The Value of Wetlands in Protecting Southeast Louisiana from Hurricane Storm Surges

TLDR

Global interest in coastal wetlands grew after the 2004 tsunami and Hurricanes Katrina and Rita, yet interdisciplinary studies linking hydrodynamics and economics for Gulf temperate marshes remain scarce. The study combines hydrodynamic surge simulations with economic valuation to demonstrate how coastal marshes and vegetation reduce storm surge and protect property in southeast Louisiana. Simulations of four storms along a sea‑to‑land transect reveal that surge levels decrease as wetland continuity and vegetation roughness increase. Regression analysis shows that increases in wetland continuity and vegetation roughness lower storm surge, with a 0.1‑unit rise in continuity cutting damages by $99–$133 and a 0.001 rise in roughness by $24–$43, equivalent to saving 3–5 and 1–2 properties per storm.

Abstract

The Indian Ocean tsunami in 2004 and Hurricanes Katrina and Rita in 2005 have spurred global interest in the role of coastal wetlands and vegetation in reducing storm surge and flood damages. Evidence that coastal wetlands reduce storm surge and attenuate waves is often cited in support of restoring Gulf Coast wetlands to protect coastal communities and property from hurricane damage. Yet interdisciplinary studies combining hydrodynamic and economic analysis to explore this relationship for temperate marshes in the Gulf are lacking. By combining hydrodynamic analysis of simulated hurricane storm surges and economic valuation of expected property damages, we show that the presence of coastal marshes and their vegetation has a demonstrable effect on reducing storm surge levels, thus generating significant values in terms of protecting property in southeast Louisiana. Simulations for four storms along a sea to land transect show that surge levels decline with wetland continuity and vegetation roughness. Regressions confirm that wetland continuity and vegetation along the transect are effective in reducing storm surge levels. A 0.1 increase in wetland continuity per meter reduces property damages for the average affected area analyzed in southeast Louisiana, which includes New Orleans, by $99-$133, and a 0.001 increase in vegetation roughness decreases damages by $24-$43. These reduced damages are equivalent to saving 3 to 5 and 1 to 2 properties per storm for the average area, respectively.