Danube River

Category: Inland Aquatic Biomes.

Geographic Location: Europe.

Summary: From western Europe to the Black Sea, the Danube River and its catchment area join 19 nations in conservation efforts to ensure the region's ecology and prosperity.

Second only to the Volga in size among Europe's major rivers, the Danube River extends over 1,770 miles (2,850 kilometers) with a drainage basin area of 315,000 square miles (817,000 square kilometers). This watershed area receives effluents from hundreds of tributaries and rivers. Approximately 83 million people live within its catchment area.

The Danube River headwaters begin where the Brigach and Breg streams conjoin at the far southwest corner of Germany. Its headwaters are memorialized at a site known as Karstaufstoßquelle on the outskirts of Donaueschingen in the state of Baden-Württemberg. The Danube flows through 10 countries: Germany, Austria, Slovakia, Hungary, Croatia, Serbia, Bulgaria, Romania, Moldova, and Ukraine. Its basin includes lands in Poland, Switzerland, Italy, Czech Republic, Slovenia, Bosnia and Herzegovina, Montenegro, Republic of Macedonia, and Albania. The Danube first flows easterly, then cuts sharply southward near Budapest, capital of Hungary, before resuming its eastward flow where the Vuka River joins it at Vukovar, Croatia. The Danube flows through three other European capital cities—Vienna, Bratislava, and Belgrade—on its way to the Black Sea.

Ecoregions Along the River

The Middle European Corridor—the full stretch of the Danube—is a fertile zone with thick loess soils supporting high populations within cities, farming towns, and hamlets. Distinct ecosystems unfold across an ancient panorama of verdant alpine mountain ranges, mixed boreal and temperate forests, grasslands, open prairie, meadows, and marshlands. The Upper Danube refers to the stretch of river extending from its source in Germany's Black Forest to the edge of Bratislava at the entry to the Carpathian Mountains. For centuries, vast tracts of oak, beech, spruce (Picea abies and P. excelsa), and fir (Abies alba and A. pectinata) supported thriving lumber and woodworking industries. Mining and hunting also were important Danubian occupations.

Commercial silviculture and extensive logging radically altered the ecology of the region, replacing old forest stands with uniform plantations largely unsuited to the shrubs, herbs, plants, and wildlife that originally thrived on the soils and understory of mixed forests. In 1999, the Naturpark Südschwarzwald Association was formed to protect the beauty of the Southern Black Forest region; the reserve area includes the Southern Black Forest Nature Park. It is a cooperative project with participants from more than 100 local communities. Residents of the park strive to protect the region's unique balance of traditional lifestyles within the ancient forest.

Roughly two-thirds of all runoff waters into the Danube originates in the mountains and foothills of the Alpine Space ecoregion. During the past 100 years, alpine temperatures have risen 1.5 degrees C (2.7 degrees F), which is double the global average. Future changes in climate are predicted to alter the relative seasonal abundance and scarcity of mountain precipitation, which in turn will accelerate weather extremes such as occurrences of extreme flooding and drought in many areas dependent on alpine runoff.

The Alpine mountain region connects with the Carpathian Mountains at Bratislava; from there, the Carpathians extend across central and eastern Europe. The Middle Danube basin extends from the Gate of Devin just outside of Bratislava to the Iron Gate at the border of Serbia and Romania. It includes the Gemenc Béda-Karapancsa wetlands of Hungary and the Kopački Rit in Croatia, as well as the Gornje Podunavlje of Serbia and Montenegro, lower Drava-Mura wetlands, and the Tizsa River Basin. The area provides habitats for a varied animal population, including white-tailed eagles, terns, black storks, otters, beavers, and sturgeon. More than 250,000 migrating waterfowl fill the skies of the floodplains encompassed in this singular international flyway.

Waterways, Wetlands, and Wildlife

The Danube-Carpathian region defines a watershed area whose boundaries include Germany, Rumania, Ukraine, Poland, and Bulgaria. Approximately 80 percent of the water draining from the Carpathians flows into the Danube River basin. This region includes some of the most important wilderness, old-growth forests, and wetland areas in Europe. The Danube is a prominent landmark that has served as an important rallying point for international protests against intensive channelization of the river for navigation and hydroelectric power. In 1984, the Duna Kör (Save the Danube) movement originated in response to the announcement of the $3 billion Gabčíkovo-Nagymaros hydroelectric power project on the Czech Republic-Hungary border.

At the mouth of the Black Sea the Danube opens into three tributaries, the Chilia, Sulina, and Sfântu Gheorghe, which feed into the Danube Delta, one of Europe's largest wetlands. These wetlands are renowned as breeding and resting grounds for critical populations of pelican (including the Dalmatian pelican), wild geese (including 90 percent of the world's population of red geese), ibis, cormorant, swallow, as well as freshwater fish. More than 5,000 terrestrial species have been documented in the delta and lower Danube region, including the shy otter, mink, foxes, bears, wolves, muskrats, tortoises, and hares.

