from The American Heritage® Dictionary of the English Language, 4th Edition
- n. Geology The line defining the lowest points along the length of a river bed or valley.
- n. Geology A subterranean stream.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The line that connects the lowest points in a valley or river channel, and thus the line of fastest flow along a river’s course.
from the GNU version of the Collaborative International Dictionary of English
- n. A line following the lowest part of a valley, whether under water or not.
- n. The line of continuous maximum descent from any point on a land surface, or that cutting all contours and angles.
from The Century Dictionary and Cyclopedia
- n. A line upon a topographical surface which is a natural watercourse, having everywhere the direction of greatest slope, and distinguished by having the lines of straight horizontal projection which cut it at right angles on the upper sides of the curves of equal elevation to which they are tangent.
from WordNet 3.0 Copyright 2006 by Princeton University. All rights reserved.
- n. the middle of the chief navigable channel of a waterway that forms the boundary line between states
- n. a line following the lowest points of a valley
For those of you who don't know, a thalweg is the last remnants of water where a fish can survive when the water has receded.
Apparently, the border was agreed as being the 'thalweg' middle of the deep water channel to you & me at Algiers in 1975 but once you are out of the mouth of the Shatt-al-Arab there is no thalweg anymore.
Davidson also taught the group a few new definitions, "thalweg" being the favorite.
The escarpment has been shaped into numerous irregularities, indentations, and promontories, and is pierced by thalweg ravines, gorges, and rocky passages connecting the plain and plateau.
In this straight channel stream, bars form in the regions of the stream away from the thalweg.
In straight streams, bar-like deposits can form in response to the thalweg (red arrows in Figure 5) and helical flow.
Riffles, another type of coarse deposit, develop beneath the thalweg in locations where the faster flow moves vertically up in the channel.
The line of maximum velocity or thalweg moves from side to side within a channel.
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.
It has been abundantly supplied with water; in fact, the whole vein (thalweg) subtending the left bank would respond to tapping.