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Résumé :
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Major floods, even extraordinary floods, are a part of the natural environment. They have always occured and few regions of the world can claim to be free of their threat. Flood level marks and old chronicles inform us of such events. In the past few years, however, extreme hydrological conditions appear to have become more frequent : we have become conscious, not only of more floods, but also more periods of low flow. Do these events result from the natural variability of the climatic or hydrological conditions, or are they already the consequence of anthropogenic influences? There is clear proof of a change in the energy balance of the atmosphere at global level, on wich the climatic and hydrological processes primilary depend. On the other hand, regional and local changes are more difficult to detect and are insufficiently explored. Recent flood events show that, with the help of technical and non-structural measures, measures can be taken against the indesirable consequences of floods but, for them to be effective, people must always be prepared for a flood event. Dikes must be maintained and houses must be built in such a way that they withstand floods and that property can be removed to safety. Tanks with pollutants or toxic material must be made secure. If people take precautionary measures seriously and pursue them consistently it will be much easier to suffer floods and disaster in the future. In this, it is important that hydrologists provide accurate and timely forecasts of flows and flood levels. This Workshop made it possible to engage in an intensive and very rewarding exchange of experience about recent flood events and means for dealing with such events
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