ASSESSMENT ON CAUSES OF FAILURE AND REMEDIAL MEASURES FOR ULA GENETA IRRIGATION DIVERSION HEADWORK (THE CASE OF KURFA CHALE WOREDA, EASTERN ETHIOPIA)

Abstract

Diversion headwork usually function as key facilities for irrigation project development, and many of them had been designed and constructed in the county by various organizations in the previous years. However, their functionality to the intended design period is still the questionable subject of this sector. To this end, Assessment on causes of failure and remedial measures for Ula Geneta irrigation diversion headwork, found to be a crucial research matter. An approach is made to investigate the prevalence of problem that causes to malfunctioned the diversion headwork and to understand the problems occurred in hydrologic and hydraulic estimation as well as to check and analysis the stability of proposed structural components. Field survey has been made to understand the current conditions of the diversion headwork. Through the observation the causes on the structures that exposed it to malfunctioning and their consequence on the scheme as a whole have been identified. After the sources of problem is identified possible remedial measures is drawn, that may use as benchmark to renovate the scheme. This will help as a basis for securing function of the Ula Geneta diversion headwork and any other diversion system under operation. Whereas the surveying work, key informant, focused group discussion interview and various cross-section measurement was also done which helped to identify the most frequent problem of headwork, sedimentation around the and upstream of headwork and intake gates which resulted in gate clogging, jamming and stop for water convey. Recently, main factors observed leading Ula Geneta diversion headwork malfunctioned, which will hinder its functionality in the future too are improper location of the headwork, with in short distance of headwork location from the spring eye, i.e. which is the source of water for this project, severe accumulation of boulders and sedimentation at upstream of headwork, scouring at downstream apron and damage for apron structures, undermining or usage of inadequate dimensions of head gates and dimensions of the vertical drop weir settling basin length. In general, the major constraints that involved in malfunctioning diversion headwork, which concerned with scheme implementation and level of community involvement were also identified in this assessment.