As wind-generated waves enter shallower coastal waters they generally become unstable and break, dissipating a fair amount of their energy. However, the remaining energy in the broken waves still have the capacity to cause shoreline erosion and/or suspend bottom sediment, which degrades water quality.
Oyster reefs help reduce the amount of wave energy that reaches the shoreline because they constitute physical obstacles that force waves to break at certain locations and dissipate more of their energy in the process.
The Conservancy, Natural Capital Project and the University of Southern Mississippi are incorporating a coastal protection model into the interactive Coastal Resilience tool to calculate the potential of living shorelines and restored oyster reefs (which can be approximated as trapezoids) and reef domes to reduce wave height and wave energy in coastal areas. The model and online tool, called Nearshore Waves, have been developed for Mobile Bay, Alabama, but will be expanded to Galveston Bay, Texas, and Charlotte Harbor, Florida. This work is complementary with efforts to build relevant local applications that engage communities to identify hazard reduction and climate adaptation strategies. These estuaries were chosen because they have relatively high coastal population centers and are extremely vulnerable to rising sea levels. They are also places with critical coastal ecosystems and present opportunities to further enhance coastal protection and restoration having already invested in actively restoring oyster reefs, seagrass beds and salt marshes.
The initial Nearshore Waves tool quantifies the amount of wave breaking induced by oyster reefs by modeling profiles of wave height in the nearshore in the presence and absence of those structures.