ABSTRACT
In a series of large floods have occurred in northern Switzerland, whereas the preceding period, from 1940 to 1970, was relatively quiet. In northern Switzerland, periods with frequent floods have alternated with quieter periods. The fact that flood frequencies do not change simultaneously over such a small area as Switzerland indicates that global factors such as temperature increase or solar radiation cannot be directly responsible for these changes. The flood frequencies in northern Switzerland are often in phase with rivers in Spain, Italy and the Czech Republic, but less so with those in Germany. Flood frequency patterns appear to be similar in Switzerland and in the Czech Republic, although neither individual flood events nor the seasonal flood distribution match. In Switzerland, as well as in other European regions, periods with many floods have alternated with periods poor in floods. The flood frequency periods are not always in phase in Europe.
