Check the Factors Affecting the Extent of Flood Zoning Using the Geographic Information System of the Karun River in the Area of Zaras Castle to Jafarabad

In this study, the flood zoning in the Karun River in the area between Zaras Castle and Jafarabad has been determined. For this purpose, using the topographic map and satellite images, the exact course of the river was determined and the initial processing was done on its information. Then flood zoning was obtained with return periods of 500 years, 200 years, 100 years, 50 years, 25 years, 10 years, 2 years.

In this research, flood zoning of Karun river, which is one of the main and permanent rivers of Khuzestan province. was investigated in the area from Zaras Castle to Jafar Abad. The aim of the current research is to zonate the risk of flooding occurrence and identify the villages at risk of flooding, through the preparation of the river boundary map for the return period of 500 years, 200 years, 100 years, 50 years, 25 years, 10 years, 2 years in the Karun river using the Hec-RAS model in the ARC-GIS environment. In this research, the discharges of this river are based on the probability of its occurrence using Johnson sb statistical distribution was calculated.

In this research, in addition to calculating flood depth and flow velocity parameters, factors such as shear stress and flow strength for different return periods were calculated and investigate. Shear stress and flow strength are effective parameters in the flood risk, so it is important to investigate them.

In this research, flood inundation risk zoning was done and the villages at risk of flooding were identified by preparing a map of the River boundary for the return period of 500 years, 200 years, 100 years, 50 years, 25 years, 10 years, 2 years, and Discharges of this river were calculated based on the probability of its occurrence using the statistical distribution of Johnson sb. Among the 10 villages located along the Karun river, Jafarabad villages, Hasht Lak Kanaar, Zaras Qala, Lali New Road bridge are the most vulnerable areas, which regardless of the rules of construction and non-observance of the river boundary are built in its main bed. Factors such as the change of land use and the transformation of floodplains into agricultural and garden lands, disregarding the river boundary and encroaching on the floodplain of the river have increased the potential of flood risk and as a result the villages are more vulnerable, especially in the flood zone with a return period of 500 years.