Houston-Galveston Navigation Channels, Texas Project. Navigation Channel Sedimentation Study, Phase 2

Abstract

The U.S. Army Engineer District, Galveston, has recently enlarged the Houston Ship Channel from a 40-ft (12.2-m) depth by 400-ft (122-m) width to a 45-ft (13.7-m) depth by 530-ft (162-m) width. Previously, a three-dimensional (3-D) numerical model study was implemented at the U.S. Army Engineer Research and Development Center's Coastal and Hydraulics Laboratory to evaluate the salinity and circulation impact of this enlargement. The enlarged channel is nearly complete. Preliminary evaluations indicate a higher than anticipated rate of deposition in the channel reach near Atkinson Island. The purpose of this investigation was to determine if this new shoaling rate was a permanent feature of this new channel or a single anomalous event. If this considerably larger deposition is a permanent condition then the planned disposal locations must be expanded. The project will determine the possible effects on sedimentation in the channel based on dredging records, field data, vessel effects, and hydrodynamic changes due to the channel's enlargement.

Houston-Galveston Navigation Channels, Texas Project. Navigation Channel Sedimentation Study, Phase 2 Plan Simulations

“…It is also important to note that the validated model performed well for shoaling distribution in the channel and surrounding shallows but the rate of shoaling was underpredicted, especially in the ship channel. The model was only able to account for 20 percent of the deposition rate experienced in the field (Tate et al 2008). The model's low prediction of the shoaling volume may be due to several factors requiring more research and analysis, including the possibility of fluid mud, the application of suspended sediment loads, and the fate of dredged material.…”

“…The CHL then proceeded to develop a validated sediment model of the Houston-Galveston ship channels and surrounding shallows (Tate et al 2008). Figure 1 shows the areas included in this modeling effort.…”

“…The rate of shoaling in the channel and the overall volume of material being deposited were somewhat lower than that found in nature. Details of the sediment model validation as well as the ADH and TABS-MDS codes can be found in Tate et al 2006 and2008. …”

“…Preliminary evaluations of the enlarged channel indicate a higher than anticipated rate of deposition in the channel reach near Atkinson Island. A Coastal and Hydraulics Laboratory investigation (Tate and Berger 2006) was charged with determining if this higher deposition rate is a permanent feature or only a temporary issue. A preliminary study focused on the change in currents, as determined by the model, from the preenlarged channel to the new configuration and a sediment tracer analysis.…”

“…The end result is a model that is capable of reproducing tides, circulation, salinity, and sediment transport in Galveston Bay. In addition to these properties, the model also includes the effects of vessel traffic on the sediment transport in the area (Tate et al 2008). Now that the validated sediment model is available, plan simulations can be performed to analyze the effects of various changes within the system.…”