The Influence of Watershed and Development Characteristics on the Cumulative Impacts of Stormwater Detention Ponds

Stormwater detention ponds are a popular stormwater management practice in many communities, and city ordinances often require the uniform use of detention ponds on all new developments. Although peak flow reduction can be achieved immediately downstream from a development, this practice may not be successful for controlling peak discharges from the watershed as a whole. The purpose of this research was to correlate watershed and development characteristics with the cumulative impacts of detention ponds in a watershed. A sensitivity analysis was performed to evaluate the influence of six watershed and development characteristics in synthetic watersheds. The sensitivity analysis evaluated two watershed characteristics: shape and slope. Four development characteristics were evaluated: size, intensity, stage, and sequence. Of the six watershed and development characteristics considered in the sensitivity analysis, watershed shape, the stage of development within the watershed, and the sequence of development within the watershed had the greatest effect on the cumulative impacts of detention ponds in the watershed. These three factors determined the pattern of impacts that occurred within a watershed. Development intensity, development size, and watershed slope contributed to the magnitude of the impacts which were created, but they were not the overriding factors that determined the pattern of impacts. These system-wide factors are not typically considered in the design and management of stormwater systems.