A Novel Framework for Urban Flood damage Assessment

Abstract

In the current study, a novel method is proposed to analyze the simultaneous impacts of non-stationarity in hydrological time series and land-use changes in urban areas to predict future floods and probable damage. For this purpose, rainfall frequency and land-use changes analyses were conducted for two time periods (first: 1979–2009 and second: 1979–2019), and the results were compared. Then, hydrologic modeling of the catchment was carried out using the HEC-HMS model, and obtained hydrographs were fed to the HEC-RAS2D model for estimating flood inundation areas. Using the financial information of assets and their damage functions, flood damages related to these two periods were evaluated through the HEC-FIA model. The results indicated that in the low return periods (e.g., 2-year flood), the damage in the second period was decreased with respect to the first one but increased for the return periods of 5 to 100 years. In the surface runoff, a 4.65% increase due to land-use change and a 12% increase due to rainfall non-stationarity signed the important role the hydrologic condition plays compared to land-use changes in flood modeling. Moreover, flood damage showed a 136% increase on average, and among the two studied factors, the non-stationarity of rainfalls is considerably more effective on flood intensification. All the points show that the studied socio-hydrological system is completely dynamic.