Three-dimensional modeling of sediment transport in a partially stratified micro-tidal estuary

Abstract

A 3D numerical model was used to investigate sediment trap effectiveness in a partially stratified micro-tidal estuary. The modeling domain was a 16 km reach of the St. Johns River, Florida, and two tributaries: the Ortega and the Cedar Rivers. The Cedar flows into the Ortega a few kilometers from the confluence of the Ortega and St. Johns Rivers. Sediment traps have been proposed as a remedial measure to minimize the transport of contaminated sediments from the Cedar River into the Ortega-St. Johns River system. The model simulations investigated the effect of traps at three different locations along the Cedar River. For each trap, three different sediment removal efficiencies (40%, 60%, and 80%) were simulated. Sediment removal efficiency is defined as the percentage of incoming sediment that deposits in the trap. The simulations showed that the upstream-most trap had minimal impact on reducing the flux of sediment out of the Cedar River, whereas the downstream-most trap had a significant impact.