Danube

With an average water flow of around 6855 m³/s and a total length of 2857 kilometres, the Danube is the second largest and second longest river in Europe after the Volga. The river drains large parts of Central and Southeastern Europe. It flows through or touches ten countries (Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Romania, Moldova and Ukraine) - more than any other river on earth.

The Danube takes its name from the confluence of two headwaters, the Brigach and the larger Breg, both of which rise in the central Black Forest. It crosses three large basin landscapes: the northern Alpine foothills and the Vienna Basin (upper reaches), the Pannonian Plain (middle reaches) and the Wallachian Plain (lower reaches). It cuts through the dividing mountains in narrow valleys, the best-known sections of which are the Danube breakthrough at Beuron, the Wachau, the Hainburg Gate (also known as the Pressburg Gate) and the Iron Gate. The river flows into the Black Sea via the extensive Danube Delta.

The Danube is one of the oldest and most important European trade routes and connects different cultures. Political tensions and wars repeatedly caused closures and obstructions of the waterway. Since the fall of the Iron Curtain, the Danube has regained its economic importance. The river connects many species-rich and unspoilt natural areas and is an important location for hydroelectric power plants.

Names and etymology

The Danube, like most rivers in the German-speaking world, has a feminine name. In Middle High German it was called diu Tuonowe (early New High German Tonaw, Donaw). The root word -ouwe ('river floodplain, -landscape') of its Old High German compound name may have contributed to the feminine gender of today.

All modern names of the river - including Romanian Dunărea, Bulgarian, Serbian, and Croatian Dunav, Slovenian Donava, Hungarian Duna, Turkish Tuna, and Slovak, Russian, Polish, Czech, and Ukrainian Dunaj - derive first from the name Dānuvius of Roman times (with the river god of the same name), but go back to older roots. Danube, like the river names Dnepr, Dnister, Donets, and Don, is possibly Iranian or Celtic in origin. The names could be derived from the Iranian-speaking Scythians and Sarmatians as well as from the Celts of Eastern Europe. An exact linguistic assignment is difficult, since both tribes reached the Danube and the Danube, furthermore both Celtic and Iranian are Indo-European languages and therefore the word "river" in Old Iranian (cf. Avestan dānu, Ossetian don) and Celtic (cf. Welsh Donwy) goes back to the same Indo-European root *dʰenh₂- 'to flow'. In the Celtic language family, this is said to go back to the goddess Danu (also Danann).

In ancient times, the Danube had two names for a long time: Ister or Hister, in ancient Greek Ístros (Ἴστρος), was a name for the lower course, Danube was called only the upper course. Some Roman cities on the lower reaches of the Danube bore the suffix ad Istrum - for example, Nicopolis ad Istrum. This word stands to a general Indo-European hydronym *heisr- 'fast, hurtig' and is also traced back to the Celtic words ys 'fast, tearing' and ura 'water, river'. According to another interpretation, ys also stands for 'high, low' and thus, like the Latin altus, denotes both aspects of the vertical. In the area of the former Celtic settlement area, besides the old names of the Danube, a number of other names for other rivers are derived from this stem:

Hans Bahlow attributed the root sound *is- with the roots *es-, *as-, *os, *us- or *aus- (all supposedly 'marsh/moor water'). Another interpretation assumes a hypothetical Indo-European root *es or *is, interpreted as a generic name for '(flowing) water'.

It was not until the turn of the century, when the Roman Empire had expanded over the entire course of the Danube and the cartographic connections were developed, that the unity of both sections of the river was recognized. Even until the end of antiquity, Ister was a common name for the river, while Dānuvius tended to refer only to the upper reaches. Since the Danube rises in the Black Forest and flows into the Black Sea, it is sometimes jokingly referred to as the Black River.

Disc brooch with depiction of the river god Dānuvius, 150-250 AD (Roman Museum Vienna).

