Influences of Street Tree Canopy Type and Amount on Stormwater Runoff Temperature

Thermally enriched air and stormwater runoff from urban areas have been identified as contributing heat sources to downstream surface waters. To date, the study of air quality, cooling, stormwater, and health benefits of urban forests have been widely covered, but surprisingly little research has focused on quantifying the relationship between urban air and stormwater runoff temperatures and furthermore, how these heat sources may affect downstream ecosystems. We measured temperature, water, and weather variables (air, pavement, and runoff temperatures, precipitation, solar radiation), and tree metrics (type, height, canopy cover fraction) at 12 study sites in Portland, Oregon during the warm summer season of 2016...

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Final Report: Understanding the Relationship Between Urban Trees, Stormwater Runoff, and Cold-Water Streams in a Changing Climate

Climate change in the Northwest is causing warmer summer stream flows that can decimate cold-water species like salmon. This problem can be worsened in shoreline embayments or small streams that receive direct stormwater runoff from warm city environments. There has been little assessment, however, at the source: how urban warming – or cooling, such as by tree shade – affects curbside runoff temperatures from streets to storm drains. This research found that warm summer runoff might be cooled at its source via small adaptations in urban forestry, although with an important and unanticipated trade-off between managing street tree canopy type and amount. Evidence was drawn from monitoring a set of residential street...

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