Gis-Based Physical Land Suitability Assessment For Surface Irrigation: Case Of Katar River Watershed, Ethiopia

Abstract

The is study aimed to assess the physical land suitability for surface irrigation in Katar River watershed by using Geographic Information System (GIS). Watershed delineation, identification of irrigable land, and estimation of surface runoff and irrigation water requirements were the steps followed. Irrigation suitability factors such as slope, characteristics of soil such as type, texture, depth, drainage and land use/cover were classified based on the Food and Agricultural Organization guideline for land evaluation in to highly suitable (S1), moderately suitable (S2), marginally suitable (S3) and marginally not suitable (N) suitability classes independently, where the final potentially irrigable land was identified by weighting the factors of suitability. Irrigation water requirement of four commonly grown crops (Tomato, potato, Cabbage and small vegetables) were computed from climate, crop and soil data inputs using Crop Water Requirement (CropWat8.0) software and the capacity of low flow (90% time of exceedance flow of Katar River) were estimated. The suitability analysis of the parameters indicated that 45.33% of slope, 99.6 % of soil, and 79.9 % land use/cover of the study area were classified as potentially suitable for irrigation development . By weighing analysis of all parameters 93.47 % of the study area was found in a range highly suitable to that of marginally suitable whereas about 6.53 % was restricted for irrigation developments. By comparing the required water and available monthly flow of the river, the river had insufficient capacity for irrigation application of the command area.