Urban vegetation impacts on the hydrology of Dayton, Ohio

“Both the amount of stormwater runoff and its rate of discharge are greatly influenced by urban development. But one of the many benefits afforded by urban vegetation is its amelioration of extremes in urban runoff regimes. Using data for a 6-h, 1-year storm event on surface cover types for the city of Dayton, OH, the specific role of vegetation in lessening urban impacts on runoff is assessed. Estimates of runoff are obtained for 77 of Dayton’s 79 neighborhoods for three scenarios: one for existing cover types (artificial surfaces, exposed soil, herbaceous cover, and tree canopy cover); one in which trees are hypothetically removed; and a third that places exposed soil in vegetation and increases tree canopy cover to achievably greater amounts. For this intensive storm in which the role of vegetation is less readily apparent than for gentler storms, existing tree canopies alone work to lower potential runoff by about 7%. This could be increased to nearly 12% by modestly increasing canopy coverage of the land surface. Effects on potential peak runoff rates are found throughout the city. Results suggest that when these hydrologic impacts are coupled with tree and other vegetation impacts in the city, a city can justify increasing attention to planning and managing its urban vegetation resource.” [abstract]