Bandsar is a traditional large plot, which is built by creating an embankment on the level lines in the plains around ephemeral rivers, or is built across the waterways like small dams in the hill region, and directing and maintaining the flood or runoff of the hillslopes and uplands. So, it is a solution for harvesting rainwater in arid and semi-arid areas. Therefore, the purpose of this research is to locate and prioritize the suitable areas of the Bandsar in the watersheds of the Qaenat region to control floods, recharge the Qanats, wells, and springs in arid areas with the Best-Worst Method (BWM) and Geography Information System (GIS). In order to determine and locate suitable sites for the construction of Bandsar from 12 different criteria, including slope, distance from rivers, distance from villages, distance from Qanats, distance from roads, distance from faults, distance from wells, geomorphology, geology, permeability, available source, and land use has been used. Criteria were weighted using the BWM method, and the priority of each criterion was determined. Results showed that among the considered criteria, distance of river with a weight of 0. 214 has the first rank, permeability with a weight of 0. 151 has the second rank, and slope with a weight of 0. 1123 has the third rank. The study area divided into 12 zones based on natural resource priority, that named the English alphabet (A-J). Finally, region B with a score of 0. 63 is the best region and region J is the worst region with a score of 0. 15.