Extreme floods in the summer of 1880 in the Austrian monarchy and their impact on water management in Bohemia and Austria

The 1860s and 1870s brought years of extreme drought to Central Europe. In the field of hydrology, these extremes led to the establishment of the Hydrographic Commission of the Czech Kingdom in 1875. The end of the 1870s brought a major change.  The years 1880 to 1882, which brought a series of floods, were a truly extraordinary change. In our contribution, we focused on the floods in the summer of 1880, when the western part of the Austrian monarchy was hit by repeated floods in June and August.  We are preparing the floods and their processing for our Map of Extreme Floods (MEF) application, which is now included among the professional goals of the Floods Working Group PAGES. Methodologically, this involves the collection and interpretation of documentary sources. The aim is to fix the data obtained, check it, and, in particular, present the flood event in its entirety.    The August floods occurred in two phases, approximately from August 4 to 6 and then again from August 12 to 16. A characteristic feature of this flood is the fact that the extreme flows did not reach large rivers such as the Elbe or Danube, but mainly their tributaries and often smaller mountain streams. Among affected localities  was the imperial residence of Bad Ischl. This flood was an unplanned surprise for emperor's Franz Josef "50th birthday," August celebration. Given the concentration of important guests from across the monarchy and abroad, we can assume that the flood gained significance even in the highest imperial circles. The situation was also extreme in other parts of the monarchy. Some locations in Moravia experienced two to three floods within three months. This is because devastating floods had already hit the northern windward side of the Czech border mountains and parts of the Moravian mountains in June. In August, the industrial city of Ostrava was catastrophically affected by flooding, which remains the largest known flood to date. The level reached on August 5, 1880, was not exceeded even by the catastrophic floods of July 1997. This led, for example, to the immediate development of a project to regulate the Ostravice River. The experience with these floods and, ultimately, the catastrophic floods in Tyrol in September 1882 led to the adoption of Imperial Laws 116 and 117 on torrent control and land improvement. In August 1880, the railway connection between Vienna and Krakow, Vienna and Bad Ischl, and Munich was interrupted in many places. Therefore, this flood was also a lesson for domestic railway engineers. It is likely that these floods led the head of the Prague Hydrological Service, Prof. A. R. Harlacher to develop a modern hydrological forecasting method based on flow balancing, which he and his colleague J. Richter developed between 1882 and 1884 and successfully tested in 1886.  Our contribution is further example of the truworthy of the thesis that major extreme floods usually, but not always and everywhere, brought significant progress in hydrology and changes in water management.