Application of remote sensing techniques to deal with scale aspects of GRACE data to quantify groundwater levels

Groundwater has become an indispensable source of irrigation and drinking water. Industrial dependence on groundwater has also increased drastically. This has led to the rapid exploitation of groundwater. There is accelerating concern about the depletion of groundwater water levels and the deterioration of groundwater quality due to geogenic and anthropogenic causes. The availability of groundwater data is a huge concern, as it requires both time and capital. GRACE satellite project has become a very important tool for groundwater data access. The latest version of GRACE data provides terrestrial water storage, which is the sum of surface and groundwater. The present study details the method to access GRACE satellite data and prepare a spatial map for analysis. It also discusses how to handle data at different resolutions to quantify meaningful correlations. Further, groundwater data is correlated with nitrate data (both are at different grid resolutions) to throw light on the relationship between the important anthropogenic contaminant (nitrate) and groundwater levels. This provides insights into the linkage of quantity with quality. In brief, the important contributions of the paper are: • To provide the methodology to access GRCAE data and prepare spatial maps. • To handle the variables at different grid resolutions. • To correlate two GIS maps at different spatial resolutions.