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Urban Forests, Environmental Quality and Human Health

Urban Tree Effects on Water Flow and Quality

[photo:] Residential street  with fallen leaves along curbUrban runoff, in addition to causing severe water quality problems, is highly damaging to infrastructure and aquatic habitats.  Impervious surfaces (roofs, streets, parking lots) reduce infiltration, increase runoff, reduce groundwater flow, and transports urban pollutants (e.g., bacteria, thermal, metals, pesticides, organics, salts, nutrients) to streams. Trees and other urban vegetation, on the other hand, decrease runoff and increase groundwater flows by increasing infiltration and below-ground storage, reduce sediment loads from landscape and channel erosion, reduce thermal shocks to streams through their cooling effects on surfaces and air, and provide organic matter (food) resources to stream ecosystem food webs.  Their leaves, when transported to streams may well increase ecological functions by increasing beneficial microbial activity (e.g. denitrification) and  helping to convert various water pollutants to less toxic forms.

This research in urban hydrology and stream ecology focuses on how vegetation and impervious surfaces affect stream water flows and quality, as well as biogeochemistry and ecological function. This work includes investigations of the breakdown and transport of organic matter in streams, the impacts of heavily urbanized areas on stream flow and water quality, the ecology of pathogens in urban streams, and how tree cover affects stream temperature.

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Last Modified: 03/13/2009