Catchment area

Geography and water flow

The Danube catchment area covers about 817,000 square kilometres. It is somewhat asymmetrical; 56 percent of the area lies on the left (north) side of the Danube, 44 percent on the right. Nevertheless, the tributaries of the smaller right side contribute about two thirds of the water volume, which is due to the larger area of high mountains here, which also intercept a large part of the moisture brought in by west and southwest winds.

This is reflected in the fact that in the southern Pannonian basin the Sava, by far the most water-rich tributary, flows in from the right and the Tisza, barely half as large, the longest tributary of the Danube, flows in from the left. Further downstream, the water flow of the Morava, which comes from the right, exceeds that of the Pruth, which comes from the left at the Danube delta and is about five times as long, by a good factor of two. And even in the German Danube basin, the three largest left tributaries (Altmühl, Naab and Regen) together carry less water than the right tributary Lech, which is only the third largest in this part. By far the largest tributary of the upper Danube, the Inn, is at least equal to the Danube at its confluence in Passau, and at Ulm the Danube is even surpassed by the Iller by a good third.

Most of the larger tributaries originate in the Eastern Alps and Carpathians, as well as in the mountains of the Balkan Peninsula. The Carpathians are not a mountain range bordering the Danube basin, but protrude into it because they are drained on the east side by the Siret/Prut system. They separate the lower Danube basin from the middle one. The Alps, with their north-eastern foothills, also jump in and divide the middle and upper Danube.

Source Flows

At Donaueschingen, the Brigach and Breg rivers flow together to form the Danube. Of the two headwaters, the Breg, which rises somewhat further south and higher, is the somewhat larger river according to all hydrological characteristics. In addition, the source pot of the Danube brook near the union of the two headwaters is traditionally considered the source of the Danube. From here, the Danube has a length of a good 2810 kilometres.

Tributaries

The rivers Tisza, Prut, Sava, Drava, Olt, Sereth and Inn each have a length of over 500 kilometres. Rivers with a water flow of over 500 m³/s are Sava, Tisza, Inn and Drava.

Tributaries of the Danube with more than 140 kilometres of river length
Tributary	at km	Page R/L	Length in km	Discharge in m³/s	Comments
Iller	2587,9	R	147	71	carries more water at the confluence than the Danube
Lech	2496,4	R	264	114
Isar	2281,7	R	295	175
Inn	2225,2	R	518	738	at the confluence wider and at times more watery than the Danube
Traun	2125,0	R	153	135
Enns	2111,8	R	254	195
Leitha	≈ 18300,	R	180	10	flows into the tributary Moson-Danube
Raab	1794,0	R	250	18
Kapos	≈ 14980,	R	113	4,4
Drava	1382,5	R	749	670
Save	≈ 11700,	R	945	1722	most water-rich tributary of the Danube and longest from right
Morava	1104,5	R	185	255
Timok	845,7	R	203	24
Iskar	637,0	R	368	54
Jantra	536,7	R	285	47
Altmühl	2411,6	L	220	16
Naab	2385,3	L	165	50
Rain	2379,2	L	169	40
Kamp	≈ 19850,	L	153	9
March	1880,3	L	358	109
Waag	1765,8	L	403	152
Hron	1716,0	L	298	55
Ipeľ	1708,2	L	233	21
Tisza	1214,5	L	1308	813	longest tributary of the Danube
Temesch	≈ 11500,	L	340	47
Jiu	691,6	L	331	94
Olt	600,6	L	737	190
Vedea	≈ 5300,	L	224	12
Argeș	432,0	L	327	73
Ialomița	231,1	L	417	40
Sereth	155,1	L	596	230
Pruth	134,1	L	953	110

Islands

The Danube has numerous larger and smaller islands. The best known include the Upper and Lower Wöhrd in Regensburg, the Jochenstein, the Danube Island in Vienna, the Great Schütt Island, Margaret Island in Budapest, the Great War Island near Belgrade and the Balta Ialomiței in Romania.

List of tributaries taken from the Handbuch für Donaureisen, Vienna 1935, published by the Erste Donau-Dampfschiffahrts-Gesellschaft (First Danube Steamship Company)


River basins and main watersheds in Europe


Catchment area and main tributaries of the Danube