Assessment of the Susceptibility of Urban Flooding Using GIS with an Analytical Hierarchy Process in Hanoi, Vietnam

The incidence of floods is rapidly increasing globally, causing significant property damage and human losses. Moreover, Vietnam ranks as one of the top five countries most severely affected by climate change, with 1/3 of residents facing flood risks. This study presents a model to identify flood susceptibility using the analytic hierarchy process (AHP) in the GIS environment for Hanoi, Vietnam. Nine flood-conditioning factors were selected and used as initial data. The AHP analysis was utilized to determine the priority levels of these factors concerning flood susceptibility and to assess the consistency of the obtained results to develop a flood-susceptibility map. The performance of the model was found to be significant based on the AUC value for the obtained receiver operating characteristic (ROC) curve. The flood-susceptibility map has five levels of flood susceptibility: the area with a very high susceptibility to flooding accounts for less than 1% of the map, high- susceptibility areas for nearly 11%, moderate-susceptibility areas for more than 65%, low- susceptibility areas for about 22%, and very low-susceptibility areas for 2%. Most of Hanoi has a moderate level of flood susceptibility, which is expected to increase with urban expansion due to the impacts of urbanization. Our findings will be valuable for future research involving urban planners, and disaster management authorities and will enable them to make informed decisions aimed at reducing the impact of urban flooding and enhancing the resilience of urban communities.