Danube River
Geography
The Danube is the second longest river in Europe, after the Volga, and also the longest river within the European Union. It originates in the Black Forest of Germany and flows in a generally southeasterly direction, passing through four Central and Eastern European capitals before emptying into the Black Sea via the Danube Delta in Romania and Ukraine.
Course
The Danube's course spans a distance of approximately 2,850 kilometers (1,770 miles), draining into the Black Sea through a large delta, the Danube Delta, which is a UNESCO World Heritage Site and the best preserved on the continent. The river flows through or acts as part of the borders of ten countries: Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Romania, Moldova, and Ukraine.
Tributaries
The Danube has nearly 300 tributaries, most of which are also located in the Carpathian Basin. The largest tributaries, in terms of their contribution to the total water flow of the Danube, are the Drava, the Tisza, and the Sava, all of which flow into the Danube from the right side.
Hydrology
The Danube is a mixed river in terms of hydrology – its flow is determined by both snowmelt and rainfall. Its average discharge at its mouth is 6,500 cubic meters per second. The river's water levels can vary greatly: the difference between the highest and lowest recorded levels at Budapest is 9.5 meters.
Flora and Fauna
The Danube is home to a rich variety of wildlife due to its range of habitats and large size. The river and its tributaries support numerous species of fish, making it an important fishing resource. The Danube Delta is particularly rich in bird species, including several globally threatened species such as the Dalmatian Pelican, the Great White Pelican, and the Pygmy Cormorant.
Human History
The Danube has been a significant trade route for many centuries, and its importance grew with the development of river steam navigation in the 19th century. Today, it is an important waterway for international trade, connecting Western and Eastern Europe.
The Danube is navigable by ocean ships from the Black Sea to Brăila in Romania and by river ships to Kelheim, Bavaria, Germany; smaller craft can navigate further upstream to Ulm, Württemberg, Germany. About 60 of its tributaries are also navigable.
Cultural Significance
The Danube has been a frontier of the Roman Empire and is filled with historic and cultural landmarks. The river has inspired numerous musicians, artists, and authors, including Johann Strauss II, who composed the famous waltz "The Blue Danube".
Environmental Issues
The Danube's water quality has been affected by pollution from industrial and agricultural sources, but efforts are being made to address these issues. The International Commission for the Protection of the Danube River (ICPDR) is an organization that promotes and coordinates sustainable water management in the Danube River Basin.