Interannual hydrological variability in the Mississippi River Basin based on contemporary geodetic measurements and land surface models

The impact of climate change on terrestrial water storage (TWS) is critical for understanding the global hydrological process. The Global Positioning System (GPS) measurements, Gravity Recovery and Climate Experiment (GRACE), and GRACE Follow-On (GFO) data were used to measure the processes involved in the hydrological process in the Mississippi River Basin (MRB) from 2002 to 2021. The common-mode component (CMC) of the GPS network in the MRB obtained using principal component analysis (PCA) was utilized to study the hydrological loading deformation. The data from GRACE/GFO and hydrological models revealed a long-term trend of reduction in the TWS and obvious depletion of the groundwater storage (GWS) in the southwestern part of the MRB. Both GRACE/GFO and the GPS can accurately detect elastic land deformations in the MRB due to hydrological anomalies caused by El Niño/ Southern Oscillation (ENSO), while the sensitivity of GPS in Tennessee regions to net precipitation around 2016 is higher than that of GRACE/GFO. Furthermore, numerous interannual fluctuations and long-term periodic signals observed in both GPS and GRACE/GFO measurements are found to be intimately connected with hydrological processes and ENSO. The findings demonstrate that modern geodetic methods are useful in monitoring the impacts of climate change on hydrological process.