Low-lying river deltas are thought to be particularly vulnerable to climate change and sea level rise. Places like the Niger River Delta, in Nigeria, could be overrun with flooding without new techniques to break the flow of incoming water.
This design from a Hungarian group called Szövetség’39 is one idea. It aims to build artificial dykes to encourage the growth of mangrove trees, which have long existed in delta areas. The dyke is meant to trap sediment, building a barrier to break water surges.
Called CALTROPe, the dyke is made of hollow metal tubes twisted into a heavy, two-footed structure that’s anchored to the bed. The mangrove trees grow within the tubes, eventually taking root. As well as slowing water, the vegetation also provides nutrients and encourages seafood to populate.
“They are installed [so] the ensemble can follow natural shore evolutions and help the endangered areas adapt to new conditions by capturing sediment and forming a dam,” says Szövetség’39’s press release.
Rebuilding mangrove forests on river deltas have been championed by groups like the World Wildlife Fund and the U.N. Environment Program. And, metal reefs to encourage natural sediment build-up are a popular strategy among resiliency designers, as we saw recently with this proposed project in New York Harbor. It’s not the solution, of course. But it might be one of them, and it has the advantage of being what’s already there.