After the flood: The fluvio-lacustrine landforms of Northern Botswana

Abstract

The Middle Kalahari of northern Botswana contains three palaeolake basins, with shorelands enclosing an area of 60,000 km 2, linked to the Okavango Delta and the adjacent Chobe and Zambezi rivers. Two major stages of the palaeolake system at 940-945 m (Lake Palaeo-Makgadikgadi) and 936 m (Lake Thamalakane) are identified, prior to the final desiccation of the lakes over the last 2,000 years. The former is tectonic in origin, and last existed c. 35,000 B.P., whilst the Lake Thamalakane stage has existed on a number of occasions, particularly at 17,000–12,000 B.P., and can be explained by increased precipitation and inflow feeding a complex system of fault-controlled lakes, ultimately controlled by the Mambova falls at the Chobe-Zambezi confluence. A number of factors influencing the behaviour of the Okavango Delta and its adjoining basins can be identified on different time scales, and are discussed in relation to planning for future water development.