waterway engineeringwaterway engineering chapter 4

1、Chapter 4Factors influencing channel design4.1 water levels4.2 tide predictions4.3 wind, waves, and currents4.4 design vessel4.5 sedimentation4.6 environmental sustainability4.1 water levelsMaximum water levels Minimum water levels frequenciesDurationsamplitudes of water-level fluctuationsWater leve

2、ls can be affected by storm surges, seiches, river discharges, seasonal lake-level changes, and ocean tides.4.2 tide predictionsThe National Ocean Service (NOS) predicts tide height and tide ranges.Figure 4-1 shows spring tide ranges for the continental United States.4.2 tide predictions4.3 wind, wa

3、ves, and currentsEstimates of wind, waves, and currents are needed to determine theireffects on vessel motions and controllability, to estimate the rates of sediment erosion and deposition, to determine the extent and characteristicsof salinity intrusion, and to define flushing characteristics.4.3 w

4、ind, waves, and currentsThe following situations are especially important and require careful consideration:1. Tankers in ballast (light ship) condition2. Bulk: carriers in ballast (light ship) condition3. Automobile or car carriers4. Container ships with containers on deck5. Ferry boats6. LNG and l

5、iquefied petroleum gas (LPG) ships4.4 design vesselspecial conditions:1. Suitable wind, wave, and current conditions and visibility limitations2. Use of high tide for additional water depth3. One-way traffic with bridge-to-bridge communications between other vessels4. Speed restrictions to reduce sq

6、uat, ship-generated wave heights, and shore damage4.5 sedimentationThe aspects of sedimentation that must be considered for deep-draft navigation projects are:(1) characteristics of the native soils through which the project passes(2) characteristics of sediments introduced into the upper reaches of

7、 the project by riverine flows(3) characteristics of sediments introduced into the lower reaches of the project by littoral processes and salinity intrusion(4) hydrodynamic and water chemistry conditions in the project region4.6 environmental sustainabilityThe following physical changes require evaluation:1. Salinity2. Tide heights (water levels)3. Current velocities and duration4. Water circulation pattern5. Shoaling and erosion in the vicinity of the channel6. Possible