Three ways to measure degradation:
Micklin (2000) writes that the Aral Sea is a surface-fed rather than groundwater-fed lake: it relies upon water contributions from the Amu Darya and Syr Darya. Since it is located between Central Asia's Kara-Kum, Kyzyl-Kum, and Baetpakdala deserts, its evaporation rate is relatively high. Lake evaporation contributes, however, to the atmospheric and ambient temperature of the surrounding area– a “climate cooling” function, so to speak, that is increasingly unavailable in the Aral Sea Basin.
The change in Aral Sea depth over the centuries, therefore, has largely been a function of river inflows, less the outgo from evaporation. According to Field (1954), previous to 1880, glacier advance in the mountains led to reduced riverine influx to the Aral Sea; however, world temperatures were lower then, which also affected the evaporation rate. That level remained remarkably stable, with lake level variations of plus or minus one meter.
Between 1960 and 1987, the Sea divided into two lakes, North and South. The South lake has also divided. One small lake lies to the west and another, larger lake to the east, although at times there has been a channel between the North and South.
1. Depth
Between 1960 and 1998, the level of the smaller lake fell by 13 meters; the level of the larger lake fell by 18 meters.
2. Surface area
In 1960, the Aral Sea was the fourth largest inland body of water, covering 67,000 square kilometers between Kazakhstan and Uzbekistan. According to the Environmental Justice Foundation, over the last fifty years, its size has shrunk by 40,000 square kilometers. The above photo is one of many that captures the loss of depth and the salty, silty soil quality of the former Aral Sea bed.
3. Salinity
The Aral Sea was a brackish lake, with salinity about one-third of the world's oceans. In 1960, already compromised, its salinity measured 9.9 grams of salt per liter. In 1998, the large sea measured approximately 45 grams of salt per liter (455% increase); the small sea, approximately 30 g/l salinity (303% increase).
The increased salinity, loss of water depth and lake area for this groundwater-fed lake should not surprise us. In some months, river contribution to the Aral Sea is ,nothing. Furthermore, when river water does come into the Aral Sea, its quality has been greatly compromised by agricultural and human use. Many of these salts are pesticide and fertilizer residue. The aridity of the region means that these salts are carried by the wind and breathed in by humans.
Three ways to measure economic loss
The loss of Aral Sea depth has ruined lake commerce. Trawlers that once plied the sea for fish (according to BBC, about 44,000 tons annually) are now stranded on the sandy lakebed. The maritime trade route between these two rural areas of Kazakhstan and Uzbekistan has literally dried up.
The degradation of the Aral Sea area has also reduced habitat and species diversity in Central Asia. UNEP/GRIDA-Arendal has a great overview:
In 1960, the Aral Sea region was the home of:
70 species of mammals‚ now, 32 species of mammals
310 species of birds–at present, 160 species of birds
5-7 kinds of livestock fodder no longer grow in region
Disease and death of cattle and sheep showed marked increase.
The increase in Aral Sea salinity has also changed the species that can live within the water itself. Again, according to UNEP/GRIDA:
24 species of fish are at risk: two species now extinct.
The reason for the dearth of riverine input and poor water quality: unsustainable, inefficient, and failing irrigation systems. Check back on Tuesday for Part 2: Agriculture versus the Aral Sea.
The cost of Aral Sea degradation on human health has been horrific: Check back Wednesday for Part 3: The Aral Sea and Public Health.
References:
I am especially indebted to Beach, et al, for terminology‚ see Worth Reading Page, General;
Phillip Micklin's great book on Central Asian water and Neil Field's 1954 article on resource geography of the Amu Darya‚ see Worth Reading, Central Asia General.
UNEP/GRIDA-Arendal Home Page‚ Capacity Building and Environmental Knowledge for Eastern Europe, the Caucasus, and Central Asia: their Aral Sea Page is cited above.
The FPA Climate Change blog gives a world overview of what the Aral Sea represents specifically-see Bill Hewitt's article on the latest reports
Map: Unimaps.com: Aral, the Dying Sea page has other great maps
Photo: (U.S.) National Geographic Society
