Abstract:
Assessing available land resources for irrigation is important for planning their use and
sustainability of irrigation system. This study was initiated to assess the irrigation suitable
areas of the watershed. The assessment of surface irrigation suitability for Awata sub-basin
was conducted in Guji Zone, Oromia region. The Watershed covers a total area around
148614.8 ha in Genale Dawa Basin. Gathering of the standards for irrigation suitability
corresponding to slope, soil data, land use/cover, distance from outlets and delineation of the
study area, estimation of crop and irrigation water requirements were made to identify
potential irrigable area. Irrigation suitability assessment was evaluated based on FAO
guidelines. Based on the analysis, 3.5 % of slope, 66.08 % of soil, 45.03 % of land use /cover
and 40.15 of distance from the water source of the study area were identified to be in the
range of highly suitable, 16.18% slope, 33.92% soil,46.67% of the distance from water
sources are moderately and 21.53% slope and 25.95% marginally suitable for surface
irrigation. Whereas, 58.79% of slope, 29.02% of land use/cover, and 2.99% distance from
water supply were classified as not suitable for irrigation using surface methods. It was also
found much of the land is not suitable for surface irrigation. The weighted overlay analysis of
the factors and the result obtained that, the total surface irrigation suitability potential of the
study area is 18098 ha, from this; the potentially irrigable land was obtained by multi-criteria
analysis as 11098.03 ha. By comparing gross irrigation demand of irrigable land with the
available flow in rivers, a gross irrigation demand of potentially irrigable land of 11098.03 ha
are not fulfilled with the present flow, so providing a means of water storage is necessary to
irrigate the potential command area.
