divide
divides
I think you refer to the Watershed.... say rain falls on a mountain side & some of it eventually flows into the River Anything & some flows into the next valley, the River Zoobeedoobeedoo. Where the dividing line is, (Between the Anything & the Zoobeedoobeedoo) is the Watershed.
You can find one by going up the river thing in the Valley Windworks. Look for a small area of land next to the river. The Electirizer is on that space.
Humbolt Valley is one.
The river Nile.
It as at least one called Valley River.
Victoria is the Murray river which separates Victoria and NSW. The main one in Melbourne is the Yarra.
There are many locations in the United States which have the name River Valley. One area is located in the state of Wisconsin, another is in the state of Minnesota. In order to located the River Valley one is looking for, more specific information would be needed.
The Indus Valley Civilization.
phospholipid bi-layer
Tigris-Euphrates
The Phoenicians.