Dust emission controls on the lower Kuiseb River valley, Central Namib

Global contemporary dust research has identified large inland basins as significant sources of mineral aerosols in the atmosphere. Smaller fluvial sources have received lesser attention despite their global prevalence. To determine the emissive potential of any dust source requires the identification the hydrologic, synoptic and meteorologic state of the system. This study considers the Kuiseb River, which is a significant dust source in southern Africa, and clearly highlights the fluvial-aeolian link in the emission process and emphasises the supply limited nature of such sources. MODIS satellite imagery combined with synoptic circulation and wind speed data were analysed to establish emission frequency in the context of climatology and flood frequency data. Twenty-two emission events were detected between 2005 and 2008, occurring from April to August, driven by north easterly winds largely associated with west coast troughs and berg winds. The ephemeral flooding of the Kuiseb River was identified as the most likely contributor of sediment to the lower reaches while topographic channelling may enhance the wind flow.