Actual evapotranspiration (AET) is the process through which water is transported from land surfaces to the atmosphere through evaporation from water bodies and soil, and transpiration from vegetation. This study analyzes the spatial and temporal patterns of AET in the Grand Ethi- opian Renaissance Dam (GERD) region from 2001 to 2023, with a focus on climate variability and land use/land cover (LULC) changes. Aquantitative methods explanatory research design was adopted, AET was simulated using the Surface Energy Balance Algorithm for Land (SE- BAL), executed on Landsat and MODIS imagery within Google Earth Engine (GEE). To analyze rainfall variability, CHIRPS (Climate Hazards Group InfraRed Precipitation with Station data) was used to provide high-resolution precipitation estimates, offering a more detailed under- standing of temporal and spatial rainfall patterns. LULC change was measured through a Ran- dom Forest classifier to identify changes in forest cover, agricultural land, water bodies, and built-up land use. Random Forest regression analysis was utilized to explore the relationship between AET and climatic drivers, such as rainfall and land surface temperature (LST). An overall increase in AET post-GERD reservoir impoundment was recorded, from 5.4 mm/day in 2020 to 6 mm/day in 2023, driven by rising rainfall (R² = 0.93) and falling LST (R² = 0.87). The Mann-Kendall trend test showed no notable change in annual rainfall (Kendall's tau = 0.047, p = 0.77), but a weak negative trend in LST (Kendall's tau = 0.27, p = 0.073). The LULC analysis revealed deforestation and decline cropland, along with the expansion of water bodies and built- up areas, due to the GERD construction and water filling. The Random Forest model was result- ing showed rainfall was highly explained with value (R² = 0.93, MAE = 0.32), confirming a strong correlation between AET and climatic variables. The findings underscore the vital role of the GERD in managing local hydrological cycles and climate, necessitating adaptive manage- ment strategies and continuous monitoring It is recommended to implement interventions such as utilizing innovative technologies to reduce evaporation, promoting sustainable land and water management practices, enhancing climate monitoring, supporting reforestation efforts, and en- gaging local communities. Effective management of natural resources is crucial for achieving long-term ecological resilience in the region