ASSESSMENT OF DESIGN PRACTICES AND PERFORMANCE OF SMALL SCALE IRRIGATION STRUCTURES IN SOUTH REGION

Abstract

In developing countries, one of the best alternatives to consider for reliable and sustainable food security development is expanding irrigation development. For countries like Ethiopia where the principal component of project development (finance) is a constraint to develop mammoth dams for irrigation, small scale irrigation can be an alternative solution to enhance production. The southern region as part of the country has been implementing such schemes. Despite remarkable achievements, some of the implemented schemes have totally failed and some are performing below their capacity. A case study considering 26 existing small scale irrigation works (1/3 of the total schemes) in the south region is carried out for this research work and attempt is made to understand the causes of the major problems that are related to the design consideration of the different components of the structure and identify the gap in knowledge between the current design practices and performance of the structures. The pre and post construction institutional aspects, planning problems, economic problems and operation problems are also given due attention. Some of the many structural problems in the existing irrigation structures are problems of sedimentation at the headwork and main canal, problem of seepage through foundation and main canal, downstream scouring, drying of rivers, damage on impervious and flexible apron, change of river course, clogging of outlets and damage on CD works. Likewise, some of the institutional & operation problems are lack of adequate community participation, water right conflict among up streamers and down streamers, market problems, proper handing over problem, lack of proper training and the like. The causes for these problems are generally attributed to the problems in planning, design, implementation and operation of the irrigation schemes.