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Summary of Proposal HYD0247

TitleAfrican Wetlands – Monitoring of Water Balance and Vegetation Dynamics in African Deltas and Coastal Ecosystems with TerraSAR-X data
Investigator Hochschild, Volker - Universitaet Tuebingen, Geographisches Institut
Team Members
Dipl.-Geogr. Helmschrot, Joerg - Universitaet Jena, Geoinformatics, Geohydrology and Modelling
Dipl.-Min. Boehm, Christoph - H. G. Geo Data Solutions GmbH, Remote Sensing
Dr. Bartsch, Annett - Vienna University of Technology, Institute of Photogrammetry and Remote Sensing
Dr. Mazzega, Pierre - LEGOS/OMP, Laboratoire d’Etudes en Géophysique et Océanographie Spatiales
SummaryWetland monitoring is becoming increasingly important due to global climate change and human impacts on wetlands water budget. These global and regional impacts may cause potential economic and environmental threats to the wetland areas of Africa. So accurate and up-to date information of the characteristics and the current trend of these changes, provided by modern satellite systems like multipolarimetric TerraSAR-X, are needed in resource management, environmental protection as well as in global change studies. Wetlands are remote objects which have been observed and monitored over a long period. The main interest in wetland monitoring has not only been the areal extent of these ecosystems, but also the spatial and temporal distribution, circulation and physico-chemical characteristics of surface and subsurface water in the wetland and its basin over time and space. The main objective of the African Wetland project is the evaluation of the potential of TerraSAR-X X-band data to map different wetland areas in relation to water balance parameters. TerraSAR-X data will be used in combination with other remote sensing sensors by applying data fusion techniques. This synergetic remote sensing analysis comprises object oriented detection and classification of TerraSAR-X data with the major advantages of the high spatial resolution, the fast repetition cycle and the full-polarimetric capabilities in combination with high resolution optical data (QuickBird, etc.) and other microwave sensor data (ENVISAT, ALOS), available for the four selected test sites in Africa.The methodological approach of the African Wetland project is threefold: (1) With its fast repetition cycle of 11 days TerraSAR-X data will enable multitemporal change detection applications to observe the transition periods between wet and dry seasons with a higher time resolution as ERS and ENVISAT (35 days). This multitemporal quantification of the areal extent of inundated areas and height variations of vegetation species is of tremendous importance for the estimation of water balance alterations. (2) The signal intensity and the polarimetric information content are key issues in the detection of inundated areas as well as for different vegetation species, since optical data has its limits during the cloudy rainy seasons. Nevertheless data fusion techniques will be applied to combine TerraSAR-X data with high resolution optical and other microwave data. Simultaneous to the satellite acquisitions extensive ground measurements of surface roughness, vegetation height, etc. will be carried out in the wetlands and in the surroundings. (3) Apart from these multisensoral evaluations also new object oriented classification approaches should be developed for applications in wetland hydrology as well as a comparison of the different spatial acquisition modes of TerraSAR-X, to determine the highest potential for future wetland applications. Since the four test sites are quite large in extension the data requirements focus on time frequent acquisitions throughout the transition periods in Southern Africa (flooding July–August 2007 and 2008, rainy season October 2006 – March 2007 and October 2007 – March 2008) and in Western Africa (March – September 2007 and 2008) in all image modes (SC, SM, SL and SH) with quite steep incidence angles. The intended product types are .MGD and .GEC. The expected deliverables of the African Wetland project are temporal maps of the water budget and vegetation development of different African wetlands, which will be used together with field surveys and rainfall-runoff simulations to identify the impact of large scale human impacts (afforestations, etc.) within the catchments on different scales. Funding is applied for after successful launch of TerraSAR-X within the 6./7. Framework-Programme of the EU as well as for national funds (DFG, BMBF in Germany). Project planning costs are provided by the different universities and companies involved.

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