urban drainage

• Where is the River Lea located? -Originates in Chiltern Hills, flows Southeast through Eastern London, then joins River Thames.
• History RL: Formerly industrial/commercial site, derelict, residual contamination as it was a depository for rubble of demolished buildings WWII
• Reason for River Restoration: Flood Risk

  Poor access

  State of dereliction

  
  

  Due to change in morphology, encouraging flow conveyance pushing issues downstream to the lower course to the bank.
• Before RL River Restoration


  Derelict

  Abandoned

  Lack investment
• After RL River Restoration: Areas of park raised forming wetland bowl.

  
  

  Bank reprofiled undertaken to lower bank and reconnect the channel to flood plains

  
  

  Vegetation planted to encourage biodiversity and reduce flood risk
• SUDs used: Wetland bowl

  Porous asphalt strips

  Rainwater harvesting

  Filter drain strips
• East River Lea: Swales from upcourse to lower course, discharging into habitat pools and wetwoodland areas adjacent to RL.

  
  

  This acts as attenuation ponds installed with weins limit outflow & maintain minimal depth

  
  

  Fluvial flooding , biodiversity, water quality
• North Park Wetland: Wildlife haven for kingfishes, water moles, grey herons.

  Filter strips installed adjacent mitigating outflow as they capture runoff. Runoff then discharged through catchpits to stream networks to watercourse. Soft landscape - recycled thermoplastic material (C+)

  
  

  Fluvial flooding , biodiversity , water quality
• Benefits: Created new flood storage facilities

  New bank side ecosystem

  Improved public access

  Materials -cost effect and sustainable

  Detail taken account climate change
• Failures: Need to improve flood risk upstream to have maximum impact downstream

  Ensure adoptable scheme
• Before RR Flood Risk

  5,000 homes
• Soil cleaned


  400,000 m3
• Rubbish removed


  500,000 tones
• Trees planted


  2,000
• Organisations


  Thames Water

  Greater London Authority 2015