Modeling storm runoff reduction through urban forestry

Effects of urban forests on runoff reduction have been conceptualized in management practice, but not well quantified due to lack of practical application tools. In this study, a storm runoff reduction model was developed and applied in an urban watershed in Bismarck, North Dakota. Methods and analyses conducted in this model were based on research embodied in the Small Watersheds Model TR55 (USDA SCS, 1986) and the Single Tree Rainfall Interception Model (Xiao et al, 1998, 2000). This model simulates storm runoff reduction at the individual tree level for different size storm events. It fully considers the effects of microclimate, soil, land cover, tree species, and tree size on runoff reduction. The total amount of storm runoff and amount of runoff reduction is reported. Thus, the model is a management tool for professionals needing to include trees as BMPs in stormwater management programs.