An average of 50,000 lives are lost in this way each year, mainly in developing countries. The loss to the world economy amounts to more than 50 billion USD. This is 9 times more than just a few decades ago. This increase is primarily attributable to population growth, building in high-risk areas, and the steadily increasing value of modern infrastructure.
Floods are responsible for the lion's share of such damage, and their numbers are constantly rising. In Belgium alone (the Maas and Schelde River basins), the 1995 floods carried a price tag of 1 billion BEF. Causes of floods include urbanisation, soil erosion, climate changes generating modifications in the precipitation profile, and more frequent and more violent storms.
One can reduce the effects of natural disasters through sound disaster management. Such management entails both prevention (assessment of risks, regional and local planning), forecasting, and adequate assistance. Remote detection is an ideal aid for such efforts, and is already well-established in each of these phases.
Satellite images, for example, are used to determine zones which are endangered by floods, volcanic eruptions or landslides.
When time series of satellite data with high temporal frequency are available, deviations in a pattern can point to an impending disaster. This is true for volcanic eruptions and earthquakes: satellites are able to detect even minor deformations in the earth's crust. Data from weather and other satellites are also indispensable for hydrological models which are used to help predict floods.
Finally, satellite images are the only tool which can help one to quickly assess the repercussions of a natural disaster which has occurred (or is still occurring) over a large area. This, too, can be of vital importance in providing adequate assistance.