Water Allocation to Small Scale Irrigation Schemes Using the Results of Analysis from WEAP Model: An Application to Mekabo Scheme in Tigray, Ethiopia

The recently commissioned Mekabo Small Scale Irrigation (SSI) scheme may inevitably fail to collect all its water demand from Agula River because upstream water users traditionally privilege themselves with superior water rights. With the present growing desire for constructing more SSI schemes in Tigray region, it is highly likely that the current intensive water competition further escalates to a more stressful level. Given the need for a fair water distribution among all water users, the WEAP model has been employed to develop a management strategy and to perform a rigorous water balance and water allocation analysis. Accordingly, the information about six SSI schemes along Agula River was input in WEAP. A workable water management strategy was adopted and values for the two most insightful indicators "Demand Site Coverage" and "Unmet Demand" were computed and compared. The WEAP Model has competently responded to the probing management strategy and has provided a deep insight into the performance of assigned water allocation scenarios. The findings have shown that, if a fair water allocation were the only primary interest, assigning an equal priority to all water users would be a recommendable choice in WEAP. However, if the study aims at satisfying the full demand of a specific water user; therefore, assigning two-extreme priority settings could be the best-preferred management strategy.