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Environmental problems of Northern Eurasia

The Aral Sea

<<< Air Pollution: conclusions | Environmental Problems Index | Location and History to the 20th Century >>>

Introduction

The Aral Sea is one of Central Asia's youngest inland water bodies, probably first appearing in the late Pleistocene, fts closed endoreic drainage basin is dominated by two of the largest rivers in Central Asia, the Amudarya and Syrdarya, which rise in the mountains to the south and east and flow across the deserts of the Turanian plain to feed the Aral Sea. Following a history of human use of these water resources that dates back more than 3000 years, the late 20th century has been marked by an abrupt acceleration in water offtakes. Intensive development of irrigated agriculture since the 1950s in the then Central Asian republics of the USSR resulted in a dramatic decline in the volume of water entering the sea from its two major tributaries, fn 1960, the Aral Sea was the fourth largest lake in the world, but since that time it has lost two-thirds of its volume, its surface area has been halved, its water level has dropped by more than 16m and its salinity has increased to reach that of sea water.

These dramatic changes have had far-reaching effects, both on- and off-site. The Aral Sea's fishing industry has completely ceased to function as most of its native organisms have died out, and the Amudarya and Syrdarya deltas have been transformed due to the lack of water, affecting flora, fauna, and soils. The receding sea has had local effects on climate, and the exposed sea bed has become a major new source of saline aerosols that contaminate surrounding agricultural land. The irrigated cropland itself has been subject to problems of salinization and waterlogging due to poor management with consequent negative effects on crop yields. Drainage water from these schemes is highly saline and contaminated by high concentrations of agrochemical residues which have been linked to poor human health in the region. The development of irrigation has not been the only cause of desertification in the Aral Sea basin, however. Widespread grazing pressures, technological developments, such as construction and drilling activities, and excessive exploitation of woody shrubs for fuel wood have also contributed to the degradation of the region.

This ecological demise of the Aral Sea and its drainage basin is often cited as one of the foremost examples of modern human-induced environmental degradation (Micklin, 1988; UNEP, 1992a, b; Glazovsky, 1995a; UNDP, 1995). After a brief review of the Aral Sea prior to the 20th century, this chapter focuses largely on the last fifty years, a period during which dramatic changes have been recorded in its physical geography.

<<< Air Pollution: conclusions | Environmental Problems Index | Location and History to the 20th Century >>>

 

 


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