The Danube: Secrets of its origin in the Black Forest

The Danube, Europe's second-longest river at an impressive 2.857 kilometers, hides a fascinating secret at its source in the Black Forest. In fact, there is no clearly defined source, but rather several rivers vying for the title of "true source of the Danube."

The well-known saying "Brigach and Breg bring the Danube to the river" already hints at the unique nature of the Danube's source in Donaueschingen, where these two headwaters converge. From here, the river's unique journey through ten European countries begins, finally emptying into the Black Sea.

In this article, you will discover the surprising history of the source of the Danube, explore its competing origins, and learn why the question of the true origin of the Danube is more complex than you might think.

The Black Forest as the cradle of the Danube

One of Europe's most remarkable river journeys begins in the southeastern part of the Black Forest. This region, between the foothills of the Black Forest and the Swabian Alb, is home to a special natural phenomenon – the source of the Danube. As the birthplace of this mighty river, the Black Forest is characterized by a surprising complexity that even many locals aren't fully aware of.

Geographical features of the source area

The source area of ​​the Danube extends into the southeastern Black Forest, a region of scenic and cultural diversity. To the south, the area borders Switzerland. What makes this region special is its location on an important European watershed. Only about 100 meters northwest of the Breg source, the major European watershed between the Rhine and the Danube.

The geographic characteristics of the Black Forest create ideal conditions for the formation of numerous springs. Rainwater seeps into the Black Forest soil, flows underground to the edge of the Black Forest, and resurfaces in various places. These hydrological features make the region a true "land of springs."

Furthermore, the Baar's karstified Muschelkalk hills characterize the surrounding area, contributing to the formation of at least 22 springs near the confluence. These together discharge between 400 and 1000 liters of water per second—an impressive natural phenomenon that demonstrates the region's abundance of water.

In addition to the Danube, the Schwarzwald-Baar district is also home to the sources of other important rivers:

• The Elz spring near Schönwald

• The Gutach spring near Schönwald

• The Neckar source in Villingen-Schwenningen

This diversity of springs makes the region a hydrological hub of European importance.

The three competing sources at a glance

When it comes to the true origin of the Danube, three sources are at the center of discussion:

1. The Breg spring near Furtwangen: It lies at an altitude of 1078 m above sea level, about six kilometers northwest of Furtwangen near St. Martin's Chapel. Since the Breg is not only the longest (46 km) but also the most water-rich source of the Danube, its source is considered hydrographically to be the true source of the Danube. The Breg's catchment area covers an impressive 291,6 km².
2. The Brigach spring: Together with the Breg, it forms the second most important source river. However, the Brigach is shorter and less water-rich than the Breg, which is why it is not considered a major source according to hydrological criteria.
3. The symbolic source of the Danube in Donaueschingen: In the palace gardens of the Princes of Donaueschingen, one of Germany's most famous and beautiful springs is located. What bubbles up from the earth here is rainwater from the Black Forest, which flows underground to the edge of the Black Forest and reemerges in Donaueschingen. This spring is one of several karst springs in the palace gardens.

The well-known rhyme "Brigach and Breg bring the Danube to the river" succinctly summarizes the hydrological reality. In fact, the confluence of the Breg and Brigach rivers in Donaueschingen is now considered the official beginning of the Danube. This is where the famous Danube Cycle Path begins, a favorite with cyclists from all over the world.

For centuries, scholars debated the true source of the Danube until the following definition was established: The main branch of a river system is determined by the larger tributaries at the confluence points. According to this definition, the Breg spring in Furtwangen is the true source of the Danube.

Brigach and Breg: The true source rivers

While the true origin of the Danube has been debated for centuries, two rivers are at the center of this debate: the Brigach and the Breg. The old saying "Brigach and Breg bring the Danube to the surface" perfectly summarizes the hydrological reality. Only after the confluence of these two bodies of water does the river officially bear the name "Danube" – but which of the two is the actual main source?

The Breg spring near Furtwangen

At an altitude of 1078 metersThe Breg River rises near St. Martin's Chapel at Kolmenhof, about six kilometers northwest of Furtwangen. This source is located only about 100 meters from the European watershed between the Rhine and Danube. According to hydrological and geographical criteria, the Breg River is considered the main branch of the upper Danube system.

The Breg spring has been relocated in various locations over the centuries. While it was formerly located in the Briglirain area (also called Brücklerain), length and discharge measurements in the 1950s led to its current location in the Martinskapelle area. On a hike from the spring to the mystical Günterfelsen rocks and further to the Brendturm tower, you can explore the impressive Black Forest landscape.

The Breg's 46-kilometer-long route leads through idyllic Black Forest valleys before joining the Brigach River in Donaueschingen. Indeed, it's hard to imagine that this quiet stream would become such a significant river as the Danube, which eventually crosses ten European countries.

