Thoughts From Engineers: Coastal Barrier Protection Informs Adaptation Strategies

We’ve closed out 2024 with record-breaking national disasters and, as a country, we’re starting to rethink foundational paradigms and long-established policies. The Federal Emergency Management Agency (FEMA) issued a new Federal Flood Risk Management Standard, effective Sept. 4, 2024, to better reflect current and future flood risks and fortify structures accordingly. The National Oceanic and Atmospheric Administration (NOAA) is revising precipitation forecasts to better integrate climate-science projections, and many cities are undertaking some form of flood-mitigation planning.

We’re living in a time that’s primed for experimentation, because the tools and building standards of the past may no longer achieve safe or satisfactory outcomes for tomorrow. Equally important to these discussions are the land-use policies and related programs that will see us through extreme conditions.

Mission and Design of CBRA

The Coastal Barrier Resources Act (CBRA) was enacted in 1982 (bit.ly/CBRA1982) to “minimize the loss of human life, wasteful expenditure of federal revenue, and damage to fish, wildlife and other natural resources.” The law creates a system of land units called Coastal Barrier Resources Systems (CBRSs) that satisfy criteria designed to protect ecologically unique as well as hazardous coastal landscapes unsuited for development. Within the CBRS, all federal financial assistance (e.g., flood insurance via the National Flood Insurance Program (NFIP), housing loans, local infrastructure funding and more) is removed; these areas still can be developed with private and/or local funding, and many have.

CBRA was recently reauthorized through the Bolstering Ecosystems Against Coastal Harm (BEACH) Act (bit.ly/BeachAct) on Nov. 20, 2024. An additional 294,000 acres of coastline were added, with a total land area affected at 3.8 million acres, traveling through several states along the eastern seaboard down to the Gulf of Mexico and including along the Great Lakes.

The law’s impact in terms of cutting NFIP-related expenditures—while keeping development densities low and out of hazardous areas—was examined in a recent study by Druckenmiller, Liao, Pesek, Walls and Zhang, “Removing development incentives in risky areas reduces climate damages and yields co-benefits,” appearing in the journal Nature Climate Change in August 2024 (bit.ly/RemoveDevIncentives). The identification of suitable “control” plots—coastal areas “statistically indistinguishable” from CBRA “treatment” areas—was key to achieving credible results. Anyone with an interest in the study’s methodology, which uses a form of spatial machine learning to find comparable control plots, should check out the article for further detail. Through comparative analysis, the authors were able to make important conclusions about the law’s effects.

Shaping Development on Coastlines

One of the study’s most-interesting aspects relates to CBRA’s effect on development. The authors found that CBRS units have 83 percent less buildings per acre than control areas. Moreover, CBRS designations didn’t result in lower property values—in fact, dwellings in CBRS units increased in mean sale price as did the per-acre assessed value. Although the net effect on development in CBRS units resulted in 50 percent less built-up area in 10 out of the 13 states examined, development appeared to hinge on which state and local policies either promoted development with subsidies and incentives or adopted a pro-environmental approach in line with CBRA’s mission.

In terms of what’s happening outside the boundaries of a CBRS unit—in so-called “spillover areas”—the findings also are interesting, showing increases in property values as well as significant NFIP-related cost savings. Development tended to be sparse directly outside CBRS units but became progressively denser with increasing distance from CBRS boundaries, raising development by 37 percent outside of the CBRS. Land values increased not just because of higher densities, but because of higher structure values. In general, spillover areas near CBRS units experienced property values that were 50 percent higher than property values in control areas.

Notably, the authors determined that annual flood insurance claims per acre were 40 to 64 percent lower in spillover areas outside of CBRS units than in the study’s control areas. The authors stress that these differences were not due to differences in terms of proximity of structures to shoreline or proportion of land in floodplains—which were nearly identical in treated and control areas. The authors believe properties in spillover areas near CBRS zones benefited from the natural storm- and flood-resilient characteristics of undisturbed coastal areas.

Trial and Error—and Progress

The study’s findings are important because they disprove the notion that property values will suffer in hazardous coastal areas with removal of government spending and other forms of financial aid and support. This study, in fact, provides empirical evidence of the very favorable economic outcomes these policies can deliver, which includes shaping and redirecting building patterns where hazardous and flood-prone conditions make it necessary, increasing property values, and saving millions in disaster-related expenditures.

Withdrawing federal funds significantly altered the numbers of buildings and people in these hazardous coastal zones, and this cause (and effect) is worth noting. As the authors point out, the broader applicability of these policies to other flood-risk areas—such as floodplains—warrants serious consideration.

Studies such as this help inform us in our search for policies that work under extreme climate and weather scenarios. In some parts of the country, communities at risk of riverine or coastal flooding are engaged in experimental thinking and innovative land-planning partnerships. Sometimes, age-old policies and preconceptions need to be flipped and roundly cast off as remnants of another time.

We shouldn’t hold back if the latest research or pilot projects make a compelling case for trying something new. These efforts and initiatives are pioneering, exploratory and increasingly necessary. In time, trial and error will yield answers and progress that our circumstances demand. 

 

Chris Maeder CivilGEO Thoughts From Engineers