I've run into this several times in looking at the hydraulics and
tunneling in the area. The theory has some interesting aspects but
at least one huge weakness; water wouldn't have flowed from Lake
Moeris unless the Nile flood exceeded about 175'.
It's interesting that they came up with the pump concept but never took
it a little further to include building the pyramid with it.
There are few other references to the Ur Nile and this is one of their
most intruiging concepts. There was apparently a river here and it can
be seen on the satellite picture originating in Norther Central Libya.
This is the current origination for the water in the largest hydraulic
project of its type ever undertaken; The Great Manmade River Project. A
river at this level might be a source for water pressure at Giza but
there is scant evidence it flowed even as late as 3000 BC.
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Man fears the pyramid, time fears man.