The Brigach spring and its course

The Brigach River rises at an altitude of 925 meters near the Hirz farm in St. Georgen. A unique feature: Nowhere else does a river spring originate in the cellar of a farm. From there, the water is piped to the publicly accessible spring system.

Above the water source, you can admire a copy of the so-called Brigach relief or "Three Gods Stone." The original of this approximately 2000-year-old stone, depicting a stag, a hare, a bird, and three heads, was discovered in 1888/1889 during the renovation of the kitchen vault at the Hirzbauernhof farm and testifies to the early importance of the spring. Many researchers consider it the remains of a Celtic-Roman spring sanctuary.

After flowing for about 40 kilometers, the Brigach finally reaches Donaueschingen, where it joins the Breg. Along its course, it passes, among other places, the village of Brigachtal and the historic Zähringer town of Villingen.

Comparison of water volumes and flow speeds

The dominance of the Breg as the main source river can be proven by clear hydrological data:

Parameter	Brigach	Breg
Water flow	3,37 m³ / s	5,95 m³ / s
Einzugsgebiet	195,0 km²	291,2 km²
Length	40,2 km	45,9 km
Source height	940 m	1078 m

The table clearly shows: The Breg not only carries almost twice as much water like the Brigach, but also has a larger catchment area and is longer.

Interestingly, despite different water flows, both rivers have similar flow velocities in many places. This makes them particularly interesting for comparative studies from an ecological perspective. While the Breg still carries relatively clean water over long stretches, the Brigach receives heavier, almost untreated wastewater inflows at three locations.

Although the two source rivers share great similarities in their geological environment and gradient, the varying levels of human influence have led to significant ecological differences. The section of the Danube beginning after the confluence, however, occupies an intermediate position between the two source rivers in many chemical properties.

The source of the Danube in Donaueschingen: myth and reality

Between mystical veneration and geological reality lies the famous source of the Danube in Donaueschingen – a place that has never lost its fascination despite scientific discoveries about the "true" sources of the Danube. The artfully framed spring in the castle park attracts thousands of visitors from Germany and abroad every year and is considered the town's tourist centerpiece.

The famous spring pot in the castle park

The spring is located in the castle park of Donaueschingen, picturesquely nestled between the town church of St. Johann, built in Bohemian Baroque style, and the Princely Fürstenberg PalaceWhat makes this place so special is the fascinating spectacle of the small water bubbles that rise like pearls in the turquoise spring water. This karst spring pours impressive 50 to 150 liters of water per second.

The spring water, known as the Danube Stream, flows underground through the palace park and flows into the Brigach River after just 100 meters at the Danube Temple. The spring itself is artfully framed by a wrought-iron enclosure, giving it a majestic appearance.

The allegorical sculpture group "Mother Baar," created by the sculptor Adolf Heer, has watched over the spring since 1896. This figure symbolizes the Baar landscape and, lying in its lap, shows the "young Danube" the way to the Black Sea.

The current appearance of the spring is the result of several transformations:

• For centuries, the spring was enclosed only by a simple square wall

• In 1875, Prince Karl Egon III had a more elaborate version built

• From 2013 to 2015, the source of the Danube and its surroundings were extensively renovated

During the last renovation, not only were the enclosure and the figural group restored, but accessibility was also improved with a wider staircase and an elevator. Furthermore, an interactive information terminal with extensive information about the Danube was installed.

Historical significance for the region

The historical significance of the source of the Danube dates back to Roman antiquity. The oldest evidence dates back to 15 BC, when the Roman general and later emperor Tiberius rode north from Lake Constance and found "the sources of the Danube after a day's journey." The Roman poet Ausonius also mentioned the source in 368 AD.

The source of the Danube in Donaueschingen is repeatedly mentioned in medieval chronicles and maps. The oldest precise cartographic representation appears in Sebastian Münster's Cosmographia, published in 1544. At that time, the place name "Donaueschingen" was already common for "Eschingen," first mentioned in a document in 889 – an indication of the early importance of the Danube for the town.

The centuries-long dispute over the “true” source of the Danube led in 2020 to a Solomonic decision by the Baden-Württemberg Ministry of the Interior:

1. The source in Donaueschingen remains recognized as the source of the Danube for historical reasons because it is documented has been bubbling in the city since 1488

2. Furtwangen may also call itself the “Danube source town”, as the Bregur spring is scientifically considered to be the actual source

As the Stockach Court of Fools already suggested in 1984: "The dispute is far too beautiful to be ended forever by a single verdict." Indeed, both towns are cleverly exploiting the situation for tourism, as the source of the Danube is an important attraction for both Donaueschingen and the entire region.

