Flooding Assessment of Qaleh Chai basin Using MABAC Multi Criteria Decision Making Method

Floods are considered the country's most frequent and destructive hazards, causing significant damage every year. Prioritizing basins regarding flood potential is the first step in managing this natural hazard. The Qaleh Chai basin, located in Ajabshir County (East Azerbaijan Province), is considered one of the basins with high flood hazard potential. Therefore, preparing flood hazard maps in this basin seems essential for flood hazard management. The main objective of this study is to prioritize the flood potential of hydrological units of the Qale Chai basin using multi-criteria decision-making techniques and geographic information systems. In the present study, 11 criteria effective in the flood potential of sub-basins were used. These criteria are: Elevation, slope, River density, lithology, Gravilius coefficient, land use, Normalized Difference Vegetation Index (NDVI), precipitation, order of stream, number of streams and area. In the following, the Analytical Network Process (ANP) model was used to determine the weight of the criteria and the MABAC model was used to prioritize hydrological units and identify units with high flood potential. The results of weighting the criteria using the ANP model showed that the lithology, slope, and Normalized Difference Vegetation Index (NDVI) had the highest weight with coefficients of 0.191, 0.189, and 0.135, respectively, which indicates that these criteria play an important role in the flooding potential of hydrological units. In contrast, the two criteria, the number of streams and the order of streams had the lowest weight. Prioritizing the hydrological units also showed that units 2A, 2B and 1C have high flooding potential. These units cover an area of over 125 Km2, which includes 30% of the basin's total area. Hydrological units with high flood potential due to high slopes and lack of suitable vegetation provide conditions for the formation of surface runoff and, as a result, floods in these basins.