Synergistic Pathways of the Grand Ethiopian Renaissance Dam (GERD) and green legacy initiative in shaping hydrological stress and land surface temperature in Abay Basin

The Great Ethiopian Renaissance Dam (GERD) construction and the Green Legacy Initiative (GLI) have significantly contributed to environmental resilience, including climate change mitigation, soil moisture, hydrology, riparian vegetation, and agricultural land. The present study evaluated changes in Land Use and Land Cover (LULC), moisture, and temperature conditions between February 2018, 2022, and 2025. Landsat satellite imagery was employed to classify LULC changes. Normalized differences indices for vegetation (NDVI), water (NDWI), soil moisture (NDMI), soil adjusted vegetation index (SAVI), evaporation stress index (ESI), and land surface temperature (LST) were analyzed via the ArcGIS software. A linear regression model was used to analyze the association between LST and spectral indices. Results indicate that LULC changed significantly between 2018 and 2025, with agricultural land decreasing by 12.61% and bare land by 94.29%. Meanwhile, forestland, grassland, and water bodies grew by 156.48%, 202.04%, and 1150.29%, respectively. The NDWI also exhibited an increasing trend of 3% around the reservoir following the reservoir filling practices, decreasing by 4%, particularly in the western and southern parts of the sub-basin. Minimum ESI increased from 0 to 0.289. Maximum ESI increased by 254.25% indicating a new vegetation moisture content or reduced stress. Minimum LST decreased by 1.3. Maximum LST increased by 5.8°C due to the GERD and GLI. All spectral indices are negatively associated with LST and positively associated with ESI. Thus, the GERD and GLI projects significantly improve vegetation cover, enhance water bodies, increase soil moisture, and reduce LST. Further studies should be conducted to assess long-term environmental and socio-economic impacts.