I'm downvoted, but why? I'm simply making the obvious observation - that the river got this low 2000 years ago, but today the drop is blamed on climate change.

> the pictured carvings are on collapsed rock shelves, presumeably these were above normal river level when carved and in a two thousand year period the river has undercut the rock shelf and they've colapsed to below the usual river level.

You presume something that is not expressed in the article. There's nothing about the river undercutting the rock shelf and causing a collapse - that's an act of imagination on your part.

If you simply take out the political, environmental slant (out of the article, and your mind) and just look at what is stated, the most obvious conclusion is that every so often this river drops lower than usual. And that droughts, floods, etc have always been part of life on earth.