Assessment of Surface Water Resources Based on Different Growth Scenarios, for Borkena River Sub-basin, Awash River Basin, Ethiopia

Abstract

The total annual river flow at the Awash Kombolcha sub-basin of the Borkena river station was estimated to be 4.6 billion cubic meters by 2019-2030. The current average annual flow at the exit measurement station is 544.5Mm3 of the water resources available in the study area. The monthly peak flow of the Borkena River occurs from July to September. In addition, the highest monthly average flow is in August and the lowest is in June, with values of 150.7 million m3 and 6.1 million m3 respectively. WEAP model performance or model calibration was simulated between 1998 and 2018 and quantitative statistics were calculated for each previously observed flow coefficient of determination, R2, Nash Satcliff efficiency, etc. Percent bias, evaluated using PBIAS), then R2 = 0.988 and NSE = 0.70 PBIAS = 0.8 results. Assuming a relatively low reserve flow of over 92% corresponding emission analysis concept of 142 million population was considered as input. The performance balance of the model is 2019 demand data and simulated flow data at the Khemiessy exit supply. In the 2030 average growth scenario, the herd of livestock increased again by 1,610,161 to 1,776,937, with a corresponding growth rate of 0.7% per annum of 81.9 million m3 . This means that annual water usage has increased by 90.5% compared to the current scenario. Other optional implants such as rainwater harvesting, surface water harvesting, and groundwater need to be booked to meet the peak demand for dry months where the availability of surface water resources in these scenarios is felt in all water utilization sectors.