Whittlesey Washes Flood Defence System | Royal HaskoningDHV

Strengthening Whittlesey Washes for future generations

Although protecting the low lying land of East Anglia from flooding has been a fact of life for around 400 years, the need for maintaining effective flood defences has been significantly highlighted by the recent devastating floods in the UK.

The Whittlesey Washes south of the River Nene near Peterborough is a large area of open land, surrounded by embankments, which act as a flood storage reservoir when high tides and high river levels coincide. More than 35,000,000 cubic metres of water can be stored on the area, then released back into the river as the tide recedes.

When safety inspections identified that remedial work was essential to reduce the risk of a breach during an extreme flood event, the Environment Agency commissioned Royal HaskoningDHV to assess possible options and design solutions.

Eddie Robinson, Royal HaskoningDHV’s project manager explains: “The challenge was to find a sustainable solution that would safeguard the site for the next 100 years, be in keeping with the landscape, and not adversely affect the wildlife and bird population.  We had to find innovative and cost effective ways of working to meet industry standards for embankments and cooperated closely with the Environment Agency to clarify safety levels and acceptable risk.”

Extensive ground investigations and hydraulic modelling were used to investigate a number of scenarios and agree a solution that would meet all the stakeholder requirements. The embankment is being strengthened and reshaped, sloping gently to blend in with the environment, and reinforced with geotextiles for a more natural look.

Sustainability and biodiversity are high on the agenda, with kingfisher banks designed to encourage wildlife as well as hibernacula for reptiles and amphibians (such as great crested newts). Most of the work is being done over the summer months to avoid disturbing over wintering birds.

Royal HaskoningDHV’s skills and expertise in flood risk management and proactive approach made an invaluable contribution to the project.

Nicola Oldfield

The Environment Agency’s project manager