PERFORMANCE EVALUATION AND IMPACT ASSESSMENT OF MEKI - ZIWAY IRRIGATION SCHEME IN THE CENTRAL RIFT VALLEY

Abstract

Knowledge of the performance of existing irrigation schemes helps to identify alternatives that may be both effective and feasible in improving system performance. The purpose of this study was to evaluate the performance of the Meki-Ziway irrigation scheme using different performance indicators (application, storage, distribution, overall irrigation efficiencies and agricultural and water use comparative performance indicators) used as a tool. The study has been focused on identifying the benefits and constraints of technical, socio­ economic and environmental aspects of the irrigation scheme In order to undertake this research primary and secondary data were collected. Primary data include canal water flow measurement, measurement of irrigation water applied to three farmers fields (from the head, middle and tail end water users) using volumetric method, moisture content determination of the soil and semi- structured questionnaire survey and group discussion. Secondary data such as yearly pump operating hour yield per year, area irrigated per crop per year, farm gate price of crops, and other studies like design documents were collected. The result indicated that application and storage efficiency of the irrigation project were 48.71 % and 61.74 %. Distribution losses, which indicates the amount of water lost during transportation of water from the source to the field canal is 45.55%. The over all irrigation efficiency of the scheme is 25.06%. From the analyses of the comparative performance indicators, the result of the • ratios of RWS and RIS ranges from 0.92 to 3.35 and 0.63 to 6.68. Output per cropped area and per unit command area of the seasons vary between 24,412.24 birr/ha to 3,733.10 birr/ha and 273.97 birr/ha to 3579.70 birr/ha respectively. The output per unit irrigation supply ranges from 0.17 to 2.49 birr/m^. Output per water consumed varies from 0.62 to 4.41 birr per m^. The finding of questionnaire survey shows that there are many technical, management, and institutional problems that constrain irrigation performances. Although irrigation is crucial in increasing food production; the government has found it increasing difficult to finance the cost of irrigation operation and management. This has led to rapid deterioration of infrastructure, poor management and subsequent wastage of water and advancing waterlogging and salinity. Poor system performance and the government inability to do something about it have retarded the efforts to increase farmers' participation in irrigation. Therefore, farmer's involvement in irrigation planning should be considered from the beginning.