1. Department of Geography; University of Bonn; Meckenheimer Allee 166 53115 Bonn Germany
2. Steinmann Institute of Geology, Palaeontology, and Mineralogy; University of Bonn; Nussallee 8 53115 Bonn Germany
3. Department of Geomatics and Land Management; Makerere University; P.O. Box 7062 Kampala Uganda
4. Department of Geography, Geoinformatics, and Climatic Sciences; Makerere University; P.O. Box 7062 Kampala Uganda