Code
U12
Sector
Urban
Other sector(s)
Agriculture
Forest
Hydro Morphology
The complete description of the NWRM
Summary

Infiltration basins are vegetated depressions designed to hold runoff from impervious surfaces, allow the settling of sediments and associated pollutants, and allow water to infiltrate into underlying soils and groundwater. Infiltration basins are dry except in periods of heavy rainfall, and may serve other functions (e.g. recreation). They provide runoff storage and flow control as part of a SuDS ‘train’. Storage is provided through landscaped areas that allow temporary ponding on the land surface, with the stored water allowed to infiltrate into the soil. The measure enhances the natural ability of the soil to drain water by providing a large surface area in contact with the surrounding soil, through which water can pass.
Infiltration basins may also act as “bioretention areas” of shallow landscaped depressions, typically under-drained and relying on engineered soils, vegetation and filtration to reduce runoff and remove pollution. They provide water quality benefits through physical filtration to remove solids/trap sediment, adsorption to the surrounding soil or biochemical degradation of pollutants. Water quality is, however, a key consideration with respect to infiltration basins as the potential for the infiltration to act as a vector for poor quality water to enter groundwater may be high. Pre-treatment may be required in certain areas before infiltration techniques are appropriate for use, for example swales or detention basins to reduce sediment loading and retain heavy metals and oils.
Infiltration basins have the potential to provide ancillary amenity benefits. They are idea for use as playing fields, recreational areas or public open space. They can be planted with trees, shrubs and other plants, improving their visual appearance and providing habitats for wildlife. They increase soil moisture content and help to recharge groundwater, thereby mitigating the problems of low river flows.

Illustration(s)

Explicative scheme of the MAR principle

Source: Andras Kis’ presentation, NWRM Workshop 1

 

Possible benefits with level
Benefits Level
ES1 - Water storage
Medium
ES3 - Natural biomass production
Low
ES4 - Biodiversity preservation
Medium
ES5 - Climate change adaptation and mitigation
Medium
ES6 - Groundwater/aquifer recharge
High
ES7 - Flood risk reduction
High
ES8 - Erosion/sediment control
Low
ES9 - Filtration of pollutants
High
ES10 - Recreational opportunities
Medium
ES11 - Aesthetic/cultural value
Medium
PO2 - Improving status of physico-chemical quality elements
Low
PO4 - Improving chemical status and priority substances
Low
PO5 - Improving quantitative status
Medium
PO7 - Prevent surface water status deterioration
Medium
PO8 - Prevent groundwater status deterioration
Low
PO9 - Take adequate and co-ordinated measures to reduce flood risks
High
PO11 - Better protection for ecosystems and more use of Green Infrastructure
High
PO12 - More sustainable agriculture and forestry
Low
PO14 - Prevention of biodiversity loss
Medium
BP1 - Store runoff
High
BP2 - Slow runoff
High
BP5 - Increase evapotranspiration
Low
BP6 - Increase infiltration and/or groundwater recharge
High
BP7 - Increase soil water retention
Low
BP9 - Intercept pollution pathways
High
BP10 - Reduce erosion and/or sediment delivery
Medium
BP14 - Create terrestrial habitats
Medium
BP16 - Reduce peak temperature
Low
BP17 - Absorb and/or retain CO2
Low

Case studies per NWRM