Which of the following terms is synonymous with the average of high water levels?

• A. Mean high water (MHW)
• B. Mean lower low water (MLLW)
• C. Tide datum
• D. Tidal average

Answer: (A)

The term that is synonymous with the average of high water levels is "Mean High Water" (MHW). This concept refers specifically to the average height of all the high water levels recorded over a significant period, typically 19 years, which is used to determine the baseline for various marine and coastal management purposes.

Mean High Water is crucial for navigation, shoreline construction, and legal considerations regarding coastal property. By providing a consistent reference point, it helps in assessing the impacts of tides and ensuring accurate charting of navigable waters. The other terms, while related to tidal measurements, focus on different aspects of tidal level assessments. Mean Lower Low Water (MLLW) addresses the average of the lowest tide levels, while tide datum refers to a reference plane determined by tidal elevations for gauging water levels. Tidal average is a broader term that could include various averages, but it doesn't specifically denote the average of high water levels like MHW does.