thalweg
/ˈtɑːlvɛɡ
/ /ˈθɑːlwɛɡ /noun Geology
A line connecting the lowest points of successive cross-sections along the course of a valley or river.A river adjusts to variations in seasonal changes in volumetric flow by means of its thalweg (the thread of fastest flowing water), its flood plains, and its underground flow....
- The common boundary between the States of Arkansas and Mississippi in the Mississippi River is the thalweg, which is the middle of the main navigable channel followed as the principal course of downstream navigation.
- Along all three of the Maine/New Brunswick boundary rivers, the actual boundary follows the middle of the main channel, but it is only on the St. Croix that the term thalweg is expressly used.
Origin
Mid 19th century: from German, from obsolete Thal 'valley, dale' + Weg 'way'.