A web search turns up these few sites immediately. There are dozens more.

[4] Lehner has suggested (1985, 116) that along the eastern edge of the Giza Plateau (the area where the Sphinx is located) all land higher than an elevation of 60.7 feet (18.5 meters) above sea level remained above the annual inundations of the Nile during the Fourth Dynasty. In fact, Lehner (1985) found some suggestions of an Old Kingdom surface that is only 57.4 feet (17.5 meters) above sea level. As Lehner (1985, citing the work of K. Butzer) notes, the flood plains of the middle-Third Millennium B.C. (Old Kingdom times) have persisted in essentially the same form until the present day; there has not been a rise in the alluvial plain since the Old Kingdom period, as was once assumed.
Hassan (1949).stated that in the Old Kingdom, during the annual inundation of the Nile, barges could be floated right up to the edge of the Giza Plateau. Even in this century, unusually high Nile waters have flooded around the base of the Great Sphinx (Ali Hassan, personal conversation, June 1991).
In April of 1991, using seismic techniques, we located the water table at an elevation of about forty-six to forty-nine feet (fourteen to fifteen meters) above sea level in the sand-filled courtyard area approximately 328 feet (100 meters) east of the Sphinx Temple, between the modern restaurant and the Sphinx and Valley temples. In this courtyard area, the bedrock surface is buried under approximately forty-nine to fifty-nine feet (fifteen to eighteen meters) of sand; that is, the surface of the bedrock in this local area is at an elevation of about 6.6 to 16.4 feet (two to five meters) above sea level. The pyramids of the Giza Plateau sit at a higher elevation than does the Sphinx; thus, the base of Khafre's pyramid is situated at an elevation of approximately 230 feet (seventy meters) above sea level.

[www.antiquityofman.com]


The Giza complex lies at an elevation of about 100m above sea-level on a latitude 30° north of the equator, towards the northern end of a vast cemetery of the ancient Egyptians associated with their Old Kingdom capital city of Memphis.

[www.egyptvoyager.com]


Butler believes that the granite part of GIII, being left undressed by the builders, played no part in the intended design.) For elevation above sea level he gives the following data

GI ........................................limestone base - 114......apex - 394

GII .......granite base - 134..... limestone base - 136..... apex - 408

GIII ......granite base - 141......limestone base - 180......apex - 269*


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