Sustainable Drainage Systems (SuDS)
Photo credits: Robert Bray Associates
Sustainable Drainage Systems (SuDS) are features designed and implemented into the landscape to slow, store, divert, filter and improve the quality of surface water. By mimicking nature, they increase the capacity and potential of the land to regulate water, reducing demand on the underground drainage network. SuDS provide sustainable options for managing surface water locally, delivering the BGI vision.
Benefits of Blue Green infrastructure
- Reduce the risk of flooding
- Prevent water pollution and erosion
- Provide valuable habitats and corridors for wildlife
- Green spaces / path networks for health and wellbeing
- Provide educational resource and pride in community
- Recharge groundwater to prevent drought
- Reduce demand on the combined sewer system
- Evapotranspiration and climate regulation
- Improve air and noise quality
- Build resilience to climate change
- Increase capacity to cope with population growth
- Support the economy (housing, tourism, investment)
Explaining SuDS features
Gather rainwater / prevent runoff
- Rainwater harvesting uses water butts or storage tanks, to collect water for re-use
- Green roofs / living walls absorb water, reduce runoff, improve water quality and creates valuable habitats
- Bio-retention / raingardens allows rainwater to filter through vegetation to a drainage layer below, providing cleaning and storage
- Permeable paving allows water to soak through the surface, allowing for temporary storage, reducing the flow of water and removing pollution
- Infiltration trenches an underground reservoir, absorbs storm runoff
- Infiltration basins are shallow features where stormwater runoff is stored and percolates, their larger surface area allows for more storage
- Soakways store water in a buried Geocellular chamber to increase volume
Moving and filtering surface water
- Filter drains are trenches lined with geotextile and filled with gravel, which carry runoff water into a drain or pipe. Common alongside roads.
- Swales are linear grass covered depressions that guide surface water overland to a storage or flow system. They can form a network between road verges, storage ponds and wetlands and provide water retention and filtering benefits, removing pollution.
- Canals and rills are open channels with hard edges that can be planted to provide treatment and silt removal, whilst conveying water in urban areas
- Filter strips are vegetated buffers, placed upstream of the drainage system. They dissipate runoff and remove silt. They can provide a valuable corridor for wildlife, whilst protecting watercourses from erosion
Collection and water treatment
- Detention basins are designed to temporarily hold back storm runoff and allow contaminates to settle. They then drain into a watercourse or surface water drainage system. They are designed to be dry outside of flood events
- Retention ponds retain a certain aomunt of water at all times. They help to remove nutrients, trace metals, cliforms and organic matter
- Wetlands are specifically constructed shallow areas with wetland vegetation. They filter and remove nutrients, using algae and plants. They provide vital open space, opportunities for recreation and improved habitat.
Are SuDS required by law?
- The Water and Environment Water Services (WEWS) (Scotland) Act 2003 made provisions for the protection of the water environment. It made SuDS a legal requirement for all new developments (excluding single dwelling and properties that discharge to coastal waters). SEPA, Scottish Water, local authorities and developers are tasked ensuring these are delivered successfully.
- The Water Environment (Controlled Activities) (Scotland) Regulations 2011 commonly referred to as the Controlled Activities Regulation (CARS) provides regulation for SuDS.
- The Flood Risk Management (Scotland) Act 2009 requires local authorities to produce flood risk management plans for Potentially Vulnerable Area’s (PVA’s), highlighting where flooding can be managed sustainably.
- Planning advice notes are issued by government
An overview of SuDS for kids
Where to find more information