Physical Geography
  Tectonics and Geology
  Climatic Change
  Climate at Present and in the Past
  Rivers, Lakes, Seas and Wetlands

Biomes & Regions
  Arctic Environments
  Boreal Forests
  Mixed and Deciduous Forests
  Steppe and Forest-steppe
  Arid Environments
  The Mountains of Northern Russia
  The Mountains of Southern Siberia
  The Caucasus
  The Mountains of Central Asia
  Lake Baikal
  The Far East

Environmental Problems
  Radioactive Contamination
  Oil and Gas Development
  Air Pollution
  The Aral Sea Problems
  Deforestation and Degradation of Forests
  Nature Protection and Conservation

Images of Russian Nature
  Geographic Index
  Systematic Index
  Alphabetical Index

Nature Reserves
  Northern Russia
  Central Russia
  Povolzhye (Volga river basin)
  Southern Russia
  Ural Mountains
  Western Siberia
  Eastern Siberia
  Far East

‘отографии природы –оссии
  √еографический каталог
  —истематический каталог
  јлфавитный каталог

Nature Landscapes of the World
  North America
  South America

Field Ecology Education
  Instructive Videos
  Instructive Manuals

Ёкологический ÷ентр Ёкосистема на Facebook Ёкологический ÷ентр Ёкосистема ¬ онтакте

ётуб канал Ёкосистема YouTube EcosystemaRu

—качать приложени€ Ёкосистемы Ёко√ид из магазина Google Play / Play Market
—качать приложени€ Ёкосистемы Ёко√ид из AppStore / iTunes
¬идео-360 по экологии на нашем Youtube канале

Bird Decoys for European Birds: Songs, Calls, Sounds, Bird voices - application for Android download from Google Play / Play Market for free

Share this page with your friends:

( ) : : = = + +

Russian Nature

Home | Physical Geography | Biomes & Regions | Environmental Problems | Images of Russian Nature | Nature Reserves

Our Field Ecology Center published more than 180 methodical materials for nature studies. Some of them are in English:
Mobile educational application: Ecological Field Studies Techniques on Play.Google Mobile field guide Birds of North America: Songs and Calls Decoys on Play.Google WILD FLOWERS OF RUSSIA Field Identification Guide on Play.Google Mobile field guide Birds of Russia on Play.Google Mobile field guide Birds of Russia Songs, Calls and Voices on Play.Google Mobile field guide Birds of Europe Songs, Calls and Voices on Play.Google Mobile field guide Birds of Europe Songs, Calls and Voices on Play.Google
Mobile Educational Apps and Field Identification Guides for Russian, European and American Birds
Applications for Android and iOS are available at GooglePlay and AppStore

Please put an active hyperlink to our site (www.rusnature.info) when you copy the materials from this page

Physical Geography of Northern Eurasia

Rivers, Lakes, Inland Seas, and Wetlands


<<< The Balkhash | Physical Geography Index | Lakes Ladoga and Onega >>>

The Issyk-Kul

Lake Issyk-Kul is the largest in the mountains of Central Asia and is one of the world's deepest. The lake was formed in the lower Carboniferous and, being located in a tectonically active region, experienced frequent level changes caused by tectonic movements and associated regional climate change and the varying regime of glaciers (Tsigelnaya, 1995). Extensive archaeological and historical data confirm that numerous transgressions, often accompanied by an overflow, occurred between the 2nd century BC and the 1st century AD, about the 4th-6th, 7th-8th centuries, and between the second half of the 18th and the first half of the 19th centuries. Regression phases followed the transgressions, most notably during the 14th and the 16th centuries when the lake level was lower than now. The 20th century was a period of falling lake level. This reduction is caused primarily by natural variability of water flow in the lake tributaries which is enhanced by water abstraction for economic needs (Ratkovich, 1993; Tsigelnaya, 1995). With respect to the hydrochemistry of the Issyk-Kul, there are a number of features which this lake does not share with other large lakes. In particular, its open part is characterized by a uniform horizontal and vertical distribution of the main ions, which indicates a good water exchange between various areas of the lake and the development of a deep circulation (Tsigelnaya, 1995). The mean salinity of the Issyk-Kul is 5 ppt which puts it at the fresh-water end of saline lakes. Apparently in the early stages of lake development, its water was fresh but now it has entered a period of gradual salt accumulation and increasing sulphate concentrations. This indicates a transition from the hydrocarbonate sulphate to the sulphate type (Tsigelnaya, 1995).

The Issyk-Kul drains a high mountainous catchment with low biotic production and the annual river discharge is low in comparison with the lake volume. The discharge to volume ratio is only 0.2 per cent for the Issyk-Kul while for the Balkhash it is 13.4 per cent (Tarasov, 1961). As a result, the supply of nutrients and organic matter is low and the Issyk-Kul is a typical mountainous oligotrophic lake with low biological productivity. It has only twenty two fish species, ten of which have been introduced into the lake, and the mean fish catch is 1.9 kg ha-1. This is marginally lower than in the other large unproductive lakes, such as Baikal, Ladoga, and Onega, and much lower than in the Balkhash, Sevan, and Chudskoe, where it varies between 7 and 30 kg ha-1 (Tsigelnaya, 1995).

<<< The Balkhash | Physical Geography Index | Lakes Ladoga and Onega >>>




Recommend this page to your friends:

* *