HYDRODYNAMIC SIMULATION AND PARTICLE-TRACKING TECHNIQUES TO IDENTIFY SOURCE AREAS TO PUBLIC WATER INTAKES ON THE ST. CLAIR-DETROIT RIVER WATERWAY IN THE GREAT LAKES BASIN

Source areas to public water intakes on the St. Clair-Detroit River Waterway were identified by use of hydrodynamic simulation and particle-tracking analyses to help protect public supplies from contaminant spills and discharges. This paper describes techniques used to identify these areas and illustrates typical results using selected points on St. Clair River and Lake St. Clair. An existing two-dimensional hydrodynamic model of the St. Clair-Detroit River Waterway was reparameterized to improve estimation of local flow velocities. Improvements in simulation accuracy were achieved by computing channel roughness coefficients as a function of flow depth, and by determining eddy viscosity coefficients based on velocity data. The reparameterization was combined with refinements in the mesh geometry near 13 public water intakes on the St. Clair-Detroit River Waterway to improve the resolution of flow velocities while maintaining consistency with flow and water- level data. Scenarios representing a range of likely flow and wind conditions were developed for hydrodynamic simulation. Particle-tracking analyses were used to combine advective movements described by hydrodynamic scenarios with random components associated with sub-grid-scale movement and turbulent mixing to identify source areas to public water intakes.