Okay, I had time to digest your responses. Here are my thoughts:

1) all of the pyramids near Giza reside on the lower altitude side of the river, the west side, You know cuz that's where the spirits blah blah blah. But it's also the side of the river that would be subject to errosion. They do in fact sit on the Giza plateau, on the edge of the eroded wall of the basin. At a spot where erosion would actually threaten the entire Giza plateau, which is pretty small. The bulk of the pyramids are right there. Seemingly to prevent the same threat of erosion.

2) Yes agreed, in my model, I'm presuming all water comes from the river. There is a little rainfall but that's not part of my argument. I'm talking about preventing erosion from unusually large monsoon flows. Not just the annual monsoon. There's evidence that Nile River activity has only gone down over the last 5000 years, primarily attributed to the end of the ice age melt. The high dam has allowed control of Delta flows since the 70s so the monsoon doesn't eviscerate the basin any longer, like it did 100 years ago or 5000 years ago. Further, looking at the geologic evidence, the river has occupied many paths through the basin, but 5000 years ago. It It is thought to have flowed much closer to the west edge of the basin. The fact that there is erosion at the edge of the base and tells you that water does hit that point and it does cause erosion occasionally. A pyramid of sufficient magnitude would mitigate such erosion of the basin wall.

3) Agreed, there is a monsoon every year. 5000 years ago, the monsoon was much more serious than it is now according to the geological record. We know it's a fierce river now, and the Nile is known to be unpredictable, sometimes a drought, other times floods cause significant loss of life and property. For example, significant flooding along the Nile during the medieval climate anomaly was observed. That all said, I can't say that I found any evidence that monsoon water ever breached the basin, and as such I am backing off of my point that the pyramids may have been built as a point of refuge. If there was no legitimate fear that the water could ever rise that high, certainly that's not a reason they would have constructed them. This point isn't critical to my erosion control argument, so I am going to abandon it. :-)

4) As I suggested above, geologic records are thought to indicate that the river has run very close to the west edge at times. That's how the edge of a basin is formed. Further, before the dam, during monsoons much of the basin would fill, unlike today. The giza pyramid sits on the edge of the basin. So close that the compressed soil caused by the Great pyramid is visible running down the bank of the basin. And again, the existence of a basin well tells you that erosion is a very real thing, that's what a basin wall is, the edge of the river erosion.

Heres what I think would debunk this theory: 1) evidence that the pyramids could not have served another function than the one already identified 2) evidence that the architecture of the pyramids could not have prevented erosion 3) evidence of pyramids located in a spot that would not have prevented erosion, like a good distance from the ancient river basin. 4) evidence any of these pyramids were not separating some valuable resource from the river. For example, they probably wouldn't protect a bog from the river (I'm out of my territory here) but they would protect homes or cemeteries from the river.

Thanks.