Simulating Dredged-Material Placement at Open-Water Disposal Sites

A new approach is described for the quantitative assessment of open-water disposal activities with regard to short- and long-term morphology of dredged material placed on the seafloor at designated open-water disposal sites. A personal-computer driven numerical simulation, called the Open water Disposal Area Management simulation (ODAMS), is described. The simulation automatically grids the disposal area and incorporates existing short-term (minutes to hours) and long-term (weeks to months) fate models to predict the bottom bathymetry for multiple disposals of dredged material. Several disposal scenarios such as random placement around a buoy, line placement, and individually specified disposal locations are possible. Before-and-after bathymetry comparison is also an option. The simulation is intended to assist in planning and managing open-water dredged material disposal sites. Bathymetric predictions from the simulation and subsequent volume computations are compared to actual hydrographic survey results from a yearlong series of disposal operations at a current open-water disposal site. Predicted bathymetry is in good agreement with the hydrographic survey results, and the volume comparison is within 10%.