  The depletion and variations of groundwater storage~(GWS) are of critical
importance for sustainable groundwater management. In this work, we use Gravity
Recovery and Climate Experiment (GRACE) to estimate variations in the
terrestrial water storage~(TWS) and use it in conjunction with the Global Land
Data Assimilation System~(GLDAS) data to extract GWS variations over time for
Indus river basin~(IRB). We present a data processing framework that processes
and combines these data-sets to provide an estimate of GWS changes. We also
present the design of a band-limited optimally concentrated window function for
spatial localization of the data in the region of interest. We construct the
so-called optimal window for the IRB region and use it in our processing
framework to analyze the GWS variations from 2005 to 2015. Our analysis reveals
the expected seasonal variations in GWS and signifies groundwater depletion on
average over the time period. Our proposed processing framework can be used to
analyze spatio-temporal variations in TWS and GWS for any region of interest.
