What Can We Do To Protect Our Coastal Communities From Extreme Weather Damage? – CleanTechnica

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Joe DiStefano, CEO of UrbanFootprint, wants you to be aware of the surprising overlap between prominent regional climate risks and domestic migration patterns. It’s clear that we’re witnessing a growing trend of people moving into areas prone to extreme weather threats, such as coastal communities. DiStefano says that it is critical that asset stakeholders begin leveraging socio-demographic and community data to assess the prospective financial impact of pressing climate risks. This is an especially crucial task for insurers and financial guarantors who want to develop accurate risk models, set appropriate premiums, and prepare for potential claims.

I thought of DiStefano’s remarks as I attended the Florida Shore and Beach Preservation Conference in St. Augustine earlier this year. Despite notable climate threats facing the nearby Jacksonville, FL community, the region remains one of the fastest growing cities in the country, with projected growth of 53% by 2060.

To further demonstrate this contradictory dynamic, the UrbanFootprint team conducted a deep-dive evaluation of hurricane wind risk in Jacksonville, finding that:

• Of the $79.4 billion of residential property in Jacksonville, there are homes worth $32.5 billion built before the region’s 2001 building code change to protect against hurricanes, posing a heightened physical risk. Notably, during Hurricane Irma, 68.79% of claims were residential, emphasizing the importance of assessing hurricane risk to homes across residential areas.
• 485,000 Jacksonville residents are either (a) older than 65 years of age or (b) live 2x below the poverty line. High concentrations of vulnerable community members and homes built pre-2001 overlap, causing considerable concern.
• Elderly people are more likely to struggle with evacuation and face heightened health risks (like injuries and disrupted medical care) during and after hurricanes, while over 90% of storm-related deaths in the past 32 years have happened in impoverished or disadvantaged communities.

Ultimately, this points to the importance of analyzing risk at an asset level and linking this assessment to not just climate and weather data, but also sociodemographic and community data that can uncover deeper, hidden risks with significant financial implications — especially for coastal communities.

Methods to Stall Wave Action from Sea Level Rise

What are some nature-based methods that can aid coastal communities to ward off sea level rise?

A marsh terrace is a mound of mud, above the high tide line, that chops down waves at the high tide line. It drops the wave energy and keeps the march protected. It allows sentiment to collect and presents as one of a multiple line of defense strategy to increase resiliency. Mud is high organic soil, and if a majority of plants are located in a muddy target area, they can be successful wave barriers, with winged terraces limiting the degradation.

What about dunes as protection for coastal communities? What are the best practices for restoring coastal dune systems? How do we turn newly planted sea oats into structurally different, mature, and thick dunes as quickly as possible? The problem with dune restoration is the problem with ecological restorations, generally, which fail 80% of the time. Newly restored ecosystems are much more affected by elements like severe weather or drought.

Most dune grasses take multiple seasons to establish, but, with big storms that can wreck these systems, devastation can occur. Yet dunes can make the difference in shoreline protection of coastal communities, as the mature dune creates a habitat for aeolian transported sentiment — that movement and weathering of sand particles behind and parallel to the shoreline. Interspecific facilitation, in which plants are grouped in clumps, or intraspecific facilitation, in which various plants help each other against stresses, are approaches to ensure the dynamism of young dune plantings.

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A Case Study of Beach Erosion & Attempted Solutions

Addressing sea level rise includes modeling to assess low, intermediate, and high sea level rise curves and to increase elevations of dune design by adding dune vegetation. For example, the original replenishment project in Flagler Beach, FL, in 2014 had included 330,000 cubic yards of sand, but that increased by 1 million cubic yards in the aftermath of Ian and Nicole due to a 20 ft. deflation of the dune/ beach profile.

A loss of 1 million – 1.9 million cubic yards of beach occurred, and, after these 2 hurricanes, a LiDAR immediate post storm assessment took place and offered the capacity to assess every few inches of beach. A FL inland landfill district was nearby, and it was the inland source of sand relocation. The projects completed in 2023 restored 10.8 miles of eroded dune and resulted in 23 average widening of dune. The entire dune was revegetated after placement.

The total project cost was $22.9 million. But it wasn’t enough to ward off more storms. A storm just this week caused more serious damage of the busy A1A area. In fact, the Florida Department of Transportation says there have been 20 washouts in the area in just the last year and a half.

Jason Harrah, a project manager with the U.S. Army Corps of Engineers, anticipates another beach renourishment project will pump 1.3 million cubic yards of sand onto the beach. The recreation of the flat beach where people can place their towels will be 140 feet wide. The dunes will be 19 feet high and even with A1A. Flagler Beach will also get a new seawall.

What Features Contribute to Beach Erosion or Resilience?

What do we know about sand movement? Sand movement depends on the littoral drift and longshore transport rates. A huge problem exists, for instance, with balancing a relatively stable, wide beach with a wide navigable inlet. An inlet slows down the littoral drift. Sediments move from one side of the inlet to another through tide-generated current transport and wave-generated current transport. Groins are used on occasion to hold deep concrete in place, but their use depends on the onshore wave action.

In fact, there are a whole lot of factors that come into play when figuring out beach and shoreline erosion: are there tidal inlets, barrier islands, particular ocean action, back-barrier bars?  Any substantive beach remediation project needs understanding of sediment transport and deposition as well as any beach-inlet interactions. 

Did you know that the American Shore and Beach Preservation Association has a database that includes beach erosion trends over 100 years? Beach renourishment projects have placed 1.7 billion cubic yards of sand in the US over the years, with 350 million cubic yards in FL alone, with first event taking place in 1935.

The costs involved in sand renourishment are almost too much to digest. In the early years, it cost around $10-$25 per cubic yard to do this kind of renourishment; then it elevated to between $7.5 million – $10 million in 1980s. Today it’s about $50 cubic yards to get inland sand sources as offshore sources have become nearly depleted.