Prioritization of Suitable Sites for Underground Dam Construction Using the TOPSIS Multi-Criteria Decision Making Model in the Sadeghabad Watershed, the Province of Fars

Construction of underground dams (UGDs) is a method of water harvesting in arid and semi-arid regions facing the drought crisis. UGDs are structures constructed in the hidden waterways that can store water in their upstreams. The most important problem in the construction of such dams is finding the right place. The purpose of this research is to locate and prioritize suitable areas for UGDs using the TOPSIS multi-criteria decision making method on the Sadeghabad Watershed, the Province of Fars. By performing field surveys and considering: slope percent, distance from fault, land use, and lithological units inappropriate areas were removed and a map of potential areas for the construction of an underground dam was prepared. According to expert judgement and review of scientific resources, 9 criteria, namely water quantity, dam length and height, reservoir storage coefficient, reservoir volume, abutment, slope, water demands (domestic, agriculture, and industry) and accessibility (road, village, and borrow area) were used to prioritize appropriate locations. Accordingly, 17 initial sites were selected based on expert judgment considering the criteria and overlapping of the base maps. The results indicated that water quantity and water demands with the weights of 0.308 and 0.2048 had the highest rating in priority in locating the underground dam, respectively. In contrast, the length of the axis of the dam and the supporting base of the dam with the weights of 0.019 and 0.023 had the lowest rating in priority. Finally, sites 15, 2, and 14 were given the first to the third priorities. Therefore, due to the serious limitations of groundwater resources in most parts of our country, and particularlyin the Province of Fars, these methods are useful for identification of suitable sites and construction of the UGDs.