Thermal Enrichment of Stormwater by Urban Pavement

Abstract

Urbanization is known to increase the temperature of surface runoff during storm events and to increase the mean summer monthly temperature of receiving waters downstream It affects the temperature of streams as follows: urban construction, comprising roads, parking lots, roofs and sewers, reduces the original forest canopy, and increases impervious areas and, thus, surface runoff. Increased runoff in turn causes wider channels and more surface ponds, both of which lead to more exposure of stormwater to solar radiation, exacerbated by canopy loss. Increased imperviousness also leads to decreased infiltration and baseflow, which reduces the dilution of heated stormwater. Changes in the texture and color of the ground cover are also significant sources of thermal enrichment in an urban watershed. Elevated stream temperature is the inevitable result of these synergistic effects.