ASSESSING FARM WATER MANAGEMENT AND INFRASTRUCTURAL PERFORMANCE OF KOGA IRRIGATION SCHEME; IN THE CASE OF INGUTI UNITE

Abstract

Irrigation scheme performance was assessed to evaluate the field water managements and its infrastructural performance .The principal objective of this study was to evaluate field water management and infrastructural performance of Koga irrigation scheme specifically Inguti unit using selected internal performance indicators. Moreover, an institutional support service was evaluated to understand how the scheme is being administered. Field data such as discharge, soil moisture content, and soil physical properties and infrastructures performance were collected. Field surveys and group discussions among the farmers/beneficiaries and Water User Associations (WUA) was also conducted to evaluated existing situation of the support service in the scheme and its performance of WUA. From house hold survey 493 users55 beneficiaries were selected by stratified random sampling. Field surveys and group discussions among the farmers/beneficiaries and Water User Associations (WUA) was also conducted to evaluated existing situation of the support service in the scheme and its performance of WUA. From house hold survey 493 users55 beneficiaries were selected by stratified random sampling. Secondary data such as crop data, climate data and design documents were collected from National Meteorological agency and Koga Irrigation Project office. CROPWAT 8.0 model, GIS and Microsoft office (excel and word) were used for data analysis and documentation in this thesis. Average conveyance efficiency values ranged from 81 to 86.5% for lined (secondary and tertiary canals) and about 64% for unlined tertiary canals. The maximum water loss observed was 0.19 and 0.21l/s/m on lined (secondary and tertiary) canals respectively. And also the maximum water loss observed in unlined tertiary canals was 0.26l/s/m. The average field storage efficiency was found to be 78.9 % and the average field water application efficiency was 53.5%. Average values of the scheme water level ratio, cropped area ratio and infrastructural effectiveness was 85.8%, 94% and 96.2% respectively. The performance of the irrigation scheme was weak due to poor field water managements as indicated above. This might be attributed due to a number of factors observed at field such as illegal water abstraction, unequal distribution of irrigation water, sedimentation of canals and inadequate operation and canal maintenance. Field survey indicates sedimentation, cracking and weeds problems in the lined canals. The overall efficiency of scheme in the Inguti unit was found to be 46.3%. This implies organizational set up and legal enforcement of bylaws and institutional support service was weak to fully maintained and managed irrigation water in the fields