01 May 2014

Revitalization of the Wienfluss

19th-century urban development involved the development of sewerage. Until then, the rivers were the main collectors, and the smaller streams served as channels. The Ördögárok stream in Buda, and the Rákos stream in Pest exuded unbearable stench before being eradicated. The second capital of the Austro-Hungarian Monarchy partly buried, partly forced underground the putrid channels which emanated putrid stench and usually also served as garbage dumps. Few people know that at that time the capital of the Monarchy also faced similar problems. There a firm and drastic intervention was necessary because of the floods and disease risk of the Wien river, which gave the name of the city. 

The Wien river being covered, ca. 1895.

The rapid improvement of the water quality after the installation of sewerage confronted Vienna city planning with new challenges. The river is no longer considered an enemy, and they slowly take the first step to the figurative and literal rehabilitation of the Wien river. The river, which not only gave the name of the city, but during its history also defended it from the enemy.

The case of the chicken and the egg – Which Wien was before?

The name of Wien was first used in the Salzburg Yearbooks of 881, in the form “ad Uueniam” (ad Weniam), but it is not clear whether it refers to the city or to the river. In Lower Austria it is quite frequent that a settlement along the Danube is named for the local tributary river (e.g. Enns, Ybbs, Aggsbach etc.), thus historians and etymologists think it likely that Vienna was named after the Wien river.

The Wien river as the natural line of defense of Vindobona

The river had a special importance for the development and progression of Vienna. It played a strategic role in the city’s southeast line of defense. In ancient times the legionary camp of Vindobona was surrounded on two sides by the Wien river and the Ottakring creek, forming two natural ditches around the settlement. In Roman times, the ramose side-branches of the Danube created a veritable archipelago on the widening floodplain, and the Wien poured into one of these branches.

The mouth of the Wien river (right), and the city walls of Vienna in 1686

Just like in Csallóköz – the Schüttinsel to the south of Bratislava/Pozsony/Preßburg –, the main branch of the Danube in Vienna was not suitable for navigation. The Donaukanal known today started to take shape in the Middle Ages from a side branch of the Danube, where the sailors could approach the imperial city, like they did on the Moson branch of the Danube in the Hungarian section. The Wien poured into the Danube at the easternmost bastion of the city, where above its mouth it formed a section of the moat called Graben.

The river bed before regulation

Queen Sissy was also here.

The Wien river has its source in the Vienna forest, on a hillside rising above the village of Rekawinkel, 540 meters above sea level. The source is built up, and a plaque preserves the memory of Queen Elizabeth visiting the Kaiserbründl in 1882. The size of the source spout is deceptive, as if it were only the start of a peaceful brook, not of the river, which repeatedly threatened by flood the city of Vienna.

Similarly to the Danube, the Wien river has two source branches. The Dürre (Dry) Wien and the Kalte (Cold) Wien merge between the houses of the village of Pressbaum, at the end of the An der Wien Street. The river runs straight, in eastern-northeastern direction to the border of the city of Vienna. This can be considered the natural section of the river. Leaving Purkersdorf, the river turns east-south-east, and reaches the Donaukanal in a regulated bed.

In Vienna, the Wien is a “district-dividing” river, that is, no district reaches over the other bank of the river. The city section – similarly to the Ördögárok in Budapest – is partly covered since the regulations.

The Ördögárok of Vienna

The sandstone forming the main mass of the Wienerwald mountain range significantly determines the water yield of the barely 34 km long Wienfluss. This stone absorbes pretty hard the rain water, so a large part of the rainfall finds runoff for itself in teh valleys. Since the bedrock of the greatest part of the 230 square kilometer large basin is sandstone, and the other part fells on urban area, covered with concrete, thus the Wien river comes near to be defined as a torrential watercourse (wild creek). A characteristic feature of torrential streams is that they also have a certain water yield in dry periods, but due to a rainfall (and the rocky catchment area) this can increase up to a hundred or a thousand fold. The runoff floods are quick, and before the digital era they practically could not be anticipated.

In the Wien river, the average yield is only 200 liter per second, or 0.2 cubic meters. In case of flood, this value can climb up to 450 cubc meters. A river with such an unpredictable water yield usually cannot be tolerated near to a large city.

