in hydrography, it is the place of the depressed points more than a catchment basin that collects relative meteoric waters to the same river basin making to meet them in the main collector who practically follows the same tracing.

or thalweg.

thalweg in geology is a line representing the profile of a land surface, drawn as a series of cross-sections that crosses all contour lines at right angles.


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The word thalweg is also used in hydrology. It refers to a line drawn to join the lowest points along the entire length of a streambed or valley. This is occasionally called a valley line. The term is also sometimes used to refer to a subterranean stream that percolates under the surface and in the same general direction as the surface stream.

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