http://www.sciencemag.org/news/2020/06/when-dikes-burst-salt-marshes-might-lessen-deadly-flooding

A dike in the Netherlands is protected by a fringe of salt marsh (brown and black).

On 25 December 1717, a massive storm blew into the Netherlands. Powerful waves eroded the dikes that kept back the North Sea and an estimated 14,000 people drowned. After the flooding subsided, engineers took stock of the damage. Now, an analysis of the breaches combined with assessments from another deadly flood in 1953 show that salt marshes can protect dikes during storms—and how they may reduce flooding if the dikes fail.