Impacts of ship movement on the sediment transport in shipping channel

The duration of ship-generated waves （wake waves） and accelerated currents can generate significant influences on the sediment transport. A 3-D numerical model is presented to estimate these effects. The hydrodynamic model is the 3-D Reynolds averaged Navier-Stokes （RANS） equations including the standard k - ε model while the 3-D convection-diffusion model is for the resuspended sediment transport. This hydro-sedimentary model is firstly validated with the trench experimental results, and then applied to the open channel with a moving ship. The computed results demonstrate that the resuspension generation mainly depends on ship speeds, barge number, and the relative distance away from ship. The acceleration effects of ship on the sediment transport are analyzed as well.

Zoning Marine Disposal for Dredged Material Management:A Case Study in Vietnam

The fast growth of Hai Phong ports in the two last decades requires not only their upgrading facilities but also expanding port area and dredging their shipping channels(existing and new ones)that generate a huge amount of unused dredged materials.While all existing dumping sites in sea waters and on land get over capacity,looking for new dumping sites in sea waters is an urgent need.This study is to zone coastal waters of Hai Phong for suitable dumping sites meeting sustainable coastal management.Multi-criteria overlay analysis on GIS platform was employed with the criteria of natural conditions,environment and socio-economics for zoning coastal waters of Hai Phong.These criteria were detailed into eight subcriteria and then developed to eight GIS weighted thematic sub-layers of bottom depth,litho-hydrodynamics,ecosystems,distribution of benthos,distance to residential areas and tourist sites,distance to aquaculture area,distance to ecosystems and distance to conservation areas.Analysis results show the highly suitable zone for dredged material dumping in South,South West Hai Phong at depth below 15m to the deeper areas.Disposals of dredged materials in the zone would minimize impacts on the environment,ecology and socio-economics in surrounding waters and coastal areas.

Study of narrow waterways congestion based on automatic identification system(AIS)data:A case study of Houston Ship Channel

Using automatic identification system(AIS)data,this article first has extended the definition of three widely used roadway congestion indices to maritime transportation systems(MTS),traffic speed index(TSI),traffic rate index(TRI),and dwell time index(DTI).Next,a methodology is developed to measure the indices based on AIS data,considering various factors,including path geometry,time of day,and the type and size of vessels,and finally the method has been applied to the AIS data of the Houston Ship Channel(HSC)to evaluate the applicability in real cases.The results show that although average TSI and TRI cannot represent waterway congestion,the real-time values(rather than the average)at the micro level can help finding location,time,and severity of traffic congestion.Besides,while TSI and TRI have shortcomings,both average and real-time dwell time index(DTI)can quantify traffic congestion and highlight severity in different waterway segments for different types of vessels.When congestion happens at some narrow waterways,vessels need to wait at sea buoy or docks,thus dwell time index(DTI)can quantify traffic congestion better than in-transit indices such as travel speed,TSI.According to HSC DTI,most tankers experience long waiting times at the sea buoy and Galveston Bay,while cargo vessels experience delays at Bayport and Barbour’s Cut terminals.This paper helps the decision-makers quantify congestion in different sections of a waterway and provides measures to compare congestion for national competing projects at different waterways.