Contribution of the GRACE Satellite Mission to Mapping Water Mass Variations in River Basins

Abstract. In the context of climate change, there is a need to understand the dynamics and temporal fluctuations of continental water. Such knowledge is essential for the development of more effective and sustainable management strategies for this indispensable resource. The Earth's gravitational field is not constant but varies over time due to factors such as mass redistribution during the hydrological cycle. The GRACE satellite mission (Gravity Recovery and Climate Experiment) provides valuable information about the geodynamic behaviour of our planet by estimating variations in the continental water storage from the temporal changes in the Earth’s gravity field.
The aim of this work is to demonstrate the contribution of satellite gravimetry to identify patterns of variation in continental water masses within large river basins. For this purpose, a regional study of the TWS (Total Water Storage) derived from GRACE was carried out, focusing on the spatial and temporal changes detected in the La Plata Basin in South America. The periods with the most extreme variations between 2019 and 2023 were analyzed, and the TWS was compared with satellite precipitation data, to subsequently relate them to ENSO events that occurred in the region. The results show that GRACE detected the significant changes in water storage, highlighting in particular the severe drought that occurred in this basin in 2022.