Urban Canopy Holds More Water
- Trees can decrease the amount of peak water discharge during storms by slowing the flow of water to the ground and holding water within the canopy.Kuehler, E., Hathaway, J., and Tirpak, A. (2017). Quantifying the benefits of urban forest systems as a component of the green infrastructure stormwater treatment network. Ecohydrology.
- Urban tree canopy, which can hold more water than their forest counterparts due to greater space for canopy spread, can retain 20-80% of the annual rainfall under canopy, depending on the climate of an area.
- However, heavily forested areas can reduce runoff by 26% compared to non-forested areas.Nowak, D.J., and Dwyer, J.F. (1970). Understanding the benefits and urban forest ecosystem. Urban and Community Forestry in the Northeast, 25-46.
Retaining Soil Composition
- Soil infiltration rates under a tree canopy are 50% higher than outside of the tree canopy.Center for Watershed Protection (2016). Review of the available literature and data on the runoff and pollutant removal capabilities of urban trees.
- Individually, urban trees can wick up to 47 gallons of water out of the soil each day and thus provide more soil water-holding capacity for the next rainfall event.Center for Watershed Protection (2016). Review of the available literature and data on the runoff and pollutant removal capabilities of urban trees.
- Tree roots increase the rate of infiltration by 63%, and in soils that are severely compacted, the presence of tree roots increases infiltration by 153%.Center for Watershed Protection (2016). Review of the available literature and data on the runoff and pollutant removal capabilities of urban trees.
- In Dayton, Ohio the tree canopy reduced runoff by 7%, and a 5% further increase in canopy was predicted to reduce runoff by 12%.Cotrone, Vincent. The Role of Trees and Forests in Healthy Watersheds. Pennsylvania State College of Agricultural Sciences Research and Extension Programs, 1-5.