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.
- 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.
Retaining Soil Composition
- Soil infiltration rates under a tree canopy are 50% higher than outside of the tree canopy.
- 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.
- 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%.
- In Dayton, Ohio the tree canopy reduced runoff by 7%, and a 5% further increase in canopy was predicted to reduce runoff by 12%.