The Oldest Danubian Island in Vienna - The Alberner Schotterbank

MAGYARUL

Let's start with a riddle: Which is the oldest natural island still in existence on the heavily regulated, straightened, and de-insulated section of the Danube in Vienna? If there is one at all. 

Of course there is; otherwise, the question would be pointless to begin with, and there would be no reason to even write this post. In any case, this is by no means obvious on the ground; in fact, given its morphology, it should rank among the youngest islands, and everything points to the fact that this riverbed was created by humans between 1972 and 1988, when the Danube regulation carried out between 1870 –1875 was revised in Vienna, creating the bleakest urban zone in the river’s history, known as the Überschwimmungsgebiet, where the natural riverbeds of the time lay on the banks for a long time, like dead fish after the cyanide pollution of the Tisza river. A hundred years later, these remains were dredged up and buried beneath a 21-kilometer-long artificial island called the Donauinsel, which has one positive aspect: it was ultimately not built up with office buildings and apartments, but instead developed into a city park, featuring varied topography and a diverse shoreline despite its straight, paved banks. 

Along the Donauinsel, bays, peninsulas, and quieter stretches of water bordered by rock embankments have been created—and even separate Danube islands—to replace the natural tributaries that have been eliminated and so to increase biodiversity. One such artificially created island is the Albern Gravel Bank (Alberner Schotterbank), which could easily be called an island due to the floodplain forest that has developed on it, interrupted at only one point by the highly spectacular pipeline system connecting the Schwechat oil refinery with the Lobau oil terminal. 

On Monday, May 11, 2026, in the early afternoon, during a low-water period of 150 centimeters—with the water level slightly receding—measured at Wildungsmauern, a significant overflow was observed in the approximately 20-meter-wide side channel next to the Alberner Schotterbank. The water flowed extremely rapidly in the deep channel between the extremely steep, eroded bank walls composed of massive pebbles. On both sides, tree roots hang in the air. There are two human-made reasons for this: one is the Freudenau Dam, downstream of which lies the Alberner Schotterbank; the other reason can be traced back to the same project, albeit somewhat indirectly. This is because beneath dams, the riverbed suddenly deepens, the original water level drops, and the islands are left dry. 

That’s what happened here as well; this gravel bar is very close to the dam, and it functioned as a gravel bar right up until the dam was built. As a result of the drop in water level downstream, it became an island, which is why the forest was able to grow there, and why the side channel began to dry up. In Austria, they typically don’t leave things like this alone and set about dredging. Between 2023 and 2024, with a brief interruption when the Boris flood deposited an astonishing amount of silty sediment and debris in the area, they dredged out the deep channel still visible today, despite protests from regular beachgoers [1]. The dredged gravel was used to counteract the deepening of the main channel and was spread out below the Freudenau dam. Some online maps still show the old situation of the river, so many visitors may be surprised to find that the island can no longer be reached on foot even at low water, a fact that beachgoers have resented ever since; conversely, the wildlife is quite grateful for the isolation. 

The Alberner Schotterbank in 1856.

The Alberner Schotterbank first appears on Pasetti’s 1856 nautical chart of the Danube. It was closer to Mannswörth than to Albern, and was located on the opposite bank. At that time, Albern was a small fishing village belonging to Kaiser Ebersdorf, which suffered greatly from the Danube’s floods. It was destroyed by the “Himmelfahrtsgieß” flood of 1501, and then by the “Allerheiligengieß” flood of 1787, when erosion by the Danube washed away 85 hectares of land, including the village itself [2]. It was then that the fishermen relocated to the site of the present-day settlement. In 1809, Napoleon, passing through here, dismantled the village to build a pontoon bridge using the beams from the houses in Albern.  

The Alberner Schotterbank in 1938.

The upsilted island before the dredging, 2023. 

The current situation

On Pasetti’s map, it appears that one of the islands in the vast Danube side channel—which was dammed off between 1836 and 1841 opposite the settlements of Albern and Mannswörth—was split in two by the dam, with the smaller, shoal-covered section remaining in the floodplain. We are most likely witnessing the very moment of the Alberner Schotterbank’s birth; in other words, this island in the Danube—now part of Vienna—will soon be blowing out two hundred candles on its birthday cake. The Albern gravel bar is a true relic. It is not so much its formation as its survival that is considered a miracle. Although it is inseparable from the history and territory of the Donauinsel today, it is very distinct from it.

Recommended and cited literature:

 

[1] https://www.krone.at/3157759

[2] Wasser | Stadt | Wien 

Black Lacquer Danube

MAGYARUL

Following the river regulation carried out in Vienna between 1870 and 1875, and the subsequent urbanization, very few of the original branches remain of the once anastomotic Viennese Danube. Nevertheless, the old hydrographic names have survived to this day in the Austrian capital; at every turn, we come across street names and neighborhood names such as Am Hubertusdamm in Floridsdorf, Überfuhrstraße, and Floridsdorfer Aupark, all of which are linked to the history of the former Danube island, Schwarze Lackenau. Despite the fact that this island ceased to exist more than a century and a half ago, the flood-prone lands were built over, and its buried, then partially revitalized tributary was left as green space—perhaps out of respect—which anyone can walk through, provided they are aware of what once lay beneath their feet. Which, of course, is by no means obvious.

The Schwarze Lackenau before the Viennese river regulations

Above Vienna, the Bisamberg on the left bank is in a similar position to the next “gate” downstream, between Devín and Hainburg, dividing the Austrian Danube into sub-basins. Above it, the Tullnerfeld once boasted a Danubian archipelago as rich as the Marchfeld that opens up below the Bisamberg. The Schwarze Lacke was one of the first left-bank Danube tributaries of the Marchfeld, branching off below Langenzersdorf opposite Leopoldsberg—easily recognizable by its church—and rejoining the main channel near Floridsdorf via a seven-kilometer-long, inverted “S”-shaped channel. The island it surrounded, like many others in the Vienna area, was known as an “Au”; today, the hydronym Schwarze Lackenau has become the name of the settlement. 

