Surge and Wave Modeling for the Louisiana 2012 Coastal Master Plan

The goal of the study was to evaluate various coastal restoration and protection projects and the associated benefits for reductions in storm surge and wave height. Efforts in numerical modeling have been made to create a database of storm surge and wave responses to a set of hypothetical storms under current and various future conditions. The ADvanced CIRCulation (ADCIRC) and the Unstructured Simulating WAves Nearshore (UnSWAN) models were selected for this study. A coarser version of the state-of-the-art, southern Louisiana, unstructured mesh was developed to reduce computational overhead while maintaining critical hydraulic features. Model outputs were reviewed and analyzed from coastwide and onshore-transect points of view. The potential benefits of restoration and protection projects proposed in the Master Plan were examined by comparing Future without Action outputs to the Master Plan outputs. Hurricane protection projects, such as levees, provide remarkable protection at their leesides but increase and redistribute surge water at their front sides. Narrow, restored landscapes, such as barrier islands or ridges, may provide wave attenuation to some extent but, in many cases, provide minimal benefits in surge level reduction. Larger-scale restoration projects, such as sediment diversions, can result in land accretion and enhance vegetation coverage, thus resulting in notable benefits associated with damping waves and storm surge and ultimately reducing risk for inland communities.