Floods
 Every year rain severely affects the Earth causing considerable damage to towns, roads and agriculture with a high loss of life. Many of the world’s urban centres are in low-lying areas subject to flooding, and rapid identification and response to flooded areas are essential to avoid common environmental phenomenon turning into disasters.
One of the biggest problems during these emergencies is to obtain an overall view of the phenomenon, as aerial observation is often impossible due to prohibitive weather conditions. The Synthetic Aperture Radar (SAR) instrument, which can collect data independently of weather and light conditions, is an excellent solution to this problem.
 A multitemporal technique is normally used to identify and highlight the flooded areas. This technique uses black and white radar images of the same area taken on different dates and assigns them to the red, green and blue colour channels in a colour image. The resulting multitemporal image clearly reveals changes on the Earth’s surface by the presence of colour in the image; the hue of the colour indicating the date of the change and the intensity of the colour the degree of change. The application of this technique is dependent on rapid access not only to the disaster images, but also to the archived images of the "normal" situation for comparison.
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