Preliminary Study on Siltation in Pussur Navigation Channel with Regulating Structure

In view of the serious problem of siltation rate in Waterway Engineering, feasibility of the scheme is studied from the perspective of sedimentation on Pussur River of Bangladesh in this paper. Based on the analysis of the tide, sediment and topography of the waterway and numerical simulation, the characteristics of the flow movement in the project reach, the influence of the dredging channel on the flow and the siltation were analyzed. With the excavation of channel, due to the influence of dynamic changes and elevation difference, the siltation of the channel is about 0.70–1.79m/a near Inner Bar area, and is more severely in the upper section near Chalna. The implementation of the preliminary regulating structure can increase the velocity and reduce the siltation of the local section. Yet the siltation of the upstream and downstream sections may be added due to changes of flow with the structure. The further scheme should be optimized from the angle of increasing the velocity in channel and reducing the influence to upstream and downstream. The feasibility results can provide scientific basis for the design and construction departments.

Houston Ship Channel Expansion Improvement Project – Navigation Channel Improvement Study : ship simulation results

In 2020, the US Army Engineer Research and Development Center (ERDC), Coastal and Hydraulics Laboratory, provided technical oversight during a navigation study to assist the Galveston District evaluation of different channel widening alternatives for larger ships transiting the Houston Ship Channel (HSC), Texas. The widening proposals encompassed several areas of the HSC including the Bay Section, the Bayport Ship Channel, Barbours Cut Channel, and the Bayou Section. The study was performed at the San Jacinto College Maritime Technology and Training Center (SJCMTTC) Ship/Tug Simulator (STS) Facility in La Porte, TX. The SJCMTTC STS is a real-time simulator; therefore, events on the simulator happen at the same time rate as real life. A variety of environmental forces act upon the ship during the simulation transit. These include currents, wind, waves, bathymetry, and ship-to-ship interaction. Online simulations of the project were conducted at SJCMTTC over a 3-week period – May through June 2020. Several mariners including Houston Pilots and G&H tugboat Captains participated in the testing and validation exercises. ERDC oversight was performed remotely because of the COVID-19 pandemic. Results in the form of engineering observations, track plots, and pilot interviews were reviewed to develop final conclusions and recommendations regarding the final design.

Engineering and design of the Lightning Point Shoreline Restoration Project in Bayou La Batre, Alabama

Lightning Point, located in Alabama at the confluence of the Bayou La Batre navigation channel and Mississippi Sound, is a culturally and ecologically valuable site with an extensive history of shoreline erosion. Between 1916 and 2019, the shoreline experienced approximately 750 to 1,000 ft of shoreline retreat as a result of severe weather events and anthropogenic causes such as shoreline modification and response efforts related to the Deepwater Horizon oil spill. Moffatt & Nichol worked with The Nature Conservancy to restore the lost habitat and resources through ecology-based engineering and design. The Lightning Point Shoreline Restoration Project is a 1-milelong living shoreline that includes approximately 4,700 ft of segmented, overlapping breakwaters, 40 acres of marsh and upland habitat creation, and 10,000 linear feet of tidal creeks. The project was designed to include a diversity of habitat types (subtidal, intertidal, higher scrub-shrub) and to serve as a resilient restoration solution capable of adapting in the face of sea level rise and increasing storm activity.

Sediment Transport and Morphological Response to Nearshore Nourishment Projects on Wave-Dominated Coasts

Nearshore nourishments are constructed for shoreline protection from waves, to provide sediment nourishment to the beach profile, and to beneficially use dredged sediment from navigation channel maintenance. However, it is poorly understood how placement morphology and depth influence nearshore processes operated on wave-dominated coasts. This study investigates the wave fields, sediment transport, and morphological response to three common nearshore nourishment shapes, nearshore berm (elongated bar), undulated nearshore berm, and small discrete mounds, with numerical experiments utilizing the Coastal Modeling System. The nourishments are placed in depths between 3 m and 7 m with a volume of approximately 100,000 m3 and between 400 m and 1000 m in alongshore length. Numerical experiments are carried out in three distinct coastal settings with representative wave climates and geomorphology. Simulation results indicate that shallower, more continuous berms attenuate the most wave energy, while deeper, more diffuse placements retain more sediment. Results from this study improve the understanding of nearshore nourishment shapes and can support decision makers identifying the most appropriate construction technique for future nearshore nourishment projects.

Vessel Scheduling Optimization Model Based on Variable Speed in a Seaport with One-Way Navigation Channel

To improve the efficiency of in-wharf vessels and out-wharf vessels in seaports, taking into account the characteristics of vessel speeds that are not fixed, a vessel scheduling method with whole voyage constraints is proposed. Based on multi-time constraints, the concept of a minimum safety time interval (MSTI) is clarified to make the mathematical formula more compact and easier to understand. Combining the time window concept, a calculation method for the navigable time window constrained by tidal height and drafts for vessels is proposed. In addition, the nonlinear global constraint problem is converted into a linear problem discretely. With the minimum average waiting time as the goal, the genetic algorithm (GA) is designed to optimize the reformulated vessel scheduling problem (VSP). The scheduling methods under different priorities, such as the first-in-first-out principle, the largest-draft-vessel-first-service principle, and the random service principle are compared and analyzed experimentally with the simulation data. The results indicate that the reformulated and simplified VSP model has a smaller relative error compared with the general priority scheduling rules and is versatile, can effectively improve the efficiency of vessel optimization scheduling, and can ensure traffic safety.