Assessment of Surface Water Resources in Case of Muger Sub Basin, Ethiopia

Water resources assessment (WRA) is the process of measuring, collecting and analysing relevant parameters on the quantity and quality of water resources for the purposes of a better development and management of water resources. The aim of this research is Assessment of Surface Water Resource in Case of Muger Sub Basin in Ethiopia. The future possible local climate variables are extracted from Abbay basin RCM and then the bias-corrected with observed meteorological variables which are then used as input to the soil and water assessment tool (SWAT) model as climate data, in addition to climate data soil data, land use land cover, slope of the sub basin and weather Generator together are used to simulate future water yield of Muger sub-basin. Soil and Water Assessment Tool (SWAT) was adopted to perform runoff simulation. The good performance of the SWAT model was confirmed, with a Nash-Sutcliffe efficiency (NSE) and determination coefficients (R2) of 0.76 and 0.99 respectively during calibration for monthly runoff, Nash-Sutcliffe efficiency (NSE) 0.63 and determination coefficients (R2) 0.99 respectively during validation for monthly runoff. The variation of precipitation in Muger sub basin decreased by (2010-2023), (2024-2037) and (2038-2050) from base period (1996-2009) will be 0.36%, 1.076% and 1.74% respectively, Maximum Temperature in sub basin increase from base period (1996-2009) by 0.55%, 2.32% and 4.6% and also minimum temperature in Muger sub basin increase by (2010-2023), (2024-2037) and (2038-2050) from base period (1996-2009) was 0.83%, 2.80 and 8.54% respectively. From this study, it was observed that due to climate change Average annual water yieldin Mugersub basinin (1996-2009), (2010-2023), (2024-2037), (2038-2050) is 4634.07 Mm3, 4525.92 Mm3, 4456.20 Mm3 and 4411.89 Mm3 respectively. Generally as Temperature increase in the study area the amount of rainfall decreases which directly affect the amount of water yield.