Reconstruction of a paleo-lakesystem at UNESCO World Heritage Site Tsodilo Hills, Kalahari, Botswana: MIS3 and MIS2 ecosystem dynamics, climate, weather and environmental variations derived from sedimentation processes and bio-indicators

• Applicants: Dr. Kai Hartmann; Professor Dr. Frank Riedel
• Subject Area: Physical Geography
• Term: from 2015 to 2023
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 281420578

Natural permanent lakes are recently an exception in the Kalahari. The geology and precipitation patterns inhibit a long lasting existence. However, during Late Pleistocene and Holocene time large lakes spanned a considerable part of the recent semi-arid Kalahari basin. The palaeolakes indicate a much higher groundwater level under different climate conditions.An outstanding example is the former Tsodilo lake in northwestern Botswana within the basin of the Okavango Delta. The correspondent small inselberg chain frames a ca. 30 km2 wide basin with fossil-bearing lake carbonates to the east. With one of the highest concentrations of rock art in the world (4500 rock paintings over an area of less than 10 km2), Tsodilo has been called the 'Louvre of the Desert' and inscribed in the list of UNESCO World Heritage Cultural Sites in 2001. Human activities and environmental change are documented in and around the hills. Prior investigations of mostly British researchers revealed the existence of an at least periodically extensive lake during time slices of some thousand years since ca. 40000 years ago until the end of the last glacial time. Likely this lake provided the livelihood for the stone-age hunters and gatherers. Lacustrine fossils provide evidence of changing water quality and sedimentation patterns. So far neither the maximum extents of the former lake nor the hydro-climate conditions responsible for long-term existence have been reconstructed. The aim of this project is a “holistic” reconstruction of the lake ecosystem dynamics and its vicinity as well as the responsible hydro-climatic preconditions. Hereby, geomorphological analyses and the geochemical/physical properties of the sediments will enable a reconstruction of processes (e.g. run-off, dune movement, etc.) affecting the former landscape. Therefore, e.g. statistical algorithms applied on high-resolution grainsize distributions shall unravel settings and quantify transport processes while multivariate geochemical/mineralogical data analyses will provide information about the water budget. Isotope data from gastropod shells shall reveal information about the seasonality of precipitation. The latter may indicate former predominant atmospheric circulation pattern in southern Africa. Fossils will provide further information about water temperature, depth and nutrition content of the lake. This information will enable us to estimate the resources provided by the lake and the risks (e.g. bilharziosis) for the people. In case of sufficient preservation of fossil pollen during certain time slices, the reconstruction of palaeo-vegetation will provide an estimation of temperature and precipitation changes as well as a derivation of diversity and density of huntable wildlife.

• DFG Programme: Research Grants
• International Connection: Botswana
• Cooperation Partner: Professor Dr. Elisha M. Shemang