Desktop Methodology for Estimating Maintenance Dredging Requirements for Widened and Deepened Navigation Channels

Estimates of maintenance dredging quantities were needed for a proposed widening and deepening of a navigation channel. However, detailed numerical modeling of sediment transport was not desired at the time. Channel sedimentation rates were estimated based on a new semi-empirical methodology. The methodology is based, on a simplification of the sediment deposition equations. Basic inputs to these equations include water velocities, total suspended sediment concentration (TSS), critical bottom shear stresses for erosion and deposition, Manning friction coefficient, bulk density of settled muds, and settling velocity for sediment particles (flocs). These equations are solved at discrete locations along the channel and integrated over time to give an overall sedimentation rate. The desktop methodology is applied to the Matagorda Ship Channel (Texas) widening and deepening project. The methodology offers a relatively simple way to estimate changes in maintenance dredging quantities for modifications to existing projects.