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Sustainable Urban Drainage Systems

Updated on May 27, 2014

What are Sustainable Urban Drainage Systems?

Sustainable Urban Drainage Systems, or SUDS for short, refers to a range of drainage systems that manage rainwater during storms or periods of heavy rain. Sustainable drainage techniques include temporarily storing the water, slowing it down so it drains away slowly, or diverting it to use else where.

This lens forms part of a series including Permeable Paving and How to Build an Extensive Green Roof. Check them out for more detailed information on permeable paving and green roofs.

Why do we need Sustainable Urban Drainage Systems?

Naturally rain water filters through the ground and eventually finds its way into rivers and streams where it flows out to the sea. When we pave over or build on naturally permeable land we make it impermeable and so rainwater flows over the surface and into the nearest drain, or permeable land. When the rain water flows over an impermeable surface to a permeable surface or drain it is called run off. When too much land is paved or built on the remaining permeable land can become inundated with run off, or the local drains can become over loaded, in both cases this leads to flooding.

Benefits of Sustainable Urban Drainage Systems

  • Reduced risk of flooding
  • Better water quality
  • Increased biodiversity (better for wildlife)
  • Attractive water features/visual amenity

Sustainable Urban Drainage System Methods

  • Rainwater harvesting
  • Green roofs/green surfaces (Evapo-transpiration)
  • Permeable surfaces
  • Rain gardens/storm water attenuation systems

Water butt / rain barrel
Water butt / rain barrel

How Sustainable Urban Drainage Systems work

Rainwater Harvesting

Rainwater harvesting is a form of source control where rain water is captured from roofs and other impermeable surfaces and stored close to its source for future use. The simplest example of this would be a rainwater butt or rain barrel connected to the down pipe of household guttering. The water that falls on the house roof is stored in the water butt or rain barrel to be used to water plants or wash cars at a later time. Larger more elaborate systems can include buried tanks under the house or garden. The benefits of this method include limiting the amount of rain water that flows directly into surface drains as well as providing a water resource, possibly reducing water bills.

Residential Green Roof
Residential Green Roof

How Sustainable Urban Drainage Systems Work

Green Roofs

Green roofs are a useful tool in sustainable drainage systems. Like rainwater harvesting green roofs are a form of source management. A successful green roof uses layers of waterproof and insulating membranes to protect the structure of the roof, over which a planting membrane or special lightweight soil is placed. The green roof is then planted with specialist hardy plants. Green roofs work by slowing the passage of water and storing some of it within the plants themselves. The plants then release their stored water through evapo-transpiration. In this way the storm water is evaporated directly from its source, without flowing into any drains.

For more information on green roofs and instructions on how you can build one, read my How to Build an Extensive Green Roof lens.

Permeable paving
Permeable paving

How Sustainable Urban Drainage Systems Work

Permeable Surfaces

Permeable surfaces allow water to flow through them instead of flowing across them. Examples of permeable surfaces might include resin bonded gravel, or block paving. These systems provide all the usual benefits of hard surfaces such as car parking and walk ways, whilst allowing the rain water to drain naturally. It is important that the below ground construction of permeable surfaces be fully permeable.

For more information on permeable surfacing, and why you should consider this method for your driveway, please read my Permeable Paving lens.

Rain Garden
Rain Garden

How Sustainable Urban Drainage Systems Work

Rain Gardens

Rain gardens are a form of storm water attenuation system. Here rain water from impermeable surfaces such as roofs or road/drive ways is directed into a shallow depression that fills with water when it rains. Rain gardens can be constructed using waterproof liners, but must be permeable to allow water to slowly drain into the surrounding soil. Rain gardens can be designed to be an attractive addition to a property, with careful landscaping and planting. Rain gardens are not constantly wet, but dry out in periods of drought. This mimics many habitats in nature, therefore benefiting local wildlife and biodiversity.

Recommended Reading

Rain Gardens: Managing Water Sustainably in the Garden and Designed Landscape
Rain Gardens: Managing Water Sustainably in the Garden and Designed Landscape

From on of the creators of the London Olympic Park, and RHS Chelsea Gold Medal winner, Nigel Dunnett. This book discusses the theories and ecology of rain gardens. Nigel Dunnett is always a good read!

 
Water Centric Sustainable Communities: Planning, Retrofitting and Building the Next Urban Environment
Water Centric Sustainable Communities: Planning, Retrofitting and Building the Next Urban Environment

From a professional perspective this book explains to importance of SUDS and an integrated approach.

 
Small Green Roofs: Low-Tech Options for Greener Living
Small Green Roofs: Low-Tech Options for Greener Living

This book is a good 'how-to' for the enthusiastic amateur wanting to create their own green roof.

 
The Professional Design Guide to Green Roofs
The Professional Design Guide to Green Roofs

A more in depth look at green roof technology for the professional architect or landscape architect.

 

Please feel free to ask any questions... - ...I would love to help!

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    • ashleydpenn profile image
      Author

      ashleydpenn 4 years ago

      Thanks Tamara. You're spot on right! Thank you for taking the time to leave a comment.

    • tammywilliams09 profile image

      tammywilliams09 4 years ago

      Thanks for sharing. This is a great way to save money and time with Rainwater Harvesting which uses rain barrels, Green Roofs which grow plants, Permeable Surfaces allows natural drainage and Rain Gardens would add a lot of beauty to the environment.