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Evaluating Retention Capacity of Infiltration Rain Gardens and Their Potential Effect on Urban Stormwater Management in the Sub-Humid Loess Region of China

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Shuan Tang at Yangzhou University
Shuan Tang
Wan Luo at Yangzhou University
Wan Luo
Zhonghua Jia at Xi'an University of Technology
Zhonghua Jia
Wenlong Liu at Yangzhou University
Wenlong Liu
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Recognized as an effective low impact development (LID) practice, rain gardens have been widely advocated to be built with urban landscaping for stormwater runoff reduction through the retention and infiltration processes; but the field performance and regional effect of rain gardens have not been thoroughly investigated. In this paper, we presented a four-year monitoring study on the performance of a rain garden on stormwater retention; hydrological models were proposed to predict the potential effect of rain gardens on runoff reduction under different storms and the future urban development scenarios. The experimental rain garden was constructed in a sub-humid loess region in Xi’an, China; it has a contributing area ratio of 20:1 and depth of 15 cm. During the study period, we observed 28 large storm events, but only 5 of them caused overflow from the rain garden. The flow reduction rate for the overflow events ranged from 77 to 94 %. The runoff coefficient from the contributing area (RC) was reduced to less than 0.02 on annual basis, and 0.008 over the four years average. Field observations also showed that infiltration rate remained stable during the operation period. The predictions based on the future landuse and storm variability of the study area showed that by converting a small fraction of the city land area into rain gardens, the negative hydrological effect from expansion of impervious area can be reduced significantly. The challenge, however, lies in how to plan and build rain gardens as an integral part of the urban landscape.
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Evaluating Retention Capacity of Infiltration Rain
Gardens and Their Potential Effect on Urban Stormwater
Management in the Sub-Humid Loess Region of China
S. Tang
1
&W. Luo
2
&Z. Jia
2
&W. Liu
3
&S. Li
1
&Y. Wu
1
Received: 29 September 2015 /Accepted: 25 November 2015 /
Published online: 2 December 2015
#Springer Science+Business Media Dordrecht 2015
Abstract Recognized as an effective low impact development (LID) practice, rain gardens
have been widely advocated to be built with urban landscaping for stormwater runoff reduction
through the retention and infiltration processes; but the field performance and regional effect of
rain gardens have not been thoroughly investigated. In this paper, we presented a four-year
monitoring study on the performance of a rain garden on stormwater retention; hydrological
models were proposed to predict the potential effect of rain gardens on runoff reduction under
different storms and the future urban development scenarios. The experimental rain garden
was constructed in a sub-humid loess region in Xi’an, China; it has a contributing area ratio of
20:1 and depth of 15 cm. During the study period, we observed 28 large storm events, but only
5 of them caused overflow from the rain garden. The flow reduction rate for the overflow
events ranged from 77 to 94 %. The runoff coefficient from the contributing area (RC)was
reduced to less than 0.02 on annual basis, and 0.008 over the four years average. Field
observations also showed that infiltration rate remained stable during the operation period.
The predictions based on the future landuse and storm variability of the study area showed that
by converting a small fraction of the city land area into rain gardens, the negative hydrological
effect from expansion of impervious area can be reduced significantly. The challenge, how-
ever, lies in how to plan and build rain gardens as an integral part of the urban landscape.
Keywords Rain garden .Storm runoff .Design storm .Infiltration .Overflow.LID
Water Resour Manage (2016) 30:983–1000
DOI 10.1007/s11269-015-1206-5
*W. Lu o
luowan@yzu.edu.cn
1
State Key Laboratory Base of Eco-Hydraulic Engineering in Arid Area, Xi’an University of
Technology, Xi’an, China
2
Department of Agriculture and Water Resources Engineering, Yangzhou University, Yangzhou,
China
3
Department of Biological and Agricultural Engineering, North Carolina State University,
Raleigh, NC 27695-0001, USA
Content courtesy of Springer Nature, terms of use apply. Rights reserved.
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Urban stormwater treatment using bioretention
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  • J HYDROL
Urban stormwater has negative environmental and ecological effects. Bioretention systems are starting to be used in efforts to mitigate these effects. A bioretention system receiving water from a light industrial catchment and a busy road was designed, built and monitored for changes in soil physics as well as hydrological and hydrochemical efficiency. The soils in the bioretention system were designed to have high metal removal potential and high permeability to compensate for undersized bioretention volume. The inflow hydrograph was a series of sharp peaks with little baseflow, typical of runoff from impervious surfaces. The bioretention system smoothed the hydrograph by reducing peak flow and volume for all 12 events monitored in detail. Overflow occurred in 10 events indicating the increased permeability did not fully compensate for the undersized volume. Runoff was heavily polluted with sediment and heavy metals, in particular zinc. The majority of the zinc, lead and Total Suspended Sediments were removed from the stormwater that flowed through the bioretention system, with TSS and total zinc concentrations reducing by orders of magnitude. Despite high removal efficiency, median concentrations of zinc exiting the bioretention system still exceeded ecosystem health guidelines and the bioretention system was both a source and sink of copper.
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