thalweg

• 山谷底部或河床沿线的海拔最低点连线，也是河流或水道中最深、最适航的通道，常用于划定边界。

A noun referring to the line of lowest elevation along the bottom of a valley or the deepest, most navigable channel of a river or waterway, often used to define boundaries.

1. Boundary line in a waterwayC2formal

   The middle of the main navigable channel of a river or waterway, used as a boundary between states or countries.

   深泓线

   • The treaty established the thalweg as the official border between the two nations.
   • Disputes over the thalweg often arise when the river changes course.
   • International law uses the thalweg principle to define maritime boundaries.

2. Lowest line of a valleyC2formal

   A line connecting the lowest points along the floor of a valley or riverbed.

   谷底线

   • The thalweg of the valley guided the path of the ancient glacier.
   • Geologists mapped the thalweg to understand the drainage pattern.
   • The hiking trail follows the thalweg of the canyon.