Land Suitability Evaluation for surface and sprinkler irrigation Using Geographical Information System (GIS) in Guang Watershed, Highlands of Ethiopia

摘要

The main objective of this study was to spatially evaluate land suitability for surface and sprinkler irrigation in the Guang watershed, Ethiopia based on FAO guidelines. Geographical Information System (GIS) techniques were used to develop land suitability map. The 30 m spatial resolution Digital Elevation Model was used to generate slope by using “Spatial Analyst Tool Surface Slope” in ArcGIS environment. Land characteristics (LCs) used as criteria for irrigation requirements were soil depth, soil texture, electric conductivity, pH, drainage and slope factors. The irrigation suitability map was made by matching between reclassified LCs with irrigation land use requirements (LURs) using GIS model builder. Surface soil samples from different soil types were collected and analyzed in the soil laboratory of Amhara Design and Supervision Works Enterprise (ADSWE). The crop suitability evaluation was made by matching between reclassified LCs of the watershed with crop LURs using GIS model builder. The results showed that 990.25 ha (39.61%) of the Guang watershed were highly suitable (S1) for surface irrigation method. However, 2370 ha (94.8%) of the region was unsuitable (N) for sprinkler irrigation method due to soil salinity, drainage and pH. This showed that the surface irrigation method was more efficient than the sprinkler irrigation method to intensively and extensively use the land. The resultant map can assist decision makers in ensuring that lands are used according to their suitability. Keywords: land suitability evaluation, irrigation methods, GIS, Guang watershed