The source of the Danube in Donaueschingen, however, is more than just a tourist attraction – it is a place steeped in mythological significance. Since time immemorial, special springs have had spiritual significance, as evidenced by spring sanctuaries and the worship of spring nymphs. The source of the most powerful river in the Roman Empire was presumably under the protection of the goddess Abnoba.

Thanks to the efforts of the city of Donaueschingen to make the source and the Young Danube visible and tangible in the cityscape, this special place will remain a fascinating destination for Danube lovers from all over the world for generations to come.

The phenomenon of the Danube sinkhole

A fascinating natural phenomenon occurs just 20 kilometers from the confluence of the Brigach and Breg rivers: the young Danube suddenly disappears into the ground. This geological miracle, known as the Danube Sinkhole, makes the Danube a unique river with two estuaries—into the Black Sea and the North Sea.

Where the young Danube disappears

Between Immendingen, Möhringen, and Fridingen, the Danube water sinks into the porous limestone layers of the subsoil at several points. The main sinkhole is in the "Auf dem Brühl" area between Immendingen and Möhringen. Numerous sinkholes form in the riverbed here, allowing the water to disappear completely. In dry periods, visitors are treated to an astonishing spectacle: the riverbed is completely dry.

The intensity of the subsidence has increased over time. While 100 years ago, the Danube dried up for about 60 days a year, today it is dry for at least 180 days. These "full seepage days" pose a challenge to the local flora and fauna.

The underground connection to the Rhine

The vanished Danube water travels a distance of approximately 12 kilometers underground, crossing the main European watershed. After about 60 hours, it reemerges into the Aachtopf, Germany's most abundant spring. From there, it flows via the Radolfzeller Aach into Lake Constance and finally into the Rhine, which leads to the North Sea.

In fact, this underground passage was scientifically proven through dye experiments as early as the end of the 19th century. The average flow velocity of the water is approximately 188 m/h at a gradient of 14,5 per thousand.

Geological explanation of the natural wonder

The cause of this phenomenon is the calcareous rock layers of the Upper Jurassic, which make up a large part of the Swabian Alb. Chemical dissolution processes have created cracks and cavities in the limestone over millions of years.

Uplift processes in the Earth's crust associated with the formation of the Alps also caused the geological strata on the southern edge of the Swabian Alb to dip particularly sharply. The seeping Danube water thus follows the natural gradient toward Lake Constance.

This unique natural spectacle was designated a “National Geotop” in 2006 and is one of the most impressive geological sights in Germany.

From source to mouth: The course of the Danube

After the confluence in Donaueschingen, the Danube's impressive journey begins, stretching over 2857 kilometers, making it Europe's second-longest river. With an average water flow of around 6855 m³/s, it finally flows into the Black Sea via the extensive Danube Delta.

The Danube through ten countries

No other river in the world flows through or touches as many countries as the Danube. On its way, it passes through:

1. Germany (Baden-Württemberg and Bavaria)

2. Austria

3. Slovakia

4. Hungary

5. Croatia

6. Serbia

7. Bulgaria

8. Romania

9. Republic of Moldova

10. Ukraine

Within Germany, the Danube flows approximately 650 kilometers through Baden-Württemberg and Bavaria. Major capitals such as Bratislava, Vienna, Budapest, and Belgrade are located along its banks. Indeed, the Danube region is home to approximately 80 million people.

As the Danube flows through various landscapes and climate zones, it changes character several times. The section along the cataracts between Serbia and Romania is particularly spectacular, where dramatic gorges alternate with bays and wider river passages.

The Danube Gorge near Kehlheim

The Danube Gorge near Kelheim is one of Bavaria's most impressive natural wonders. Over a distance of approximately five kilometers, the mighty river has carved its way through limestone cliffs up to 80 meters high, formed about 150 million years ago when the area was still a shallow sea. This geological formation, also known as "Weltenburg Narrows“, is a protected nature reserve and one of the oldest in Bavaria, having been placed under protection by King Ludwig I as early as 1840.

This natural spectacle can be seen particularly impressively on a boat trip from Kelheim to Weltenburg Monastery The ships glide through the deepest and narrowest part of the Bavarian Danube, past steep cliffs with imaginative names like "Bavarian Lion," "Bishop's Cap," and "Napoleon's Trunk."

At the end of this spectacular river landscape, visitors will find Weltenburg Monastery, Bavaria's first monastic settlement dating back to the 7th century. It is known not only for its monastery church of St. George, built in the Baroque style by the Asam brothers, but also for the oldest monastery brewery in the world.

