Development and implementation of GIS-based methods for the assessment of meso-scale climate change impacts in sub-Saharan Africa, with special reference to the Okavango catchment
Climate change is a global phenomenon with very diverse regional manifestations. This cumulative dissertation explores some of the possible impacts of climate change in selected regions in sub-Saharan Africa and assesses their spatial dimension with the help of Geographic Information Systems (GIS). The primary study area is constituted by the Okavango River catchment in southwestern Africa, shared between the three countries Angola, Namibia and Botswana. While the region is a hot spot for environmental change, it is also heavily influenced by socioeconomic transformation processes and it is necessary to take into account the interplay between those factors. Population growth and changing climate put pressure on the stressed water resources that enable agriculture, livestock rearing, mining, household supply and tourism on the one hand and are needed by the sensitive ecosystem on the other. Today, sophisticated climate models and GIS provide the means to generate high resolution estimates of climatic trends and integrate them with other spatial data for detailed impact and risk assessments. Six peer reviewed publications in international scientific journals cover different aspects of the issue for this thesis. Article I analyzes the political and environmental situation in the main study area, the socioeconomic background of the riparian states and the current and projected water situation against the background of population growth and climate change. A special focus lies on the integrated water resource management in the arid region. Compared to other parts of the world, the Okavango basin is an example for a study region with an extremely poor data situation. This is in part due to the long period of civil war in parts of the catchment, which made data acquisition almost impossible for 27 years. Article II presents a regionalization scheme for climate model data that contributes to provide access to high resolution climate model simulations for stakeholders and decision-makers. It utilizes the free and open-source GIS software SAGA and is applied on historical runs and future scenarios of the REMO regional climate model, forced with the general circulation model ECHAM6 as well as ERA-Interim reanalysis data. Article III presents an example for the application of high resolution climate model data. Together with remote sensing, pedologic and demographic data, an integrated land degradation risk assessment is undertaken to identify hot-spots where a long-term decline in ecosystem function and land productivity is likely to occur. Article IV shows a second example for the application of the regionalized climate scenarios. In a fuzzy-analysis, the climate information is combined with soil data and compared with the optimal growth conditions of several crops to evaluate the present and future agricultural potential in the Okavango region. Article V and VI complement the thesis with an example for the linkage of climate data with social indicators in a secondary study area in East Africa. For the two countries Kenya and Uganda, an extensive spatial analysis of a possible climate-conflict link is conducted and contrasted with the findings of field surveys. Furthermore, the possible influence of recent oil findings in the region on the local communities' vulnerability to climate change is elaborated.