The human and economic costs of flooding have been particularly obvious in recent years across the UK.  BESS research is contributing to greater understanding around natural flood management in two ways:

  • Providing evidence about the role biodiversity plays in stabilising soils and reducing peak flooding events in both coastal areas and upland rivers.
  • Providing evidence about the wider role ecosystem restoration could play in mitigating longer term impacts and drivers of flooding.

Key messages:

  • Coastal ecosystems play an important role in reducing flood risk.
  • Saltmarsh biodiversity mitigates coastal erosion.
  • Ecosystem restoration and management within the context of the Ecosystem Approach provides multiple benefits.
  • River restoration helps stream ecosystems to adapt to climate change.
Saltmarsh and mudflats alleviate storm surges

Cai Ladd from CBESS studying saltmarsh accretion and erosion.

With sea levels rising and storminess expected to increase, the management and restoration of coastal ecosystems such as saltmarshes and mudflats will become an increasingly important component of flood prevention for low-lying coastal communities.  Tom Spencer and colleagues recorded water heights along 45 km of Norfolk coastline during the storm surge event of 5-6 December 2013 [1-3].  There was considerable variation in maximum water heights and impacts between different local areas, influenced by the presence of mudflats and marshes.  Regional forecasts of storm surges could be improved by including the local effects of the particular coastal setting and the extent of coastal ecosystems.
Saltmarsh biodiversity mitigates coastal erosion

CBESS - Hammering Erosion Cores. Credit Hilary Ford

Both above-ground vegetation and plant roots shelter coastal soil from waves and rain, physically bind the soil together and also support microbes that stabilise soils.  Hilary Ford and colleagues from CBESS found that saltmarsh plants vary in how well they stabilise soil and that more diverse plant communities with their greater root biomass offer better resistance to erosion [4].  Having high plant biodiversity is likely to be most important in coastal areas with more sandy soils as these are more prone to erosion.
Better flood management can provide multiple benefits 

River restoration not only reduces flood risk, but also potentially generates a broader range of benefits. For instance, planting strips of shading woodland next to streams is one way of mitigating rising temperature impacts. Researchers at DURESS have shown that planting native deciduous woodland in buffers (> 60 m) wider than commonly used for shading alone can also increase stream productivity, possibly enhancing resilience [5].  Streams draining from deciduous woodland had more particles of leaf litter and so a greater density of macroinvetebrates [5].  The impacts of climate change on streams could also be mitigated by reducing river pollution and improving water oxygenation [6].  Click here to find more evidence about the multiple benefits to be gained from river and wetland restoration in the Killer Facts’ compilation by Alister Driver, the National Biodiversity Manager at the Environment Agency. 

Publications from BESS researchers:

  1. Spencer, T., et al., Where local matters: impacts of a major North Sea storm surge. Eos, Transactions American Geophysical Union, 2014. 95(30): p. 269-270.
  2. Spencer, T., et al., Southern North Sea storm surge event of 5 December 2013: Water levels, waves and coastal impacts. Earth-Science Reviews, 2015. 146: p. 120-145.
  3. Spencer, T., S.M. Brooks, and I. Moller, Floods: Storm-surge impact depends on setting. Nature, 2014. 505(7481): p. 26-26.
  4. Ford, H., et al., Soil stabilization linked to plant diversity and environmental context in coastal wetlands. Journal of Vegetation Science, 2016. 27(2): p. 259-268.
  5. Thomas, S.M., S.W. Griffiths, and S.J. Ormerod, Beyond cool: adapting upland streams for climate change using riparian woodlands. Global Change Biology, 2015. 22(1): p. 310-324.
  6. Verberk, W.C.E.P., et al., Field and laboratory studies reveal interacting effects of stream oxygenation and warming on aquatic ectotherms. Global Change Biology, 2016. 22(5): p. 1769-1778.

Prepared by Laura Harrison, Anna Middlemiss and Charlie Parkin.