John McCauley
Northwestern Arizona University
USGS Emeritus
189 Wilson Canyon Road
Sedona, AZ 86336
Co-Investigators:
Gerald Schaber, Northwestern Arizona
University & USGS Emeritus
Carol Breed, NAU & USGS Emeritus
Bahay Issawi, Egypt
Hugues Faure, France
André Simonin, France
Joachim Pachur, Germany
Stefan Kroepelin, Germany
Paleodrainages of the Sahara, SIR-C


OBJECTIVES
Use SIR-C/X-SAR data in a synoptic mode with other remotely sensed data, field, and cartographic data to map relic Cenozoic drainage systems across the Sahara from the Red Sea Hills, Egypt, to the Chad Basin and Atlantic Ocean.

Demonstrate applicability of SIR data, used with Landsat, SPOT and high-altitude photographic data, as a new, cost-effective remote geophysical tool for exploration geology.

Produce a major report on the distribution of paleodrainages in the Sahara, their relations to the basic tectonic elements of North Africa (basins and swells), and their economic potential.


PROGRESS
CDs containing relevant Sahara "Data Takes" have now been received (two key CDs arrived as recently as mid-September '95). Most CDs containing survey data in areas of interest have been distributed to our Co-I's. A list of some 50 scenes we have selected for special processing has been submitted to JPL, primarily for sites in eastern Libya, northern Sudan, and the Sinai Peninsula, where several promising examples of sand-buried paleodrainage patterns are revealed by the L-band radar. We estimate that our total request for special processing will be about 250 scenes, when all of the inputs are received from our foreign Co-I's.

We have completed preliminary review of all the Saharan swaths received by the Paleodrainage Team (to Sept. '95). This was done on the PI's Pentium computer system which allowed the production of enhanced and scaled survey images at the 1:500,000-scale, which were then registered to 1:500,000-scale Tactical Plot charts of North Africa, provided to us by the U.S. Army Topographic Engineering Center, Ft. Belvoir, VA. These charts show all of the visible (surface) drainage systems located by conventional mapping system. By comparing them with the SIR-C radar images, because of the ability of SIR-C to image into the shallow subsurface in sand covered areas, we are able to delineate previously unrecognized watercourses. Our ultimate objective is to produce a map at the largest practical scale (1:2,000,000?) showing the newly found drainages against a background of those already mapped. This map is expected to have broad practical applications for water resources, mineral exploration, and land use in several parts of North Africa. This effort will also make use of the astronaut photography and ERS-1 data. Extensive collaboration has taken place over the past eighteen months with our foreign Co-I's and Collaborators, both by fax, e-mail, and in person before, during and after the Uberlingen meeting.

(1) Data analysis plans and long range plans were discussed and an invitation was extended to our group to participate in field work in the Sahara with the newly funded German desert team under the direction of Dr. Stefan Kroepelin, University of Cologne, Germany. New vehicles, equipment, base camp buildings, etc. are currently being assembled as part of this new project, entitled "Environmental and Cultural Change in Arid Africa." We intend to follow up on this opportunity at the earliest possible time (probably Oct./Nov. '96).

(2) Also in Germany, Dr. Joachim Pachur, Free University of Berlin has agreed to take the lead in investigating the SIR-C coverage of the Wadi Kufra area in southeast Libya. We reported preliminary work on this river system at the Spring AGU Meeting in Baltimore. A graduate student of Prof. Pachur (Mr. Frank Rottinger, who attended the Uberlingen Meeting) who will do his Ph.D. on newly defined paleoriver systems in the southern Sahara will be coming to our facility in Flagstaff this fall to begin work with SIR-C data. Both German groups have access to Libya whereas we do not and are happy to defer to them.

(3) Data analysis planning with the French group at the University of Marseilles also took place after the Uberlingen meeting and we had preliminary discussions about their possible return to northeastern Chad for various Quaternary studies and visits to key paleodrainage localities that are also presently out of reach of U.S. investigators for political reasons.

