HR: 14:25h
AN: H53K-04    [Abstracts]
TI: Hydrological characterization of volcanic island by DEM generation using ASAR (ENVISAT): Galapagos
AU: d'Ozouville, N
EM: Noemi.Dozouville@ccr.jussieu.fr
AF: Pierre et Marie Curie University, UMR.7619-Sisyphe, case 123, 4 place Jussieu, Paris, 75252, France, Metropolitan
AU: * Violette, S
EM: violette@ccr.jussieu.fr
AF: Pierre et Marie Curie University, UMR.7619-Sisyphe, case 123, 4 place Jussieu, Paris, 75252, France, Metropolitan
AU: Benveniste, J
EM: Jerome.Benveniste@esa.int
AF: European Space Agency - ESRIN, via Galileo Galilei, casilla postale 64, Frascati, 00044, Italy
AU: Wegmuller, U
AF: Gamma Remote Sensing, Thunstrasse 130, Muri, CH-3074, Switzerland
AU: Deffontaines, B
EM: benoit.deffontaines@univ-mlv.fr
AF: Marne-la-Vallée University, LGGI, 5 Bd. Descartes, Champs-sur-Marne, Marne La Vallée, F- 77454, France, Metropolitan
AU: de Marsily, G
AB: Low topographic oceanic islands often suffer from scarcity of freshwater resources and are poorly characterized due to their complex internal structure and challenging access. Remote sensing has proved to be an effective tool to generate valuable data for hydrological analysis. However, these are usually tested over areas with existing validation databases and not always where the need is greatest. Here we address the need for topographical data for hydrological understanding of Santa Cruz Island (Galapagos Archipelago) where no high resolution, no high accuracy topographical data exists. 97 percent of Galapagos territory consists of inaccessible National Park land which makes the use of indirect methods indispensable. We used new ASAR data (ENVISAT) for Digital Elevation Model generation, in order to extract drainage network, watersheds, and flow characteristics from a morpho-structural analysis. Results show the high potential of this data for both interferometric and radargrammetric generation methods. If interferometry suffered from low coherence over highly vegetated areas, it showed high precision over the rest of the island. Radargrammetry gave consistent results over the entire island, and detail was enhanced by integrating the SRTM as an external DEM. Validation of the extracted river networks and watersheds was carried out using ground-based field observations, comparison to drainage network extracted from aerial photographs and to high resolution (1 m) satellite imagery. For the first time watershed characteristics and flow paths are made available for an island of the Galapagos archipelago. Drainage networks and underground percolation are strongly influenced by fractures.
DE: 1625 Geomorphology and weathering (0790, 1824, 1825, 1826, 1886)
DE: 1640 Remote sensing (1855)
DE: 1800 HYDROLOGY
DE: 1829 Groundwater hydrology
DE: 1879 Watershed
SC: Hydrology [H]
MN: 2007 Fall Meeting