waterway engineeringwaterway engineering chapter 5

1、Chapter 5Estuary hydraulics5.13 tide prediction tables5.14 nonastronomical forces5.15 waveforms5.16 winds and wind-generated waves5.17 setup, setdown, and storm surge5.18 seiche5.19 fresh water sources5.20 episodic events5.21 changes in sea level5.22 apparent sea level rise5.23 sea level rise impact

2、 on navigational channels5.1 definition5.2 purpose of estuary classification5.3 classification options5.4 flow predominance5.5 null point5.6 salinity effects on shoaling5.7 summary of estuary classification5.8 tide-generating forces5.9 tide terms5.10 types of tides5.11 spring of neap tides5.12 influ

3、ence of moon and sun5.1 definitionAn estuary is an area of interaction between salt and fresh water.5.2 purpose of estuary classificationThere are many types of estuaries, and design problems may vary greatly with the type of estuary. Correct classification alerts the designers to potential environm

4、ental and maintenance-dredging problems.5.3 classification optionsEstuaries also are classified by topography and salinity structure. Ratio parameters of flow, stratification, and stratification-circulation can be used to identify the salinity structure class.5.3.1 Topographic Classification1. Coast

5、al Plain Estuaries2. Fjords3. Bar-built Structures4. Other5.3.2 Classification by Salinity Structures1. Highly Stratified2. Partially Mixed3. Well-Mixed or Homogeneous5.3.2 Classification by Salinity Structures5.4 flow predominance5.5 null pointAlong with the concept of flow predominance, it should

6、be noted that the net flow may be balanced at a certain point (i.e., no net flow occurs in either direction). This point is called the null point.5.6 salinity effects on shoaling5.7 summary of estuary classificationThe classification of estuaries uses variables of topography, river flow, and tidal a

7、ction as factors influencing saltwater and freshwater mixing.Ultimately, the salinity characteristics of an estuary determine the unique features of the system.5.8 tide-generating forcesTide generating force is proportional to the mass, theinverse proportion with the square of the distance.5.9 tide

8、termsSeveral basic terms are used to describe tides. High water is the watersurface level at its highest extent during one cycle. The term is also used to denote the time at which highest water-surface level occurs.Similarly, low water refers to the lowest water level.5.10 types of tides1. Diurnal2.

9、 Semidiurnal3. Mixed5.12 influence of moon and sunAnother factor that influences tide is the declination of the moon and sunthe angular distance north or south of the equator.5.14 nonastronomical forcesNonastronomical forces also can produce waves. A tsunami, or seismic sea wave, is a very long wave that originates in a disturbance in the sea floor.5.15 waveformsAs the wave progresses up, the estuary, the waveform changes shape, the face becomes steeper,