PRESENT-DAY LUNETTE SEDIMENT CYCLING AT WITPAN IN THE ARID SOUTHWESTERN KALAHARI DESERT

Witpan is a pan depression in the southwestern Kalahari Desert. The pa n fringing lunette dune has a number of notable characteristics: a hig hly active crest; the lower lunette pediment is cemented; and the lowe r lunette supports a highly developed and active gully system. Geomorp hological and sedimentological considerations are used to evaluate the interaction of wind and water in shaping contemporary lunette process es. It is considered that like other pans in the area, groundwater act ivity influences pan floor sediment availability and transport, that t he present highly seasonal climatic regime permits the interaction of aeolian transport of sediment to the dune and its return to the pan fl oor by water during storm events, creating a cycling process favoured by sedimentary properties that promote surface runoff.