Development and Application of a Coastal Flooding Model to Address Compound Flooding with a Changing Climate

Resilience planning for coastal communities requires hazard-modeling technologies that can capture the impact of climate change on the frequency of occurrence and intensity of a hazard, as well as provide hazard demand parameters to support resilience assessment at community or regional scales. With support from NOAA, NSF, and the NIST Center of Excellence on Risk-based Community Resilience Planning, a compound flood modeling system has been developed that couples storm tracking, wind field, precipitation, hydrologic, wave and hydrodynamic models to predict the “total water level” (tides + waves + surge + runoff) due to a storm event, either for current or future climate. In developing the storms for future climate, we use the greenhouse emission and radiative forcing scenarios identified by the International Panel on Climate Change (IPCC) and downscale an ensemble of global climate model results to provide sea surface temperature and local environmental conditions for a physics-based hurricane model that predicts track and intensity of the storm. A parametric rainfall model (P-CLIPER) uses track intensity and speed information to produce hourly-averaged rainfall along the track; it is fed into a Coupled Routing and Excess STorage hydrology model (CREST), which then routes the runoff through the watershed. Streamflow from CREST at so-called handoff points on major streams, and parametric wind fields based on the hurricane model’s parameters, are then fed into the coupled ADCIRC+SWAN hydrodynamic plus wave model from which we obtain spatial and temporal hazard maps (that is, wind speed, surge height, wave height, and coastal and inland inundation) for the coastal area under study. Project background, model components, and application to the Tar/Neuse/Pamlico watersheds of North Carolina will be presented.