Important tributaries on the way to the Black Sea

The Danube's catchment area covers approximately 817.000 square kilometers. Numerous important tributaries feed the mighty river. The most important are:

Nebenfluss	Position	Length (km)	Water flow (m³/s)
Tisza	exclusive links	962	810
Save	right-wing	945	1670
Inn	right-wing	518	738
drau	right-wing	966	670
Prut	exclusive links	967	105

Major tributaries of the Danube in Germany

Here is a table with the most important tributaries of the Danube in Germany, sorted by their water flow:

Nebenfluss	page	Length (km)	Water flow (m³/s)	Mouth
Inn	right-wing	518	738	Passau
Isar	right-wing	295	175	Deggendorf
Lech	right-wing	264	114	Marxheim
Provinces	right-wing	147	71	New Ulm
Altmuehl	exclusive links	227	23	Kelheim
Naab	exclusive links	165	49	Regensburg
Rain	exclusive links	103	32	Regensburg
Wornitz	exclusive links	132	20	Donauworth
Breg	right-wing	46	6	Donaueschingen
Brigach	exclusive links	40	3,4	Donaueschingen

Interestingly, the right tributaries (Alpine rivers) carry significantly more water than the left tributaries. The Inn, at its confluence in Passau, even carries more water than the Danube itself, and the Iller, at its confluence with the Danube in Neu-Ulm, carries more water than the Danube at this point.

Most of the larger tributaries originate in the Eastern Alps, the Carpathians, and the mountains of the Balkan Peninsula. Rivers such as the Siret and Olt are each over 500 kilometers long.

In total, the Danube draws water from 19 countries, connecting 83 million people. The annual volume of water flowing into the Black Sea is approximately 203 billion cubic meters.

The Danube Delta: A unique ecosystem between Romania and Ukraine

The Danube Delta (Romanian: Delta Dunării, Ukrainian: Дельта Дунаю) is a fascinating natural wonder that stretches from the estuary of the Danube into the Black Sea. With a total area of ​​approximately 5.800 km², it is the second largest delta in Europe after the Volga Delta.

Geography and location

The delta is divided into 82,5% Romanian territory in the historical region of Dobruja and 17,5% Ukrainian territory in the Odessa Oblast. Since 1990, it has been protected as a biosphere reserve, with approximately 4.178 km² (72% of the total area) designated as a nature reserve.

The delta is crossed by three main branches of the Danube:

• The Chilia arm in the north (forms the Romanian-Ukrainian border)

• The Sulina arm in the middle

• The Sfântu-Gheorghe arm in the south

To the south lies the Razim-Sinoie lagoon complex, which is also part of the biosphere reserve.

ecological importance

The Danube Delta is home to the world's largest contiguous reed bed area and is considered one of the most important wetlands in Europe. This unique floodplain landscape, with its reed belts, floating islands, and oxbow lakes, is estimated to be approximately 13.000 years old. Remarkably, about one-fifth of the wetland lies below sea level.

The delta is a dynamic system: every year, it pushes itself about 40 meters further into the Black Sea due to the accumulation of billions of tons of alluvial material. At the same time, erosion is occurring along the coastline south of Sulina, partly caused by reservoirs that retain the natural sediment masses.

Biodiversity

The delta’s biodiversity is impressive:

• About 5.200 animal and plant species have been catalogued so far

• ÜOver 300 bird species, including the largest pelican colony in Europe
• 45 species of freshwater fish

• Over 1.200 plant species, from typical marsh vegetation (reeds, sedges, dwarf willows) to woodland areas with poplars, oaks, willows and wild fruit trees

Millions of migratory birds from Europe, Asia and Africa use the delta as a breeding and resting area.

Protection status and international recognition

The Danube Delta enjoys several protection statuses:

• Biosphere reserve since 1990

• UNESCO World Heritage Site since 1991

• Ramsar wetland of international importance (since 1991)

• Part of the European Natura 2000 network

• “Landscape of the Year 2007-2009” by the International Friends of Nature

In 2000, Romania, Bulgaria, the Republic of Moldova, and Ukraine committed to the protection and restoration of wetlands along the lower Danube. The 6.000 km² "Green Corridor," initiated by WWF, created the largest cross-border protected area and restoration project in Europe.

Conclusion

The history of the Danube is far more complex than initially assumed. Indeed, Europe's second-longest river presents itself as a fascinating natural wonder right from its source. While the Breg source is scientifically considered the main source, the Danube source in Donaueschingen retains its historical significance.

Ultimately, the combination of its various source rivers, the unique phenomenon of the Danube Sinkhole, and its impressive journey through ten countries makes the Danube one of the most remarkable rivers in the world. The Black Forest, as its source region, plays a central role – this is where the extraordinary story of a river that connects Europe like no other begins.

You can explore this fascinating region for yourself – whether at the Breg spring near Furtwangen, the artistically designed Danube spring in Donaueschingen, or along the first few kilometers of the young Danube. Each of these places tells its own story about the origins of one of Europe's most important rivers.