A Theoretical Stemflow Model for Urban Trees with an Evaluation of Current Street Tree Pit Design and Practices

Cities across the world are dealing with storm water runoff and its management, as urbanization leads to urban densification. The use of urban forestry has become widely accepted as a more resilient means to address storm water management problems in the face of densification and climate change. The project’s development of a theoretical stemflow model works to predict the volume of stemflow on an event basis for several common tree species that are used in the Metro Vancouver area as street trees. The model is based on a linear relationship between stemflow volume (L) and precipitation depth (mm) in relation to tree diameter at breast height (DBH) (cm). The model performed well and was able to reasonably predict stemflow volumes based on inputs of DBH and precipitation. Based on two modeling approaches, it was found that modeling stemflow based on grouping all trees together is more accurate in comparison to modeling stemflow based on grouping the trees by genus.