Hochwasser#

Flood, water level or runoff exceeding a certain limit (usually the lowest high-water level of a year). This limit is calculated from the water levels and flow rates or local topographical characteristics. In hydrographical statistics the term is also used for the peak value of a hydrographic curve.

Before 1821 high-water marks of the River Danube were only occasionally recorded. Since then continuous records have been kept of the water levels of Linz, since 1828 also of Stein (Krems) and of Vienna. Soon after, other marks were also recorded. From 1893 additional flow-rate values and studies of the high waters of the River Danube were recorded. Because of occurrences of extreme draughts and high waters the hydrographical central office (Hydrographisches Zentralbuero) was established in the Ministry for the Interior in 1893 and the national hydrographical service in 1894. The latter is still responsible for the observation and recording of the hydrological cycle, for the observation of water levels and the high-water information service.

The most extensive floods of the River Danube occurred in 1501, 1787, 1899, 1954 and 1991. On the tributaries to the River Danube the highest water levels so far were recorded on the Rivers Enns 1572, Traun 1594, Salzach and Inn 1598. The area around the River Mur/Mura was particularly hit by extensive floods in 1938, that of the River Drau/Drava in 1903, 1965 and 1966. Severe floods in 1997 particularly affected parts of Lower Austria, as various southern tributaries of the Danube overflowed the levees. Floods can be caused by heavy rain and snow fall, by excessive thawing or by ice jams. After the regulation of the larger rivers at the end of the 19th century, structural alterations to the Austrian water courses carried out after World War II mainly served the purpose of protection against floods. Since the 1980s the ecological functions of a body of water have been paid more attention in planning alterations, so that more and more flood plains and retention basins have been built to protect against floods.

Literature#