Increase of flood water levels on the middle Danube

摘要

Over 110 years there has been an increase in flood water levels at Bratislava by more than 60 cm, which is a significant change. It is difficult to answer the question why there is an increase of water levels at stations on the Danube. Likely there will be more causes: 1. Reduction of the gauging cross-section because of dykes and embankment construction, in Bratislava, and upstream and downstream of Bratislava. In 1899 the city was flooded. 2. Rise of sediments and gravel accumulations in the river channel near the gauging station. 3. Another reason is that there was no dyke break in the Slovak Danube reach in 2002 and 2013. Therefore, the transformation of the flood wave was slower, and the water levels were higher compared to 1899 and 1954, when the Danube dykes were broken downstream of Bratislava (Svoboda et al. 2000, Pekarova et al. 2013, 2014). 4. Alleviation of the channel of the middle Danube downstream of Devin Gate is a natural process (Hronec 1969), resulting from changes of the Danube bottom slope (Fig. 3).