Climate change effects, including rising sea level and increasingly powerful storms, have put many coastal communities at risk. To mitigate damage, governments have responded by building higher seawalls. But a new study finds there is a more cost-effective, green solution: Instead of blocking water with walls alone, absorb it with marshes first. Previous studies suggest that areas behind marshes experience significantly less damage during coastal storms compared with those without a living buffer. While past research has assessed the protective benefits of individual marshes, the new study employed modeling techniques to compare how different shore profiles and plant species help reduce wave energy. Seagrass, for example, will simply bend and flow with a wave. Mangroves, on the other hand, are far more rigid and effective at absorbing ocean energy. The researchers used their model to analyze how much shorter a protective seawall could be if it sits behind various types of marsh. Furthermore, they compared the cost of building a higher seawall with that of establishing or replanting a marsh. To test the model in a real-world context, the researchers looked at a seawall elevation and marsh restoration project already underway in Salem, Massachusetts, U.S. The local municipality there has planted two species of native seagrass, Spartina alterniflora, locally known as cordgrass, and Spartina patens, or salt hay, to restore the marshes. Armed with information about species, density of plantings and coastal topography, the study’s modeling estimated the seawall could be up to 1.7 meters (5.5 feet) shorter if it…This article was originally published on Mongabay
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