Stormwater Management: Relationship Between Watershed Urbanization And Aquatic Environment

STORMWATER MANAGEMENT

Defining the Problem

Stormwater runoff can be defined as “…the water that flows over the land from rainfall during or after a storm event or as a result of snowmelt” (Pyzorha 1994). Generally, part of this runoff will be absorbed through infiltration, while the rest will make its way to streams and lakes. As watersheds experience an increase in urbanization, however, impervious coverage increases, thereby reducing infiltration. Reduced infiltration increases the possibility and intensity of flooding (Booth and Jackson 1997), as well as the likelihood that runoff will become contaminated with pollutants, thereby threatening aquatic ecosystems. The relationship between watershed urbanization and aquatic ecosystem conditions has long been recognized and studied (Klein 1979, Benke et al 1981, Pitt and Bozeman 1983, Booth and Jackson 1997); even so, Arnold and Gibbons (1996) state that traditional stormwater planning has emphasized engineering for safety. This approach focuses on moving large amounts of runoff out of an area by collecting runoff in ditches and pipes, and then diverting it into nearby streams. A growing concern, however, has been for the downstream effects of this approach to stormwater management. Flooding, erosion, sedimentation and contamination are all possible outcomes from this approach. It is this concern for

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