Optimal Allocation Of Water Resources To Competing Demands Under Diffrent Scenarios In The Katar Sub-Basin, Central Rift Valley Basin, Ethiopia

Abstract

As water is significant forever, analysis of both available and water demand within the basin is critical. This will enable to formulate water allocation strategies and allocation principles for present and future planning. Lack of sufficient knowledge about available water resources, unbalance between supply and demand coordination in water resources management, conflicts among different water use sectors, and improper distribution of available water resource in the river watershed are still a serious problem in the world including Ethiopia. Therefore the major goal of this study was to estimate the current and future demand and supply of water and water allocation scenario for Katar River sub basin. To achieve this, evaluation of water demands were modeled using the WEAP model. Future water demand was estimated using three different scenarios namely short-term, medium term, and long-term scenario. According to the result obtained from the model, the total estimated mean annual surface runoff that leaves the basin is 289.61MCM. Both the calibration and validation result showed a very good performance with a value of R2 and NSE of 0.96, and 0.85 for calibration and 0.98, and 0.99 for validation respectively. The estimated mean annual actual evapotranspiration, precipitation, interflow, and Base flow is 2649.72 MCM, 3095.67 MCM, 78.74 MCM and 77.60 MCM respectively. Total available annual stream flow at the outlet Point of Katar River is 445.95 MCM. Current water demand for Domestic, Industrial, Livestock, and Irrigation was 45.13 MCM. The water demand result shows there is no shortage of water in the current situation. To forecast water demand up to the year 2050 three basic scenarios were formulated. The first scenario, short term scenario has not much effect on future water demand. In the medium term and long-term scenario, the development of irrigation activities and expansion of industries in the catchment was applied. In the medium and long-term scenario shortage of water demand will happen in Industrial and irrigation. Based on the result of this research it has been recommended that both water supply and demand side management measures should be well implemented in an integrated manner.