Dynamics of Water Storage in the Urucuia Aquifer System: An Approach Using GRACE, GPM, and Google Earth Engine

Abstract

The intensive exploitation of groundwater resources, driven by agricultural expansion and climate change, raises concerns about the water sustainability of large aquifer systems. Traditional in situ monitoring presents challenges such as high costs and irregular well coverage, hindering the understanding of aquifer dynamics on a large scale. In this context, remote sensing emerges as a viable alternative. This study analyzed variations in groundwater storage in the Urucuia Aquifer System (UAS) between 2002 and 2023. Gravitational field anomaly data from the GRACE (Gravity Recovery and Climate Experiment) mission and precipitation data from the GPM (Global Precipitation Measurement) mission were used, processed through the Google Earth Engine (GEE) platform. The results revealed a decreasing trend in water storage at a rate of -17.12 ± 2.92 mm/year and a total water deficit of 47.9 ± 8.2 km³ over the study period. The identified seasonal fluctuations were insufficient to offset the cumulative losses, and precipitation, although variable in space and time, did not show a trend that would explain such a decline. The reduction in stored water suggests that intensive groundwater extraction, along with land use changes, has significantly reduced the aquifer's net recharge. The UAS plays a critical role in maintaining the baseflow of the São Francisco River tributaries, underscoring the importance of public policies and continuous monitoring to support water management strategies in regions under strong anthropogenic pressure, such as the MATOPIBA region.