Desiccation of The Aral Sea

The Aral Sea is a closed basin situated in Uzbekistan and Kazakhstan with an extremely large catchment area. The desert landscape receives less than 90mm of rainfall per annum and exhibits a strong continental climate characterised by extreme temperatures in the summer and winter. The sea has no outflow but two rivers the Amu Dar’ya and Syr Dar’ya feed the basin with waters of snowfield and glacial origin (Laity 2008).

The Aral Sea once extended 66 100 km² but problems developed with the diversions of its premiere inputs in the 1960s and 70s. By 1987, 60/70% of the Aral Sea’s volume had been lost, with a water level reduction of 14m (Glantz, 2007). The Aral Sea became split into two bodies of water, the Large Aral Sea and the Small Aral Sea (Sorrel et al, 2006). Water levels had been known to fluctuate over the Holocene with marine fossils and relict shore terraces providing evidence of 20-40m oscillations in response to changes in the climate system and the subsequent implications for river discharge. Current changes are far from natural.

     

The affects of hydrological change in the Aral Sea are wide ranging. Diversion for the purpose of cotton and rice field irrigation has seen huge increases in the Aral Sea’s salt concentration, decimating the local fishing industry. Sorrel et al (2006) report surface water salinity rose from 10.4 g kg^-1 in 1960 to more than 80 g kg^-1 in 2003. In addition, strong winds transported toxic dust onto farms several hundred kilometers downwind from sediments that had once been covered under water. Life expectancies of approximately 3.5 million people have been cut significantly as a result of exposure to toxic chemicals. Rates of disease among children is increasing with intoxication of heavy metals causing renal tubular dysfunction, in addition to increased number of cases of tuberculosis, malignancies and psychiatric disease  (Kaneko et al, 2011; Matsapaeva et al, 2010). Desiccation of the Aral Sea has also had extensive climatic impacts. Small et al (2001) illustrate the changes in surface air temperature since the disruption of the Aral Sea’s inputs. Mean, maximum and minimum temperatures near the Aral Sea have changed by up to 6^o C. The magnitude of change decreases with distance from the 1960s shoreline.

This example demonstrates the enormous control humans can have on the environment, potentially causing irreversible damage. Not only do we have the power to change the environment, but also threaten the well being of the contemporary society, ecological communities, and even regional-scale climatic outputs. The scale of the damage caused in the Aral region is testified by the 300 projects proposed to alleviate crisis. Furthermore, responses are aimed towards minimising the damage, not restoring to former characteristics. Small et al reinforce the recklessness of many contributions by suggesting, “If every expert brought a bucket of water, the Aral Sea would be filled again”…  

References

Laity, J. (2008) Deserts and Desert Environments, Chichester: Willey-Blackwell