Gis Based Physical Irrigation Potential Assessment: The Case Of Sibilu River Catchment, Ethiopia

Abstract

Evaluating the suitability of a landscape for irrigation in advance is critical for the sustainability of an irrigation system. It needs supplementation from irrigated agriculture during dry season. Assessment of land suitability for irrigation purpose is important to utilize scarce resources efficiently and effectively for sustainable production of crops. There were only few studies on assessment of irrigation potential in Ethiopia and none has been done in the study area. Therefore, the aim of study was to assess the physical irrigation potential of Sibilu River catchment, using Geographic Information System. The irrigation suitability factors such as slope soil and land use land cover were weighted overlay in order to determine the most suitable land by using pairwise analysis in order to determine the weight of each parameter. The collected data were checked for inconsistency using double mass curve and the missing metrological data were filled by normal ratio method. Irrigation suitability factors were classified based on the Food and Agricultural Organization guideline for land evaluation in to highly suitable, moderately suitable, marginally suitable and not suitable classes, where the final irrigable land was identified by weighting the factors of suitability. The study used slope, soil and land use/ cover for irrigation suitability analysis with Geographic Information System based. The irrigation suitability analysis of these factors in dicated that 56.5% of slope,19.3% of soil and 89.82% of land use/cover area were in the range of highly suitable for surface irrigation system. Over all the weighted overlay analysis of these factors gave potential irrigable land 57.53% of the study area were found to be highly suitable whereas 0.42% not suitable for irrigation developments. To grow on these identified irrigable areas, three crops such as cabbage, potato and pepper were computed from climate input data using Food and Agricultural Organization penman-monteith in CROPWAT 8.0 software and the command area was identified by comparing the irrigation water demand and water potential of the water source in the study area. In Conclusion, Sibilu River is highly suitable for surface irrigation in terms of suitability factors. However, only 133 ha were irrigable and therefore the dry flows should be increased or ground water should be constructed and water should be stored to meet irrigation potential.