Effect of Urban Catchment Composition on Runoff Temperature

Abstract

Urban runoff adversely impacts cold-water stream environments due to sporadic fluxes of thermally enriched runoff. This adversely impacts tourism in regions that support trout and salmon streams. Research on storm water control measures (SCMs) has shown that meeting the 21°C trout threshold is not consistently feasible with current SCM technologies. Thus, it is important to consider other factors in storm water temperature management, such as catchment characteristics. Median and maximum runoff temperatures from a shaded parking lot were consistently lower than those from a nearby unshaded lot. This suggests the need to implement a tree canopy cover in trout-sensitive catchments. A light-colored chip seal pavement was compared to a traditional hot-mix asphalt pavement; the light-colored chip seal produced median storm water temperatures that were 1.4°C lower than the standard hot-mix asphalt. It was shown that runoff temperature measurement location is critical when evaluating SCM performance, and that underground conveyances can substantially reduce runoff temperature.