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Nature study measures how much salt marshes can reduce waves in an extreme storm

A study published in Nature measured the contribution of salt marshes to wave attenuation during extreme storms, at a time when storms have been battering northern Europe.
In a full-scale flume experiment an intact salt marsh was exposed to waves up to 2 m significant wave height.
The marsh substrate persisted with negligible erosion, with average surface lowering of about 7 mm over roughly 21 hours.
The vegetation was progressively damaged: after about 21 hours above-ground biomass fell to 20 to 25 per cent of its initial level and stem length dropped by 47 per cent.
The vegetation's contribution to wave attenuation was 6 to 22 per cent for 0.75 m waves and 0 to 6 per cent for 2 m waves.
In a global analysis, vegetation was most effective on low-energy coasts with waves up to 1 m, where attenuation generally exceeded 10 per cent and reached up to 50 per cent.

Maximum wave height tested: 2 m significant wave height Attenuation on low-energy coasts: generally above 10 per cent, up to 50 per cent
Why it matters for exams: Nature-based coastal defence and the journals that publish such findings are asked in environment questions.
Kerala PSCUPSC
26 October 2026 Source: Nature

In plain words

Salt marsh Coastal wetland flooded by salt water at high tide — A low coastal wetland of salt-tolerant plants that is flooded and drained by tides.

Wave attenuation Reduction in wave energy and height — The weakening of waves as they travel across shallow water or vegetation.

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