Evaluating Short-Circuiting Potential of Stormwater Ponds

The authors began a study in 2008 (Glenn, 2008) investigating the impact that different inlet and outlet configurations of stormwater ponds may have on short-circuiting potential. The study team created several theoretical ponds with varying inlet and outlet locations using the Surface Water Modeling System (SMS) and RMA2 and ran hydraulic simulations to investigate the unique flow patterns within the ponds. Short-circuiting in a pond is dependent upon the time and distance traveled by the flow of water from the inlet to the outlet. The team traced the flow paths and velocities of massless particles for each simulation to determine the pond configuration that most effectively prevented short-circuiting. Subsequently, the study has been expanded to include varying inflows and pond volumes. For each configuration, the team determined a dimensionless quantity, the Short-Circuiting Index (SCI) that is based on the detention time, pond geometry and inflow and was used to assess each pond's potential for short-circuiting. The results are compared with a different methodology, the Flow Path Ratio (FPR) that is based on the relative distance between the pond inlet and outlet and was developed by the Florida Department of Environmental Protection and Water Management Districts (Department, 2009).