Performance Of Rehabilitated Irrigation Systems: A Case Study Of Igomelo Irrigation Scheme In Tanzania

ABSTRACT 

Many irrigation systems indicate failures with respect to their anticipated benefits. However, improvement of these schemes can be brought about through their rehabilitation. The aim of this study was to evaluate the performance of Igomelo rehabilitated irrigation scheme covering both the performance of irrigation water distribution systems and the roles of irrigators association.The scheme was divided into three reaches upper, middle and tail end. Three plots with maize, tomatoes and onions from each reach were randomly selected. Amount of water entering the plots were monitored for adequacy, equity, dependability and productivity analysis. Also three canals each from the mentioned reaches was assessed for seepage, maintenance and conveyance efficiencies. The IA wasevaluated using indicators such as structures’ condition, effectiveness in fees collection (EFC) and financial self sufficiency (FSS). A structured questionnaire was administered in order to obtain information on irrigation and roles of irrigators association. The conveyance efficiencies in the main canal were 68.2% with values between 69and 87% for tertiary canals. Seepage ranging between 0.044 and 0.104l/s per meter lengthwas also observed in the canals. A SCI of 90% was obtained showing structures in good working condition.Despite a good FSS (1.10 -2.21) some structures lack some components. Adequacy in water supply is good with Relative Water Supply (RWS) between 0.92 and 3.96with highest RWS at the middle reach. However, the dependability in water supply was low while equity in water supply was observed in tomato plots than in maize and onions. The output per unitwater supply for tomato was between 684.4 and 14492.55 US$ha-1while the highest output per unit water 3 supply for tomato and maize were (1.68kg/m3 )and (0.83kg/m3 )respectively. However, not significantly different (p< 0.01). From both the IA and the water distribution systems the performance of the scheme is good.