Forecasting Wind Set-up in a Coastal Estuary

Current operational forecast models do not have the ability to adequately resolve the Indian River Lagoon (IRL), a long, but narrow, shallow estuary on Florida's east central coast. The models are therefore unable to forecast wind set-up, a factor that contributes to local flooding and the overall health of the lagoon – affecting seagrass beds, oyster habitats, and transport of nutrients and sediments. This investigation adopts an analytic approach to forecasting wind set-up that is designed to guide the local National Weather Service (as part of the NWS Nearshore Wave Prediction System) in allocating resources for high resolution hydrodynamic simulations if the situation warrants. This work represents a component of a NOAA CSTAR project designed to identify high impact wind forcing from coarse resolution ensemble output. This study looks at a significant wind event, e.g. a frontal passage, and employs a parameterization of wind set-up based on modifications of the well-known Zuider Zee formula. Using wind speed, wind direction, fetch, and bathymetry as inputs to the Zuider Zee formula yield a predicted wind set-up height. By modifying the Zuider Zee formula, the predicted wind set-up height can be tuned to best match the observed (or modeled) set-up. Three titanium pressure gauges are deployed in stilling wells at critical locations in the IRL. The Simulating WAves Nearshore model (SWAN), with a high resolution unstructured grid over the IRL, will be used for validation. Wind forcing is driven by the Short Range Ensemble Forecast model (SREF).