Shallow geophysical techniques to investigate the groundwater table at the Great Pyramids of Giza, Egypt

Abstract

Abstract. The near-surface groundwater aquifer that threatened the Great Pyramids of Giza, Egypt, was investigated using integrated geophysical surveys. A total of 10 electrical resistivity imaging, 26 shallow seismic refraction, and 19 ground-penetrating radar surveys were conducted in the Giza Plateau. Collected data for each method were evaluated by state-of-the art processing and modeling techniques. A three-layer model depicts the subsurface layers and better delineates the groundwater aquifer and water table elevation. The resistivity of the aquifer layer and seismic velocity vary between 40 and 80 Ωm and between 1500 and 2500 m s−1, respectively. The average water table elevation is about +15 m, which is safe for the Great Sphinx, but it is still subjected to potential hazards from the Nazlet El-Samman suburb where the water table elevation reaches 17 m. A shallower water table at the Valley Temple and the tomb of Queen Khentkawes, with a low topographic relief, represents severe hazards. It can be concluded that a perched groundwater table is detected in the elevated topography to the west and southwest that might be due to runoff and capillary seepage.

Exploring a near‐surface subsidence over a rehabilitated underground mine through ambient seismic noise tomography in combination with other geophysical methods

“…However, if there are not enough refracted paths crossing the cavity (returning first‐arrival energy), then it will not be easy to identify the low‐velocity zone, which could act as a blind zone. This problem is critical in water‐resources investigations, where saturated unconsolidated materials are located between unsaturated unconsolidated material and the bedrock (Hanei, 1986; Sharafeldin, 2019).…”

Sustainability problems of the Giza pyramids

“…The second system is linked to water. The bearing layers belong to the formation of broken limestone (below Sphinx area), where the depth of groundwater ranges from 4 to 7 m below the surface [7].…”

“…The second aquifer is a broken carbon aquifer that covers an area beneath the pyramid and sphinx plateau, where the depth of the groundwater ranges from 4 to 7 m. The recharge of the aquifer underneath the Sphinx area occurred mainly through diversion of the water network and overall urbanization. The shallow water table elevation at Nazlet El-Samman village reaches 16-17 m and might recharge the aquifer below the Sphinx and Valley Temple, which is considered a severe hazard on the site [7].…”

“…The sources of this degradation can generally be classified as: nature, time, and man-made. In recent years, the great pyramids and the Great Sphinx have been threatened by rising groundwater levels caused by water infiltration from the suburbs, irrigation canals and mass urbanization surrounding the Giza plateau [7]. The rising of groundwater levels represents a threat to the Egyptian Heritage of the Giza Pyramids Plateau (GPP) particularly since the area surrounding the plateau has been developed into the suburb of Greater Cairo.…”

“…Understanding the passage ways of rain water on the plateau, groundwater and sewage from both the Nile flood plain and Abo Roash area play an important role in the conservation strategy for the unique artifacts of the Giza Plateau Two regional aquifers are located behind the Sphinx statue with a water level at a depth of 1.5 to 4 m below the surface (for example). The second aquifer is a broken carbon aquifer that covers an area beneath the pyramid and sphinx plateau, where the depth of the groundwater ranges from 4 to 7 m. The recharge of the aquifer underneath the Sphinx area occurred mainly through diversion of the water network and overall urbanization [7].…”