Infiltration efficiency and subsurface water processes of a sustainable drainage system and consequences to flood management

• Published in: Journal of flood risk management Vol. 13; no. 3
• Main Authors: Archer, Nicole A. L., Bell, Rachel A., Butcher, Andrew S., Bricker, Stephanie H.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-09-2020; John Wiley & Sons, Inc; Wiley
• Subjects: Aquifers; Boreholes; Drainage systems; Flood control; Flood management; Flooding; Floods; Groundwater; Groundwater levels; Infiltration; Infiltration rate; Moisture content; natural flood management; Rain; Rainfall; Rainfall infiltration; Sensors; Soil; Soil compaction; Soil permeability; Soil profiles; Soil properties; Soil water; Soils; Subsurface water; Sustainability; sustainable drainage systems; urban drainage; Urban sprawl; Water content; Water table
• ISSN: 1753-318X; 1753-318X
• DOI: 10.1111/jfr3.12629

With increased intensity rainfall events globally and urban expansion decreasing permeable surfaces, there is an increasing problem of urban flooding. This study aims to better understand rainfall infiltration into a Sustainable Drainage System (SuDS) permeable pavement, compared with an adjacent Green Area of made ground, in relationship to groundwater levels below both areas. Both areas were instrumented with soil water content and matric potential sensors and four shallow boreholes were instrumented with groundwater level sensors. Surface infiltration rates were measured using a double‐ring infiltrometer. Results showed that average infiltration rates of the SuDS (1,925 mm/hr) were significantly higher than the Green Area (56 mm/hr). The SuDS was well designed to transfer rainfall rapidly to the aquifer below, where groundwater levels rapidly rose within 1 hr of a 1 in 30 year event (32.8 mm/hr). In comparison, soil compaction of the made ground Green Area decreased infiltration rates, but still enabled the majority of rainfall events to infiltrate. The aquifer below the Green Area responded more slowly, as lower matrix potentials facilitated water retention in the soil profile, slowing water draining to the aquifer. This work reiterates the importance of ensuring a 1 m separation depth between the base of the SuDS infiltration zone and aquifer depth.