ASSESSMENT OF SURFACE IRRIGATION POTENTIAL OF GUDER SUB-BASIN, ABAY RIVER BASIN, ETHIOPIA

Abstract

Assessing available land resources for irrigation is important for planning their use. Irrigation land suitability assessment has an important role in the utilization of scarce physical land resources. The study aimed at the surface irrigation potential and land suitability assessment for using GIS tools. By delineating the boundary of the study area, irrigation suitability of each physical land was classified based on the FAO guideline for land evaluation into S1, S2, S3, and N suitability classes independently, where potentially irrigable land was identified by weighted overlay analysis of factors of suitability. The main suitability factors using to identify the existing and potential irrigable land were slope, soil, land use/cover, and distance from water supply (sources). Surface water availability and land potentially suitable for irrigation development were considered. Surface water potential was examined by analyzing long-term daily historical river discharges. Analytical Hierarchy Process with the integration of GIS-based multicriteria decision making an approach using DEM and Sentinel 2A satellite data was utilized to evaluate land suitability for Surface irrigation in Guder sub-basin. A pairwise comparison matrix is used to establish the weights. About, 0.3 % area is classified in the class as highly suitable, 47.6 % as moderately suitable, 49.8% in marginally suitable, and 2.4 % in unsuitable for Surface Irrigation. The total command area which can be irrigated in upper, middle, and Lower Guder Catchment are calculated and found to be 122,515.3 ha, 130,027.06 ha, and 67,491.25 ha respectively. The result after overlay analysis in Arc Map indicated that approximately 317,748.71 ha (47.9%) of the Guder sub-basin is suitable highly to moderately for surface irrigation. The potential of surface water was evaluated concerning the water requirements of dominant crops in the study area. In the Upper Guder 13,272.72 ha could be irrigated with the available river flow for the maximum gross water demand. Similarly, it is 50,571.43 ha and 11,639.43 ha for Middle and Lower Guder watersheds respectively. Among the total potential suitable land in Guder sub basin the river flow can irrigate 75,483.58 ha (23.9%) area. Thus, the irrigation potential can be met by storing water during rainy season flows