Locating suitable flood-spreading areas with the best-worst decision-making method (Case study: Farrokhi Dam Watershed, South Khorasan Province)

In recent decades, the problems caused by the occurrence of droughts on one hand and destructive floods on the other hand, have led the country's water resources managers and those involved in the implementation of flood-spreading and artificial feeding plans. The use of water harvesting structures as one of the solutions to reduce flood damage along with the optimization of flood exploitation in the restoration of natural resources has been common for a long time in different parts of the world. Considering that by carefully designing and implementing these measures, the possibility of flooding and damages can be significantly reduced and the underground aquifers can be fed. In this research, the integration of geographic information systems (GIS) and the best-worst method (BWM) was used to determine suitable flood-spreading areas. Twelve influential criteria were identified based on the opinion of experts in the region for flood-spreading, and the weight of each criterion was calculated using the BWM, and the permeability criterion with 0.33 had the most impact on location. The information layers were prepared in the GIS environment for each criterion, finally, by combining the information layers, the entire region was zoned according to the weighted criteria. The results showed that most of the area is in a completely unsuitable condition with an area of 298,725 ha, unsuitable with an area of 21,000 ha, an average condition with an area of 14,300 ha, as well as suitable and completely suitable areas with an area of 45,811 ha. In addition, permeability, slope, and geology respectively with weights of 0.5, 0.186, and 0.13 have obtained the first to third ranks.