Advertisement

Radar Images and Geoarchaeology of the Eastern Sahara

  • Farouk El-Baz
  • Cordula A. Robinson
  • Turki S.M. Al-Saud
Part of the Interdisciplinary Contributions To Archaeology book series (IDCA)

Abstract

The first Shuttle Imaging Radar (SIR-A) instrument was flown in earth orbit in November 1981. Data were obtained pertaining to a flat, sand-covered region in the eastern Sahara of North Africa. These data revealed courses of three channels or dry river courses varying in width from 8 to 20 km. This revelation increased interest in the geomorphology of desert regions and implications thereof to the geoarchaeology of prehistoric environments, particularly in southwestern Egypt.

For radar waves to penetrate desert sands and reveal the underlying topography, the surface material must be dry and fine grained. Moisture reflects radar waves and interferes with their penetration ability, and the size of sand grains has to be less than one-fifth of the wavelength of the radar waves. These two conditions are satisfied in the eastern Sahara. More data obtained by SIR-C and Radarsat confirm these findings.

Identification of the dry river courses explains the prevalence of prehistoric wet conditions, which allowed the existence of plants, animals, and man throughout the eastern Sahara. It also explains the underlying reasons for the location of oases in this hyper-arid region. The eastern Sahara must have been supplied by water through the ancient rivers, from occasional rainfall, even after their courses were buried by wind-blown sand. The analysis of unveiled river courses shows that they originate from highland massifs in the Sahara or from the sub-Saharan belt of the Sahel. The latest time water flowed in these courses was during the last pluvial, from 11,000 to 5,000 years ago. Alternation of wet and dry episodes brought life and death, respectively, to this region as indicated by human implements as well as flora and fauna of a savanna-like environment.

Much of the water that flowed in these rivers must have seeped into the substrate to be stored as groundwater. This would have occurred along fractures in the host rock or through the rock’s primary porosity, especially in areas that were water rich such as beneath the numerous inland lakes that persisted during humid periods. Ample proof of this phenomenon is provided by the high productivity of the “Nubian” groundwater aquifer in the eastern Sahara. Thus, a detailed knowledge of the geomorphology of the desert allows us to understand better its archaeological record as well as its groundwater resources.

Keywords

Shuttle Radar Topography Mission Radar Data Radar Image Western Desert Fluvial Erosion 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

Preview

Unable to display preview. Download preview PDF.

Unable to display preview. Download preview PDF.

