thalweg

American  

[tahl-veg, -veyk] / ˈtɑl vɛg, -veɪk /

noun

1. a line, as drawn on a map, connecting the lowest points of a valley.

2. Chiefly International Law. the middle of the main navigable channel of a waterway that serves as a boundary line between states.

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thalweg British  

/ ˈtɑːlvɛɡ /

noun

1. the longitudinal outline of a riverbed from source to mouth

2. the line of steepest descent from any point on the land surface

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thalweg Scientific  

/ täl′vĕg′ /

1. The line defining the lowest points along the length of a river bed or valley, whether underwater or not.

2. A subterranean stream following a course similar to that of an overlying surficial stream.

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Etymology

Origin of thalweg

1860–65; < German, equivalent to Thal, now obsolete spelling of Tal valley (cognate with dale ) + Weg way ¹

Example Sentences

When there’s low water, Chinook are relegated to spawn in the thalweg, or the lowest part of the river, said Pete Verhey, state fisheries biologist for the Snohomish and Stillaguamish basins.

From Seattle Times • Oct. 24, 2022

But at the bend of a meandering stream, the thalweg moves to the cut bank.

From Textbooks • Jan. 1, 2017

In the straight parts of the channel, the thalweg and highest velocity are in the center of the channel.

From Textbooks • Jan. 1, 2017

The dates form a kind of square with a sharp triangle to the south, upon the left bank of the thalweg, which overflows them during floods.

From The Land of Midian — Volume 2 by Burton, Richard Francis, Sir

Here, seven and a quarter miles from the mouth, the stream measures about twenty yards broad, the thalweg is deep and navigable, and the water, bitumen-coloured with vegetable matter, tastes brackish.

From To The Gold Coast for Gold, Vol. II A Personal Narrative by Burton, Richard Francis, Sir