The Danube Delta is the second largest river delta in Europe, following the Volga Delta, and is the most well-preserved delta on the continent. It is formed where the Danube River flows into the Black Sea. Most of the Danube Delta is located in Romania, specifically in Tulcea County, with a small portion in Ukraine’s Odesa Oblast. The total area of the Danube Delta is approximately 4,152 square kilometers (1,603 square miles), of which 3,446 square kilometers (1,331 square miles) are in Romania. The Razim–Sinoe lagoons, which cover about 1,015 square kilometers (392 square miles) and include 865 square kilometers (334 square miles) of water, are located south of the main delta. Together with the delta, the total area reaches 5,165 square kilometers (1,994 square miles). The Razim–Sinoe lagoon complex is closely connected to the delta in terms of geology and ecology. The combined area of the Danube Delta and the lagoon complex is recognized as a World Heritage Site.
Geography and geology
The modern Danube Delta began forming around 4000 BC in a bay of the Black Sea as the sea level rose to its current level. A sandy barrier blocked the Danube bay where the river first built its delta. After the bay filled with sediment, the delta expanded beyond this barrier after 3500 BC, creating several layers: the St. George I (3500–1600 BC), the Sulina (1600–0 BC), the St. George II (0 BC–present), and the Chilia or Kilia (1600 AD–present). Other smaller layers formed in nearby lakes and lagoons, such as Chilia I and II to the north and Dunavatz to the south. Much of the silt and soil in the delta and its growth came from erosion caused by people cutting down forests in the Danube basin during the first and second millennia. Geologist Liviu Giosan told The New York Times:
Today, the delta has a large shortage of sediment because of dams built on the Danube and its tributaries in the late 20th century. A network of shallow channels created in the delta helped reduce this shortage on the land but increased erosion along the coast. The Danube Delta is a low area covered with silt and soil, mostly wetlands and water. It has a complex mix of marshes, channels, streams, and lakes. The average height is 0.52 meters, with 20% of the area below sea level and more than half not higher than one meter. Dunes on the largest flat areas (Letea and Caraorman) reach heights of 12.4 meters and 7 meters, respectively. The largest lakes are Dranov (21.7 km²), Roșu (14.5 km²), and Gorgova (13.8 km²).
The Danube splits into three main branches in the delta: the Chilia, Sulina, and Sfântul Gheorghe. The last two form the Tulcea channel, which continues as one body for several kilometers after separating from the Chilia. At the mouths of each branch, new land forms as the delta grows.
The Chilia branch, in the north, is the longest, youngest, and most active, with two smaller deltas and one small delta still forming at its mouth (toward Ukraine).
The Sulina branch, in the center, is the shortest, which made it widely used for transportation and heavily changed. A main port and one town are located at its mouth. A channel was built to protect ships from the sea, extending 10 kilometers into the ocean.
The Sfântul Gheorghe branch, in the south, is the oldest and least populated. Its silt helped create the Sacalin Islands, which are now 19 kilometers long.
The Danube Delta is one of Romania’s sunniest and driest areas. The average yearly temperature is 11°C (−1°C in January and +22°C in July), with 300 to 400 mm of rain each year.
The delta is part of the Pannonian steppe ecosystem in Eastern Europe, with some Mediterranean influences. As a young and still-growing region, the Danube Delta supports a wide variety of plants and animals, many of which are rare in Europe. It has 23 natural ecosystems, with wetlands and water being most common. Higher ground has dry environments, and between wet and dry areas are swampy zones where plants and animals adapt to both water and land. Where fresh and salt water meet, special physical, chemical, and biological processes occur, creating a unique ecosystem called the "beforedelta." Musura Gulf, north of Sulina, and Saint George Gulf are examples of this type of environment.
The Danube Delta is a key stop for birds migrating from six major regions, including Mongolia, the Arctic, and Siberia. Over 320 bird species live there in summer, with 166 nesting and 159 migrating. More than one million birds, including swans, ducks, and coots, winter in the delta.
The area includes the Danube’s branches, streams, and channels. It is rich in plankton, worms, mollusks, grubs, and sponges, and has many fish species, such as carp, pike, pike perch, sheat-fish, and freshwater sturgeons (sterlet, Vyza, and Danube mackerel).
Lakes, ponds, streams, and channels in the delta have a variety of floating and underwater plants, such as Myriophyllum, Ceratophyllum, Vallisneria, Nymphaea alba, Nuphar lutea, Trapa natans, Alisma plantago, and Salvinia natans, Stratiotes aloides, and Spirogyra. Important fish include tench, common bream, common rudd, Prussian carp, wels catfish, European perch, and northern pike.
