The modern Danube Delta began forming after 4,000 B.C. in a gulf of the Black Sea, when the sea rose to its present level. A sandy barrier blocked the Danube gulf where the river initially built its delta. Upon filling the gulf with sediments, the delta advanced outside the barrier-blocked estuary after 3,500 B.C. building several successive lobes: the St. George I (3,500-1,600 B.C.), the Sulina (1,600-0 B.C.), the St. George II (0 B.C.-Present) and the Chilia or Kilia (1600 A.D.-Present).
The Danube Delta is a low alluvial plain, mostly covered by wetlands and water. It consists of an intricate pattern of marshes, channels, streamlets and lakes. The average altitude is 0.52 m, with 20% of the territory below sea level, and more than half not exceeding one meter in altitude. Dunes on the most extensive strandplains of the delta (Letea and Caraorman strandplains) stand higher (12.4 m and 7 m respectively). The largest lakes are Dranov (21.7 km²), Roşu (14.5 km²), Gorgova (13.8 km²).
The Danube branches into three main arms into the delta, Chilia, Sulina, and Sfântu Gheorghe. The first two branches form the Tulcea arm, which continues as a single body for several kilometers after the separation with Chilia arm. At the mouths of each arm alluvionary processes take place, sign that the delta is continuing its expansion.
|Length (km)||Flow (m³s) (1921-1990)|
Chilia, in the north, the longest, youngest, and most vigorous, with two secondary internal deltas and one in full process of formation at its mouth (to Ukraine).
Sulina, the central and thus the shortest arm, which consequently led to its extensive use for traffic and severe transformation. At its mouth is located the main port and the single settlement with urban charactersitics of the Romanian part of the delta. Because of the alluvium deposited at its mouth, a channel gradually advancing into the sea (presently it has 10 km), was built in order to protect the navigation.
Sfântu Gheorghe (Saint George in Romanian), in the south, is the oldest and more sparsely populated. Its alluvium has led to the creation, beginning with 1897, of the Sacalin islands, which as of today measure 19 km in length.
The climate of the Danube Delta is continental with strong influences from the vicinity of the Black Sea and its prevalent amphibian environment. It is the driest and sunniest region (70 days with blue sky, 2500 hours of sunshine/year) of Romania. The mean annual temperature is 11°C (-1°C in January and 22°C in July), with mean precipitation between 400and 300 mm/year, decreasing from west to east. The evaporation is around 1000 mm/year, favorized and amplified by the strong and frequent winds, resulting in long periods of drought in the summer. The northwest winds cause frequent storms in spring and autumn. In the interior of the delta the continental character of the climate is very pronounced.
The Danube Delta falls within east European steppe ecosystem, with Mediterranean influences. As a young region in full process of consolidation, the Danube Delta represents a very favourable place for the development of highly diverse flora and fauna, unique in Europe, with numerous rare species. It hosts 23 natural ecosystems, but due to the extent of wetlands the aquatic environment is prevalent; the terrestrial environment is also present on the higher grounds of the continental levees, where xerophile ecosystems have developed. Between the aquatic and terrestrial environments, is interposed a swampy, easily flooded strip of original flora and fauna, with means of adaptation for water or land, depending on the season or the hydrological regime. At the contact between freshwater and sea water, some special physical, chemical and biological processes take place, which determined biologists to consider this area as a very different ecosystem called beforedelta. Musura Gulf, north of Sulina, and Sfântu Gheorghe Gulf are considered the most representative for this type of ecosystem.
Situated on major migratory routes, and providing adequate conditions for nesting and hatching, the Danube Delta is a magnet for birds from six major eco-regions of the world, including the Mongolian, Arctic and Siberian. There are over 320 species of birds found in the delta during summer, of which 166 are hatching species and 159 are migratory. Over one million individuals (swans, wild ducks, bald coots, etc.) winter here.
It comprises tha Danubes arms, as well as a series of more important streamlets and channels. It is an environment very rich in plankton, worms, mollusca, ephemerides, grubs, spongiae, with numerous species of fish, such as the carp, pike perch, sheat fish, and freshwater sturgeons (sterlet, Vyza, Danube mackerel).
Includes the lakes, to which various ponds, streamlets and channels are added. They are characterized by a rich floating and submerse flora (Myriophyllum, Ceratophyllum, Vallisneria etc. under the water; Nymphaea Alba, Nuphar luteum, Trapa natans, Alisma plantago etc., floating plants with roots near the lakes borders; Salvinia natans, Stratiotes aloides, Spirogyra etc., floating plants without roots, having negative effects for the aquatic bioproductivity). Of the fish, the most important are Tinca tinca, Abramis brama, Scardinius erytrophalmus, Carassius auratus gibelio, Silurus glanis, Perca fluviatilis, Exos lucius etc.
