Flood risk assessment and zoning using multi-criteria Aras technique and single hydrograph (Case Study: Upstream Basin of Soltan Meshkinshahr Bridge Hydrometric Station)

Floods are one of the largest and most common forms of natural hazards, and identifying areas prone to floods is one of the basic measures in natural resource management and development planning. Therefore, the aim of the present study is to zoning the basin upstream of the Soltan Meshkinshahr Bridge Hydrometric Station in terms of flood potential. To achieve this goal by field studies and resource review, first 11 effective factors of flood occurrence in the region including slope, dem, lithology, distance from the fault, precipitation, land use, distance from the river, flow velocity, flow time and soil, were identified and extracted in GIS environment. The standardization of the maps was done using the fuzzy method and then in order to weight the proposed criteria, the CRITIC method was used and the final analysis and modeling was performed using the Aras model. The results showed that the factors of slope, lithology, land use and dem were by weight values, respectively; 0.164, 0.156, 0.118 and 0.116 have the greatest impact on flooding in the study area. Also, according to the results, 20.46 and 32.02 square kilometers of the area, respectively, are in a very high-risk and high-risk category, which indicates the high potential of this basin for floods. The results also showed that the time required for water to flow to the outlet varies from 0 seconds (rain falling on the outlet itself) to 68,000 seconds (over 17 hours). In this case, smooth areas near the basin with the highest time and lowest speed and also in the pastures on the northeast side with the lowest time and highest speed reach the watershed exit point. Therefore, flood risk zoning can be effective in carrying out conservation, watershed management and management measures in this basin.