Tidal Hydraulics (EM 1110-2-1607), Chapter 2: Definition and Forcing Functions of Estuaries

This chapter defines an estuary and the forces that drive it. It classifies estuaries by topography and by salinity structure, using stratification numbers and flow predominance, and introduces the null point and the way salinity affects shoaling.

It then reviews the forcing functions: tide-generating forces and tide terms, the types of basic tides, spring and neap tides, the influence of moon and sun, tide prediction tables, and tidal constituents. It covers nonastronomical forces such as winds and wind waves, setup and setdown, seiche, and storm surge, along with freshwater inflow and changes in sea level.

The chapter ends with a summary on classifying an estuary, which is where any study of a particular estuary should start.

In this chapter

• Definition
• Classification of Estuaries
• Tides and Other Long Waves
• Winds and Wind-Generated Waves
• Freshwater Inflow
• Changes in Sea Level
• Summary: Classifying an Estuary