The reed plats and floating reed islands (called plaur in Romania are the most common and well known components of the Danube Delta. Vegetation of this ecosystem consists of common reed (Phragmites communis), and near river banks mace reed (Typha latifolia, Typha angustifolia), sedge (Carex dioica, Carex stricta), Dutch rush (Scirpus radicans, Scirpus lacustris), brook mint (Menta aquatica) etc. They constitute ideal spawning and nestling grounds. The plaur is a mixture of reed roots, grass and soil, usually floating or anchored on the bottom. As a rule, the reed surrounds the lakes and ponds, slowly invading the water surface. This type of ecosystem is noted for the variety and large populations of birds, some of them very rare. The most important are the tufted duck (Aythya fuligula, red crested pochard (Netta rufina), mallard (Anas platyrhincos), Greylag goose (Anser anser), Pygmy cormorant (Phalacrocorax pygmaeus), purple heron (Ardea purpurea), Great white egret (Egretta alba), little egret (Egretta garzetta), Spoon bill (Platalea leucorodia), White pelican (Pelecanus onocrotalus), Dalmatian pelican (Pelecanus crispus), Mute swan (Cygnus olor), Glossy ibis (Plegadis falcinellus). A recent and welcomed spreading has the pheasant (Phasianus colchicus). Among the mammals, there is the otter (Lutra lutra), mink (Mustela lutreola), little ermine (Mustela erminea aestiva), wild boar (Sus scrofa), wild cat (Felis silvestris), and in the winter, the hare (Lepus europaeus), and on the brink of disappearing from the delta, the wolf and the fox. The enot dog (Nyctereutes procynoides), bizam (Onda zibethica), and to some extent nutria (Myocastor coypus) are recent species successfully adapted.
The firm land of the delta used to be covered with large groves of willow trees, cut almost entirely and replaced with Canadian poplars. On the riverbanks kept in natural state, small groves of willow trees (Salix alba, Salix fragilis, Salix purpurea, Salix petandra, Salix triandra etc.) can still be found, mixed with white poplar (Populus alba). Occasionally, the willow trees form corridors along the Danubes arms and bigger channels. On the levees of Letea and Caraorman, mixed forests of oaks (Quercus robur, Quercus pedunculiflora) with various trees (Fraxinus pallisae, Ulmus foliacea, Populus tremula), shrubs (Prunus spinosa, Crataegus monogyna, Rosa canina, Berberis vulgaris etc.), and liana (Vitis silvestris, Hedera helix, Humulus lupulus, Periploca graeca, which reaches up to 25m) grow on sand dunes. On the Letea levee, these exotic looking forests grow especially in the depressions between the sand dunes, in small groves called hasmace. Fauna of this region includes Meadow Viper (Vipera ursinii), Osprey (Pandion haliaetus), Eagle Owl (Bubo bubo), etc.
The Danube Delta is perhaps the least inhabited region of temperate Europe. In the Romanian side live about 15,000 people, of which 4,600 in the port of Sulina, which gives an average density of approx. 2 inhabitants per km². The rest is scattered in 27 villages, of which only three, all situated marginally, have more than 500 people (2002). The town of Tulcea, at the western edge of the delta, but not included in it, has a population of 92,000 (2002). It represents the node of the region and the gate to the delta. The acute isolation and the harsh conditions of living, based mainly on subsistence, made the Danube Delta a place of emigration, or at least of transit. Very few of the people born here stay through adulthood; at the same time, the origins of the inhabitants fall within a wide range, as people from the most various places of Romania can be found in the delta. The total population has somewhat remained constant throughout the 20th century; there were 12,000 inhabitants in the 1890s, and 14,000 before the Second World War. Romanians count for approximately 80%, and Ukrainians for 10%. Other people living in the delta include Greeks, Turks and Bulgarians (1992). Distinctive for the region, but very vague as an ethnic entity are the Lipovans, descendants of the Orthodox Old Rite followers who fled Russia in the 18th century from religious persecution. About a third of the employed population is engaged in fishing and pisciculture, while another third is engaged in farming (1996). However, the quasi-totality practice fishing, more or less legally, as a means of subsistence or extra money.
Starting with the 15th century, the Danube Delta was part of the Ottoman Empire. In 1812, following the Russo-Turkish War the borders of Ottoman and Russian Empires were set by Kilia and Old Stambul Channels of Danube, and in 1829 by Georgievsky Channel. The Treaty of Paris of 1856 which ended the Crimean War, Danube Delta together with two districts of Southern Bessarabia was included in the Principality of Moldavia and was established an international commission which made a series of works to help navigation. In 1859, it became part of the United Principalities of Wallachia and Moldavia. In 1878, following the defeat of Ottoman Empire from Russia and Romania, the border between those two was set again by Kilia and Old Stambul Channels.
Historically, in Romania, part of Danube Delta was marked as a reserve back in 1938.
In Ukraine, the Danube branch of Black Sea State Reserve was established in 1973. In 1981 it was reorganized into Natural Reserve "Danube Fluxes", and in 1998 it was extended into Danube Biosphere Reserve.
Reed was intensively harvested during the Communist era. The regime had plans of transforming the delta into a large agro-industrial zone. Although the first modern agricultural exploitation dates form 1939 (Ostrovul Tãtaru), just from the 1960 on have large areas been drained and converted, to the detriment of wetlands. As of 1991 agricultural land in the delta surpassed 100,000 ha, and more than a third of its surface has been affected by crop cultivation, forest pantation or pisciculture arrangements. As a result of these changes, as well as the increasing pollution and eutrophication of the Danube waters, and decades overexploitation and poor regulations on fishing (commercial and recreational), the fish population is in visible regress.
In 2004, Ukraine inaugurated work on the Bistroe Channel that would provide an additional navigable link from the Black Sea to the popolous Ukrainian section of the Danube Delta. However, because of the negative impact which this new channel may have upon the fragile ecosystem of the Delta, the European Union advised Ukraine to shut down the works. Romanian officials threatened to sue Ukraine at the International Court of Justice. Under the presidency of Kuchma Ukraine had responded that Romania is just afraid of the competition that the new channel will bring, and continued working on the channel. Under the presidency of Yuschenko, who visited Romania in 2005, both sides agree that professionals should decide the fate of the channel. In the long-run, Ukraine plans to build a navigation channel, if not through Bistroe Channel then through another channel.