The capacity of urban forest patches to infiltrate stormwater is influenced by soil physical properties and soil moisture

• Published in: Journal of environmental management 2019-09, Vol.246, p.11-18
• Main Authors: Phillips, Tuana H., Baker, Matthew E., Lautar, Katie, Yesilonis, Ian, Pavao-Zuckerman, Mitchell A.
• Format: Article
• Language: English
• Subjects: Ecohydrology; Ecosystem services; Infiltration; Soil properties; Stormwater management; Urban forest
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2019.05.127

Forest patches in developed landscapes perform ecohydrological functions that can reduce urban stormwater flows. However, urban forest patch contributions to runoff mitigation are not well understood due to a lack of performance data. In this study, we focus on the potential of urban forest patch soils to infiltrate rainfall by characterizing rates of unsaturated hydraulic conductivity (K) in 21 forest patches in Baltimore, Maryland. Soil bulk density, organic matter, soil moisture, percent of coarse fragments (≥2 mm), and texture were evaluated at the same locations to assess drivers of K. The K was significantly higher in soils with high sand content and related positively with the percent of coarse fragment material in the soil. Forest patch size did not impact K. We estimate that 68 percent of historic rainfall could be infiltrated by urban forest patch soils at the measured K rates. Continuous monitoring at one forest patch also showed that K is dynamic in time and influenced by antecedent soil moisture conditions. We conservatively estimate that unsaturated urban forest patch soils alone are capable of infiltrating most rain events of low to moderate intensities that fell within these forest patches in the Baltimore region. Considering this ecohydrologic function, the protection and expansion of forest patches can make substantial contributions to stormwater mitigation. •Urban forest patches can infiltrate low to moderate intensity rainfall events.•Sand and coarse fragment content drives infiltration.•Small patches had similar infiltration rates to larger forest patches.•Infiltration rates are dynamic in time and depend on antecedent soil moisture.