A balancing lake (also flood basin or Sustainable urban drainage scheme) is a term used in the U.K. describing a retention basin used to control flooding by temporarily storing flood waters.[1]: Glossary The term balancing pond is also used, though typically for smaller storage facilities for streams and brooks.
In open countryside, heavy rainfall soaks into the ground and is released relatively slowly into watercourses (ditches, streams, rivers). In an urban area, the extent of hard surfaces (roofs, roads) means that the rainfall is dumped immediately into the drainage system. If left unchecked, this will cause widespread flooding downstream. The function of a balancing lake is to contain this surge and release it slowly.[1]: Part E Failure to do this, especially in older settlements without separate storm sewers and foul sewers, can cause serious pollution as well as flooding.
- ^ a b "Milton Keynes Drainage Strategy – Development and Flood Risk: Supplementary Planning Guidance" (PDF). Milton Keynes Council. May 2004. Archived from the original (PDF) on 23 October 2021. Retrieved 11 June 2021.