Dictionary term
Tidal Datum
Direct answer
Tidal Datum: A Tidal Datum is a local reference elevation derived from a defined phase or statistic of observed water levels over a specified epoch.
A Tidal Datum is a local water-level reference based on tide observations.
A Tidal Datum is a local water-level reference based on tide observations.
A Sun–Earth orientation for seasonal, atmospheric, tidal, and terrestrial terms.Quick reference
- Use when
- Use Tidal Datum only with its full name, station, realization epoch, and relation to geodetic datums.
- Do not use it for
- Do not extend a local Tidal Datum into hydrologically different waters without measurements and an authorized transformation.
- Reference category
- Seasons & Earth Almanac
- Related terms
- Tidal Range, Semidiurnal Tide, Astronomical Season, Equinox
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The story behind Tidal Datum
Long tide-gauge records enabled national agencies to establish consistent local datums such as Mean Lower Low Water.
Tidal Datum in spiritual tradition
Spiritually, a tidal datum shows that even a zero line must be defined with evidence and place.
Tidal Datum: fact and faith, kept distinct
This is a factual calendar, astronomy, Earth-science, cultural-history, or observational reference. It can support wonder and practical planning without becoming a claim of fate, spiritual causation, or private revelation.
Tidal Datum in numerology
Tidal Datum is not a numerology claim. Any numbers attached to it should retain their ordinary scientific, calendrical, navigational, or historical meaning unless a separate symbolic interpretation is clearly labeled.
Why Tidal Datum matters
Charts, coastal boundaries, flood thresholds, and engineering elevations need a stable stated zero.
Tidal Datum at work: an example
A charted depth referenced to Mean Lower Low Water is not measured from the same zero as an elevation referenced to a land datum.
Where interpretation stops
Tidal Datum is presented as sourced astronomy, calendrical, Earth-science, cultural, or instrument-history reference. Definitions should distinguish measured phenomena from civil convention and historical interpretation, preserve location and time dependencies, and avoid turning factual sky data into a deterministic personal claim.
Sources and editorial method
Research references used for this entry include:
- NOAA Tides and Currents Glossary - Operational definitions for tides, tidal currents, ranges, datums, bores, and amphidromic systems.
- Source
- The Great Almanac Dictionary
- Category
- Seasons & Earth Almanac
- Also appears in
- Seasons & Earth Almanac
- Aliases
- None listed
- Last updated
- 2026-07-16
Name the coastal reference level
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More in Seasons & Earth Almanac
- Astronomical Dusk
- Civil Dusk
- Diurnal Tide
- Glory
- March Equinox
- Nautical Twilight
- Season Length Asymmetry
Common questions
What is Tidal Datum?
A Tidal Datum is a local reference elevation derived from a defined phase or statistic of observed water levels over a specified epoch.
How is Tidal Datum used in an almanac?
Use Tidal Datum only with its full name, station, realization epoch, and relation to geodetic datums.
What should I avoid when interpreting Tidal Datum?
Do not extend a local Tidal Datum into hydrologically different waters without measurements and an authorized transformation.
