5. Zoning Flood Risk of Catchments Prone to Flooding by Geographical Information Systems Analysis Approach

Flood risk prioritization is considered necessary and important because of their development on the margins of floodplains recognizing and paying attention to rivers. Therefore, the prioritization of watershed sub-basins is one of the most important solutions for the comprehensive management of watersheds and is also very important in natural resources management. This research aims to prioritize and zonate flood sub basins of the Gavkoshak watershed in the west of western Shiraz city and 13 km eastern Kazerun city based on morphometric parameters using a geographic information system (GIS). To prioritize and zoning the sub-basins based on all the investigated variables, the new combined method of morphometric analysis and statistical correlation was used, and the relationship between the parameters and the weight of each of them was analyzed using Kendall's tau correlation and weighted sum analysis (WSA) methods. The results show that the new prioritization method was not able to determine the ordinal priority of all watershed sub-basins, but this method is based on the degree of risk and finally preparing the flood zoning map, indicating the division of the area into five low-risk zones (31 sub-basins), relatively low risk (4 sub-basins), moderate risk (5 sub-basins), relatively high risk (1 sub-basin) and high risk (2 sub-basins). Therefore, by having this map and the results obtained from it, which means knowing the areas in terms of flood potential, it is possible to prioritize correctly in management decisions, projects in flood-prone areas with very high and dangerous flood potential, especially areas that are at risk of damage caused by floods.