thalweg

[ tahl-veg, -veyk ]

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.

thalweg

/ 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

thalweg

/ 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.

Word History and Origins

Origin of thalweg¹

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

Word History and Origins

Origin of thalweg¹

C19: from German, from Thal valley + Weg way, path

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