July 31, 2001 ROLLA, Mo. -- In the land of pharaohs and sphinxes, civil engineers from the University of Missouri-Rolla are trying to solve a new riddle: Why are some of Egypt's most treasured antiquities crumbling into dust?
UMR researchers studied antiquities during a recent visit to the Egyptian city of Luxor -- home to the Temple of Luxor, the Court of Ramses II and the Avenue of the Sphinxes. There, Dr. Richard Stephenson, professor of civil engineering, and Adam Sevi, a graduate student in civil engineering, took samples of the soil, rock and water surrounding the antiquities, then brought the samples back to their labs for analysis.
By studying the samples, the researchers hope to gain a better understanding of why the ancient sandstone structures are deteriorating. They also hope to help the Egyptian government find some possible solutions to the problem.
"What we're trying to do right now is find out exactly what's happening from a geotechnical perspective, and narrow down the possible solutions to the problem," says Stephenson.
Working with the National Research Institute of Astronomy and Geophysics in Egypt, and with support from the University of Missouri Research Board, Stephenson and Sevi visited Egypt between May 19 and June 3 to gather soil, sandstone and water samples from six archaeological sites in Luxor. The city, formerly known as Thebes, is located in central Egypt along the Nile River.
The area's ancient shrines are threatened by irrigation and drainage practices, which have contributed to a rise in the water table and high salt concentrations in surface soils, Sevi says.
Because of the rise in the water table, the groundwater comes into contact with the foundations, columns and walls of the antiquities, causing structural damage. "The sandstone used in these structures is relatively porous and relatively weak," Sevi says. The porosity allows for capillary action -- the phenomenon that occurs when a liquid sticks to surfaces and "climbs," much like water does when touched by a paper towel.
Capillary action causes the water to rise into a structure, further compounding the problem.
"The up-sweeping groundwater appears to be dissolving the cementing agent in the sandstone, and the sandstone basically goes back to sand," Sevi notes. "Additionally, due to the intense heat and very low humidity common in southern Egypt, groundwater is rapidly evaporated at the surface. Any salts that were in the groundwater would precipitate out during evaporation, causing salt buildup in and on the sandstone blocks. These salt precipitates may be expanding and possibly speeding the degradation by exploding the sandstone from the inside out."
Luxor's soil, Sevi adds, is "perfect capillary soil, unfortunately."
While much of the damage to Luxor's antiquities has occurred over time, "the rate of degradation has increased dramatically in recent years," Sevi says. Modern irrigation and drainage practices have added to the problems, Stephenson says.
One Swedish company is trying to address the problem by pumping groundwater back into the Nile River, Stephenson says. "But I'm not sure there's a big enough pump to lower the water table enough," he says.
"The problem may be unsolvable in economic terms," Stephenson says. He adds that the UMR study is a preliminary investigation, the purpose of which is to help better define the scope of the problem.
"The idea is to get a better understanding of the chemical properties of the soil and the water, and the capillary action of the sandstone," he says.
One of Luxor's most famous antiquities, the Temple of Luxor, was built upon the site of a small Middle Kingdom temple and was constructed by the 18th Dynasty pharaoh Amenhotep III, who reigned from 1391-1353 BCE.
The UMR antiquities study came about as a result of another UMR research project in Egypt. Ahmed Ismail, a Ph.D. candidate in geology and geophysics at UMR and a native of Egypt, is also employed by Egypt's National Research Institute of Astronomy and Geophysics. While on leave from the research institute, Ismail is using ground-penetrating radar to map the groundwater in the Luxor region. He is working with Dr. Neil Anderson, a professor of geology and geophysics at UMR.
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