Current action refers to the effects of water moving in oceans or lakes.
Unlike water flowing under the influence of gravity down a river channel, movement of water in oceans and large lakes is caused by tidal cycles, wind, and temperature and density differences in the water (NOAA 2018). Gravitational attraction of the Earth to the Sun and the Moon, and its rotation about its axis, causes predictable cyclic rise and fall of large bodies of water. The rise and fall of tides results in movement of water that is most noticeable where it encroaches on coastlines, estuaries, bays, and harbors as the tides “come in,” and recede from them as the tides “go out.” Tidal currents are called “flood” or “ebb” in the rising and falling of tides, respectively. Because the tidal range is relatively uniform at any particular place along the coast, the reversing currents create equilibrium landforms, until some major natural or human-caused event disturbs the shape of the tidal channels or...
- NOAA (2018) Currents (Webpage). National Ocean Service, U.S. Department of Commerce, National Oceanographic and Atmospheric Administration. https://oceanservice.noaa.gov/education/tutorial_currents/. Accessed 20 Jan 2018
- USACE (2008) Water wave mechanics. Chapter 1 in Coastal engineering manual. U.S. Army Corps of Engineers Engineering and Design Manual EM 1110-2-1110 (Part II). http://www.publications.usace.army.mil/Portals/76/Publications/EngineerManuals/EM_1110-2-1100_Part-02.pdf?ver=2016-02-11-153511-290. Accessed 20 Jan 2018