Analysis of Rainfall-Runoff, Evapotranspiration, Groundwater Recharge and Storage Anomalies under Climate Change and Land Use Land Cover Change Stresses in Bilate Sub-Basin, Ethiopia.

Abstract

Ethiopia's Bilate sub-basin is highly vulnerable due to a number of factors, including shifting land use and land cover, erratic rainfall patterns, frequent climate changes, and rising temperatures. These variables may have a significant impact on evapotranspiration, runoff, river flow conditions, groundwater recharge, storage, and water level fluctuations. Greenhouse gas emissions, agricultural expansion, poor land use management, and extensive deforestation contribute to significant effects on the water balance systems of the sub-basin. Previous studies and recent field observations indicate that groundwater levels in deep boreholes are declining. However, the local community lacks technical knowledge about perennial water resources and river flow conditions in ungauged catchments. The study also observes that predictions of the effects of climate change on actual evapotranspiration and groundwater recharge rate, as well as evaluations of groundwater storage anomalies, have not been investigated in this sub-basin. The main objective of this research is to raise awareness of the rainfall-runoff and flow conditions of the Bilate River in an ungauged catchment, actual evapotranspiration, groundwater recharge, and trace the groundwater storage anomalies under the effects of climate change and anthropogenic stresses by coupling Station-based hydro-climatic data, including precipitation, temperature, wind, humidity, and radiation, were collected from the Ethiopian National Meteorology Agency from 1989 to 2020, along with stream flow data and well completion report data from the Ethiopian Ministry of Water Resources and Energy. Spatial data, including soil texture, topography, and slope data, were also used for this study. Projected precipitation and temperature were acquired from the CORDEX Africa platform using RCP4.5 and RCP8.5 scenarios. Static groundwater water levels data from 16 wells were measured using a dip meter. GRACE/GRACE-FO terrestrial water storage data from JPL, CSR, and GFZ, GLDAS data including SMS P, Q, ET, and CWS from CLM, NOAH, and VIC portals were obtained. The study employed R-programs, Arc-GIS-10.3, ENVI-5.3, and ERDAS-2015 for land use land