Terrestrial Water Storage and Ground Water Variability Across the River Basins in Nigeria Using Satellite Gravimetry

Abstract

Terrestrial water storage (TWS) plays an important role in the global water cycle. Measuring dynamic changes in TWS is essential for water resources management, weather-related hazard monitoring and agricultural production. The Gravity Recovery and Climate Experiment (GRACE) and its following mission (GRACE-Follow on) have provided monthly terrestrial water storage anomalies (TWSA) at a quasi-global scale. Water resource management in Nigeria faces increasing challenges due to climate variability, population growth, and land use changes. This study presents a satellite-based, remote sensing approach in the estimation of Terrestrial Water Storage (TWS) dynamics across Nigeria’s twelve River Basin Development Authorities (RBDAs), utilizing data from the GRACE and GRACE-FO satellite missions. The research aims to quantify monthly TWS anomalies, and additionally, it estimates groundwater storage anomalies (GWSA) by integrating GRACE-derived TWS with soil moisture and surface water datasets. Results reveal pronounced seasonal fluctuations in TWS, with wet seasons (April – October) showing positive anomalies and dry seasons (November – March) marked by deficits. Southern basins like Lower Benue and Cross River exhibited higher water retention, while northern basins such as Sokoto faced persistent water stress. Long-term trends indicate a decline in TWS recovery during recent wet seasons, particularly in 2024, suggesting the impact of climate change and increased evapotranspiration. Numerically, there is over 1000 percentage change in TWS between 2004 to 2024. Groundwater remained relatively stable, acting as a buffer during dry spells, whereas surface water and soil moisture showed more dynamic responses to rainfall and evaporation. The study concludes that satellite-based monitoring offers a robust framework for understanding Nigeria’s hydrological dynamics. It recommends basin-specific interventions, including improved dam infrastructure, climate-resilient land use practices, and groundwater recharge strategies. These insights are vital for informing national water policies and enhancing resilience against future hydrological uncertainties.