| Summary: | River runoff is the single largest contributor to the Arctic Ocean's freshwater budget. The Lena River in Eastern Siberia is one of the major rivers flowing into the Arctic Ocean. More than 50% of the total runoff from the mainland originates from the four large rivers Ob, Yenisei, Lena and Mackenzie. Global warming is expected to significantly influence the amount and temporal dynamic of river. The average annual discharge of fresh water from the six largest Eurasian rivers into the Arctic Ocean has already increased by 7% over the last century. It has been demonstrated, that the timing and magnitude of discharge of Arctic rivers is strongly linked to snow mass storage during the winter and the subsequent melt. The melting of the accumulated snow during spring leads to extreme flooding that represents the major hydrologic event of the year. About 40% of the Lena River's annual discharge is released during this few weeks lasting spring flood. Studies of the spring flood process mainly rely on hydrological modelling and sparsely available in situ gauge measurements. Also remote sensing techniques are applied to map and monitor the spatial and temporal evolution of the event. We present a new approach to delineate water levels during spring flood events that solely relies on the evaluation of high resolution SAR data provided by the TerraSAR-X and TanDEM-X satellites. The German Earth Observation satellite TerraSAR-X was launched in 2007. It provides SAR data in different modes and resolutions. Operationally single and dual polarization is possible. Since 2010 it is flying together with its twin satellite TanDEM-X in close formation enabling single pass interferometry. Here, the primary mission goal is the generation of a global digital elevation model (GDEM) in outstanding quality and resolution that allows classifying the shoreline and land’s topography at an unprecedented level of detail. The spatial resolution is 12.5 meters with a vertical accuracy of 2.5 meters. Our test site covers the central part of the ...
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