The prediction of sediment erosion and deposition magnitudes has challenged
many investigators. One- and two-dimensional sediment transport models are
commonly used for predicting sediment scour and deposition. They are adequ
ate for many engineering applications; however, for some problems, only a t
hree-dimensional model should be used. A three-dimensional model is necessa
ry for predicting sediment erosion and deposition whenever significant seco
ndary currents exist, such as in river bends, crossings, distributaries, or
diversions. In diversions, for example, the sediment load may not split in
the same proportions as the flow. A three-dimensional model can be used to
estimate the sediment split. This paper presents a description of the thre
e-dimensional numerical model CH3D-SED and the governing equations for the
model. The validation of the model and its application to the Deep Draft Na
vigation Project on the lower Mississippi River also are presented.