By Zhong-Ren Peng
Back-to-back hurricanes left an unnerving scene on the Florida coast in November 2022: Several homes, and even swimming pools, left over the ocean as waves eroded the property beneath them. Dozens of homes and apartment buildings in the Daytona Beach area have been deemed unsafe.
The destruction raised a disturbing question: How much property along the rest of the Florida coast is at risk of collapse, and can it be saved?
As the director of iAdapt, the International Center for Adaptation Planning and Design at the University of Florida, I have spent the past two decades studying climate adaptation issues to help answer these questions.
Rising seas, aging buildings
Living by the sea has a strong appeal in Florida – beautiful beaches, ocean views and often pleasant breezes. However, there are also risks, and these are exacerbated by climate change.
Sea levels are predicted to rise an average of 10 to 14 inches (25-35 cm) on the US East Coast over the next 30 years, and 14 to 18 inches (35-45 cm) on the Gulf Coast, as the planet warms. Rising temperatures also increase the intensity of hurricanes.
With higher seas and larger storm surges, sea waves more easily erode beaches, weaken seawalls and submerge cement foundations in corrosive salt water. Together with subsidence, or sinking land, they make coastal life more risky.
The risk of erosion varies depending on the soil, geology and natural shoreline changes. But it is widespread in US coastal areas, especially Florida. Maps produced by engineers at the Florida Department of Environmental Protection show that most of Florida’s coast faces a critical erosion risk.
Aging or poorly maintained buildings and seawalls, and older or poor construction methods and materials, can dramatically exacerbate the risk.
Designing better building codes
So what can be done to minimize the damage?
The first step is to build sturdier buildings and strengthen existing ones according to advanced building codes.
Building codes change over time as risks increase and construction techniques and materials improve. For example, design criteria in the Florida Building Code for South Florida have changed from requiring some new buildings to withstand 146 mph sustained winds in 2002 to 195 mph winds in 2021, meaning a powerful Category 5 hurricane.
The town of Punta Gorda, near where Hurricane Ian made landfall in October 2022, showed how homes built to the latest building codes have a much better chance of survival.
Many of Punta Gorda’s buildings were rebuilt after Hurricane Charley in 2004, shortly after the state updated the Florida building code. When Ian hit, they survived with less damage than those in neighboring towns. The updated code required new construction to withstand hurricane-force winds, including having shutters or impact-resistant window glass.
However, even homes built to the latest codes can be vulnerable, because the codes do not adequately address the environment in which buildings sit. A modern building in a low-lying coastal area may face damage in the future as sea level rises and the shoreline erodes, even if it meets current flood zone height standards.
That’s the problem coastal residents faced during hurricanes Nicole and Ian. Flooding and erosion, exacerbated by sea level rise, did the most damage – not wind.
The dozens of beach houses and apartment buildings that became unstable or collapsed in Volusia County during Hurricane Nicole may have originally looked fine. But as the climate changes, so does the coastal environment, and one hurricane can make the building vulnerable. Hurricane Ian damaged seawalls in Volusia County, and some could not be repaired before Nicole struck.
How to reduce the risk
The damage in the Daytona area in 2022 and the fatal collapse of a condo tower in Surfside a year earlier should be a wake-up call for all coastal communities.
Data and tools can show where coastal areas are most vulnerable. What is missing are policies and enforcement.
Florida recently began requiring state-funded constructors to conduct a sea-level impact study before beginning construction of a coastal structure. I believe it is time to apply this new rule to any new construction, regardless of the financing source.
A comprehensive sea-level impact study requirement should also allow for risk-based enforcement, including barring construction in high-risk areas.
Likewise, vulnerability audits – especially for multi-storey buildings built before 2002 – can check the integrity of an existing structure and help spot new environmental risks from sea level rise and beach erosion. Before 2002, the building standard was low and enforcement was lacking, so many of the materials and structures used in those buildings do not meet today’s standards.
What property owners can do
There are a range of techniques that homeowners can use to fortify homes against flood risks.
In some places this may mean raising the house or improving the grading of the site so that surface water runs away from the building. Installing a sump pump and remodeling with storm-resistant building materials can help.
FEMA suggests other measures to protect against coastal erosion, such as replenishing beach sand, reinforcing seawalls and anchoring the home. Engineering can help communities, at least temporarily, through seawalls, dams and increased drainage. But in the long term, communities will need to assess the vulnerability of coastal areas. Sometimes the answer is to relocate.
However, there is a disturbing trend after hurricanes, and we see it with Ian: Many damaged areas see a lot of money pouring in to rebuild in the same vulnerable places. An important question that communities should be asking is, if they are already in high-risk areas, why rebuild in the same place?
Zhong-Ren Pen: Professor of City and Regional Planning, University of Florida
Disclosure Statement: Zhong-Ren Peng receives funding from National Science Foundation, Florida Sea Grant, and Florida Department of Transportation.
Reposted with permission from The Conversation.