Blowing the rivers: Regional-scale control of the drainage network by wind in northern Kalahari (Africa)

Abstract

Understanding the impact of aeolian processes on the regional-scale dynamics of fluvial systems in semi-arid regions is a major issue in the framework of climate change. Although the interactions between aeolian and fluvial processes have been studied on a meter to kilometer scale, few studies have upscaled to the regional scale. Using satellite images and SRTM-1 digital elevation models we document the formation of parabolic dunes and foredunes along the main rivers of the southern Angolan Plateau and northern Kalahari Basin (Africa). We demonstrate that these aeolian features derive from interactions between the morphology of the drainage system, the wind pattern, the vegetation cover and the transport capacity of the rivers. As a retro-action phenomenon, the progradation of parabolic dune fields induces tens-of-kilometers shifting in rivers courses in the northern Kalahari basin. The mechanism proposed has implications in terms of fluvial dynamics, river capture, geometry of clastic deposits in basins or source-to-sink budget.