River restoration

• What is river restoration?

  The process of managing rivers to reinstate natural processes to restore biodiversity, providing benefits to both people and wildlife.

  Reintroducing natural processes can reshape rivers to provide the diversity of habitats required for a healthy river ecosystem and ensure their long-term recovery by addressing the root cause of the issue.
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration)


  Description of the River Lea's course:

  • flows from north of Luton in Bedfordshire to its confluence with the River Thames in E London
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - The damage before restoration:


  • Old abandoned factories > pollutants and dumping old cars etc > unappealing landscape > derelict
  • Contaminated ground so had to clean the soil
  • Overgrown & low value > poor quality env
  • Hard to access river > overgrown veg and debris
  • Invasive species > Japanese Knotweed undermine building foundations and costs millions to remove
  • Dumping of goods - lots of white goods e.g. fridges
  • Poor biodiversity & habitat
  • Poor aesthetic env
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - aims and objectives:

  • Designs of parklands will create more than 100ha of Metropolitan Open Land when transformed after games
  • Includes restoring waterways - protect and enhance visual presence in N of park
  • Promote access and recreation along waterways
  • Enhance flood-risk management, water storage and cleaning
  • Wetland bowl & wet woodland in N > help manage floodwater > protect 5,000 homes
  • In the S - 800m Waterworks River will be widened by 8m > will be planted with reeds to extend ecological connectivity
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - what was done? ~ Modification of topography of site


  Raised areas by 9m
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - what was done? ~ wetland bowl in N


  • Widening of river channel > decrease existing levels to suit
  • Plateaus formed for venues & facilities around river and access routes
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - what was done? ~ permeable pavements


  • Porous asphalt strips used in concourse areas around venue e.g. Velodrome
  • Porous asphalt > throughout pedestrian concourse areas of park > strips act as collection systems for overland runoff generated > convey water into granular trenches below strips which contain perforated pipes > drain catchpits
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - what was done? ~ wetland 'pathways' 


  • Traditional road gullies & combined kerb drainage collection systems were used
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - what was done? ~ filter strips/ drains


  • Adjacent to wetland pathways
  • Capture runoff > collected water discharged through catchpits into downstream networks > outfalls into adjacent watercourse
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - what was done? ~ Swales


  • Incorporate check dams at intervals to decrease velocities & provide open water features alongside wetland pathways
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - successes:


  • Infiltration
  • Management of extreme flood events taking into account potential impacts of climate change
  • Interception and treatment of surface water contamination
  • Protect groundwater and local watercourses from pollution from surface runoff
  • Increased biodiversity
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - failures:


  10 years later:

  • Microplastics
  • Toxins > disease for animals and humans
  • Waste in river
  • Pollution
  • Contaminants
  • 1000 hours of sewage spilled
  • Pumped untreated waste 91 times into River Lea waterway > undoing restoration
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - Interested parties ~ Atkins Engineers:


  • Did a 15 year job in 3
  • On-budget, sustainable > 98% or 445,000 tonnes of rubble recycled
  • Placed native flora and fauna > local ecosystem
  • 23 bridges > scaled down after Olympics
  • Tested 46 plants and flowers and selected the best (bioengineering)
  • Engaged local community
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - Interested parties ~ Canal and Rivers Trust:


  • 'Greatest waterway restoration the country has ever seen, turned neglected abused rivers and canals into jewels, now a real asset'
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - Interested parties ~ London Olympic Legacy Committee:


  • 'Waterways are a vital element in making the Park unique'
  • 'The park and waterways will play an important part in fulfilling the economic growth potential'
  • 'Provide LT relationships with businesses, developers and operations > commercial and employment benefits'
• EXAMPLE: London Olympic Park - The River Lea (SUDS and river restoration) - Interested parties ~ Thames Water:


  • Pumped waste for 1000 hours into wetlands
  • Pumped untreated waste 91 times into waterway > pollute rivers > pollute ocean > negative impact on aquatic ecosystems