Integrated analysis of water storage variability using GRACE and SHETRAN modelling system in the Central Rift Valley basin of Ethiopia

The Central Rift Valley (CRV) basin in Ethiopia has undergone significant hydrological changes driven by climate variability, population growth, and agricultural intensification. However, the understanding of long-term water storage dynamics remains limited due to a lack of in-situ data, which continues to hinder effective water resource management. GRACE satellite observations combined with physically based hydrological modelling were used to assess Total Water Storage Anomalies (TWSA), Groundwater Storage Anomalies (GWSA), and the often-neglected surface water storage component of the hydrological mass balance. Results reveal an increase in TWSA after 2010, which is attributed to enhanced rainfall from an unusual clustering of ENSO and IOD events and to limited groundwater abstraction. Integration of satellite data and modelling provides insight into the temporal dynamics of groundwater storage. This study highlights the need for integrated water resources management strategies that account for climatic variability and increasing anthropogenic pressures in vulnerable basins like the CRV.