Browsing by Author "Nienkemper, Pamela"

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    Aerial Imagery for Monitoring Land Use in East African Wetland Ecosystems
    (IEEE, 2009) Franke, Jonas; Becker, M.; Menz, Gunter; Misana, Salome B.; Mwita, Emiliana J.; Nienkemper, Pamela
    Anthropogenic pressure and environmental change processes are key drivers of the recent intensification in the agricultural use of East African wetlands. Land shortage and degradation of upland areas as well as climate change effects turn wetland ecosystems into focal points of production by commercial and traditional users, entailing rapid wetland use changes and, in some instances, severe wetland degradation. An ecosystem inventory by mapping land cover and monitoring land use changes with remote sensing improves our understanding of change processes in wetlands and will contribute to the provision of decision support for sustainable use of wetland ecosystems. However, the spatial resolution of satellite systems is often too coarse to derive land use information at the plot level. In particular, small wetlands often exhibit abrupt transitions into different types of land use and landscape elements. Hence, monitoring of small wetlands requires spatially high-resolution remote sensing data, accounting for the prevailing small-scale diversity in land use. High-resolution aerial imagery, which is not available for most parts of East Africa, may provide information of wetland use/change at the required plot-level scale. Therefore, image acquisition campaigns over Kenyan and Tanzanian wetlands were realized with a common Nikon D-200 in September 2008 and February 2009, respectively. A comprehensive geo-referenced image data set that displays land use units at the plot level was obtained, used to discriminate various land cover types. Land cover/-land use maps can be derived that reveal land use trends fundamental for providing decision support for a sustainable wetland use.
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    Detection of Small Wetlands with Multi Sensor Data in East Africa
    (2012-12) Mwita, Emiliana; Menz, Gunter; Misana, Salome; Nienkemper, Pamela
    The dynamic nature and inaccessibility of wetland ecosystems restricts in situ data collection and promote the use of various remote sensing platforms. This is because of their ability to record large areas in comparatively short time peri-ods and map physically unreachable areas. Sensors in the optical and microwave range of the electromagnetic spectrum play a critical role in wetlands detection and delineation, as they complement each other in data collection. This study examined the potential of optical and microwave remote sensing in detecting the diversity of small wetlands (<500 ha) in the semi-arid and sub humid parts of Laikipia and Pangani plains and the humid parts of Mt. Kenya and Usambara highlands in Kenya and Tanzania, respectively. An intensive field survey was conducted to supplement the remotely sensed data. Decision tree, supervised and unsupervised classification techniques, facilitated the detection of floodplains and inland valley wetlands within the study sites. The results reveal that although optical and microwave data work ef-fectively in the detection of wetlands the latter would be more effective in larger wetlands than those in the scope of this study.