SUDS

• What is a SUD?

  • Sustainable Urban Drainage System
  • Aim ~ mimic natural drainage regimes within built env, thus reducing flooding, improving water quality and value of env to people and biodiversity
• What do SUDS aim to do?


  1. Storing runoff and releasing it slowly (attenuation)
  2. Collecting and using surface water at source
  3. Allowing water to infiltrate into ground
  4. Decrease transporting (conveying) surface water flow rates
  5. Filtering out pollutants
  6. Allowing sediments to settle out by naturally controlling flow of water
• 1. Swales 


  • Wide shallow drainage channels, usually dry and can be landscaped as recreational spaces
  • Shallow side slopes and flat bottom > storage and infiltration > water may evaporate
  • Vegetated > filter out pollutants and attenuation
  • (+) slows surface runoff and decrease pollution> decrease flood risk and improve water quality
  • (+) easy to incorporate
  • (-) not suitable for steep areas
  • (-) less tree space
  • (-) risk of blockages
  • (-) small scale
• 2. Permeable pavements:

  • Porous urban surface > catches precipitation and surface run off > store in reservoir while slowly allowing infiltration into soil below > slow peak river discharge
  • (+) re-establish natural hydrologic balance and decrease runoff
  • (+) less peak discharge and decrease pollutants > decrease flooding
  • (-) clog with sediment and pollutants > decrease permeability
  • (-) expensive and time-consuming
• 3. Rain gardens:

  • Shallow depressions planted with shrubs and flowers
  • (+) allows for infiltration and groundwater storage > decrease runoff
  • (+) filter pollutants
  • (+) small minimal land task
  • (+) increase evapotranspiration
  • (-) limited volume reduction
  • (-) clogging
  • (-) landscaping required
• 4. Wetlands:


  • stormwater attenuation and treatment > shallow ponds, marshy areas w aquatic veg > detain flows to allow sediment to settle > aerobic decomposition
  • (+) remove pollutants
  • (+) recreation
  • (+) buffer erosion
  • (+) habitats
  • (-) requires baseflow
  • (-) not suitable if steep
  • (-) colonisation by invasive species will increase maintenance
• 5. Filter trenches:


  • shallow excavations filled with stone > create temporary subsurface storage of stormwater runoff > filter and convey to downstream
  • (+) incorporated easily and fits next to roads
  • (-) high clogging
  • (-) blockages hard to see
  • (-) maintenance
  • (-) high cost to replace filter material