HRU-based Downscaling of GRACE-TWS to Quantify the Hydrogeological Fluxes and Specific Yield in the Lower Middle Ganga Basin

•The GRACE-TWSA-derived GWS manifest a high correlation with SWAT-HRU variables.•SWAT-HRU-based downscaling of GWS is advantageous for basin-scale surface water and groundwater management.•The specific yield has been calculated using regularised robust optimization.•The rate of groundwater decline f...

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