Author(s):
Eman Ghoneim* - Boston University
Farouk El-Baz - Boston University
Abstract:
Sand in the Great Sand Sea has been ascribed to fluvial action, its origin is still under debate. Space data facilitated the reconstruction of the Kufra paleodrainage and its terminal delta, which is likely the main sand supply for the Great Sand Sea. RADARSAT-1 and SRTM data, in conjunction with the GIS hydrologic routine, provide a complete picture of this mega fluvial system. The study demonstrates that the basin drains a large catchment area of 202,000 km2 with five main tributaries. It has a broad watercourse that exceeds in some sectors 10 km in width. Data analysis shows that the now defunct river flows northward for 950 km. The basin approaches the depression enclosing the Great Sand Sea with a delta-like alluvial fan 34,536 km2 in area. Traces of river captures are visible in the space data, at its western and southern branches. This suggests that the Kufra paleoriver was formerly connected with adjacent drainage basins. Detailed geomorphological investigation, however, suggests that regional influences by tectonic movements might have resulted in the decapitation of its upper reaches and caused the present drainages separation. The enormity of this fluvial system of a large fan that terminates at the margins of the Great Sand Sea, with the presence of late Pleistocene lacustrine deposits along the fan's fringes and in inter-dune areas, suggest that the later formed in syncline-like lowland that was occupied by a former lake. This notion supports the hypothesis that relates sand seas within inland basins to former fluvial processes.
