Sea wallsWhen is a sea wall a good idea?

By Aline Reynolds

Published 14 September 2018

Recent hurricanes like Maria and Sandy have brought crippling winds, torrential rains, and flooding to vulnerable coastal regions, in some cases killing thousands of people. Sea walls and other barriers are often suggested as a way of protecting these low-lying coastal communities, but how large should such a wall be, and where is the most effective place to build it? Environmental scientists and researchers is trying to answer these questions and more, to help curb the devastation from future hurricanes.

Recent hurricanes like Maria and Sandy have brought crippling winds, torrential rains, and flooding to vulnerable coastal regions, in some cases killing thousands of people. Sea walls and other barriers are often suggested as a way of protecting these low-lying coastal communities, but how large should such a wall be, and where is the most effective place to build it? At Columbia’s Earth Institute, a team of environmental scientists and researchers is trying to answer these questions and more, to help curb the devastation from future hurricanes.

Using a unique combination of hard science and community feedback, the project is using models and hurricane simulations to develop and evaluate prototypes of storm surge barriers and other protective mechanisms. The project will use Lower Manhattan as an initial case study, but eventually the tools and techniques that the team develops will be freely available and applicable to any coastline in the world.

“One of the things we’re probably going to focus on is the specific scenario of a sea-wall around Lower Manhattan—where to put that wall, and how high it needs to be are two of the variables we’ll be looking at,” said lead researcher Kyle Mandli, an Earth Institute affiliate and assistant professor of applied mathematics at Columbia University’s School of Engineering and Applied Science. A storm surge barrier is just one of several protection strategies for coastal communities—including artificial reefs, infrastructure elevations, and even managed retreat—that Mandli and his associates intend to investigate as part of the endeavor.

Currently, Mandli and Columbia mathematics and engineering professor Daniel Bienstock are running simulations that anticipate how storm surge and sea level rise will impact NYC’s infrastructure under existing conditions over the next approximately 50 years. The scientists will then introduce into these models interventions such as a sea-wall, restored wetlands, or artificial sand dunes to hypothesize how, and to what extent, the damages from future hurricanes can be prevented.