The role of tree phenology on urban stormwater management: a case study of two small watersheds in the Kansas City metropolitan area

Devastating stormwater volumes, related to change in climate and rapid development in urban areas, is gaining attention worldwide. While traditional runoff management strategies are dependent on gray infrastructure such as pipes to concentrate stormwater and transport it to wastewater treatment facilities or water bodies, This wording suggestion is just to communicate that these systems supplement traditional and other engineered “green infrastructure” systems in stormwater management to help make the whole system function better from a hydrologic standpoint. Therefore, understanding how urban trees impact water transfer in an urban landscape is crucial for watershed managers to guide their decisions on how to use vegetated systems as a tool in urban runoff regulation. Although there are studies in which the role of urban trees and vegetation in runoff regulation is assessed, there is lack of knowledge regarding how changes in vegetation cover influences the runoff volume and peak flows as well as how the variation of tree factors (e.g. Evergreen vs deciduous, leaf area index) affect the urban hydrology. In this study, we used the i-Tree Hydro model to assess the change in runoff volume and peak flows in two small watersheds in Kansas City Metro area in response to changes in vegetation cover and seasonality. Also, the impact of tree traits, including tree type and leaf area index, was examined. Result of this study illustrates the role of urban trees in urban runoff management and it also provides a perspective for watershed managers to develop more efficient, natural-based solutions for stormwater regulation.