The Mound Springs of Northern Ntwetwe in Makgadikgadi: Implications for the Makgadikgadi Management Plan

Abstract

The origins of crescent shaped mounds on the fl oor of Ntwetwe pan have long been debated. The preferred explanation is that they are barchan dunes, of aeolian origin, indicating a former very dry period. In detail, their morphology is inconsistent with this hypothesis. Morphological evidence is presented to show that they are mound springs. Upward discharge of water persists today, but the building of the mounds pertains to a former, wetter period when the discharge was stronger. The source of the water is the karstifi ed hinterland. There the exposed palaeolake fl oors are pitted with numerous small pans and groundwater recharge is excellent. It is this recharge that sustains the discharge associated with the mounds in Ntwetwe pan. This situation has important implications for the Makgadikgadi Management Plan. The resulting potable water and sweet grasses in Ntwetwe are essential to the game migrations, for which the area is famous worldwide. The conservation and sustainability of this ecological system depends entirely on resource management outside the area presently defi ned for development and protection, that is, in the recharge area. Overabstraction of groundwater or pollution would be detrimental, as has been seen in Australia. It is strongly recommended that the system is protected by the formation, as for the Okavango, of a buffer zone that encompasses the essential recharge area. This would signal the need for extra vigilance regarding developments here.