In Vienna, although very little remains of the old Danube islands, their history is well documented; according to the maps in the exemplary volume Wasser | Stadt | Wien, this tributary—alongside which lay anywhere from one to three separate islands—already existed in various forms as early as the 16th century. In contrast, only a single settlement on its banks, Jedle(r)see, withstood the destruction wrought by the Danube, which regularly flooded the Marchfeld and evidently Vienna, as evidenced by the flood of March 1830, commemorated on a plaque on the wall of the local manor house of the Hungarian Counts of Erdődy.

The floods that became increasingly frequent during the 18th century and reached ever-higher water levels were particularly dreaded events in Vienna. In addition to the damage caused to human life and property, each time the floodwaters receded, new sandbars and islands formed, the shape of the old ones changed, some branches silted up, and others began to develop into main channels. North of Vienna, the regulation of the Schwarze-Lacke branch also became necessary due to such a change in water flow; by the mid-18th century, there were fears that the main branch of the Danube was increasingly diverting toward the Marchfeld via this branch, these channel shifts not only threatened the surrounding agricultural areas with destruction but also endangered Vienna’s trade, should the former right-bank shipping routes silt up. Thus, it was necessary both to ensure that the Danube branch—considered the predecessor of the Donaukanal—near Nußdorf on the right bank received sufficient water supply and to close off the left-bank branches. 

After seven years of debate, in 1776 the Aulic War Council (Hofkriegsrat) approved the plan submitted by Hubert János Zsigmond, a hydraulic engineer born in Sopron, Hungary, and commissioned him to build a 7-kilometer-long protective embankment between Langenzersdorf and Nußdorf. This included more than 50 spurs extending into the main channel, which protected the new embankment from erosion. The course of the Danube had already changed significantly while the plans were being drawn up, so Hubert had to modify the plans as work progressed. The embankment, with its rather irregular course, closed off several smaller and larger river branches, each of which carried the potential for a breach during floods. One such smaller branch was the Scheibgraben, which nearly cut the Schwarze Lackenau area in half and was closed off at the last moment before a breach could occur. An embankment was also built across the island; the purpose of the Kommunikationsdamm was to ensure a connection to Nußdorf, and a ferry crossing operated at its end. However, the Hubertusdamm was completed at the very worst possible time. 

Toward the end of the 18th century, flooding became increasingly common along the Vienna section of the Danube; in some years, the Schwarze Lackenau was flooded several times. According to Historische Hochwässer der Wiener Donau und ihrer Zubringer, these occurred in the following order: (July 1771, January 1775, February 1776, June 1777, February 1784, then August, March, June, July, and August 1785, June, July, and August 1786). Barely four years after the embankment was completed, the greatest flood of November 1787 severely damaged the embankment and reopened the Schwarze-Lacke branch, which was later closed off again with a “shallow” dam (Seichdamm), but regardless of how it happened, the Hubertusdamm formed the foundation and the first section of the Marchfeld-Schutzdamm flood protection embankment, which was later built in a straight line all the way to the mouth of the Morava River towards the Hungarian border.

The original plans for the Hubertusdamm in 1783.

In Vienna, this regulation brought about extremely drastic changes between 1870 and 1875, permanently eliminating the Danube’s role in shaping the landscape around the city and enabling urbanization in the reclaimed areas. It also closed off the Schwarze-Lacke branch and cut off the western part of the Schwarze Lackenau island, which meant that the remains of the embankment built by Hubert were also leveled in the barren area of the Inundationsgebiet, a zone designed to divert floodwaters. Interestingly, the southern tip of the island near Floridsdorf remained intact; this is now the Floridsdorfer Aupark. 

The old and new route of the Viennese Danube between Jedlesee and Floridsdorf 1870-1875.

Humans took over the Danube’s role in shaping the landscape in the reclaimed floodplain, the Schwarze Lackenau area; while it was still an island, there were barely one or two houses there until the 1870s, typically shipyards, ferry stations, inns, or manor houses. Vienna’s urban expansion first reached Jedlesee; due to the housing shortage following World War I, the island’s area was subdivided in two phases, with primarily small gardens and single-family homes being built—a character the neighborhood has managed to preserve to this day. Although the Schwarze-Lacke branch was gradually filled in by 1939 at the latest, the area of the old riverbed was not built-in. 

The Schwarze-Lacke-Duna, which had already been filled in, and the parceled-up island in 1939

The section downstream of Jedlesee has preserved the shape of the riverbed the longest; this part was filled in after 1945 with debris from buildings destroyed during World War II, and later, according to some reports, the work continued using urban garbage and soil contaminated by industrial pollution—a process that, based on aerial photographs, was still underway as late as 1956. Based on a site visit, the filling was by no means uniform morphologically, likely due to land ownership issues. The parts of the private properties along the shore that extended into the riverbed typically preserved the deepest sections, alternating between the island and the shore sides, primarily in the section above the Jedlesee church. There is also a longer depression next to Teslagasse in the wooded area of Aupark Jedlesee, but where the authorities built playgrounds and sports fields, the leveling was much more thorough. 

The southern section with the latest landfill in 1956.