Across the Danube River realm, some of the animal species identified by the World Wildlife Fund (WWF) as endangered are: yellow-legged clubtail dragonfly (Gomphus flavipes), moor frog (Rana arvalis), Danube sturgeon (Acipenser gueldenstaedti), European pond turtle (Emys orbicularis), great white pelican (Pelecanus onocrotalus), grey heron (Ardea cinerea), kingfisher (Alcedo atthis), and the beaver (Castor fiber).

Global Warming and Climate Change

Global warming and climate change are expected to greatly affect the Danube River in the twenty-first century. According to the International Community for the Protection of the Danube River, the air temperature in the region will increase 1 to 1.5 degrees Celsius, causing more frequent heat waves and cooler winters. Water temperature will rise by 2 degrees Celsius. This will increase algae growth and reduce oxygen levels in the water, harming fish stocks.

Conservation Efforts

There have been a wide array of protection schemes enacted along the Danube. The Trans-European Transport Network was established in 1990 to integrate planning for comprehensive, transnational systems of transportation, energy, and communications. Inland waterways, while vital to regional economies, also are dynamic transport systems for infectious diseases, nonnative invasive species, and non-point-source pollutants, all of which have had alarming impacts along the Danube corridor and the multi-dimensional ecological systems that depend on it for survival. Dredging and channelization have affected the river's hydrology; redistributed silts and altered rates of fluid dispersion continue to have wide-ranging impacts across the catchment area. Today, more than 700 dams and weirs regulate the Danube and its major tributaries, tending to limit or damage the biodiversity of riverine, floodplain, and wetlands areas.

In 2000, the Lower Danube Green Corridor Agreement was signed into law, binding the governments of Bulgaria, Romania, Ukraine, and Moldava to protect and restore some of the vital wetlands along the lower river and the delta. More than 5,405 square miles (1.4 million hectares) of land have been placed under protection for the sustainable maintenance of wildlife, water quality, and resources for recreation.

Working in response to mandates established by the European Territorial Cooperation program, the Alpine Space Programme 2007–13 was initiated by seven countries to promote regional development in sustainable ways. The program area covers 173,746 square miles (450,000 square kilometers) and includes about 70 million people.

In 2009, eight countries signed the Declaration of Vienna, establishing a cooperative partnership to strengthen the conservation of 12 designated sites. The Danube River Network of Protected Areas includes: the Danube Riparian Forest at Neuburg-Ingolstadt in Germany; the Donau-Auen National Park in Austria; the Zohorie Protected Landscape and the Danube Floodplain Protected Landscape in Slovakia; the Duna-Ipoly National Park and the Duna-Drava National Park in Hungary; the Nature Park Kopacki Rit in Croatia; the Special Nature Reserve Gornje Podunavlje in Serbia; the Persina Nature Park, the Kallmok-Brushlen Protected Site, and the Srebarna Nature Reserve in Bulgaria; and the Danube Delta Biosphere Reserve in Romania, designated a World Nature Heritage in 1991.

These network sites were established to protect the last free-flowing areas of the river and to conserve wildlife and migratory bird habitats. In addition, they were intended to begin restoring the Danubian floodplain, more than 80 percent of which has been damaged or destroyed by dams and navigation projects since the early 1800s.

In 2011, the WWF announced the formation of a transboundary United Nations Educational, Scientific and Cultural Organization (UNESCO) biosphere reserve to protect the lands and wildlife along the Mura, Drava, and Danube Rivers in the Carpathian region, creating Europe's largest riverine protected area. The declaration was signed by Austria, Croatia, Hungary, Serbia, and Slovenia, establishing a five-country protected zone. It covers an area of 3,090 square miles (800,000 hectares) that features extensive floodplain forests, river islands, and gravel banks.

A comprehensive listing of European documents protecting the Danube and other European inland rivers is included in the Joint Statement on Guiding Principles for the Development of Inland Navigation and Environmental Protection in the Danube River Basin. This statement was published in 2007 by the International Commission for the Protection of the Danube River, the Danube Commission, and the International Sava River Basin Commission. Other guiding directives include the Danube River Protection Convention, the Black Sea Commission, the Danube-Black Sea Region Task Force, and Black Sea Synergy.

Bibliography

Bachmann, Jasmine. “Can Ecology and Water Transport Coexist?” International Commission for the Protection of the Danube River, January 2007. http://www.icpdr.org/main/publications/can-ecology-and-waterway-transport-coexist.

Baltzer, Michael. Inland Navigation in the New EU—Looking Ahead: Corridor VII or Blue Danube? Sofia, Bulgaria: World Wildlife Fund Danube-Carpathian Programme, 2004.

Damm, Marion, ed. Climate Adaptation and Natural Hazard Management in the Alpine Space. Munchen, Germany: AdaptAlp, 2011.

Eiseltova, Martina, ed. Restoration of Lakes, Streams, Floodplains, and Bogs in Europe: Principles and Case Studies. New York: Springer, 2010.

Mauch, Christof and Thomas Zeller. Rivers in History: Perspectives on Waterways in Europe and North America. Pittsburgh, PA: University of Pittsburgh Press. 2008.