Impact of river training and retention measures on flood peaks along the Rhine

For several hundreds of years the River Rhine has been influenced by human activities. This has changed the flood routing down the river. In particular weirs, which have been constructed along the Oberrhein from 1929 to 1977, and retention measures, which have been taken during the last years in order to reduce peak flow, have influenced the flood conditions along the River Rhine substantially. To quantify the effects of these measures upon flooding in the region of the Niederrhein in Germany and in The Netherlands, flood routing models were used and flood statistics were carried out using time series, which were homogenised for different river conditions using the results from the flood simulation. In addition synthetic floods were simulated in order to investigate the effects of the flood reducing measures upon very high flood peaks with return periods of 200, 500, 1000 and 1250 years. The results are the base for the definition of design floods in North-Rhine-Westphalia, Germany as well as in The Netherlands.