What is the term for the average of all high tides observed over a period of 19 years?

The term that refers to the average of all high tides observed over a period of 19 years is known as the Tidal Epoch. This concept is important in the field of surveying and coastal management, as it provides a long-term perspective on tidal patterns. The 19-year period is used because it encompasses the complete cycle of the lunar phases, which directly influence tidal variations.

Mean High Tide, while related, specifically refers to the average of the high water levels during a designated period, typically covering shorter intervals rather than the extended 19-year cycle.

The Standard Tide Line is a term that may refer to a specific method or point of measurement but does not specifically capture the average high tides over that lengthy duration.

Comparative Tide Levels are used to analyze differences between various tidal measures or over time, yet they do not reflect the specific annual averaging that defines the Tidal Epoch.

Thus, Tidal Epoch is the correct term, encapsulating a comprehensive understanding of tidal data over an extended duration crucial for effective planning and construction in coastal areas.