science

International Great Lakes Datum

International Great Lakes Datum is a science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand International Great Lakes Datum rather than just read about it. In short: The International Great Lakes Datum (IGLD) is a vertical datum to be used in and around the Great Lakes and the St. Lawrence River.

Key takeaways

International Great Lakes Datum belongs to science; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect International Great Lakes Datum to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of International Great Lakes Datum from memory before moving on to harder problems.

Reference excerpt

The International Great Lakes Datum (IGLD) is a vertical datum to be used in and around the Great Lakes and the St. Lawrence River. It is managed by the United States and Canada via the Great Lakes Coordinating Committee. It has three versions: IGLD 1955, IGLD 1985, and IGLD 2020 (expected to be released in 2027). It is based on dynamic heights with respect to the geoid. It must be updated to account for glacial isostatic adjustment in North America. It is to be used for hydraulics and hydrology: flood prediction, water levels recorded by tide gauges, etc. It is not to be used for hydrography: a chart datum will still be needed for representing bathymetry on nautical charts.

References "IGLD". NOAA Tides & Currents. Retrieved 2025-11-18. "Subcommittee on Vertical Control – Water Levels". Great Lakes Coordinating Committee. 2025-02-26. Retrieved 2025-11-18. Daniel Roman and John Crowley (2023), "Dynamic Heights for the International Great Lakes Datum of 2020", FIG Working Week 2023, International Federation of Surveyors (FIG); Orlando, Florida, USA, 28 May–1 June 2023. [1] Coordinating Committee on Great Lakes Basic Hydraulic and Hydrologic Data (1980). Establishment of International Great Lakes Datum (1955). Department of Defense, Department of The Army, Corps of Engineers. Retrieved 2025-11-18. Blust, Frank A. (2015-07-02). "History and Theory of Datum Planes of the Great Lakes". The International Hydrographic Review. ISSN 0020-6946. Retrieved 2025-11-18.

Worked examples

Example 1 — a first encounter with International Great Lakes Datum

Start with the simplest possible case. Write down what International Great Lakes Datum claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to International Great Lakes Datum before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about International Great Lakes Datum ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of International Great Lakes Datum

In research: International Great Lakes Datum appears in science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry: Engineering practice reuses International Great Lakes Datum in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom: International Great Lakes Datum is common in secondary-school and first-year university syllabi. It links to neighbouring topics Great Lakes, Surveying of Canada, Surveying of the United States, so understanding it makes those chapters shorter.
In everyday life: Look for International Great Lakes Datum outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study International Great Lakes Datum in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what International Great Lakes Datum means in your own words.
Compare your version with the excerpt and mark what you missed.
Work through the three examples above with pen and paper.
Explain International Great Lakes Datum out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is International Great Lakes Datum in simple terms?

The International Great Lakes Datum (IGLD) is a vertical datum to be used in and around the Great Lakes and the St. Lawrence River.

Why does International Great Lakes Datum matter?

Because it connects several science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study International Great Lakes Datum?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on International Great Lakes Datum.