundwater flows or geochemistry caused by intensification of groundwater use that results in significant impact on environment and on humans Challenges: To define natural regime To isolate role of GW use on the impact, eg. coastal salinity Which issues are being studied - Fall in water tables and rise in water tables regionally - Highly fluctuating water table - Quality problems emanating from exploitation eg. salinity in coastal areas, increasing mineralization of deeper aquifers, release of geogenic heavy metals associated with exploitation - Quality problems due to use of poor quality water for irrigation -Related surface water issues eg. tanks that recharge aquifers, being in disuse , partly due to gw use Building blocks of study Region based (4 regions) Issue Based (2 issues) Nation-wide analysis (at district level) Building blocks of study Region based (4 regions) Issue Based (2 issues) Nation-wide analysis (at district level) Nation-wide analysis at district level Objectives: To delineate zones of GW vulnerabilty using different criterion: a) Volumetric information: GW recharge, GW use for various purposes; Proportion GW used for irrigation b) Depth to Groundwater Table: Median depth to water table; Median fluctuation of water table c) Impact of well interference: well density and hydrogeology together impacting well interference Overlap these zones to mark regions of varying vulnerablity Building blocks of study Region based (4 regions) Issue Based (2 issues) Nation-wide analysis (at district level) Studies in four regions - Bist-Doab of Punjab: overexploitation and agropollution; groundwater balance and trend analysis - North Gujarat: overexploitation, Fluoride, Salinity, urban exploitation and pollution - Coastal West Bengal and Orissa: saline water intrusion and urban subsidence of land - Central Tamil Nadu: Noyyal sub-basin of Cauvery: overexploitation, pollution, demand from urban areas Studies in four regions Bist-Doab North Gujarat Coastal WB, N. Orissa Noyyal sub-basin of Cauvery Studies in four regions Objectives: Detailed characterization of environmental impacts of groundwater use in the region Extrapolation to parts of the country that are similar to this region Eg. North Gujarat: overexploitation of aquifers; Fluoride contamination; Urban demand of groundwater from Ahmedabad area; Coastal and inland salinity of groundwater Can be extrapolated to parts of Rajasthan Studies in four regions Fresh studies: - Collecting long-term groundwater hydrographs from Bist-Doab for better hold on groundwater balance -Collaborative work with WTC, Coimbatore on groundwater exploitation in Noyyal basin Building blocks of study Region based (4 regions) Issue Based (2 issues) Nation-wide analysis (at district level) Issue 1: Coastal salinity of groundwater Issue 1: Coastal salinity of groundwater Compiling the conceptual picture of coastal salinity across the coast Information on: Geomorphology, Hydrogeology, Tidal patterns, Observed salinity data Important regions: Gujarat (Kutch, Saurashtra, South Gujarat) Tamil Nadu (North) Central Andhra Pradesh Orissa (Central to North) West Bengal In summary Combining analysis of 4 regions with A nation-wide district level analysis and 2 issues To arrive at constraints for groundwater intensification And limits to expansion of area irrigated by naturally recharged groundwater Issue 2: Urban groundwater exploitation Patterns of groundwater use in urban areas: - Major growth of urban areas is happening in 1,00,000 – 1 million population - Most of these cities are highly dependant on groundwater ; much more than million+ cities - The locus of future GW demand in urban areas will be these towns Main data: proportion dependence of urban area on GW 100 % dep On GW 0 1lakh – 1 Million Million +