7. Application of Grace Satellite Data for Assessment of Groundwater Resources in Central Ganga Alluvial Plain, Northern India

Gravity Recovery and Climate Experiment (GRACE) is very unique to observe changes in distribution of land water storage from plant canopy to the aquifer. GRACE data gives idea about the regional changes in stored water. The groundwater withdrawal from aquifers in the entire state of Uttar Pradesh with an emphasis on the Lucknow district was studied with the help of the GRACE data and simulated soil moisture (SM) from Global Land Data Assimilation System (GLDAS). The time-series analysis of Lucknow district indicates declining trend of groundwater with mean depletion rate of 1.46 ± 0.74 cm/year. The rest of the parameters like soil moisture, rainfall, and terrestrial water storage do not show continuously declining trend. This indicates groundwater extraction at a faster rate than its recharge. To visualize the seasonal changes in groundwater storage of Uttar Pradesh from 2003 to 2012; pre-monsoon, monsoon, and post-monsoon maps were generated, to represent the overall decreasing trend. The average volumetric groundwater storage loss for the Lucknow district was found to be 0.37 km³. A positive correlation was found between GRACE-derived results and observed water-level data of CGWB (Central Ground Water Board). It is evident from the results that remote sensing is an effective tool to interpolate observed regional groundwater data of wells and to improve estimations of groundwater storage.