My question was inspired by this one - in particular, the subtopic of pumping water from the ocean to the below-sea-level basins to deal with rising sea levels (spoiler: it's horribly infeasible and impractical).

I have also read about topographic prominence, line parent(s), key cols, and the concept of a "prominence walk".

Then, I was reminded of my experience futzing around with Google Earth's elevation data when trying to understand how Lake Assal is the lowest point in Africa (-155 meters / -510 feet) yet it's unusually close to the ocean (only about 5 km from the Gulf of Aden).1

Obviously there's a saddle point above sea level which separates this lake and ocean, plus there are line parents and a prominence walk crossing this saddle point,


how about the line of lowest elevation leading up to this saddle point from each of the Lake and the Gulf, i.e. the converse of a prominence walk?

In terms of physical geography and the study of prominences, is there a formal name for this line?

1 Somewhat related: I've been intrigued for decades about how Reno, Nevada is 4500' elevation but nearby Lake Tahoe is 6220'.

  • 1
    $\begingroup$ In mathematics, the "line of steepest descent". $\endgroup$ Commented Jul 29, 2018 at 4:57


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