Data

From ancient times, access to water in arid and hyper-arid regions has been crucial for life. Increased knowledge about groundwater conditions is therefore extremely important for the future development of desert areas. Gebel Duwi, a limestone ridge, sited in the today hyper-arid Eastern Desert of Egypt, was chosen for testing current hypotheses concerning the interdependence of palaeohydrologic features and geologic settings for groundwater investigations. Two sub-basins are identified in affecting Gebel...

The focus of this thesis is the geophysical exploration of the central part of the Azraq basin in the northeastern desert of Jordan. In addition to common 1D inversion techniques, further 2D forward modeling strategies and a rarely used 2D inverse modeling scheme are applied to transient electromagnetic data. The Azraq area is of potential interest for palaeoclimatical and archaeological research in the frame of the interdisciplinary Collaborative Research Centre 806, entitled "Our Way to Europe" (CRC 806)....

The Eastern Mediterranean has been used as a passageway for human migration from Africa to the Middle East, the Balkans and Europe. The Azraq basin in the eastern desert of Jordan has been a major spot for human settlements since the middle Pleistocene. The former lake in the basin centre has developed to a hyper-saline alluvial mudflat, the Qa’ Al Azraq. In the mudflat thick sequences of alluvial sediments are deposited. Such sediment successions are promising archives used for reconstructing a...

The finely laminated sediment record of a permanent, hypersaline, desert oasis lake in the Ounianga region of northeastern Chad presents a unique opportunity to document the hydrological evolution of this groundwater-fed aquatic ecosystem during mid- and late-Holocene desiccation of the Sahara. In this study we reconstruct long-term changes in zoobenthos and zooplankton communities of Lake Yoa as their early-Holocene freshwater habitat changed into the hypersaline conditions prevailing today. Chironomid...

Der Vierte Nil-Katarakt im Nord-Sudan ist im Jahr 2008 im Hamdab-Stausee untergegangen. Geowissenschaftlich und archäologisch bislang kaum erforscht, stellte er eine einzigartige landschaftliche Versuchsanordnung dar. Am Beispiel der Insel Boni, die für die vorliegende Studie vor der Flutung im Rahmen des Sonderforschungsbereichs 389 untersucht wurde, wird gezeigt, dass die tektonisch angelegte Kleinkammerung des Reliefs und die nachfolgende, periodisch und saisonal stark wechselnde fluviale und äolische...

Terrestrial laser scanning (TLS) is a newer, active method of remote sensing for the automatic detection of 3D coordinate points. This method has been developed particularly during the last 20 years, in addition to airborne and mobile laser scanning methods. All these methods use laser light and additional angle measurements for the detection of distances and directions. Thus, several thousands to hundreds of thousands of polar coordinates per second can be measured directly by an automatic deflection of...

The sedimentological and geochemical properties of a 7.47 m long laminated sequence from hypersaline Lake Yoa in northern Chad have been investigated, representing a unique, continuous 6100 year long continental record of climate and environmental change in the eastern Central Sahara. These data were used to reconstruct the Mid to Late Holocene history of this currently hyper-arid region, in order to address the question of whether the Mid Holocene environmental transition from a humid to a dry Sahara was...

The fresh and saline lakes of Ounianga Kebir and Serir in northeastern Chad are among the very few permanent aquatic ecosystems currently existing in the hyper-arid core of the Sahara desert. The confirmed modern fauna of aquatic molluscs at Ounianga comprises three widespread species (Melanoides tuberculata, Biomphalaria pfeifferi and Lymnaea natalensis), of which only the first appears to maintain a thriving population. We recovered seven more species of gastropods, among which one is new to science...

Desiccation of the Sahara since the middle Holocene has eradicated all but a few natural archives recording its transition from a “green Sahara” to the present hyperarid desert. Our continuous 6000-year paleoenvironmental reconstruction from northern Chad shows progressive drying of the regional terrestrial ecosystem in response to weakening insolation forcing of the African monsoon and abrupt hydrological change in the local aquatic ecosystem controlled by site-specific thresholds. Strong reductions...

East African paleoenvironments are highly variable, marked by extreme fluctuations in moisture availability, which has far-reaching implications for the origin, evolution and dispersal of Homo sapiens in and beyond the region. This paper presents results from a pilot core from the Chew Bahir basin in southern Ethiopia that records the climatic history of the past 45 ka, with emphasis on the African Humid Period (AHP, w15e5 ka calBP). Geochemical, physical and biological indicators show that Chew Bahir...