Flood defence: How energy crops can help

The British summer of 2012 has so far been a complete wash out with heavy rain and floods causing events such as the Badminton Horse Trials and the Festival of British Eventing at Gatcombe Park to be cancelled. Such unseasonal weather also poses a severe risk to our homes with one in every six houses in England (5.2 million properties) at risk of flooding. The cost of flood defences and coastal erosion in the UK is likely to rise to 860 million by 2015.

The ten worst affected local authorities in England (in order of risk) are:

  • Bostondistrict
  • North Somerset
  • East Lindsey District
  • Windsor and Maidenhead
  • City of Kingston upon Hull
  • Shepway District
  • Sedgemoor District
  • East Riding District
  • Runnymede District
  • Warrington

Source: Investing for the future: Flood and coastal risk management in England. A long-term investment strategy. Environment Agency 2009.

However, many people outside these areas have been affected in the last week with 140 flood alerts from the Environment Agency for England and Wales, 13 flood warnings issued in Scotland. The southwest of England had three major flood warnings with forecasters predicting 100mm of rain (4in) across certain areas within a 24 hour period.

Energy crops such as willow grown as short rotation coppice (SRC) can be particularly useful in reducing the incidence of flooding. This is achieved by their:

  • Significant water use (SRC can use up to 1 million litres per tonne of dry matter produced per year).
  • Greater hydraulic roughness which enhances sediment retention and slows down the flow of flood water thereby reducing the likelihood of floods downstream and increasing the time available for issuing flood warnings.

Using appropriately planted energy crops could therefore provide a low cost option for reducing the danger of flooding to areas that are too small to justify expensive flood defence measures. Such an initiative would be an example of climate change adaptation and fit in with the Transition Town movement by providing a community based solution to a problem whilst also producing a crop of woodfuel for use in local buildings.

A recent report produced by Forest Research in July 2011 called Woodland for Water: Woodland measures for meeting Water Framework Directive objectives says “….the rapid growth and multi-stemmed nature of these crops makes them ideally suited to flood risk management.”

An additional benefit of energy crops is that they also provide an effective local measure for reversing the rising nitrate levels in groundwater caused by run off from agricultural fields. They achieve this in a number of ways:

  • Provide useful barrier strips that intercept run off and prevent pollution of water courses from diffuse sources e.g. fertilisers, pesticides etc.
  • The crop slows down run off and intercepts sediment.
  • The less frequent trafficking on the land means that there is a much lower incidence of nitrogen leaching compared to crops under typical arable management.

Research referred to in the Forest Research report suggests that a 10-20m wide riparian planting could remove the majority of nitrate and phosphate pollutants in surface run off.


Crops for Energy can provide advice, feasibility studies and turnkey management solutions for using energy crops for flood defence, biofilters and bioremediation. Please give us a call to discuss your project on 0844 248 2901 or email us.