Pluvial Flood Mapping for Coastal Cities - A Case Study for Charlottetown and Summerside in PEI

Quan Van Dau, Farhan Aziz, Xiuquan Wang, Rana Ali Nawaz, Tianze Pang and Muhammad Qasim Mahmood, University of Prince Edward Island, PEI, Canada


Assessing flood risk in urban areas under future climate change is essential for developing long-term national flood management policies. Using a 2D hydrodynamic model (HEC-RAS), this study attempts to develop a potential flood inundation mapping in Prince Edward Island (PEI) urban areas, with an emphasis on the City of Charlottetown and Summerside. The Chicago approach, which is based on the Intensity-Duration-Frequency (IDF) curves, was used to depict precipitation rates as a continuous function of time for 100, 50, 25, and 10-year return periods. IDF curves developed from historical extreme annual events and future projections under SSP5-8.5 throughout the 2071-2100 period were used for the current and future scenarios. The Annual Steric Trend in 2020 and 2100 obtained from the Coastal Hazard Information Platform (CHIP) were also taken into account as ocean boundary conditions in both scenarios. There were 39 culvert structures for the City of Charlottetown and 27 for Summerside configured in the HEC-RAS model. These culverts were identified by the PEI government, some of which were discovered during field visits. Due to the limited number of streamflow stations available within the domains, model validations are performed using three approaches (i) based on the available flood imagery at a specific location, (ii) extended domains from urban to county levels that contain the nearest streamflow stations, and (iii) conducted interviews with residents who have lived in the flood-prone areas for more than 15 years. The results showed a promising model output for determining flood depth and extent in these two urban areas. The main findings of this study can serve as a good example for future flood management planning in PEI.

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