What Can Homeowners Tell Us About How to Protect Shorelines?

BY CARTER SMITH

Carter Smith serves as a postdoctoral associate with Brian Silliman at Duke University’s Marine Lab. She studied at UNC-Chapel Hill’s Institute of Marine Sciences and completed her Ph.D. this past spring. With support from a North Carolina Sea Grant/NC Sentinel Site Cooperative Joint Graduate Fellowship, she surveyed coastal residents about damage to their shorelines and homes in the aftermath of Hurricane Matthew. She also gauged their attitudes about sea level rise and future hurricanes. Smith has reported her results to academic audiences and survey respondents, and here she tells us about her work.

In coastal areas, people are strongly tied to the environment. Homeowners live within sight of important coastal habitats like saltmarshes, oyster reefs, seagrass beds, and dunes. Coastal residents often have jobs that rely on the health of coastal systems, and residents and tourists both flock to the coast in order to use and enjoy the outdoors for fishing, bird watching, surfing and other recreational activities.

All of these uses put intense pressure on coastal systems — and that pressure likely will increase as more and more people move closer to the water. People have been modifying coastlines for as long as they have been living along them. They’ve done so by building homes and ports right at the water’s edge, dredging waterways for transport, and building walls to prevent flooding and to keep the shoreline from moving.

Development often unintentionally impacts habitats negatively. For example, a common practice of waterfront homeowners in North Carolina — and all over the world — is to build a seawall or bulkhead along the shoreline to protect against erosion and property damage during storms. However, these walls cause habitat loss and lower the abundance of fish and crustaceans along the shoreline. They also frequently suffer damage and are costly to maintain.

My research has focused on understanding how we can use coastal habitats to protect homes and infrastructure rather than relying exclusively on large, gray infrastructure projects, such as seawalls and bulkheads. Combining traditional coastal infrastructure, like a breakwater, with restored marsh plantings potentially can increase the protective power of that shoreline, because saltmarshes are really good at trapping sediment and absorbing wave energy. Best of all, if a natural habitat suffers damage during a storm, it may be able to self-repair or, over the long-term, grow vertically to keep pace with sea level rise.

A large component of my research has involved surveying waterfront property owners across the coast of North Carolina to understand how residents experience and perceive different coastal threats. The threats I study range from the immediate — like coastal erosion and hurricanes — to less-tangible and more long-term threats, like sea level rise and climate change. The idea is to understand why and how homeowners make decisions, which, in turn, can inform more sustainable, environmentally beneficial, and appealing solutions for shoreline protection.

With support from a North Carolina Sea Grant/NC Sentinel Site Cooperative Joint Graduate Fellowship, we surveyed over 500 coastal residents in the state. We asked questions about the condition of their shorelines and homes, whether they experienced damage during Hurricane Matthew, and their levels of concern about future hurricanes and sea level rise.

We were surprised to find that homes with natural shorelines actually had less hurricane damage than homes with bulkhead shorelines. This is probably because homes with bulkheads tended to be much closer to the water than homes with natural shorelines. Yet, despite experiencing more damage, homeowners with bulkheads were no more concerned about hurricanes than homeowners with natural shorelines.

We also found that one of the best predictors of property damage during Hurricane Matthew was whether or not the property had experienced damage during a prior hurricane. In fact, shorelines that had suffered damage from previous hurricanes were five times more likely to experience shoreline damage during Hurricane Matthew.

Bulkheads may work well for some homeowners, but our research shows that they are expensive, frequently damaged, and may not even keep homes safer from hurricanes.

Looking ahead, a changing climate likely will worsen nearly every environmental and socioeconomic problem. We must invest in sustainable coastal development options that are good both for people and our environment — and that includes considering how we can make best use of living shorelines.

Read about Carter Smith’s research on how Living Shorelines Can Enhance Saltmarsh Resilience to Hurricanes.

Watch a video about living shorelines and Carter Smith’s research.

Carter Smith also is collaborating on a new North Carolina Sea Grant research project to evaluate living shorelines after major storm events, which builds on the work she describes above by surveying more homeowners and also collecting a wider array of information about hurricane damage. Check back here soon for more information.

Lead photo: courtesy of Carter Smith