References

  1. Bagnold, R. A., 1941, The Physics of Blown Sand and Desert Dunes. Methuen and Co. Ltd., London.Google Scholar
  2. Blom, R. G., Crippen, R. E. and Elachi, C. 1984, Detection of subsurface features in Seasat radar images of Means Valley, Mojave Desert, California. Geology 12:346–349.CrossRefGoogle Scholar
  3. Elachi, C., and Granger, J. 1982, Space-borne imaging radars probe “in depth.” IEEE Spectrum 19:24–29.Google Scholar
  4. Elachi, C., Roth, L. E., and Schaber, G. G. 1984, Space-borne radar subsurface imaging in hyperarid regions. IEEE Transactions on Geosciences and Remote Sensing GE-22:383–388.CrossRefGoogle Scholar
  5. Elachi, C., Brown, W. E., Cimino, J. B., Dixon, T., Evans, D. L., Ford, J. P., Saunders, R. S., Breed, C., Masursky, H., McCauley, J. F., Schaber, G., Dellwig, A., England, A., MacDonald, H., Martin-Kay, P., and Sabins, F., 1982, Shuttle imaging radar experiment. Science 218:996–1003.CrossRefGoogle Scholar
  6. El-Baz, F., 1977, Astronaut Observations from the Apollo-Soyuz Mission. Smithsonian Institution, Washington D.C., pp. 98–100Google Scholar
  7. El-Baz, F., 1979, Siwa resort of kings. Aramco World Magazine, 30 (4):30–35.Google Scholar
  8. El-Baz, F., 1988, Origin and evolution of the desert. Interdisciplinary Science Reviews 13:331–347.Google Scholar
  9. El-Baz, F., 1991, Remote sensing and archaeology. Encyclopedia Britannica, Chicago, IL., pp. 144–161. In 1991 Yearbook of Science and the Future, pp. 144–161. Encyclopedia Britannica, Chicago, IL.Google Scholar
  10. El-Baz, F., 1998, Sand accumulation and groundwater in the eastern Sahara. Episodes 21 (3):147–151.Google Scholar
  11. El-Baz, F., 2000, Satellite observations of the interplay between wind and water processes in the Great Sahara. Photogrammetric Engineering and Remote Sensing 66 (6):777–782.Google Scholar
  12. El-Baz, F., 2001, Gifts of the desert. Archaeology 54 (2):42–45.Google Scholar
  13. El-Baz, F., 2003, Pyramids and the Sphinx. Dahesh Voice Magazine 9 (1 Summer 2003):13–18.Google Scholar
  14. El-Baz, F., and Robinson, C. A., 1997, Paleo-channels revealed by SIR-C data in the Western Desert of Egypt: Implications to sand dune accumulations. In Proceedings of the 12th International Conference on Applied Geologic Remote Sensing, pp. 469–476. Environmental Research Institute of Michigan, Ann Arbor, MI.Google Scholar
  15. El-Baz, F., and Wolfe, R. W., 1982, Wind patterns in the Western Desert. In Desert Landforms of Southwest Egypt: A Basis for Comparison with Mars, pp. 119–139. NASA CR-3611.Google Scholar
  16. El-Baz, F., Robinson, C. A., Mainguet, M., Said, M., Nabih, M., Himida, I. H., and El-El-Etr, H. A., 2001, Distribution and morphology of palaeo-channels in southeastern Egypt and northwestern Sudan. Palaeoecology of Africa edited by Klaus Heine, 27:239–258.Google Scholar
  17. El-Baz, F., Mainguet, M., and Robinson, C. A., 2000, Fluvio-aeolian dynamics in the north-eastern Sahara: Interrelation between fluvial and aeolian systems and implications to ground water. Journal of Arid Environments 44:173–183.CrossRefGoogle Scholar
  18. El-Baz, F., Slezak, M. H., and Maxwell, T. A., 1979, Preliminary analysis of color variations of sand deposits in the Western Desert of Egypt. In Apollo-Soyuz Test Project Summary Science Report: Volume II: Earth Observations and Photography, edited by F. El-Baz and D.M. Warner, pp. 37–262. NASA SP-412.Google Scholar
  19. Embabi, N. S., 1982, Barchans of the Kharga depression. In Desert Landforms of Southwest Egypt: A Basis for Comparison with Mars, edited by F. El-Baz and T.A. Maxwell, pp. 141–155, NASA CR-3611.Google Scholar
  20. Fairbridge, R., 2005, Personal communication to F. El-Baz.Google Scholar
  21. Gabriel, B. and Kroeplin, S., 1989, Holocene lake deposits in northwest Sudan. edited by J.A. Coetzee and E.M. van Zinderen-Bakker, Paleoecology of Africa and the Surrounding Islands, Balkema, Rotterdam, pp. 295–299.Google Scholar
  22. Gifford, A. W., Warner, D. M., and El-Baz, F., 1979, Orbital observations of sand distribution in the Western Desert of Egypt. In Apollo-Soyuz Test Project Summary Science Report, Volume II: Earth Observations and Photography, edited by F. El-Baz and D.M. Warner, pp. 219–236. NASA SP-412.Google Scholar
  23. Haynes Jr., C. V., 1982, Great Sand Sea and Selima Sand Sheet: Geochronology of desertification. Science 217:629–633.CrossRefGoogle Scholar
  24. Haynes Jr., C. V., 1985, Quaternary studies, Western Desert, Egypt and Sudan – 1979–1983 field seasons. National Geographic Society Research Reports. 16:269–341.Google Scholar
  25. Haynes Jr., C. V., Eyles, C. H., Pavlish, L. A., Rotchie, J. C., and Rybak, M., 1989, Holocene paleoecology of the Eastern Sahara: Selima Oasis. Quaternary Science Review. 8:109–136.CrossRefGoogle Scholar
  26. Haynes Jr., C. V., Maxwell, T. A., Johnson, D. L., 1993, Stratigraphy, geochronology, and origin of the Selima Sand Sheet, eastern Sahara, Egypt and Sudan. In Geoscientific Research in Northeast Africa, edited by U. Thorweihe and H. Schandelmeier, pp. 621–626.Bekena, Rotterdam.Google Scholar
