One-way coupling of E3SM with ADCIRC demonstrated on Hurricane Harvey

Tropical cyclones (TCs) represent a major threat to coastal communities and cause billions of dollars in economic damage yearly. Much of the TC damage is due to extreme flooding caused by a combination of coastal storm surge and heavy rainfall runoff. Accurate modeling of flooding hazards due to TCs needs to account for all relevant factors. However, some models used in operational forecasting of flood risk focus only on the storm surge, ignoring the risk of compound flooding due to the combined effects of storm surge and streamflow in the coastal zone, which requires storm surge models to be coupled with a hydrologic model that captures precipitation-driven riverine flooding. Here, we present a novel one-way coupling of the river component of the Energy Exascale Earth System Model (E3SM) with the ADvanced CIRCulation model (ADCIRC). The coupled model is validated against NOAA tidal gauge observations for Hurricane Harvey (2017). We find that the coupled model significantly improves the predicted water elevation relative to the standalone ADCIRC baseline. Validating the streamflow predictions from the river model against USGS streamflow gauge data for a variety of model configurations shows that the streamflow predictions are reasonably accurate even for the extreme discharge during Hurricane Harvey. Comparing simulations produced by different hydrologic model configurations, more accurate streamflow predictions generally correlate with better flooding level predictions in the coupled model, further supporting the role of streamflow modeling in forecasting coastal flooding induced by hurricanes.