The last major anthropogenic intervention took place between 1984 and 1992, when the drop in the groundwater level in the Marchfeld—caused by the subsidence of the Danube riverbed—began to threaten agriculture. The harmful effects of Danube regulation necessitated another intervention; the Marchfeld Canal was constructed as part of the revitalization of the northern section of the Schwarze-Lacke branch. This canal actually branches off from the Danube at Langenzersdorf, but runs parallel to the Danube for several kilometers; utilizing the former Schwarze-Lacke branch, it was routed eastward and extends almost all the way to Dévény. 

Water is only present on this section, but it seems that even this is an improvement compared to conditions in Vienna.

The revitalized northern section of the Schwarze-Lacke-Danube (now known as the Marchfeld Canal)

Here and there, the piles of soil used for backfilling are visible

Until 1870, the only way to photograph the church at Jedlesee was from a boat

The Lorettofield sports area, with the Jedlesee church—originally built on the banks of the Danube

Saint Florian and the 1830 Floodmark
on the Wall of the Erdődy Manor House in Jedlesee.

Translated with DeepL.com (free version)

Quarantine Island

MAGYARUL

"Lazing around in quarantine is good practice for octopus life", wrote Danish storyteller Hans Christian Andersen in his Danube travel diary in the spring of 1841, during the forty days he spent in quarantine in Nagyzsuppány (Jupalnic - Romania). The Habsburg Empire's cordon sanitaire, built within the framework of the military frontier, which protected the Empire's borders from invisible enemies such as viruses and bacteria from the Adriatic Sea to Bukowina. These quarantines, commonly referred to as "contumaz" stations, were lined up in regular order along the Danube border from Zimony (Zemun - Serbia) to Nagyzsuppány until the middle of the 19th century. Most of them were demolished without a trace, with the one in Nagyzsuppány, for example, now lying 25 meters under water, but the name of one of them is still preserved today on a Danubian island in Serbia.

Quarantine buildings of Pancevo (below)

"We have moved into the quarantine station, and now our Helena-life is beginning to take on its peaceful daily routine", writes German traveler Wilhelm Richter at around the same time, in the same place, at the quarantine station in Nagyzsuppány. Balázs Szálinger recommended Richter's travelogue about Hungary to me a few years ago, during the raging COVID pandemic, as a potential Danubian topic for the blog. The German Richter was luckier than the Danish storyteller, having to spend only eleven days in quarantine, as the number of days spent in quarantine was determined by the epidemic situation abroad, in this case in Wallachia, and the idleness was shortened in epidemic-free times. Even then, this protracted coercive measure was considered unnecessary, as life was rather boring in the quarantine, surrounded by wooded mountains, decorated with a small garden planted with grapevines, but closed off by prison walls and guards, where the travelers could only communicate with each other through a wooden slat, Their food (sour cabbage and fatty pork) was provided by an innkeeper, and their health was checked daily by the quarantine doctor. Travelers and merchants could rent their own furnished accommodation according to their financial means, or they were forced to share a regularly whitewashed room with others. Presumably, the quarantine stations along the southern and eastern borders of the Habsburg Empire had a similar layout, standards, and regulations to the one in Nagyzsuppány, but the one in Pancsova (Pančevo - Serbia) was somewhat different.

The quarantine building at the lighthouseless Temes estuary

A permanent quarantine station was built in Pančevo for people arriving from the Ottoman Empire (later Serbia) based on a royal decree dated June 6, 1741 [1]. An entire block of houses on the southern edge of the city at that time was designated for this purpose. This block still exists in the urban structure of Pančevo today and can be most easily identified by the Red Warehouse (Kontumaz Magazin) shown in the first picture, in the quadrangle bounded by Žarko Fogaraš, Dositej Obradović, Radoje Dakić, and Milorad Bata Mihailović streets. This place is still remembered in Serbia today, as the renowned Serbian linguist Vuk Stefanović Karadžić spent a few weeks here on his way to Western Europe.

In the vicinity of the old Pančevo Castle, the settlement that developed after the expulsion of the Turks was located on the high banks of the Temes River rather than on the wide floodplain of the Danube for geomorphological reasons. This meant that those crossing the Danube border could easily avoid quarantine if they headed not for Pančevo but for one of the nearby military frontier villages. It was therefore necessary to set up an additional quarantine station 2.5 kilometers from Pancsova, directly at the ferry crossing, later at the boat station, which at that time was below the mouth of the Temes River. This was the Vor Kontumaz, or pre-quarantine station. 

The two qarantines (inner and outer) of Pancevo in 1775 (source)

According to old pictures, it was a square, one-story, tent-roofed, massive stone building, standing next to the confluence of the Temes and Danube rivers like a late Roman burgus on the border of the empire. Some maps also included the German word "Wache," meaning that military guards were also assigned to it. After all, since 1776, epidemics had fallen under the jurisdiction of the Aulic War Council (Hofkriegsrat), i.e., the military, but it was not regular soldiers who served here, but wounded, veteran or retired soldiers. 

In 1857, under the new Danube navigation agreement, the parties (Ottoman Turkey, the Habsburg Monarchy, Württemberg, and Bavaria) agreed that if there were no signs of plague along the Danube for a year, the quarantine would be lifted [2]. The lonely, disused building was still standing in 1908 and even gained some neighbors when the famous lighthouses, now sadly falling into disrepair, were built at the mouth of the Temes.  

Lighthouses of the Temes estuary
with the quarantine station on the right. (postcard, own collection)

Ironically, the destruction of the quarantine building was caused by the relatively young Danube island named after it. Sometime between 1834 (Rauchmüller map) and 1856 (Pasetti map), a sandbar rose in the middle of the Danube, directly at the mouth of the Temes River, next to the quarantine station building. This section of the Danube below Belgrade was already quite prone to shoaling, and in the fairly wide bend of the river, the formation of the new shoal was already visible from both banks, as it was surrounded by four large islands. From the direction of the flow, these were: Ovca Island (left), the wasp-waisted Cakljanac Island (right), Stefanec Island (r) and Starcevo Island (l), all of which belonged administratively to the city of Pančevo, even though only a very narrow branch separated Cakljanac Island from Serbia in the south. 

