The only way this channel could be connected to the vertical erosion channels on the Sphinx itself is if they had somehow fashioned a pump and giant shower head to spray it from above.
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Explanation is that there was silt build-up around the Sphinx, and the silt was dredged out vertically over hundreds of years leaving the vertical erosion. There were numerous yearly religious ceremonies which involved a boat going around the monument so the silt had to be removed.
R.Temple 2009 “The Sphinx Mystery”.
It doesnt have a good beat and I cant dance to it. I give it about a 3, Dick.
Not a particularly good theory of the many out there and doesnt stand up to much more than cursory examination. Youre never going to create runnels of that length to depth ratio by slowly removing a much softer material from around something much harder. Ignores a lot of other things. I would imagine that someone could write a whole book about just this subject if they were that motivated. Id rate it slightly better than alien woo woo but not quite up the the handwaving of most gate guardians.