(4) Bahay Issawi, former Director of the Egyptian Geological Survey, spent nine days at the Sedona office of the P.I. and also visited the USGS offices in Flagstaff. This time was spent relating the SIR-C data to regional geology of Egypt and preparing the first draft of the paper submitted to the IEEE Special Issue and demonstrating various data analysis techniques for use in Egypt. Meetings were also held in Flagstaff with a representative of the Saudi Arabian SIR-C Paleodrainage Experiment. Plans for a special session on imaging radar results in Egypt were first formulated. During the time period we also spent much time revising the requirements for our experiment in order to obtain the best mission plan for possible Sahara coverage consistent with the needs of other experiments for SRL-2. The overall plan was presented to all interested geology investigators at the June 19, '94 Team Meeting at JPL.

(5) Carol Breed and the P.I. attended the SRL-2 launch (at our own expense) where we had the opportunity to discuss the merits of SIR with Dr. John Hansen, Director of Research at the Topographic Engineering Center, U.S. Army Corps of Engineers, Ft. Belvoir, VA. This led to further discussions, cartographic support, and a minor amount of funding for a demonstration project by Carol Breed for the purpose of finding desert water resources. We also helped to prepare after the mission several PIO captions (particularly SafSaf, Egypt) for JPL.

(6) Briefed the SRL-2 Astronaut Crew (May 4-5) at our facility in Flagstaff on the objectives of the Paleodrainage experiment and desert landforms in general. This was followed by an overnight field trip to the Painted Desert east of Flagstaff where they gained visual experience with sand-filled river channels, wind erosion features, sand sheets and sand dunes. Later in the year (Sept. 23), we met with SRL-1 astronaut Linda Godwin in Flagstaff to discuss preliminary results of the first flight and to attend her lecture at Northern Arizona University where our SIR work was amply referenced.


FUTURE PLANS
As explained above, we anticipate needing an additional 150 to 200 specially processed segments of SIR-C data, in order to do justice to the data and to take advantage of the field expertise of our foreign Co-I's and Collaborators. This requirement stems from the areal scope of the Saharan Paleodrainage Investigation, which covers an area roughly equivalent to that of the USA.

Prepare a synoptic map (as described above) of the newly defined SIR-C paleodrainages of North Africa.

Participate in the special conference on North African radar applications as part of the EGSMA Centennial, and submit paper.

Participate in a field campaign with the newly-formed German desert group (with direction of S. Kroepelin). Emphasis will be on radar response studies at Safsaf (in cooperation with P.I. G.G. Schaber) and the applications of SIR-C data to hydrological and archaeological prospecting. One of the key German radar experts has stated, during training sessions for desert researchers, that the paleodrainage results were the most significant of the entire mission. We expect numerous publications to come from this work, both in European and U.S. journals.

We also anticipate close cooperation and multiple publications with our numerous French colleagues. These will not necessarily be limited to paleodrainage features, but will also include studies of duricrusts (calcrete, gypcrete, ferricrete), and landscape evolution as a function of the interplay between running water and wind driven by climate change in the Sahara.


PUBLICATIONS
Schaber, G.G., McCauley, J.F., and Breed, C.S., 1994, New radar images of Safsaf Oasis and vicinity, southern Egypt, Geological Society of America Abstracts with Programs , v. 26, no. 7, p. 127. 1994 Annual Meetings, Seattle, WA.

McCauley, J.F., Breed, C.S., and Schaber, G.G., 1995, SIR-C definition of the Serir-Kufra River system in SE Libya: Poster no. P51A-4, AGU Spring Symposium, EOS Supplement , p. 5194.

McCauley, J.F., Breed, C.S., and Schaber, G.G., 1995, Mapping the Wadi Kufra paleodrainage system in eastern Libya using spaceborne imaging radar, Poster presentation at Symposium on Retrieval of bio and geophysical parameters for SAR data for land applications, Toulouse, France (October 1995), in press.

Schaber, G.G., McCauley, J.F., Breed, C.S., and Issawi, Bahay, 1995, The roles of wavelength and polarization in geologic studies at Bir Safsaf (Egypt) using SIR-C/C/XSAR data, 1995, Abstracts and Programs, Geol. Soc. of America, Annual Meetings (New Orleans, LA, November 6-9, 1995), in press.

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