The Volga Delta is the largest
river delta
A river delta is a landform shaped like a triangle, created by deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rare ...
in
Europe
Europe is a large peninsula conventionally considered a continent in its own right because of its great physical size and the weight of its history and traditions. Europe is also considered a Continent#Subcontinents, subcontinent of Eurasia ...
, and occurs where Europe's largest river system, the
Volga River
The Volga (; russian: Во́лга, a=Ru-Волга.ogg, p=ˈvoɫɡə) is the longest river in Europe. Situated in Russia, it flows through Central Russia to Southern Russia and into the Caspian Sea. The Volga has a length of , and a catch ...
, drains into the
Caspian Sea
The Caspian Sea is the world's largest inland body of water, often described as the world's largest lake or a full-fledged sea. An endorheic basin, it lies between Europe and Asia; east of the Caucasus, west of the broad steppe of Central A ...
in
Russia
Russia (, , ), or the Russian Federation, is a transcontinental country spanning Eastern Europe and Northern Asia. It is the largest country in the world, with its internationally recognised territory covering , and encompassing one-ei ...
's
Astrakhan Oblast, north-east of the republic of
Kalmykia. The delta is located in the
Caspian Depression—the far eastern part of the delta lies in
Kazakhstan. The delta drains into the Caspian approximately downstream from the city of
Astrakhan.
The Volga Delta has grown significantly in the 20th century because of changes in the level of the Caspian Sea. In 1880, the delta had an area of . Today the Volga Delta covers an area of and is approximately across. It has a classical "delta pattern". The delta lies in the
arid climate
The desert climate or arid climate (in the Köppen climate classification ''BWh'' and ''BWk''), is a dry climate sub-type in which there is a severe excess of evaporation over precipitation. The typically bald, rocky, or sandy surfaces in deser ...
zone, characterized by very little rainfall. The region receives less than one inch of rainfall in January and in July in normal years. Strong winds often sweep across the delta and form linear dunes. Along the front of the delta, one will find muddy sand shoals, mudflats, and
coquina banks.
Three Zones
The changing level of the Caspian Sea has resulted in three distinct zones in the delta.
The higher areas of the first zone are known as "Baer's mounds," named after researcher
Karl Ernst von Baer who worked in this region. These mounds are linear ridges of clayey sands, ranging from in height, and averaging about . They are between in length. Between the Baer's mounds are depressions that fill with water and become either fresh or saline bays; the height from the bottom of a depression to the peak of its neighboring mound ranges from . These depressions, called "" (from Russian through Finnish, "small lake," as in Russia's
Lake Ilmen), used to form part of the early, very deep river delta but gradually became separated from it. Because of their isolation from the fresh waters of the Volga, they are becoming increasingly saline. Together they form a "vast (more than ) and extremely diverse area of western substeppe (WSI)" which, because of the varying degrees of wetness and salinization, house a wealth of flora and fauna. The origin of these mounds and is still debated: the early suggestion that they were formed by aeolian (wind) action is now discredited, and now they are thought to have arisen either underwater or through river flow.
[Eric Bird]
'Encyclopedia of the World's Coastal Landforms, vol. 2', p. 877
The second zone, in the delta proper, generally has very little relief (usually less than one metre), and is the site of active and abandoned water channels, small dunes and
algal
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular micr ...
flats.
The third zone is composed of a broad platform extending up to offshore, and is the submarine part of the delta.
Wildlife
The delta has been protected since the early 1900s, with one of the first Russian nature preserves (
Astrakhan Nature Reserve) having been set up there in 1919. Much of its local
fauna
Fauna is all of the animal life present in a particular region or time. The corresponding term for plants is '' flora'', and for fungi, it is '' funga''. Flora, fauna, funga and other forms of life are collectively referred to as '' biota''. ...
is considered endangered. The delta is a major staging area for many species of water birds,
raptor
Raptor or RAPTOR may refer to:
Animals
The word "raptor" refers to several groups of bird-like dinosaurs which primarily capture and subdue/kill prey with their talons.
* Raptor (bird) or bird of prey, a bird that primarily hunts and feeds on v ...
s and
passerines. Although the delta is best known for its
sturgeons,
catfish
Catfish (or catfishes; order Siluriformes or Nematognathi) are a diverse group of ray-finned fish. Named for their prominent barbels, which resemble a cat's whiskers, catfish range in size and behavior from the three largest species alive, ...
and
carp are also found in large numbers in the delta region. The
lotus has been adopted as the motif of the national
flag of the neighbouring Kalmyks, since it is a venerated symbol in
their Buddhist beliefs – they are the sole European people of Mongolian (
Oirat) origin.
Protection and Destruction
Industrial and agricultural modification to the delta plain has resulted in significant wetland loss. Between 1984 and 2001, the delta lost of
wetland
A wetland is a distinct ecosystem that is flooded or saturated by water, either permanently (for years or decades) or seasonally (for weeks or months). Flooding results in oxygen-free (Anoxic waters, anoxic) processes prevailing, especially in t ...
s, or an average of approximately per year, from natural and human-induced causes. The Volga discharges large amounts of
industrial waste and sediment into the relatively shallow northern part of the Caspian Sea. The added fertilizers nourish the
algal blooms that grow on the surface of the sea, allowing them to grow larger.
References
Wetland Loss in World Deltas Coastal Studies Institute, Louisiana State University
wetlands.orgEarth Snapshot article "The Three Zones of the Volga Delta"
External links
Volga River Deltaat
NASA Earth ObservatoryVolga Deltaa
Natural Heritage Protection Fund
{{Authority control
Freshwater ecoregions
River deltas of Europe
Landforms of Russia
Caspian Sea
Biosphere reserves of Russia
Landforms of Astrakhan Oblast
Volga basin
Ramsar sites in Russia