Abstract
The water resources of Keleta catchment in the Awash River basin are utilized by various users. However, the current and future demands for water and its availability in the catchment have not been quantified. Therefore, this study aimed to evaluate the current and future water demand and availability by employing multiple climate models under the representative concentration pathways (RCP 4.5 and 8.5) scenarios. A power transformation method was applied for precipitation and linear shifting and scaling techniques were used for temperature to obtain bias-corrected future climate data. These bias-corrected daily precipitation and temperature datasets were utilized to simulate surface water availability for reference (1971–2000) and future climate scenarios (2041–2070) periods under RCP 4.5 and 8.5 using the Hydrologic Engineering Center-Hydrologic Modeling System (HEC-HMS) hydrological model. The Water Evaluation and Planning (WEAP) model was employed to assess water allocation within the catchment.The HEC-HMS model simulation results revealed that the simulated hydrograph better captured the pattern of observed hydrograph for both calibration and validation periods. The results of the maximum and minimum temperature for the future period from 2041 to 2070 revealed increase on average by 1.62 °C and 1.43 °C for RCP 4.5, while by 2.26 °C and 1.71 °C for RCP 8.5, respectively. The average annual water availability and demand under current condition were found to be 247.4 million cubic meters (MCM) and 7.13 MCM, respectively. Future surface water availability is expected to increase by 23.9% under RCP 4.5 and 28.9% under RCP 8.5 compared to the refernce period. The WEAP simulation revealed monthly variations in water availability, highlighting unmet demand during the dry months of December to February due to reduced water availability during this period. This study suggests for integrated planning and management of the catchment area, particularly focusing on various water resource development activities, especially during dry seasons.