As an important content of Earth observation using signals of opportunity, spaceborne Global Navigation Satellite System Reflectometry (GNSS-R) has attracted increasing attention from the scientific community in the last two decades. The short revisit period and moderate spatial resolution make spaceborne GNSS-R uniquely suited for monitoring large-scale surface water changes. This paper proposes a new method for rapid estimation of surface water storage (SWS) by combining surface water extent and depth. Here, the surface water extent is retrieved from spaceborne GNSS-R observations (monthly, 0.01 ° ), while the water depth is obtained by combining the surface water extent with topographic data. Taking the Amazon Basin as the study area, we obtained the variation of surface water storage in the Amazon from July 2019 to December 2024, and the results show strong seasonal and interannual variability. Comparisons to the Gravity Recovery and Climate Experiment (GRACE) total terrestrial water storage anomaly (TWSA) and satellite river discharge measurements both show strong correlations (R values were 0.90 and 0.80, with time lags of 1 and 2 months, respectively). This shows the effectiveness of our proposed method. Finally, we also report possible drought events in the Amazon basin since 2023. This rapidly updatable surface water storage information will facilitate further hydrological studies and analyses.

Esta investigación ha sido financiada por los Fondos de Investigación Fundamental para las Universidades Centrales (CHD300102263715). También ha sido financiada por el proyecto «GENESIS: GNSS Environmental and Societal Missions - Subproject UPC», Grant PID2021-126436OB-C21, financiado por el Ministerio de Ciencia e Innovación (MCIN)/Agencia Estatal de Investigación (AEI)/10.13039/501100011033 y el EU FEDER «Una manera de hacer Europa». El trabajo de Zhongmin Ma ha sido financiado en parte por el Consejo de Becas de China (CSC) a través de un Fondo Estatal de Becas (n.º 202306560073).

Peer Reviewed