Vorkontumaz station and island in 1914 (source)

With the appearance of Vorkontumac Island (Serbian phonetic transcription: Форконтумац) in the middle of the Danube, the unified main branch split into two roughly equal branches, both of which were used for shipping, as the Danube, augmented by the discharge of the Drava and Sava rivers, already had a significant discharge here. As most of the riverbed was occupied by the rapidly growing new island, whose area exceeded one square kilometer by 1866, the waters of the Danube diverted in both directions and began to reshape the two banks. Both the Hungarian, Pančevo bank and the large islands on the right bank along the main channel eroded rapidly, and the washed-away sediment was deposited along the lower part of the islands. Erosion continued to destroy the mouth of the Temes until 1908, when the banks along the lighthouses were reinforced with stone embankments, saving the quarantine building from collapsing into the Danube. This bend development has since taken away about half of Starcevo Island below the mouth of the river. 

The Форконтумац Island nowadays (wikipedia)

The exact date of the quarantine station's destruction is unknown, but it was still standing in 1914. What is certain is that the excavation of the Pančevo customs port bay did not affect the area where it stood. Its ruins and foundation walls may still exist somewhere in the riverine forest next to the lighthouse on the right bank of the Temes River. However, its name has survived in the form of the island named after it, which has since grown considerably in size. Vorkontumaz Island now covers an area of more than 4 square kilometers. Its upper peak, close to Belgrade, is inhabited, and it is here that the resort called Bela Stena (White Rock) was built, named after the white sand found here. Most of the island is covered by natural forest, divided lengthwise by the remains of old oxbow lakes, but a smaller part is a forest plantation where logging also takes place. 

Translated with DeepL.com (free version)

Literature:

[1] Linzbauer Xav. Ferenc: A Magyar Korona Országainak nemzetközi egésségügye (Pest, 1868) 

[2] Sabine Jesner: Cordon Militaire – Cordon Sanitaire. Járványmegelőzés az erdélyi katonai határőrvidéken (cca. 1760–1830) Századok 2022. 1. szám

Danubian Island of the year 2025

Autumn is here again, and the Danube Islands blog is announcing the Danube Island of the Year vote for the thirteenth time! The selection of islands follows the usual pattern: you can choose from one foreign island, one existing Hungarian island, and one disappearing Hungarian island. However, this year's selection is a bit provocative, as the list includes an artificial island in Slovakia, a revived island, and one in its final stages. 

Voting for the three nominees will take place until December 30, 2025.

Last year's winner, the Rafás island in Szigetszentmárton has been named after the guy on the left.

In the usual introduction, it is important to reiterate that the main purpose of the vote is to highlight the thousands of islands along the nearly 3,000-kilometer stretch of the river, as even locals are often unaware of the diversity of habitats and the rich and ancient history of the Danube islands. This is particularly true in light of the fact that since the start of the competition in 2013, there have been winners that have since lost their island status. Many people have visited the Seychelles islands before visiting any of the islands listed below. As this is already the thirteenth vote, it seems that a tradition has been established and, alongside other votes such as "Fish, Mineral, Insect of the Year," etc., this initiative is slowly gaining popularity not only in Hungary but also in neighboring countries.

Our winners so far:

2014. Helemba Island, Esztergom

2015. Kismarosi Island, Kismaros

2016. Szalki Island, Dunaújváros

2017. Csallóköz/Žitný ostrov, Slovakia

2018. Molnár Island, Soroksár, Budapest

2019. The Great Island of Rácalmás

2020. Kerekzátony Island, Ráckeve

2021. The Island of Mohács, Hungary

2022. Prímás Island, Esztergom

2023. Gubacsi Island, Soroksár

2024. Rafás Island, Szigetszentmárton

Current events played a role in selecting this year's nominees. This year, we visited the revitalized Erebe Island, which currently resembles a construction site, the Pap Island branch in Szentendre, where the spread of vegetation seems unstoppable, and thirdly, the Bird Island (Vtáčí ostrov, Madár-sziget) built in the Gabčíkovo reservoir, which we almost managed to reach this year with a maintenance team that weeds the island every year.

We present the nominees in alphabetical order from the Bős reservoir to the Szentendre Danube:

Erebe islands, Nagyszentjános-Ács (Gönyű)

One of the most important Danube revitalization projects in 2024 took place east of Gönyű, in the tributary of the Erebe Islands, and several videos were made about the dismantling of its parallel structures. Its ceremonial inauguration took place in February 2025, and in March we presented the newly "completed" riverbed on our blog. The nature conservation project had three objectives: to increase the biodiversity of the area, which is characterized by a network of side branches and varied gravel banks, to restore wetlands, and to improve the quality of life of the local population. In addition to its Natura 2000 classification, the importance of the archipelago is highlighted by the fact that, apart from Gemenc, it is the only place where the Danube Forest Reserve can be found. It is worth spending a whole day exploring it. 

Erebe Islands and what can be seen from it during the 1965 flood

The new riverbank, spring 2025.

Bird Island (Vtáčí ostrov, Madár-sziget) - Somorja (SK)

The Euglena viridis-shaped artificial island in the middle of the Gabčíkovo reservoir is a beauty patch on the face of the unprecedented island destruction caused by the Gabčíkovo dam. Its shores are protected from wave erosion by stone embankments, its surface is a nesting place for many bird species, and it is a safe haven for migratory birds. Since artificial habitats can only be maintained artificially, enthusiastic nature conservationists move in every year and weed out the undergrowth and trees they consider unsuitable. Other than that, access is impossible and strictly prohibited. 

