Overleg:Definition of ebb and flood (tide)

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Review by Co van de Kreeke (January 2013)

The definitions of ebb and flood are somewhat narrow and not entirely correct. The following additional information is partially based on [1] and is intended to paint a more complete picture.

In coastal oceanography the terms ebb and flood refer to tidal currents. These terms are particularly relevant for semi-enclosed basins such as estuaries and lagoons. The ebb current empties and the flood current fills the basin. The ebb current does not necessarily coincide with the falling tide i.e. the period of decreasing water level; more often than not the ebb current reverses some time after low water. Similarly the flood current reverses some time after high water. In the open sea the terms ebb and flood are ambiguous. Only when dealing with a progressive tidal wave, for example as found off the Dutch and Britisch North Sea coast, is it possible to define ebb and flood. In a progressive wave when the water level is higher than the mean level, the tidal current is in one direction and when lower than the mean level is in the opposite direction. In that case ebb is defined as the current when the water level is lower and flood is defined as the current when the water level is higher than the mean level. In a progressive wave the maximum ebb current coincides with low water and the maximum flood current coincides with high water.

Reference

  1. Darwin, G.H., 1962. The Tides, Publisher:W.H.Freeman and Company