Modeling the Ultimate Transport and Fate of Dredge-Induced Suspended Sediment Transport and Deposition
Type:
Presented during:
WODCON XVIII - 2007 Orlando, Florida, USA
Authors:
Swanson
Abstract:
SSFATE (Suspended Sediment FATE) is a computer model originally developed jointly by the U.S. Army Corps of Engineers Engineer Research and Development Center and Applied Science Associates to estimate the water column suspended sediment concentrations and bottom deposition patterns resulting from dredging operations. The model requires specification of circulation in the area of interest, the type of dredging technology used, and the loss rate and vertical distribution of initial material release. Using a random walk procedure, the model tracks representative particle classes as they disperse in the water column and settle to the bottom. Model output includes water column suspended sediment concentrations and bottom deposition thicknesses.
The model originally tracked only the initial deposition of sediment on the bottom as the local shear stress dropped below the critical deposition threshold. If the velocity (and shear stress) subsequently increased, the sediments were not resuspended. To expand the capability of the model to include resuspension and thus transport of suspended sediment after initial deposition, a two step resuspension algorithm was implemented.
The expanded model was tested to prove the concept for a simple channel configuration and an actual coastal application. Comparisons between the original nonresuspension version and the updated resuspension version were made for both applications. The addition of the resuspension calculation tended to cause a larger areal bottom deposition pattern and increased the maximum concentration away from the dredging site. The model provides consistent and reasonable results but remains to be tested against actual field data. Future work will concentrate on locating suitable data sets to verify model performance.
Keywords:
Dredging, modeling, suspended sediment, resuspension