WRF-Hydro-CUFA: A scalable and adaptable coastal-urban flood model based on the WRF-Hydro and SWMM models

An open-source urban flood model is vital for vulnerable coastal communities with limited budgets to assess emerging flood risks posed by global climate change. In this study, a hyper-resolution flood model for coastal-urban systems, WRF-Hydro-CUFA (Coastal Urban Flood Applications), is developed based on a distributed process-based hydrologic model, WRF-Hydro, to represent urban hydrologic processes. In addition, WRF-Hydro-CUFA integrates a hydraulic flow solver, SWMM, to consider flood controls of stormwater drainage. As a pilot study, the applications for past non-extreme and extreme flood events in the City of Tybee Island, USA, show that WRF-Hydro-CUFA can represent multiple flood mechanisms, including coastal and pluvial flooding. WRF-Hydro-CUFA is further implemented for operational flood predictions on a web-based dashboard, providing an opportunity for calibration and improvement. The application and enhancement processes of WRF-Hydro-CUFA can be transferred and adapted in other coastal communities facing similar flood risks but with limited access to flood models.