Changes in storm runoff with urbanization: the role of pervious areas in a semi-arid environment

Abstract

Although urban stormwater runoff has received considerable scientific attention, the role of pervious areas in the infiltration of rainfall in residential areas is not well understood. In the southwestern U.S., where poorly developed, heterogeneous soils are common, the typical residential housing development process includes extensive modification of pervious soil surfaces to accommodate the dominant tract-housing style of construction, which in tum affects soil infiltration properties. The application of a physically based rainfall-runoff model, KINEROS2, to adjacent grassland and urban watersheds shows that effective saturated hydraulic conductivity (Ks) decreases from about 25 mm/hr in the grassland area to 2.5 mm/hr in the urban area, a change that is confirmed in direction, but not magnitude, by tension infiltrometer measurements. This . change in infiltration properties results in a 3 8 percent increase in the volume of runoff from the urban area over what would be expected if the soil were undisturbed.