European watershed area of the Rhine, which empties into the North Sea via the Netherlands, and the Danube, which flows eastward emptying into the Black Sea. It enters Austria at Piz Buin in the Silvretta Alps running along the Arlberg massif and forming the border between the states of Tyrol and Vorarlberg. It reaches Bavaria, Germany via the crest of the Allgäu Alps and leaves the High Alps at the Adelegg range near Kempten. Within the Alpine foothills it runs north of the Schussen catchment area of Lake Constance towards the sources of the Brigach and Breg headwaters of the Danube in
2013 European floods between 30 and 70 years. The bulk of the rain fell in only two days in Salzburg, Tyrol, and Vorarlberg, which is thought to have a return period of more than 100 years. Following the intense rain, sporadic showers and rainfall continued to raise the risk of further flooding but no rainfall of the intensity as that seen on 31 May-2 June occurred. Some Flash flooding occurred in the Polish capital Warsaw on 9 June, as a result of thunderstorms. The flood waters were expected to exceed the levels seen during the disastrous "once in a century" Central European floods