What is defined as the mean of all high tides over a period of 18.6 years?

The mean of all high tides over a period of 18.6 years is referred to as the mean high tide. This term is crucial in coastal and marine surveying as it represents an average that accounts for variations in tides due to factors like the gravitational pull of the moon and sun, seasonal changes, and other astronomical influences. By using a lengthy time frame like 18.6 years, the calculation can smooth out anomalies and provide a reliable baseline for understanding tidal patterns.

This average is essential for various applications in surveying, environmental studies, and coastal management, allowing professionals to make informed decisions regarding land use, construction, and conservation based on predictable tidal behaviors. Understanding mean high tide is fundamental for ensuring that structures are safe from inundation and for managing ecosystems that depend on specific tidal conditions.