Pore Structure and Unsaturated Hydraulic Conductivity of Engineered Media for Living Roofs and Bioretention Based on Water Retention Data
Publication: Journal of Hydrologic Engineering
Volume 23, Issue 3
Abstract
Characterizing pore structure and hydraulic properties of engineered media used in stormwater control measures (e.g., green roofs and bioretention) is critical for accurately predicting water and contaminant flow characteristics, water availability to plants, and aeration status. In this study, unsaturated hydraulic properties, namely, the water retention characteristic (WRC) and unsaturated hydraulic conductivity (), were measured for 14 engineered media with varying compositions. Their WRCs were also used to investigate pore structures and estimate hydraulic conductivities. Results indicate that water retention dynamics in 10 pumice-based media involve complex interactions between interaggregate and intra-aggregate pores, for which the commonly used van Genuchten function is not suitable. The majority of the pores in the tested media have radii less than 1 mm, for which the Richards equation is applicable. A predictive function based on WRC and Mualem’s approach tends to underestimate at low water contents. More research is needed to study hydrological behavior of engineered media with complex pore systems under various flow conditions.
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Acknowledgments
The work is supported by the Doctoral Scientific Research Foundation of Hubei University of Technology, China, under Grant No. BSQD2016029. The authors appreciate Dr. Robyn Simcock and John Dando at Landcare Research for their help in measurement of water retention characteristic data. We would also like to thank the China Scholarship Council for providing the first author’s doctoral scholarship, and the University of Auckland for providing funding for experiments.
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Published In
Journal of Hydrologic Engineering
Volume 23 • Issue 3 • March 2018
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©2017 American Society of Civil Engineers.
History
Received: Sep 16, 2016
Accepted: Sep 1, 2017
Published online: Dec 28, 2017
Published in print: Mar 1, 2018
Discussion open until: May 28, 2018
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