Danube Delta

Student:Popa Elena-Alexandra

Group : 8219

The Danube Delta is the second

largest river delta in Europe,after

Volga Delta and is the best

preserved on the continent.

Geography and geology

• The modern Danube Delta began to form after 4000 BCE in a bay of the Black Ses, when the sea rose to its present level. A sandy barrier blocked the Danube bay where the river initially built its delta. Upon filling the bay with sediments, the delta advanced outside this barrier-blocked estuary after 3500 BCE, building several successive lobes: the St. George I (3500-1600 BCE), the Sulina (1600-0 BCE), the St. George II (0 BC-Present) and the Chilia or Kilia(1600 CE to present). Several other internal lobes were constructed in the lakes or lagoons bordering the Danube delta to the North (Chilia I and II) and toward the South (Dunavatz).

Distributaries of the DanubeThe Danube branches into three main distributaries into the delta, Chilia, Sulina, and Sfântul Gheorghe (Saint George). The last two branches form the Tulcea channel, which continues as a single body for several kilometers after the separation from the Chilia. At the mouths of each channel gradual formation of new land takes place, as the delta continues to expand.

Danube Arm Length (km) Flow (m³/s)(1921–1990)

Chilia 120 3800

Sulina 64 1250

Sfântul Gheorghe(Saint George)

70 1500

Climate

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 of Romania. The mean annual temperature is 11 °C (-1 °C in January and 22 °C in July), with mean precipitation between 400 mm/year and 300 mm/year, decreasing from west to east. The evaporation is around 1000 mm/year, 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.

Ecosystems of marshy and flooding areas

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 (Anasplatyrhynchos), 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)

History

• In 1991, the Romanian part of the Danube Delta became part of the UNESCO list of World Heritage Sites. Around 2,733 km² of the delta are strictly protected areas.

• In 1998, under UNESCO Programme on Man and the Biosphere, the 6264.03 km² of Danube Delta were established as Biosphere Reserve shared by Romania and Ukraine.

• 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.

Recorded history first noted the Delta under Dacian control before being conquered by the Romans. After invasion by the Goths the region changed hands many times. During the 15th century, the Danube Delta became 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 St George Channel. The Treaty of Paris of 1856, which ended the Crimean War, assigned the Danube Delta to the Ottoman Empire and established an international commission which made a series of works to help navigation. In 1878, following the defeat of Ottoman Empire by Russia and Romania, the border between those two was set by the Kilia and Old Stambul Channels.

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 from 1939 (Ostrovul Tãtaru), only after 1960 were large areas drained and converted, to the detriment of wetlands. In 1991 agricultural land in the delta surpassed 100,000 hectares, and more than a third of its surface has been affected by crop cultivation, forest plantation, or pisciculture arrangements. As a result of these changes, as well as the increasing pollution and eutrophication of the Danube waters, and decades of exploitation and poor regulations of fishing, the fish population has been visibly reduced.

Environment and issues

• Large-scale works began in the Danube Delta as early as the second half of the 19th century. First corrections of the Sulinaarm began in 1862, and they continued throughout the 20th century. As a result, the length of the Sulina arm was reduced from 92 to 64 km, and its flow more than doubled, thus making it suitable for large-vessel navigation. Correcting the six large meanders on its course thereby reduced the length of the Sfântu Gheorghe from 108 km to 108, and its flow also increased somewhat. Both these increases were made to the detriment of the Chilia arm, which at present remains the most unspoiled arm of the main three. These corrections, as well as the digging of various secondary channels throughout the body of the delta, have had a serious impact on the ecosystem. Natural environments have been altered, the breeding pattern of fish has been disrupted, and the flows in the main arms have increased, with serious consequences regarding the discharge of the alluvia and the erosion of the banks.

Bibiographyhttp://en.wikipedia.org/wiki/Danube_Delta

https://www.google.ro/#q=delta+dunarii+imagini

http://www.ddbra.ro/

http://www.deltadunarii.ro/istoric.html