The Rise and Fall of the Vienna Archipelago (1529-2010)

Cutting the Gordian Danube, Vienna 1875. (source)

IN HUNGARIAN

My absolute favourite book of 2023 was Wasser | Stadt | Wien. 458 pages of solid hydrology about Vienna, much of it of course about the Danube. The volume also includes nine full-page pictures of the changes in the river meanders around the city of Vienna. Lovers of urbanism will certainly find things of interest in the previously published images, but it is the floodplain patterns, which are now mainly similar to those of the Danube at Gemenc, Hungary, that are worth observing. It is a little known fact in Hungary that the Danube has caused far more serious problems in Vienna than in Budapest throughout the city's history. In historical times, the Danube flowed through a floodplain up to seven kilometres wide in Vienna, creating and destroying countless islands along this river section. The Viennese had an ambivalent relationship with the river, fearing its difficult crossing between the two banks and the many flood damages, but it was an advantage for the city in terms of trade. Around 1565, the main branch of the Danube moved away from the city and efforts by locals to bring the main shipping route back close to the city failed, leading to a compromise solution of extending the Vienna branch of the Danube, which later became the Donaukanal. 

Ugyanakkor a folyókanyarulatok vándorlása mellett a rendkívül fonatos meder gyakran okozott jégtorlaszokat. A budapestinél sokkal kevésbé stabilabb mederben a zátonyokon és szigetcsúcsokon kialakuló jégdugók gyakran eredményezték azt, hogy a télen levonult jeges árvíz kártételeinek felszámolása után a bécsiek már teljesen máshol találták meg a folyót. Ez az állandóan változó ártéri világ egyre inkább akadályává vált a város terjeszkedésének, amelyre megoldást kellett találni. Végül egy meglehetősen drasztikus beavatkozás szüntette meg a bécsi szigetvilágot 1870-1875 között, amikor is egy új, nyílegyenes medret ástak a Dunának, meghagyva egy széles, hasonlóan egyenes elöntési területet az árvizek számára. Az utóbbi időszak módosításai ezt a területet érintették, amikor a széles, kopár parti sáv helyén létrehozták a Donauinsel-t, melyet a bécsiek már sokkal inkább birtokba vehettek. 1875 után a lefűzött, kiszáradó folyókanyarulatok két utat jártak be. Ahol városi zöldfelületek területére estek, ott javarészt fennmaradtak (Prater, Alte Donau, Lobau, stb.), ahol viszont a város szövete ugrásra készen várta a kiszáradást, ott esetleg csak az utcák nyomvonala emlékeztet a régi medrekre (pl. Schwarze Lacke), többségük több méter feltöltés és beton alatt húzódnak. 

However, in addition to the migration of river meanders, the extremely braided riverbed was often clogged by iceblocks. In a much less stable bed than Budapest's, ice jams on sandbanks and islands often meant that, after the damage caused by the winter ice flood had been cleared up, the Viennese found the river in a completely different place. This ever-changing floodplain world became an increasing obstacle to the expansion of the city, and a solution had to be found. Eventually, a rather drastic intervention eliminated the Danubian archipelago in Vienna between 1870 and 1875, when a new, straight-edged bed was dredged for the Danube, leaving a wide, equally straight floodplain for the floods. More recent modifications to this wide, barren flood area included the creation of the Donauinsel, that was more easily occupied by the Viennese people. After 1875, the story of the newly created oxbows and drying river meanders took two paths. Where they fell into urban green spaces, they were largely preserved (Prater, Alte Donau, Lobau, etc.), but where the urban developers eager for more territory, only the street network may be reminiscent of the old riverbeds (e.g. Schwarze Lacke), most of them beneath several metres of landfill and concrete. 

Half a thousand years of river bend changes in Vienna 1529-2010 (source)

The nine detailed landscape reconstructions created using geographic information methods were almost begging for a .gif version. This version was most certainly created by the authors, but unfortunately the format is not compatible with the capabilities of the Guttenberg Galaxy. So I quickly put together my own version. In varying time-intervals, nine dates in total (1529, 1570, 1662-1683, 1704, 1780, 1825, 1875, 1912 and 2010), we can see the immediate surroundings of Vienna, with the Praterstern roughly in the centre.