  27. Henning, D., and Flohn, H., 1977, Climate Aridity Index Map. U.N. Conference on Desertification, UNEP, Nairobi, Kenya.Google Scholar
  28. Hoekstra, P., and Delaney, A. 1974, Dielectric properties of soils at UHF and microwave frequencies. Journal of Geophysical Research. 79:1699–1708.Google Scholar
  29. Mainguet, M. M., 1992, A global open wind action system: The Sahara and the Sahel. In Geology of the Arab World, Vol. II, Cairo University Press, Cairo, Egypt pp. 33–42.Google Scholar
  30. Mainguet, M. M., 1995. L’homme et la Secheresse. Collection Geographie, Mason, Paris. p. 335.Google Scholar
  31. Manent, L. S., and El-Baz, F., 1980, Effects of topography on dune orientation in the Farafra region, Western Desert of Egypt, and implications to Mars. In: Reports of Planetary Geology Program, NASA Technical Memo 82385, pp. 298–300.Google Scholar
  32. Maxwell, T. A., 1982, Erosional features of the Gilf Kebir and implications for the origin of Martian Canyonlands. In Desert Landforms of Southwest Egypt. A Basis for Comparison with Mars. edited by F. El-Baz and T.A. Maxwell, pp. 281–300. NASA CR-3611.Google Scholar
  33. Maxwell, T. A., and Haynes, C. V., 1989, Large-scale, low-amplitude bedforms (chevrons) in the Selima Sand Sheet, Egypt. Science 243:1179–1182.CrossRefGoogle Scholar
  34. McCauley, J. F., Schaber, G. G., Breed, C. S., Grolier, M. J., Haynes, C. V., Issawi, B., Elachi, C., and Blom, R., 1982, Subsurface valleys and geoarchaeology of the Eastern Sahara revealed by Shuttle radar. Science 218:1004–1020.CrossRefGoogle Scholar
  35. Pachur, H. J., and Braun, G., 1980, The paleoclimate of the central Sahara, Libya, and the Libyan Desert. Paleoecology of Africa. edited by M. Sarentheim E. Siebold and P. Rognon, 12:351–363.Google Scholar
  36. Robinson, C. A., 2002, Application of satellite radar data suggests that the Kharga Depression in Southwestern Egypt is a fracture rock aquifer. International Journal of Remote Sensing 23 (19):4101–4113.CrossRefGoogle Scholar
  37. Robinson, C. A., El-Baz, F., Ozdogan, M., Ledwith, M., Blanco, D., Oakley, S., and Inzana, J., 2000, Use of radar data to delineate palaeodrainage flow directions in the Selima Sand Sheet, Eastern Sahara. Photogrammetric Engineering and Remote Sensing 66 (6):745–753.Google Scholar
  38. Robinson, C. A., El-Baz, F., and Singhroy, V., 1999, Subsurface imaging by Radarsat: comparison with Landsat TM data and implications to ground water in the Selima area, Northwestern Sudan. Canadian Journal of Remote Sensing 25 (3):268–277.Google Scholar
  39. Roth, L. E., and Elachi, C., 1975, Coherent electromagnetic losses by scattering from volume inhomogeneities. IEEE Transactions on Antennas and Propagation. 23:674–675.CrossRefGoogle Scholar
  40. Salem, O., 1991, The Great Man-Made River Project: A partial solution to Libya’s future water supply.In Planning for Groundwater Development in Arid and Semi-Arid Regions, Research Institute for Ground Water, Cairo, Egypt, pp. 221–238.Google Scholar
  41. Schaber, G. C., McCauley, J. F., and Breed, C. S., 1997, The use of multifrequency and polarimetric SIR-C/X-SAR data in geologic studies at Bir Safsaf, Egypt. Remote Sensing of the Environment 59: 337–363.CrossRefGoogle Scholar
  42. Seto, K. C., Robinson, C. A., and El-Baz, F., 1997, Digital image processing of Landsat and SIR-C data to emphasize drainage patterns in southwestern Egypt. In Proceedings of the 12th International Conference on Applied Geologic Remote Sensing, pp. 93–100. Environmental Research Institute of Michigan, Ann Arbor, MI.Google Scholar
  43. Szabo, B. J., Haynes Jr., C. V., and Maxwell, T. A., 1995, Ages of Quaternary pluvial episodes determined by uranium-series and radiocarbon dating of lacustrine deposits of Eastern Sahara. Paleogegraphy, Paleoclimatology, Paleoecology 113:227–242.CrossRefGoogle Scholar
  44. Szabo, B. J., McHugh, W. P., Shaber, G. G., Haynes Jr., C. V., and Breed, C. S., 1989, Uranium-series dated authigenic carbonates and Acheulian sites in southern Egypt. Science 243:1053–1056.CrossRefGoogle Scholar
  45. Wendorf, F., and Schild, R., 1980, Prehistory of the Eastern Sahara. Academic Press, New York.Google Scholar
  46. Wendorf, F., Close, A. E., and Schild, R., 1987a, Recent work on the Middle Paleolithic of the Eastern Sahara. African Archaeological Review. 5:49–63.CrossRefGoogle Scholar
  47. Wendorf, F., Close, A. E., and Schild, R., 1987b, A Survey of the Egyptian Radar Channels: An Example of Applied Archaeology. Journal of Field Archaeology. 14:43–63.CrossRefGoogle Scholar
  48. Wendorf, F., and Schild, R., 2001, The Archaeology of the Nabta playa. In Holocene Settlement of the Egyptian Sahara, Kluwer Academic, New York, Associates, p. 707.Google Scholar
  49. Wendorf, F., Schild, R., and Close, A. E., 1993, Summary and Conclusions In: Egypt During the Last Interglacial. Plenum Press, New York, pp. 552–573.Google Scholar

Copyright information

© Springer 2006

Authors and Affiliations

  • Farouk El-Baz
  • Cordula A. Robinson
  • Turki S.M. Al-Saud

There are no affiliations available

Personalised recommendations