Managing Rainwater for Urban Sustainability Using Trees and Structural Soils
Urban Trees Enhance Water Infiltration
A group of researchers from Virginia Tech, Cornell, and University of California at Davis have been investigating innovative ways to maximize the potential of trees to address rainwater/stormwater in a series of studies supported by the U.S. Forest Service’s Urban and Community Forestry Grants Program.
Virginia Tech scientists used two container experiments to establish that urban tree roots have the potential to penetrate compacted subsoils and increase infiltration rates in reservoirs being used to store rainwater/stormwater. In one study, roots of both black oak and red maple trees penetrated clay loam soil compacted to 1.6 g cm-3, increasing infiltration rates by an average of 153%.
Structural soil reservoirs may provide new opportunities for meeting engineering, environmental, and greenspace management needs in urban areas. Further research is needed on the effects of tree roots and detention time on water quality in structural soils. Monitoring continues at four demonstration sites around the United States and updated information is posted as it becomes available.
To access the project website and learn more about the results of the research program, click on Managing Stormwater for Urban Sustainability Using Trees and Structural Soils.
Why this is Important
Global land use patterns and increasing pressures on water resources demand creative urban rainwater management. Traditional stormwater management focuses on regulating the flow of runoff to waterways, but generally does little to restore the hydrologic cycle disrupted by extensive pavement and compacted urban soils with low permeability. The lack of infiltration opportunities affects groundwater recharge and has negative repercussions on water quality downstream.
Researchers know that urban forests, like rural forest land, can play a pivotal role in rainwater/stormwater mitigation, but developing approaches that exploit the ability of trees to handle rainwater/stormwater is difficult in highly built city cores or in urban sprawl where asphalt can be the dominant cover feature.
Posted November 2009