Trees and other vegetation in urban areas considerably reduce urban-water runoff. As rain falls upon vegetation, it clings to the rough surfaces of leaves, branches, and trunks. ... By intercepting and slowing precipitation hitting the ground, vegetation substantially reduces the volume and rate of stormwater runoff.

Why does vegetation prevent runoff?

Trees and forests reduce stormwater runoff by capturing and storing rainfall in the canopy and releasing water into the atmosphere through evapotranspiration. In addition, tree roots and leaf litter create soil conditions that promote the infiltration of rainwater into the soil.

Does vegetation cause runoff?

In addition to increasing imperviousness, removal of vegetation and soil, grading the land surface, and constructing drainage networks increase runoff volumes and shorten runoff time into streams from rainfall and snowmelt. As a result, the peak discharge, volume, and frequency of floods increase in nearby streams.