Evaluation of Failures and Design Practices of River Diversion Structures for Irrigation:A Revisit of Two SSI Schemes in Ethiopia

In this paper, the design practices and failure mechanisms of two small scale irrigation (SSI) schemes (Awushoana and Kecha) in Ethiopia were evaluated. An attempt was made to understand the design problems with respect to hydrologic, hydraulic and structural design aspects. The main constraints that contributed to the malfunctioning of the irrigation system in the schemes associated with planning, institutional, social, operational and economic parameters were also assessed. The main problems observed in Kecha scheme were sedimentation at the headwork, damage of intakes and sluice gates, clogging of intakes, damages of distribution systems and ram body. Whereas accumulation of boulders, structural failures of diversion weir, damages of the intake gates, main canals, and absence of the under sluice were observed in Awushoana scheme. Some of the problems attributed to the institutional, social and operational problems due to lack of adequate community participation, the absence of Water Users Associations (WUA's), proper handing over and lack of training and maintenance, evaluation and monitoring issues. Finally, the rehabilitation measures are suggested for the failed SSI schemes. Therefore, this study will help for the SSI schemes to perform better and efficiently to increase agricultural productivity in the study region as well as other SSI schemes in Ethiopia.