Berichte des Sonderforschungsbereichs 268
- 14, 011
From Megachad to Microchad - environmental changes during the Holocene
- The investigations carried out within the project in NE-Nigeria since 1989 have been focussing on the late Pleistocene and Holocene landscape development of the south eastern Chad basin. Areas of interest include palaeodune fields, clay plains and former beach ridge systems of Lake Chad. Transgressions and regressions of Lake Chad played an important role in the younger landscape history of NE-Nigeria and have also caused great environmental changes. The term „Megachad“ is well known and describes an enormous lake with an extension comparable with the Caspian Sea of today. The term „Microchad“ stands for the other recent extreme in terms of the lake dimensions varying during the times. Environmental changes in the surroundings of Lake Chad are closely connected with transgressions and regressions of the lake. These lake level changes can be climatically induced as well as non-climatically, due to human impact. Nearly all land units have more or less been influenced by the lake, spatially as well as temporally. It is important, though, to notice the scales of the changes. Some changes took place in a millennial scale, some in the scales of centuries or decades, and at least – as can be observed every year – in a seasonal scale.
- 02, 043
Systems of Land Use in the Firgi Plains of the Chad Basin
- Studies on land use in Africa have usually been carried out by ethnologists or human geographers and were rarely concerned with data on the physical conditions of soil. There is hardly any issue, however, where interdependencies between natural and cultural factors are as evident as in the topic of land use. For this project the approach of three ethnologists, Braukämper, Kirscht and Platte, was therefore combined with the analysis of Thiemeyer as physical geographer. The area of research is the Local Government Area of Marte in the Nigerian State of Borno. As part of the Chad Basin this region is mainly characterised by clay sediments which are commonly labelled firgi by its inhabitants. Beside this general term, however, the local peasants clearly distinguish five types of soil (Kanuri: katti), to which different physical conditions and qualities with respect to their cultivation are attributed. The question arose how far can this popular knowledge, accumulated by agricultural experiences over generations, be correlated with scientific data. That is why samples of the mentioned types of soil were collected by the members of our team and analysed in the laboratory of the Frankfurt Institute of Physical Geography. The detailed presentation of this analysis has to be preceded by the classification of the respective soil types in the terminology of the indigenous farmers.