For decades the Army Corps of Engineers – the primary civil and environmental engineering arm of the United States government – has been carrying out projects to protect Miami-Dade County and its shoreline from the impacts of floods, storms, and erosion. These projects have typically taken the form of things like beach nourishment, seawalls, and artificial breakwaters, or structures built offshore to absorb wave energy. Now, the Corps is again examining potential projects to reduce the risks of coastal storms through two feasibility studies: one looking at the oceanside shore of the barrier islands, and the other looking at the coast on the western border of Biscayne Bay, including the heavily developed urban core of Miami.
As part of these studies, they are soliciting public comments as to the best means to protect the South Florida coast. Miami Waterkeeper takes the position that storm protection is critically important to the residents of visitors of South Florida, but “grey infrastructure,” or artificial structures (often made of concrete) are not necessarily the best way to protect our shores.
Miami Waterkeeper has therefore filed public comments regarding both projects, urging the Corps to pay particular attention to the benefits of nature and nature-based features (NNBF) in mitigating coastal storm risks, as these features may be particularly effective in Miami. Not only do these kinds of projects tend to be less expensive to build and maintain, but they also are dynamic and have the potential to adapt with climate change. Unlike grey infrastructure or artificial structures like artificial breakwaters, groins, seawalls, pumps, and berms, which must be consistently maintained, many types of NNBF can be self-sustaining when developed properly. For example, planting appropriate, self-sustaining native vegetation on dunes can prevent erosion and maintain dune structure in the face of storms. The more of the dunes that are protected from erosion, the less need for beach nourishment, which often can have unforeseen consequences like sedimentation on reefs.
Miami-Dade County has the advantage of already being the native home of many of the most effective kinds of NNBF such as corals, mangroves, and seagrass beds. For example, in one comprehensive scientific review, a team of researchers examined 52 restoration projects across the globe designed specifically to provide coastal protection, analyzing the degree of protection offered, costs, and benefits of each project. They found not only did coastal habitats have significant potential to reduce wave heights and provide shoreline protection, but also that they could be significantly more cost-effective than similar grey infrastructure features like breakwaters. In terms of coastal protection efficacy, they found that coral reefs reduced wave heights by an average of 70%, salt marshes by 72%, mangroves by 31%, and seagrass/kelp beds by 36%. All of these ecosystems have been devastated in South Florida, depriving our shorelines of that significant natural protection.
In addition to these significant protective effects, NNBF offer numerous benefits beyond storm protection. Restored wetlands and mangroves can serve as nurseries for economically important fisheries, and can attract kayakers, hikers, and birdwatchers. Furthermore, these ecosystems can act as nutrient and contaminant sinks, cleaning runoff from land before it enters Biscayne Bay. Similarly, dune restoration on the barrier islands with native plants not only protects valuable real estate, but also provides habitat for native species and increases the aesthetic value of our beaches even more.