Constructionof underground dams is a practical solution to save groundwater in alluvium watersheds, particularly in arid and semi-arid regions where surface water scarcity is an environmental challenge. Considering socio-economic and environmental benefits of underground dams, the accurate locating is the primary consideration for dam construction. The new technologies and methods are a step toward the proper locating to reduce the risk of underground dam construction. In this study, two methods,decision making and geographic information system (GIS) were used for locating suitable places for underground dam construction in Hamedan-Bahar watershed where water shortage has been a serious problem during the last decade. In the first step, the effective factors in locating and construction of the dams underground were identified, and then their GIS information layers were created. The primary selection maps of suitable sites were provided using Boolean logic method in ArcGIS software. The Analytical Hierarchy Process (AHP) was then applied in EXPERT CHOISE. In the next step, the results of Boolean logic and AHP methods were overlapped to provide the final selection map. A consistency rate of 0.06, showed a relatively high accuracy of weighting process. Considering the normal weights, geology and distance of well, springs and qantas were found to be the most and the least effective criteria, respectively. Furthermore, the final selection map suggested the surrounding area and the outlet of the plain as the most suitable sites for dam construction.
