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Groundwater is one of the most important natural resources and major source for fresh water. Since green revolution and industrialization, stress on groundwater has increased tremendously as its utility has increased many-folds. This is particularly true in tropical country like India, where majority of the population and agriculture depends on groundwater. With the -projected changes in the rainfall pattern across Indian sub-continent, it is imperative to study the current status of groundwater and its connection with the rainfall changes. This is essential to formulate policies and implement sustainable practices to preserve groundwater. Recently remote sensing-based estimate of groundwater changes has gained prominence, particularly so after the availability of GRACE data.
This study also has shown the usage of new GRACE CSR product which can be used in smaller basins. Trend analysis of groundwater storage shows decreasing groundwater levels across majority of the regions, with a maximum decline of about 8 cm/year in the northern plains and the Western Ghats. Though there is a good correlation found between groundwater measured by GRACE and precipitation, a seasonal analysis of rainfall and groundwater storage would have revealed more patterns and helping more understanding about how rainfall affects groundwater and to what extent. Monthly comparison between rainfall and ΔGWS using cross- correlation has shown that groundwater has been influenced by variation in rainfall after a lag of one month and rain water as a source for groundwater recharge.
Key words: Groundwater, GRACE, precipitation, Physiographic Zones, trend analysis, cross-correlation.
