PERFORMANCE EVALUATION OF WOSHA AND WERKA IRRIGATION SCHEMES IN WONDO GENET DISTRICT, SNNPRS, ETHIOPIA

Abstract

Expanding efficient irrigation development on various scales is one of the best alternatives to provide reliable and sustainable food security. However, many irrigation schemes in developing countries in general and particularly in Ethiopia are performance below capacity. Performance evaluation of irrigation schemes plays a fundamental role in improving irrigation system of a scheme by identifying where the critical problems occurred. Evaluation of irrigation schemes carried out at Wondo Genet SNNPRS, Ethiopia. The primary objective of evaluating Wosha and Werka irrigation schemes using internal and external indicators were to evaluate their performance and suggest possible interventions to enhance their capacity. Internal indicators including conveyance, application, water storage, water distribution uniformity efficiency, and deep percolation ratio were used at the head, middle and tail reach of each scheme. Moreover, external indicators of agriculture output, water supply, water delivery capacity and physical indicator were used for evaluating the schemes. The results showed that the conveyance, application, storage, distribution efficiency of 55.6, 48.2, 89.8 and 91.7%, respectively were found at Wosha irrigation scheme whereas 43.0, 59.0, 87.2 and 91.4%, respectively at Werka irrigation scheme. The agricultural output performance such as OPUIA, OPUCA, OPUIS, and OPUWC were 4213.97 US$/ha, 8732.29 US$/ha, 1.18 and 0.32, respectively at Wosha irrigation scheme and 5840.34, 8534.19, 1.77 and 0.42 respectively for Werka irrigation scheme. Water supply indicators such as RIS and RWS were 0.64 and 0.71, respectively for Wosha 0.48 and 0.55, respectively for Werka irrigation scheme. The result indicates that water delivery capacity of Wosha and Werka irrigation schemes were 1.56 and 1.32, respectively. Physical indicators revealed that irrigation ratio of 0.89 and 0.78 and sustainability of irrigated area of 2.07, and 1.46 were found at Wosha and Werka irrigation schemes. Among the internal indicators, application efficiency was very low especially at Wosha irrigation scheme due to higher water loss through deep percolation. The overall efficiency was also below the desired level, where 26.8 and 25.4 %, respectively realized at Wosha and Werka irrigation schemes. Based on the above observation, adoption of water saving practices such as deficit irrigation, surge and cutoff application to improving application, conveyance and distribution systems can enhance crop productivity per unit irrigation wate