Suitable Potential Land Evaluation for Surface Water Irrigation Using Remote Sensing and GIS–MCE in the Case of Rib–Gumara Watershed, Ethiopia

Irrigation plays a vital role to increase agricultural productivity and improve the livelihoods of the communities specifically and the economy of Ethiopia in general. However, there are gaps in development of irrigation schemes and irrigation practice. Therefore, land suitability evaluation is critical to identify the potential lands for surface irrigation. The aim of the study was to identify suitable lands for surface irrigation in Rib–Gumara watershed using remote sensing and GIS-based multicriteria evaluation techniques. The main criteria used in the study were land-use/land-cover (LULC), distance to rivers, slope, and soil physical and chemical properties like soil type, texture, drainage, depth, cation exchange capacity, electrical conductivity (ECe), pHs and exchangeable sodium percentage. The LULC types were extracted from Landsat 8 image using a maximum likelihood classifier. Surface analysis was used to extract slope factor from ASTER DEM, and watershed analysis was also employed to delineate watershed and extract rivers which are drained in the watershed. Likewise, Euclidean distance spatial analysis was also utilized to evaluate the distance of rivers to the potential land. Finally, each criterion was standardized and the analytical hierarchy process was applied to develop suitable irrigation land. The irrigation land suitability was ranked as highly suitable (S1), moderately suitable (S2), marginally suitable (S3) and not suitable (N1). Cross-tabulation was also done to understand the contribution of each factor to suitable irrigation land. The results of study show that 971.37 km2 (27.55%) of the area of the watershed was highly suitable, whereas 2291.28 km2 (64.99%) of the area was moderately suitable, 72.34 km2 (2.05%) was marginally suitable and 190.46 km2 (5.4%) was not suitable. Therefore, the government should intensively work and launch different irrigation scheme projects to utilize these potential irrigation lands of Rib–Gumara watershed.