In 1785, the river floods inundated the cellars and ground floors of the Schönbrunn castle. Since this was a very serious threat to a recently completed imperial residence, they could not postpone it any longer: the Wien river had to be regulated! However, the French Revolution and the subsequent wars intervened, thus the first regulation works between Schönbrunn and the Stubentor, near to the river mouth, could start only between 1814 and 1817. After the 1830 flood, cholera epidemic broke out in the city, thanks to which sewer channels were built on both sides of the river. They were called “Cholera channels” in the Viennese vernacular. The two parallel channels poured into the Donaukanal at the mouth of the Wien river.

In this period Buda and Pest also had their own natural sewer: the Ördögárok and the Rákos streams. The expansion of Budapest sealed the fate of both, since, instead of stream water and old Danube water, only communal and industrial (slaughterhouses, tanneries etc.) waste water flowed in their bed. The Rákos stream run on the place of today’s Nagykörút (Great Boulevard), and after the great flood of 1838 it was definitely filled up. The Ördögárok was covered up, although in 1875 this vault, along with the houses built upon it, was torn up by a huge flash flood. The memory of the Ördögárok is today only recalled by the statue of St. John of Nepomuk in the Horváth Garden.

The river, as it looks now, is the result of the works done between 1895 and 1899. Two main objectives were taken into account. The first, and most important was that the river bed had to be designed so that the Wien could no longer cause any injury in the imperial city in rapid development. To this end, the maximum flood to be expected once in a thousand years was taken into account in the design of the stone riverbed within its complete urban section. They planned to cover the complete urban section, but, due to financial reasons, this was realized only in a few places, e.g. on the Naschmarkt-Karlsplatz-Stadtpark section surrounding the city from the south. The situation is further complicated by the fact, that the urban rail, which today functions as the 4th metro line, was led along the Wien river bed. The railway line is in certain places separated only with a concrete wall from the river sometimes producing massive discharges.

The other objective was the retention of a possible runoff storage. To this end, a flood reservoir of seven basins was built in Weidlingau outside of the city, six for the Wien river, and one for the northern Mauerbach side stream, just above its estuary. The reservoirs, divided in boxes by concrete walls, can accommodate a total of 1.160.000 cubic meters of water. Normally the two streams just gurgle through them, but when the flow rate exceeds a limit value, they start to fill the basins.
In the reservoirs the vegetation settled back, in some of them a veritable small forest is grown. This was very favorable for the appearance of beavers. The rodents extinct in the 19th century were resettled in a planned form along the Austrian section of the Danube. A few stray beaver families then floated up the paved bed, and founded a colony in the Vienna flood reservoirs.

Back to nature

The Wien river will never again have a natural bed in Vienna, since in the absence of stone walls the quick floods would immediately underwash the neighboring streets, bridges and houses. Therefore, all eforts to do so are accompanied by sharp debates in the Austrian capital. This happened also to the initiative, which intends to reshape natural a 300 meters long section under the flood reservoirs, between the Ferdinand Wolf Park and the Brauhausbrücke, at the borders of the 13rd (Hietzing) and 14th (Penzing) districts.

The plan intends to divide the river to faster and slower flowing sections, by leaving its width untouched. They would settle native plants and animals on its shores.The bike path running along the river would remain where it is, and new stairs would make it easily approachable to the locals. It is not probable that the revitalization of the Wien river would penetrate deeper in the concrete jungle of the city. Although these three hundred meters may seem short, at least a few would be returned to the 34-kilometer long river from its original bed. The revitalization will be realized on the basis of the Universität für Bodenkultur. Only a few substantial floodings will show how durable this short man-made nature would be.

Although it is no revitalization, only urban planning, but closely related to the Wien river is the plan, which would cover in three stages the light rail track now running under open sky along with the river bed. This would give a new meaning to the term “river terrace”. From the three, independent terraces the first will be realized by 2015 between Pilgramgasse and Nevillebrücke.The implementation of the plan is especially justified by the fact, that the green surface of the nearby, densely populated districts varies only between 3 and 6%. Another difference from the above outlined plans is that here the needs of the people come to the forefront instead of those of the nature. Although these plans would not touch the single concreted river bed, but by covering the railway tracks, the inhabitants of Vienna would get nearer to the eponymous river.

New meaning to the “river terraces” in Vienna

Hopefully the trend will turn back in Budapest, too, and in certain suburban sections we will also let free our concrete-walled streams.

Sources used:


This article was originally published in the 12/69 issue of Élet és Tudomány, on 21 March 2014. 

Translated by Tamás Sajó

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