Current Affairs · · GS3 · Environment

Salt marshes hold firm against big waves, flume study finds

A 2026 study reported in Nature tested real salt marsh in a 300-metre wave flume and found its roots and soil stayed largely intact even under 2-metre waves. Plants cut moderate waves noticeably but did little against extreme ones. The findings support using salt marshes alongside sea walls to protect coasts.

Event date:

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  1. Note1 / 6

    WHY IN NEWS?

    • A 2026 study, reported in Nature, tested how salt marshes cope with large waves.
    • Researchers placed about 306 square metres of intact marsh in a 300-metre experimental flume in the Netherlands.
    • After 21 hours of waves, the marsh surface dropped by only about 7 mm.
    • Plants above ground lost 75–80% of their biomass, but roots and soil held.
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    WHAT THE STUDY FOUND

    ConditionReported result
    Moderate waves (75 cm)Vegetation cut wave height by a further 6–22%
    Extreme waves (2 m)Extra reduction of at most about 6%
    Global modelling, waves up to 1 mOver 10% reduction, up to 50% in some places
    Marsh surface after 21 hoursLowered by about 7 mm

    The lesson: roots and elevation provide stability, while plants add wave damping mainly in moderate conditions.

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    KEY CONCEPTS

    1. What is a salt marsh?

    It is a coastal wetland flooded by tides and covered with salt-tolerant grasses and herbs. Unlike mangroves, it lacks trees.

    1. How do marshes reduce waves?

    Plant stems create drag that slows water. Dense roots bind sediment and resist erosion.

    1. What is blue carbon?

    It is carbon stored in coastal ecosystems — mangroves, seagrasses and salt marshes. Waterlogged soils lock it away for long periods.

    1. Where are India's salt marshes?

    Mainly in Gujarat, especially around the Gulf of Kachchh, with smaller areas in Tamil Nadu, Andhra Pradesh and Maharashtra.

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    THREATS

    • Reclamation and aquaculture convert marshes to ponds, salt pans and land.
    • Coastal development for ports, roads and industry fragments habitats.
    • Sea-level rise can drown marshes if sediment cannot keep pace.
    • Pollution from sewage and industry degrades plant and animal life.
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    WAY FORWARD

    These are suggested measures, not approved policy.

    • Map marshes accurately with satellites, since estimates vary widely.
    • Restore vegetation and tidal flows in degraded areas.
    • Protect through law: Use Coastal Regulation Zone and wetland rules against destructive reclamation.
    • Combine defences: Pair marshes with embankments where waves are too strong.
    • Involve communities in conservation and fisheries.
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Sources

  • The Hindu — Science / environment coverage on salt marsh flume study · Report of a 2026 study on salt marsh resistance to large waves; figures in the note are attributed because the article was not opened directly. · 29 October 2026
  • Nature — 2026 study on salt marsh resistance in a large wave flume · Study not opened in this session; findings are carried as attributed in the body and fact-check flags. · 29 October 2026

Syllabus

PaperSubjectSub-topic
GS3EnvironmentEnvironment, conservation, climate change adaptation, disaster management
GS1GeographyCoastal geography
PrelimsEnvironmentSalt marshes, blue carbon, CRZ, wetlands

Topics

BiodiversityProtected Areas and ConservationSpecies

Practice questions

  1. Which of the following is NOT generally classified as a blue carbon ecosystem?

    1. Mangroves
    2. Seagrass meadows
    3. Salt marshes
    4. Tropical rainforests
    Show answer

    Answer: D. Blue carbon refers to coastal and marine ecosystems.

    Difficulty: medium · statement

  2. In India, the largest extent of salt marshes is found in:

    1. Kerala
    2. Gujarat
    3. Odisha
    4. West Bengal
    Show answer

    Answer: B. Mainly around the Gulf of Kachchh.

    Difficulty: medium · statement

  3. Salt marshes reduce coastal erosion mainly because:

    1. They raise sea level
    2. Their roots bind sediment and stems slow water
    3. They block tides completely
    4. They absorb salt
    Show answer

    Answer: B. Roots and stems work together.

    Difficulty: medium · statement

Mains practice

Answer-writing practice on this article. Attempt it first, then open the hints.

  1. GS3 · 150 words

    Discuss the role of coastal wetlands such as salt marshes and mangroves in reducing disaster risk and storing carbon.

    Show hints
    1. Wave attenuation
    2. sediment stabilisation
    3. blue carbon
    4. threats, CRZ
    5. hybrid defences.