The location of Vtáčí ostrov (Bird Island) just before it was destroyed by the Gabčíkovo dam.

Keyhole for seagulls wishing to reproduce

Pap island, Szentendre

If we hurry, we can still see something of Szentendre's last island on the Danube, where the tributary increasingly resembles a forest, and where water is becoming a rare visitor in the disappearing riverbed. The fate of Pap Island, would probably have been sealed by the silting up of the Szentendre Danube, but the earthworks built across the tributary greatly accelerated this process, which was not helped by the fact that the dam was later replaced by a bridge. The change is striking even over a period of decades, with this Danube island practically disappearing before our eyes. 

The Pap island on 15 October 1959. (fentrol.hu)

We must speak about what's going on the Pap Island in Szentendre.

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online polls

Voting closes at noon on December 30, 2025. The results will be announced in the first post of 2026!

Translated with DeepL.com (free version)

Neither Crayfish Nor Water

MAGYARUL

however in principle, both would be required to name an old branch of the Danube in Vienna Krebsenwasser. If neither exists anymore, it might be better to call it Unteres Heustadlwasser, as these two bodies of water formed a common riverbed in the Prater before the great Danube regulation. 

What is this all about? There is a world of difference between the appearance of the Danube in Vienna before and after 1875. Until the river was regulated, the Vienna section of the river was constantly changing and and transforming landscape, very conducive to the formation of islands and gravel bars, where no distinct main channel could develop, where the Viennese had to fight a constant battle with the river, which changed its course from year to year, and where communication between the right and left banks was rather difficult. The ancestor of the Krebsenwasser, the Heustadl-Danube, was once a main branch of the Vienna Danube, which began to migrate towards the right bank, the city, in the early 1600s, reaching its greatest width at the beginning of the 18th century. Its meandering broke through the tree-lined avenue leading to the Lusthaus and between 1704 and 1713 threatened to break through into the Vienna branch, which was the predecessor of today's Donaukanal. This catastrophe was averted by closing the Heustadl-Danube, but as a result, this branch gradually withered away during the century and was only one of many tributaries when it was finally closed off from the main branch in 1875. 

The separation of the Krebsenwasser and the Heustadlwasser after 1875. (mapire.eu)

A total of four former branches of the Danube remained in Vienna's Prater after the radical river regulation intervention of 1875, when one of the largest island destruction in the history of the Danube took place. Of the remaining branches, we have already visited the Lusthauswasser and the upper branch of the Heustadlwasser. The elimination of the Viennese archipelago with a single straight channel allowed the city to begin its expansion into the floodplain areas at the expense of the Danube's labyrinth of riverbeds, shoals, and islands. 

Where are we, what do we see? The shrinking Hesutadlwasser and the Vienna Prater. (source)

Since the Prater has long functioned as Vienna's city park, development here has been largely restricted by nature conservation considerations, and certain open water sections have been preserved, but one of Europe's busiest transport routes, the eight-lane A23 motorway, was nevertheless built here in 1978.

The lower part of the Prater and the new section of the Donaukanal. (source)

As far as the motorway is concerned, at least they took into account that it was built as a bridge over the dense, wooded area, but it is still not the classic canopy walkway that would normally be built in such a place. Due to lack of space in Vienna and other large cities, infrastructure investments are often constructed at the expense of remaining natural habitats, such as in the case of the new Vienna transport corridor planned through the Lobau floodplain on the left bank. If we look only at the Krebsenwasser without the Upper Heustadlwasser, here too two roads have further fragmented the remaining Danube backwater. The first is the Aspernallee, which runs from the Praterkai railway station to the east of the Haustadlwasser and Krebsenwasser break, arriving at the Lusthaus' star from the northeast. Road traffic runs along this road, and a narrow culvert at the intersection provides a connection between the two parts of the riverbed. To the east of the Maria Grün Catholic Church, which is used by Croatians living in Vienna, a narrow embankment leads across the riverbed, under which there is also a culvert built of concrete rings, but on this road only a forest path used by hikers leads to Dammhaufengasse. In addition, another path crosses the riverbed where the forest opens up slightly and gives way to reeds, indicating that the time has not yet come for woody plants to take over this depression.

The Krebsenwasser from the Aspernallee.

Embankment across the old riverbed, towards the Dammhaufengasse.

The remaining treeless riverbed.

The Krebsenwasser in morning sunshine, across.

The Krebsenwasser in morning sunshine, along.

The remaining water with an out-of-order gauge.

The esastern end of the Krebsenwasser.

The living and the dead.

On October 28, 2025, there was only a little water in the deepest part of the Krebsenwasser, mostly hidden from curious eyes by reeds. Hopefully, if there are any remaining specimens of the eponymous crayfish, they can hide here, waiting for rainier times. The only water gauge in the 30-meter-wide and 300-meter-long section of the riverbed was dry at this time. 

In the wooded section towards Aspernallee, the morphology of the riverbed was recognizable, but its vegetation was no different from that of the surrounding, higher-lying forest areas. The soil was somewhat softer and wetter, but there was no sign of surface water, nor was there anything to suggest its presence. The deeper part of the Krebsenwasser is probably only replenished by groundwater and precipitation, which can be sucked up through the gravel bed by the low water level of the current main branch flowing just 200 meters away.

