Abstract:
Irrigation plays a vital role to increase agricultural output and enhance the livelihoods of
the communities. Since identification of suitable areas is essential for the planning
irrigation schemes and also sustainable use of resources. However, there is limited explicit
knowledge regarding to irrigation potential of the study area. So, the research aims to assess
surface irrigation potential in the Mille River catchment. Identification of suitable irrigable
land was carried out by using an integration of geographical information system and
analytical hierarchy process technique by considering criterions incase soil properties,
slope, landuse landcover, and river proximity. Estimation of surface water availability of
the catchment was done using soil and water assessment tool. And also, the gross irrigation
requirement of selected crops (Maize, Onion, and Tomato) was determined using
CropWAT model. Potential irrigable land was identified through weighted overlying of
criterions. Out of the total area of the catchment (4426 km2), highly suitable moderately
suitable and marginally suitable 3672 km2 (83%) was suitable and the rest 753 km2 (17%)
was not suitable for defined land use. The SWAT performance was evaluated as a better
comparison between measured and simulated stream flow, as verified by 0.83 and 0.81 of
R2, 0.79 and 0.78 of NSE, and 3.3 %, and 4.8 % of PBIAS during calibration and validation
respectively. The catchment generates annual volume of 410.91 MCM. The gross irrigation
requirement of selected crops (Maize, Onion, and Tomato) was determined using
CropWAT model. So, gross water irrigation requirement of the irrigable land is 1439 MCM
in one irrigation season. Lastly, the irrigation potential of the Mille River catchment was
estimated to be 163.19 km2 (3.7 % of total land) of areal coverage under the surface
irrigation method through a comparison of surface water and crop requirements of the
catchment. Since, it is small relative to suitable land due to the scarcity of water in the dry
season. Hence, construction of storage structures (pond and reservoir) and deficit irrigation
practices will be necessary to increase irrigable land.