Reed plants and floating reed islands (called "plaur" in Romania) are common in the delta. Vegetation includes common reed (Phragmites communis), mace reed/cattail (Typha latifolia, Typha angustifolia), sedge (Carex dioica, Carex stricta), Dutch rush (Scirpus radicans, Schoenoplectus lacustris), and brook mint (Mentha aquatica). These plants provide nesting and spawning areas. "Plaur" are mixtures of reed roots, grass, and soil, floating or attached to the riverbed. Reeds often surround lakes and ponds, slowly spreading across the water.
The delta is home to many bird species, some of which are rare. Important ones include the tufted duck, red-crested pochard, mallard, greylag goose, pygmy cormorant,
Inhabitants
The Danube Delta has an average population density of 2 people per km, making it one of the least populated areas in temperate Europe. On the Romanian side, about 20,000 people live in the region, with 4,600 residing in the port city of Sulina. The remaining population is spread across 27 villages, and in 2002, only three of these villages had more than 500 people. The city of Tulcea, located at the western edge of the delta, had a population of 65,624 in 2021. It serves as a central point for the region and a main entrance to the delta.
The Danube Delta’s extreme isolation and difficult living conditions, which rely mostly on basic survival methods, have led to high rates of people leaving the area or passing through it temporarily. Few people born in the region stay there as adults. The population comes from many parts of Romania, and the origins of its people are diverse. The total number of people in the delta has not changed much during the 20th century. In the 1890s, there were about 12,000 people, and before World War II, there were 14,000. Approximately 80% of the population are Romanians, and 10% are Ukrainians. Other groups include ethnic minorities such as Greeks, Turks, and Bulgarians (as recorded in 1992). A unique but rare group in the region is the Lipovans, who are descendants of people from Russia who fled religious persecution in the 18th century.
On the Ukrainian side, at the northern edge of the delta, the town of Izmail has a population of 85,000, Kiliya has 21,800 people, and Vilkovo, the main center for the Lipovan community, has 9,300 residents.
History
Recorded history shows that the Dacians lived in the Danube Delta before the Romans took over the area. Later, after the Goths invaded, the region changed ownership many times. In the 15th century, the Danube Delta became part of the Ottoman Empire. In 1812, after the Russo-Turkish War, the borders between the Ottoman and Russian Empires were set by the Kilia and Old Stambul Channels of the Danube. In 1829, the St George Channel was also used to define the border. The Treaty of Paris in 1856, which ended the Crimean War, gave the Danube Delta to the Ottoman Empire. It also created an international commission to improve navigation in the area. In 1878, after the Ottoman Empire was defeated by Russia and Romania, the border between the two countries was set by the Kilia and Old Stambul Channels.
In 1991, the Romanian part of the Danube Delta was added to UNESCO’s list of World Heritage Sites. About 2,733 kilometers of the delta are strictly protected areas.
In 1998, under UNESCO’s Programme on Man and the Biosphere, the 6,264.03 kilometers of the Danube Delta were established as a biosphere reserve shared by Romania and Ukraine.
Historically, in Romania, part of the Danube Delta was marked as a reserve in 1938.
In Ukraine, the Danube branch of the Black Sea State Reserve was created in 1973. In 1981, it was reorganized into the Natural Reserve "Danube Fluxes." In 1998, it was expanded to become part of the Danube biosphere reserve.
Environmental issues
Large projects in the Danube Delta began in the second half of the 1800s. Work to change the Sulina arm started in 1862 and continued into the 1900s. These changes reduced the length of the Sulina arm from 92 to 64 kilometers, and its water flow more than doubled, making it easier for large ships to travel. Fixing six major bends in the Sfântu Gheorghe branch shortened it from 108 to 70 kilometers, and its flow also increased slightly. These changes harmed the Chilia arm, which remains the least altered of the three main branches. These modifications, along with the digging of smaller channels in the delta, greatly affected the environment. Natural areas were changed, fish breeding patterns were disrupted, and water flow in the main branches increased, leading to more sediment movement and bank erosion.
During the Communist era, reeds were heavily harvested. The government planned to turn the delta into a large farming and industrial area. Although farming began in 1939, large areas were drained and converted for agriculture after 1960, harming wetlands. By 1991, more than 100,000 hectares of land in the delta were used for farming, forests, or fish farming. These changes, combined with water pollution and poor fishing rules, caused fish populations to drop明显.
In 2004, Ukraine started building the Bistroe Channel to create a new shipping route from the Black Sea to the Danube Delta. However, the European Union warned that this could harm the delta’s ecosystem. Romanian officials threatened to take Ukraine to the International Court of Justice. Under President Kuchma, Ukraine claimed Romania feared competition and continued the project. Under President Yushchenko, who visited Romania in 2005, both countries agreed that experts should decide the channel’s future. In the long term, Ukraine plans to build a shipping route, either through the Bistroe Channel or another channel.