The water shortage, drying up of backwaters, and reforestation observed in the case of Krebsenwasser can be seen not only in the Prater, but also in the Lobau area on the opposite bank. This is a natural process (after the anthropogenic Danube regulation), as in the absence of water flow (flooding in the Prater is practically impossible nowadays), dust, leaves, rubbish, etc. that fall into the water cannot be washed away. However, this process can be faster or slower, depending on the precipitation and groundwater conditions in the area. The year 2025 will go down in hydrological history due to its exceptionally low water levels, and this situation is also reflected in the case of Krebsenwasser during the autumn low water period.

Here, too, there is nothing left to do but to document the final drying up. 

Translated with DeepL.com (free version)

The Mastodon of Schönbühel

MAGYARUL

If a medieval Danube boatman had been granted three wishes by a Danube goldfish, it is almost certain that among them would have been the removal, explosion, excavation, flooding, and total destruction of all the hazardous reefs. These rock monsters of Strudel, Wachau, and the Lower Danube lurked beneath the surface of the water for thousands of years, destructing ships and claiming the lives of countless boatmen. Then, somewhere, some sailor must have caught this golden fish, and during the river regulation, these rock formations were removed, blown up, excavated, or flooded. Except for a few, mostly harmless survivors.

The metamorphic reef of Schönbühel on 20 August (Kienstock 214 cm)

There are not many of these survivors, and they owe their survival to the fact that they were not in anyone's way. Of the examples presented earlier, the Jochenstein rock of St. John of Nepomuk became the end point of a ship lock, The castle on the Wörth rock remained an island, but the Strudel rapids were flooded by the Ybbs-Persenbeug dam, Spielberg, once an island fortress, was swallowed up by the floodplain forest, the increasingly less modest Hunger Stone hid from everyone, the Babacai Rock on the lower Danube shrank, and nothing remained of the deadly rapids of the Iron Gates, where much more was destroyed. This list is not complete; it could also include the previously mined limestone cliff on the Mohács Island, but it is not worth mentioning those that tower high above the riverbanks, such as the monumental Devín castle hill at the mouth of the Morava River.

However, there is also a 'wild' rock on the Danube that has not yet been tamed by river regulation, despite its dangerous proximity to the center line of the Danube. What's more, this rock is located on the Austrian section of the Danube, which has been mostly converted into a shipping channel, where the river has been almost completely dammed. There were only two places in Austria where the Danube was left - so to say - untouched by hydroelectric power plants: the Donau-Auen National Park between Vienna and Bratislava, and the pictoresque Wachau between Melk and Krems. 

The position of the reef during low water

In Wachau, the dark metamorphic rocks of the Dunkelsteinerwald rise over the Danube in many places, often accentuated by various structures, forts, monuments, and crosses. In Schönbühel, a castle and a monastery crown the amphibolite rocks of the Czech massif, which extends into Austrian territory even to the right bank of the Danube, but at the foot of the castle, a cliff resembling the back of a drowned mastodon rises out of the Danube. Viewed from the right bank, this rock formation appears to be in the middle of the river, consisting of two distinct flat humps, which means that at certain water levels it is divided into two parts. This occurs when the water level measured at the Kienstock water gauge exceeds 262 centimeters, as on 22 August 2025, the reef was uniform. Roughly estimated, the Danube completely covers the reef at a water level of around 400 cm.

The reef and the navigation channel (source: Streckenatlas der österreichischen Donau 2024.)

However, the view from the right bank is somewhat misleading, as the rock is not in the middle of the river (if it were, it would no longer be there), but closer to the castle, dividing the river into two parts in a ratio of approximately 1/3 to 2/3. Naturally, navigation takes place in the wider branch. The section below the castle is shallower, where the Danube foams and swirls in the rocky bed at low water levels, performing an activity that is economically immeasurable: it beautifies and diversifies the river. 

The metamorphic reef of Schönbühel on 22 August  (Kienstock 262 cm)

Translated with DeepL.com

Where the Danube Flows Into the Brigach

 

MAGYARUL

The source of the Danube is a topic that is better not to get involved, because its complexity requires at least the extent of a whole book. The Breg, the Brigach, the source well, statues, memorial plaques, river kilometer markers, and so on are crammed together here in such astonishing density within a few dozen square kilometers that it is easy to get lost in trying to comprehend it all. The ambiguity of physical geography and the philosophy of science creates many interesting and even absurd situations, one of which is the subject of this article.

One of the famous sources of the Danube is located in the Fürstemberg castle gardens of Donaueschingen, southwest of St. John (the Baptist) Church, in a circular pool that has taken its present form since 1875. Although it was fenced in earlier, the water from this spring originally flowed freely to the east, joining the Breg and Brigach streams at their natural confluence, from where the Danube took its name. However, man's role in shaping the landscape has also transformed this distinguished hydrographic point, with the water from the spring now flowing southwards from the basin through a 100-meter-long subterranean channel.

DANVVII CAPVT EXORNAVIT 

proclaims the Latin inscription above the confluence, deliberately supplemented with the German imperial genealogy, at the point where this underground canal ends, above which stands a Greek-style kiosk erected by German Emperor Wilhelm II in 1910. The inscription on it should refer to the Danube, but it is about the man who adorned the river with his own power and erected a historicizing antique marble temple at this somewhat less important point than the spring pond. The structure, known locally as the Little Danube Temple (Donautempelchen), was actually a gift to Prince Maximilian Egon II Fürstemberg, who was a close friend of the emperor. The source of the Danube is still owned by the princely family, and the original design documents for the small temple, on the basis of which it was renovated in 2016, are also in their possession. 

