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Hydraulic Response and Nitrogen Retention in Bioretention Mesocosms with Regulated Outlets: Part I—Hydraulic Response
Author(s) -
Lucas William C.,
Greenway Margaret
Publication year - 2011
Publication title -
water environment research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 73
eISSN - 1554-7531
pISSN - 1061-4303
DOI - 10.2175/106143010x12780288628697
Subject(s) - bioretention , mesocosm , environmental science , surface runoff , stormwater , hydraulic retention time , infiltration (hvac) , water retention , retention basin , nitrogen , interception , hydrology (agriculture) , environmental engineering , nutrient , soil water , effluent , soil science , chemistry , ecology , geotechnical engineering , geology , physics , organic chemistry , biology , thermodynamics
In bioretention systems used for stormwater treatment, runoff interception improves with increased infiltration rates. However, nitrogen retention improves with increased retention time or decreasing infiltration rates. These contrasting responses were analyzed in 240‐L experimental mesocosms using a variety of media treatments. The mesocosms were vegetated, except for one barren control. Dual‐stage outlets were installed to extend retention time and equalize hydraulic responses. One unregulated treatment was free‐draining. This part 1 paper presents the media properties and hydraulic responses. The highly aggregated media had saturated hydraulic conductivities ranging from 20.7 to 59.6 cm/h in August 2008 (austral winter), which increased to 42.8 to 110.6 cm/h in March 2009 (austral summer). The outlet regulated mesocosms provided retention over 8 times longer than the free‐draining mesocosms, while still being able to capture large events. The outlets provide adaptive management for bioretention design to improve both runoff capture and nitrogen retention.