DUNEFIELD ACTIVITY AND INTERACTIONS WITH CLIMATIC VARIABILITY IN THE SOUTHWEST KALAHARI DESERT

An analysis is undertaken of the temporal variability of climatic para meters that influence dunefield aeolian activity. Data from seven mete orological stations in the southwestern Kalahari Desert are used, span ning the period 1960-1992. Erosivity is considered through analysis of wind data, and erodibility through analysis of precipitation and pote ntial evapotranspiration, which together influence dune surface plant growth. The data are integrated using Lancaster's 'mobility' index whi ch provides a measure of potential dune surface sand transport. This i s renamed 'potential dune surface activity index', to reflect the actu al characteristic that is measured. The subsequent analysis indicates that dunefield activity is episodic and temporally variable, that both erosivity and erodibility vary through time, and that present levels of activity cannot be characterized by a single simple state. (C) 1997 by John Wiley & Sons, Ltd.