Descriptions and postcards mention that this Danube church stands on the banks of the Brigach stream, and then gloss over the absurd hydrographic situation whereby the stream flowing from the source of the Danube is in fact nothing more than a tributary of the Brigach. It then continues its channeled journey eastward for another 1-1.3 kilometers under the name Brigach until it reaches the mouth of the Breg, where it can once again be called the Danube.

Translated with DeepL.com (free version)

Four Decades of Hungary's Unique Railway Ferry

MAGYARUL

Sounds good, looks impressive, but doesn't work — the railway workers and the passengers may have thought as they waited for the Danube railway ferry at Gombos, Southern Hungary that had been just opened to the public four days earlier. According to contemporary reports, travelers could often read in the waiting rooms of the Keleti Railway Station at Budapest and in the pages of the Budapest Gazette that the railway crossing between Gombos and Erdőd would be out of service for an indefinite period of time, mainly because the Alföld-Fiume Railway Company did not have the money to build a bridge or to complete the railway line to Fiume.

The two railway ferries at the Gombos harbor bay

The Alföld-Fiume railway was originally built to transport Hungarian agricultural products from the Hungarian Great Plains to the country's largest seaport, Fiume/Rijeka, as quickly and efficiently as possible. Its starting point was Nagyvárad/Oradea, but contrary to popular belief and expectations, its terminus was not Fiume but Eszék/Osijek, even though the permits had been obtained by the private company. In the end, however, another railway company was able to build the line to the Adriatic Sea. Due to a lack of funds, construction was repeatedly delayed, and the entire Eszék-Nagyvárad line was not completed in one go, but in five separate sections between 1869 and 1871. The railway line crossed the Tisza river at Algyő via a bridge, but there was not enough money to build another bridge over the Danube, so two steam ferries were put into operation here. The official opening ceremony took place on December 20, 1870, but four days later, the crossing was shut down due to icing on the Danube.

Around 1870, railway ferries were already a well-established means of transport in Europe, mainly used in places where the construction of a railway bridge was difficult for financial and/or geographical reasons. They were used not only for river crossings but also for sea crossings, and in fact, the very first railway ferry was put into operation in the North Sea, connecting Edinburgh-Granton with the port of Burntisland on the north coast across the Firth of Forth in Scotland, and traffic continued on it for a relatively long time between 1850 and 1890. 

The ferries between Gombos/Bogojevo and Erdőd/Erdut were designed for smaller volumes of traffic than those operating between the major cities of eastern Scotland, so there was no need for huge ferries capable of carrying 20 cars and designed to withstand sea waves. The designers based their plans on a functioning river ferry in Germany. South of Duisburg on the Rhine, near Rheinhausen, a prototype of the Gombos crossing was already operating. The design of the bays built for the ferries, the method of loading the wagons and carriages, and the size of the ferries (6-9 wagons) were almost identical. The Rheinhausen ferry began operating in 1866, but only functioned for eight years after the first railway bridge was built not far to the north, which was blown up during World War II [1]. 

Old and new ferry crossing between Gombos and Erdőd in 1881. (mapire.eu)

From a transport geography perspective, there were not many good options for routing the railway line from Szabadka/Subotica to Eszék across the Danube, but the least favorable option was chosen. South of Paks, and even more so south of Szekszárd, the meandering character of the Danube changes slightly, with the stable, gravelly riverbed becoming meandering type, forming an extremely wide floodplain. In 1870, Gemenc, Mohácsi Island, Béda-Karapancsa and Kopácsi rét/Kopački Rit were also part of this extensive wetland area, which stretched eastward to the high banks of the Bácska loess plateau, reaching a width of 20-25 kilometers in places, where it would have been extremely costly to build railway embankments and bridges. Above the mouth of the Drava, this huge floodplain narrowed in only one place enough to allow a bridge to be built: at the eastern end of the Bansko brdo hills, between Kiskőszeg/Batina and Bezdán. Here, with a relatively small detour, it would have been possible to route the railway so that it touched the nearby county seat, Zombor/Sombor, and then turned south and continued towards Eszék with another bridge over the Drava. Presumably, the cost of building the two bridges was the main reason why a less geographically advantageous solution was chosen between Erdőd and Gombos, where two river crossings had to be built at a slightly lower cost, but one of them was only a branch of a Danube island.

The steam ferry seen from the Bogojevo side of the Danube (forrás)

There had been a crossing point on the Danube at Gombos before. Its significance lay in the fact that it was the first river crossing below the mouth of the Drava, between Bačka and Slavonia. Its location was not ideal either, although one of its stations was at the end of the valley directly below the castle in Erdőd, the Gombos ferry inn on the other side was 5.5 kilometers away from the nearest settlement, Bogojevo, which was mainly inhabited by Hungarians. It is interesting that the South Slavic-sounding settlement names usually meant nothing in Bačka, as floods forced residents of different nationalities to move repeatedly, so the neighboring Karavukova, for example, was an authentic Swabian village. In the case of Gombos, the usual Hungarianization of names resulted in a very special situation, as Bogojevo did not regain its original medieval Hungarian name (Boldogasszony-telke) in 1899 (the Serbian distortion of which was Bogojevo), but was named after the Gombos family, who owned the inn at the ferry, in two steps. First, the ferry inn became a railway station, and then the name of the railway station became the name of the settlement.

The end of the steep railway track at the foot of the loess hill in Erdőd

The floodplain wetlands on the left bank at Gombos and the steep loess wall at Erdőd on the Croatian side both made the railway builders' work difficult. This asymmetrical loess plateau, which is very steep in the north but flattens out towards the south, diverts the Danube eastwards at the mouth of the Drava, with its highest points dropping down to the Danube with almost vertical walls, averaging 80-90 meters above the Danube's zero level. It was not possible to build the railway line directly across this ridge, as it would have been extremely expensive and pointless to dig a gorge, for example, so the engineers decided to bypass the high loess walls at the eastern end of the ridge towards Dálya/Dalj and build the track on the flatter southern part.

