GIS-based MCDM modeling for suitable dam site identification at Yeda watershed, Ethiopia

For most developing countries like Ethiopia that primarily followed a mixed agricultural system, water conservation is the fundamental governmental policy to improve agricultural productivity and to ensure food security for the rapidly increased population. So that investigating appropriate dam site location is vital to trap and manage the liberally flowing surface water which is used for innumerable purposes. Identifying suitable dam site locations in the Yeda catchment area to deliver clean drinking water and irrigation is the fundamental subject of this work. Geographic information system (GIS) and analytical hierarchy process (AHP) are the most effective and widely accepted techniques to determine the location of suitable dam site location. To identify potential reservoir sites for multipurpose dam construction, GIS, dam suitability stream model, and multicriteria decision analysis techniques were carried out. Based on the analysis of eight influencing factors (stream density, stream order, land use and land cover, geology, slope aspect, hydrological data, distance from the road, and elevation) and overall suitability output maps, five suitable dam sites have been identified. However, dam sites No. 1 and No. 5 are conventional as suitable dam sites, but they are not really considered suitable dam sites, because of the wide cross-sectional profile (1, 200 m) of the dam proposed in the upper part of the catchment that is uneconomic to construct the dam. And the dam is identified in the lower part of the catchment located in a deeply incised and steep valley and it is difficult to construct the dam as well to extract the water for irrigation and domestic uses but it is suitable for hydropower generation. The three proposed dam sites (dam sites Nos. 2–4) in the middle part of the catchment are preferable for irrigation and clean drinking water supply.