Increasing Resilience to Current and Future Flooding Through the Integration of Hydrologic and Storm Surge Models

Low-lying coastal areas have an elevated risk (i.e. probability multiplied by consequence) of flooding from storm surges and prolonged torrential precipitation. Sea level rise can substantially enhance the vulnerability of coastal communities to flooding by increasing the storm surge heights and inundation time. Both increased surge heights and precipitation could have catastrophic impacts on coastal communities and result in the destruction of critical infrastructure, disruption of economic activities and other harmful effects. For evaluating coastal flood risks caused by the combination of flooding, due to both surge and precipitation, and the existence of infrastructure in the floodplain, it is necessary to use a hydrologic model to simulate rainfall-runoff and antecedent river conditions across coastal watersheds.

This study presents a methodology to link the Soil and Water Assessment Tool (SWAT) model and the ADvanced CIRCulation (ADCIRC) model in order to evaluate flooding from precipitation and coastal storm surge. The SWAT model has been shown to successfully simulate surface water hydrology for coastal watersheds under a variety of condition and time-scales. The simulated rainfall-runoff will be translated to river stage through a developed Support Vector Regression (SVR) rating curve model. The stage can be applied to mapping flooding area and be used as an initial condition for the ADCIRC coastal inundation model, specifically the flood extent and depth. The linking of SWAT and ADCIRC models will provide further insight into the conceptualization of flood risk across river deltas and other low-gradient coastal regions that are vulnerable to both riverine and coastal flooding. The results can assist future floodplain policy by a stakeholders across the local, state and national levels in order to attain a more resilient coastal land margin.