Application of Envisat ASAR in the Monitoring of the Catastrophic Flood Disaster

Abstract

China is a country with a lot of disasters of which floods account for a larger part. Floods in China have four main characteristics, namely large affected areas, frequent occurrences, strong outburst and significant losses, so flood disaster monitoring is meaningful. Remote sensing (RS) technology, especially with that of satellite SAR remote sensing data, has been tested as an efficient way of monitoring and evaluating flood events. Flood monitoring and evaluating has been performed for 15 times in 2005 by Remote Sensing Center of Water Resource Ministry, China. Wuzhou, sites in east gate of Guangxi province, accumulates 85% of the water that will flow into Pearl River,annual runoff 3.5 times than that of Rhine River, Europe. In June 2005, it encounters catastrophic flood rarely seen in 100 years which cause huge losses. This paper, with the support of the Sino-Euro Dragon Programme, discusses the application of Envisat ASAR data in the monitoring of flood disaster,taking the 6.23 Wuzhou flood disaster as an example. ASAR Image Mode data and Alternating Polarization data (30m in spatial resolution) are used, contrasted and analyzed in raining season. Flood areas, their distribution and effects to different land use are extracted with relative database. ASAR images are also compared with those of Radarsat in water body recognition as well as those of similar terra objects. Results showing that multi-polarization and multi-phase data (Envisat ASAR) which reflect quickly the changes and flood development, could play important roles in flood monitoring process. It does help greatly in schedule arrangements and flood controls. Some problems have also been put forward for further researches.