The steam ferries, named Duna and Dráva at Erdőd, with ship mills in the back.

They took advantage of the fact that there was a large island in the Danube just east of Erdőd, which they simply called Ada, and which was flat enough to build the Croatian terminus of the railway. First, they built a wooden bridge on its branch, which was easily damaged by floods and ice, so they later replaced it with an earth embankment. However, even then, the railway track was still relatively steep, and on several occasions, the carriages running on the steam ferry (the ferry did not carry locomotives, which were attached to the train on the other side of the Danube) arriving from Erdőd at high speed and sliding into the Danube because they were unable to brake the train sufficiently. This problem was only solved in 1881 with the use of scotch blocks [2].

The monumental new bridge and the still operating railway ferry.

However, the Danube proved to be the most formidable opponent for the steam ferry in three respects:

1. Current. Since the railway track arrived perpendicular to the banks of the Danube, a solution had to be found to load the wagons onto the steam ferry regardless of the river's current. The current could easily turn the 62-meter-long iron hull and bend the pair of rails leading to it. For this reason, a protected bay was dredged on both banks, where the rails were led into the riverbed, and a sliding, wedge-shaped bridge was used to guide the carriages onto the ferry, sometimes wading into the water up to their axles. At Gombos, on the flatter shore, this bay was more than 300 meters long and wide enough to accommodate both ferries without hindering each other's operation. On their outer sides, iron cables stabilized the hull against the current to prevent them from deviating from their course, and the steam engine mounted on the ferry pulled itself across to the other side with the help of an additional cable tow rope. The question may arise as to whether these cables hindered traffic on the river, but they were so heavy that they normally sank below the water surface, deep enough not to obstruct the traffic of steamboats.
2. Icing. When the Danube freezes over, the ferries stop running. Even if they are made of iron. On 1870 Christmas Eve, four days after the ferry's ceremonial opening, traffic came to a halt due to the appearance of ice sheets, which were still a common feature of the Danube landscape at that time. There was not much that could be done if there was ice on the Danube from December to the end of February, as the ferry was unusable during this time, and the weather forecast was not yet advanced enough to tell passengers in advance when rail traffic would resume.
3. Water level. Since both stations of the crossing were built on floodplains, it was predictable that traffic would be suspended during floods. However, not only high water levels but also low water levels threatened rail traffic. As the railway line was built in just a few years, it was necessary to wait for the lowest possible water level during those few years so that the tracks could be laid as deep as possible in the bay. However, there was no guarantee that the low water levels that had prevailed during the few years of railway construction would not be exceeded in the future. On December 7, 1871, barely a year after the handover, the water level dropped so low that traffic had to be stopped, but in such cases, at least the time could be spent usefully, e.g., by extending the track toward the riverbed [3].

The destruction of the Gombos railway bridge in 1941. (Fortepan)

These circumstances made rail traffic extremely difficult and unpredictable, and made it impossible to plan the transport of goods and passengers, especially perishable goods. The Alföld–Fiume Railway Company therefore struggled with constant financial difficulties, and Hungarian State Railways (MÁV) eventually purchased the entire company in 1884 and continued to operate the steam ferry until 1911, when the long-awaited railway bridge was built a few dozen meters south of the steam ferry route. This bridge was blown up by Yugoslavia during the German attack in 1941, rebuilt in 1947, and opened to road traffic as well. In 1977, due to increased traffic, a new road bridge was built between Gombos and Erdőd. The long bay for steam ferries on the Gombos side is still visible between the two bridges today.

The bridges at Gombos in September 2011.

The steam ferries named Duna and Dráva operated until the very last moment, until the day the bridge was inaugurated, for a total of four decades. During this time, many different postcards were made of this unique technological feature. However, the fate of the ferries after their retirement is not entirely clear. During the construction of the bridge, several towns applied to take them over, including the aforementioned Kiskőszeg, but they would also have been taken to Kalocsa and Mohács [4]. According to the Hungarian Technical and Transportation Museum, one of the steam ferries was eventually taken to Budapest, and after being fitted with a superstructure, it became the two-story boathouse of the Honvéd Rowing Club on Margaret Island. In the 1980s, it sank in the bay of Népsziget, but in 2015 it was raised, repaired, and turned into two interactive visitor centers showcasing the 2017 World Aquatics Championships and Budapest's Olympic bid. Today, it is moored at Batthyány Square. [5] [6].

However, the Danube did not remain without a railway ferry. From 1953 until 2013, a ferry carried trains between Calafat in Romania and Vidin in Bulgaria until the new Danube bridge was built. But that is another story.

Translated with DeepL.com (free version)

Literature:

[1] https://www.kultushafen-bewahren.de/geschichte/rhein%C3%BCberquerungen/

[2] Békésmegyei Közlöny, 1881-05-26 / 63. szám

[3] Magyar Ujság, 1872-01-10 / 6. szám

[4] Pécsi Napló, 1911-05-17 / 112. szám

[5] https://www.facebook.com/KozlekedesiMuzeum/posts/pfbid0382p1E8JpWLqMhSn2novauyqqEsRzjdrihNv8iswpYRNy8hVK41ihSf5EmF73GqWgl

[6] https://turizmusonline.hu/cikkek/belfold/delvideki_gozkompbol_lett_latogatokozpont_budapesten.html

https://www.hajoregiszter.hu/hajoadatlap/duna/duna/5134/3498

https://timelord.blog.hu/2013/07/10/gozkomp_a_dunan