Multi sensor systems and floods risk management in the Danube Delta
Niculescu Simona(1), Guttler Nor Fabio(1), Lardeux Cédric(2) and Rudant Jean-Paul(2)
(1) Géomer, UMR 6554, LETG, Technopôle Brest Iroise, Place Nicolas Copernic, 29280, France
(2) Institut Francilien des Sciences Appliquées, 5 bd Descartes, 77454 Marne la Vallée Cedex 2, France
The use of multi sensor systems, such as radar and hyperspectral images, and Digital Terrain Model issued LIDAR, contributes to a better comprehension of the floods in the Danube Delta, their impacts, and the risk management and sustainable development of the delta.
This paper presents the treatment of Advanced Synthetic Aperture Radar images, in C band and vertical polarization, to cartography the flooded and floodable areas during the events of the spring 2006 in the Danube Delta.
A set of implemented radar images were taken both before, during, and after the floods, on April 19-th, May 1-st, and May 8-th 2006 respectively, and during the consecutive year on June 13-th 2007. A data fusion is proposed, with the three dates of 2006, as well as the same dates plus that of 2007. Although radar imaging gives important and precise information on the location and characterisation of the flooded and floodable areas, and on essential areas in the land settlement of the territory that belongs to the administrators and the delta population, this instrument quickly shows its limits.
In order to characterize floodable zones, complementary hyperspectral images were recorded with the Compact High Resolution Imaging Spectrometer of the PROBA satellite, thus restoring accurate details of vegetal surfaces in this humid zone. The capacity of this satellite to provide hyperspectral data at multiple angles is particularly useful to characterize the deltaic vegetal stratum surface, previously detected by ASAR in some regions as floodable. Some correlations between the social and economic aspects of this vegetal stratum and their flood potential, according to different forms of agricultural practices, were established. Joint strategies based on multispectral analysis and spatial classifications using textures associated to different types of vegetation, allowed us to minimize the confusion between different vegetal classes in the wetland.
Watermark estimation during the events of 2006, were drawn by merging the data with Lidar measurements taken during the 2007 campaign, all over the Danube valley in the Romanian sector (with a precision of order 15 to 30 cm). From those models maps of floodable areas were developed, according to different hypothesis (such as level of the river flow, bursting or not of the breakwater), in order to control the episodes of the crisis. Finally, the knowledge of both the water heights, through numerical model, and the local topography, through Digital Terrain Model, allow us to determine the flooded areas and the height of their submersion.