Assessing socio-economic and climate-related impacts on natural resources in rural areas of West Africa

Kurzfassung

In many regions of Africa, high population growth rates and the related accelerating need for food, water, energy, and construction materials have led to considerable human impacts on natural resources. Agricultural areas, urban areas, and dispersed rural settlements for example are expanding at the expense of natural forest, grassland, and savanna systems. Dams, reservoirs, and irrigation systems have been constructed, affecting the availability of water and the dynamics of lakes, rivers, and wetlands, to give just few examples. In addition to these anthropogenic transformations, climate variability and change do increasingly impact natural resources, ecosystem services, and human livelihoods, particularly in the arid and semi-arid zones of Africa. This presentation gives an overview over a range of remote sensing based studies disclosing the impacts of socio-economic development and climate variability on natural resources in West and Southern Africa. We put a particular focus on rural areas which are, despite high urbanization rates, still home to a considerable part of the African population. The presented analyses utilize satellite remote sensing time series of different sensors at high to medium spatial resolution, including Landsat, MODIS, QuickBird, ASAR, TerraSAR-X, and Sentinel-1/-2. Information on land use and land cover, tree fractional cover, waterbody dynamics, fire and vegetation phenology are derived based on methods incorporating multi-sensor, multi-temporal satellite data. Analyses in the savanna biome of West Africa show for example a thinning of woody vegetation in intensively used cropland and rangeland areas, where the configuration of rural settlements and population density clearly influence the observed spatio-temporal patterns. Agroforestry systems, with a mixture of crops and trees, prevail in rather remote and scarcely populated regions but their spatial distribution is at the same time clearly influenced e.g. by climatic conditions. Well noticeable is also the increasing number of reservoirs in semi-arid regions of Africa which are constructed to meet the demand for drinking water, irrigation water, and proteins in form of fish for the growing population. Further studies will be presented that analyze natural wetland ecosystems based on the multi-sensor earth observation time series. Here, a special focus is put on the combined impact of climate variability and human modifications such as irrigation and dam construction on water availability and vegetation productivity. The presentation finally gives an outlook on the potential and added value of new and upcoming earth observation sensors for improving future analyses of socio-economic impacts in data scarce regions such as rural Africa.