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

In international law, there’s a principle that if the border between two countries is a waterway, its thalweg marks the boundary line.

From New York Times

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 Project Gutenberg

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 Project Gutenberg