The term refers to the lowest tide level predicted to occur under average astronomical conditions. This means it is the theoretical minimum water level expected when only gravitational forces of the moon and sun are considered, excluding any meteorological influences. It is frequently utilized as a tidal datum for charting and coastal engineering purposes. For example, depths indicated on nautical charts are often referenced to this level, providing a safety margin for navigation.
Its importance lies in its role as a consistent and reliable reference point. Establishing this baseline facilitates safe navigation, accurate mapping, and consistent measurement of tidal ranges. Historically, its determination has been crucial for defining territorial sea boundaries and infrastructure planning along coastlines. Understanding this value allows for better predictions of extreme low-water events and their potential impact.
