Published in Journal of Young Scientist, Vol.I
Written by Silviu AUREL
The main objective of this study was to test different methods of analysis and interpretation for satellite images used in the monitoring of natural disasters, i.e. floods, fires and earthquakes. The methods were applied on satellite images acquired by different types of missions in terms of sensor (optical and radar), spatial and spectral resolution. We used optical SPOT images with a spatial resolution of 20 m that are acquired in 3 spectral bands, Landsat images with spatial resolution of 30 m, 7 spectral bands and TerraSAR-X radar images with a resolution of 3 m. The satellite data used in this study consist of: Landsat images downloaded from free online archives (© USGS) as well as SPOT and TerraSAR-X that were provided by the Romanian Space Agency (ROSA ©). In order to obtain optimal results, the most appropriate input data should be represented by: radar images for earthquakes and floods and optical images for fires and floods. The first case study focused on the floods in the Eastern part of Romania, namely the Siret river floods on the Nanesti-Silistea sector in July 2005 and the Prut River floods that took place in late July and early august 2008. The second case study was represented by the forest fires of Corsica, which is the third biggest island in the Mediterranean Sea, located at a distance of 170 kilometers south coast of France and 80 kilometers west coasts of Italy. These fires have occurred in August-September 2003, when 27,335 hectares of vegetation were burnt. The third case study consisted of the Haiti earthquake that occurred on January 12, 2010, at 4:53 p.m. local time. It was a major earthquake with a magnitude of 7.0 on the Richter scale. The epicenter was located near the Port-au-Prince capital. The processing methods (image classification and change detection) were selected and adapted for each type of satellite data. In conclusion, remote sensing is very useful in monitoring the effects of natural disasters. A very important aspect is choosing the optimal data depending on the disaster type (floods and earthquakes – optical and radar, fires – optical). Equally important is the resolution of the images in relation to the investigated phenomenon. For example, in the case of the Haiti earthquake, satellite images with a spatial resolution better than 30 meters would have been more useful.
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