Reconstruction of Megalake Chad using Shuttle Radar Topographic Mission data

Leblanc, Marc, Favreau, Guillaume, Maley, Jean, Nazoumou, Yahaya, Leduc, Christian, Stagnitti, Frank, van Oevelen, Peter J., Delclaux, Francois, and Lemoalle, Jacques (2006) Reconstruction of Megalake Chad using Shuttle Radar Topographic Mission data. Palaeogeography, Palaeoclimatology, Palaeoecology, 239 (1-2). pp. 16-27.

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Abstract

In the 2,500,000 km2 Lake Chad Basin in central Africa, the 2000 Shuttle Radar Topographic Mission (SRTM) data have been used to supplement the existing topographic data. SRTM data produce much sharper images of the region's topography and provide new insights into debates about the nature and extent of late Quaternary Lake Chad. This paper shows that the accuracy of SRTM30, the recently released 30 arc seconds topographic data from SRTM, largely surpasses that of previous global Digital Elevation Models (DEMs) available in the region. Using a GIS we identified from SRTM30 elevation data key features in the landscape topography providing further evidence for the existence of a Megalake Chad. The SRTM30 data corroborate the presence of two ancient shorelines associated with stillstands of the paleolake at the elevation of the Mayo Kebbi and Bahr el Ghazal spillovers. We found a general flattening of the topography in the region covered by Megalake Chad which is most likely the result of wave-cut action. The SRTM30 data show that the remains of the highest paleoshoreline have a constant elevation of 325±5 m amsl. At its maximum extent, Megalake Chad had an area of about 340 000 km2 (only 8% less than the present-day world's largest lake, the Caspian Sea). The SRTM30 data also revealed ancient drainage networks in the Sahara that lead to Megalake Chad. We compiled available 14C dates to constrain Holocene Megalake Chad events. The results presented in this paper have significant consequences for improving our knowledge of regional paleohydrology and continental climate change. This study is also the first step for a GIS-based reconstruction of late Quaternary paleohydrology in tropical Africa.

Item ID: 1720
Item Type: Article (Research - C1)
ISSN: 1872-616X
Keywords: climate change, paleohydrology, Lake Chad, SRTM, GIS, DEM, Africa, paleolimnology, hydrology, terrain analysis
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Also available online from the publisher's website.

Date Deposited: 10 Oct 2007
FoR Codes: 05 ENVIRONMENTAL SCIENCES > 0503 Soil Sciences @ 0%
04 EARTH SCIENCES > 0406 Physical Geography and Environmental Geoscience > 040608 Surfacewater Hydrology @ 0%
04 EARTH SCIENCES > 0406 Physical Geography and Environmental Geoscience > 040601 Geomorphology and Regolith and Landscape Evolution @ 0%
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