The assessment of rice irrigation water use efficiency at Rwangingo marshland

Abstract

Poor water use management in agricultural sector should cause deep water volume depletion on global world therefore, this thesis is concerned totheassessment of rice irrigation water use efficiency at Rwangingo marshland. The Rwangingo marshland has a bigger dam located at 1 0 35’ 34.70’’S and 300 17’26.64’’E, Elevation 1413m with abundant water of 3,751,123 m3 in Gatsibo and Nyagatare, Eastern province of Rwanda.I have chosen to study irrigation water use efficiency because agriculture is the major consumer of water. Worldwide agricultural land might double in subsequently 50 years if trends in foodstuff consumption and existingactivities of production continue. Moreover, the Rwanda water resource board (RWB) together with the World Bank water resources group has performed a hydro-economic analysis in which projections by 2050 shows that irrigation will be the most water consuming sector and the RWB has carried out a study for the inter-catchment water transfer in which the projections by 2040 shows that the eastern province and Amayaga region will be under water deficit. Therefore Rwangingo marshland is one of the marshland that use more water for agriculture and livestock and this marshland is fencing both anthropogenic and natural problems such as water insufficiency in dry season, flooding during rainy season, undulating topography, competition of water for animal support and poor water use management. After this study, Iwas found that water conveyance efficiency of the primary, secondary, and tertiary channel varies from 40 to 77% and it means that water lost varies between 60 to 23%, the average of sum conveyance efficiency wereestablish to be 59% and average water shrink in conveyance channel was 41%. Refer to table 2, the accepted conveyance efficiency should not below 65 %, while this study obtained conveyance efficiency of 60%, it means that water in seepage, lack of clearance of canal, canal sedimentation, evaporation of conveyance loss was 41 % through clearing of canal. Rice crop water use efficiency of rice in Rwangingo marshland at whole season is 37 % in 150 day of rice growth stage.Efficient water management of Rwangingo marshland through suitablewater application efficiencies and it wasvery essentialfor understandingof proper decisions concerningthe water use managementunderneath climate variability in the future.