Performance Evaluation of Small Scale Irrigation System in Case of Degero and Gura Daso, Nejo District, West Wallaga, Oromia, Ethiopia

Performance evaluation is a practical tool to examine the achievement of irrigation management in the scheme to meet the growing food demands of the population and make viable water distribution for schemes. Therefore, this study was conducted to assess the performance of small-scale irrigation schemes using water use (input-related) physical and main output-related irrigation performance indicators from the long list of irrigation performance indicators, by using Degero and Gura Daso small-scale irrigation as a case study. This research was carried out starting from January 2022 for the irrigation season. In this study, primary and secondary data were gathered and engaged for the study purpose. For data analysis and manipulation activities, CROPWAT 8.0, GIS, Climwat2 software, and Statistical tools were employed. Then, the schemes were evaluated using groups of performance indicators such as water use, and physical and agricultural outputs. The results obtained showed that the values of relative water supply and irrigation supply were 1. 36 and 2.28 for the Degero scheme, whereas 1.16 and 2.06 for the Gura Daso scheme, respectively. This water use performance indicator shows that there was excess supplied water relative to the demand and it’s possible to increase irrigation area by effective utilization of water. Physical indicators such as irrigation ratio, sustainability of the irrigated area, and the effectiveness of infrastructure showed 0.25, 0.42, and 0.4 for the Degero Scheme, 0.57, 1.33, and 0.8 for the Gura Daso scheme, respectively. Also, the values of the output per cropped area were 3084.2 and 3847.4US$, ha. Similarly, the output per unit irrigation diverted water was 0.41 and 0.69 US$, ha for Degero and Gura Daso schemes, respectively. The output per command area was 1542.1 and 4394US$, m3 for the Degero and Gura Daso schemes, respectively. Likewise, the output per unit of water delivered and water consumed was 0.53, 0.83, and 0.73, 0.86 US$ for the Degero and Gura Daso schemes respectively. As the result showed, the Degero scheme was less performed relative to the Gura Daso scheme. Generally, in both schemes, the currently irrigated area was less than the designed command area. In the end, the following ideas were recommended: Water diversion and conveyance efficiencies in the Degero scheme are very low. Therefore, the diversion and conveyance system should be improved through the maintenance of broken irrigation infrastructures, especially sluice gates at head works and flumes at secondary canals.