Degree of Master of

Preconditions of the Aydar-Arnasay lakes formation

1. 
   The Aral Sea desiccation
   

The disappearance of the Aral Sea is a well known and widely discussed human- induced catastrophe representing severe ecosystem changes. It is commonly accepted that the modern recession of the Aral has been triggered by the diminution of inflow from the two largest rivers feeding the Aral Sea, Amudarya and Syrdarya, for irrigation purposes in Central Asia (Micklin 1988).
In particular, since the 1960s the intensity of the water use has been enhanced by the following factors: the rapid population increase, industrial development and especially irrigation farming. According to the SIC/ICWC estimates (2002), water withdrawals in the Aral Basin for irrigation purposes doubled from 1960 to 2000, composing about 90% of the total water withdrawal in the region (Roll and Alexeeva 2005). The basic indicators of water and land use in the Aral Sea Basin during 1960-2000 are presented in Table 1.

CEU eTD Collection
Table 1. Basic indicators of water and land use in the Aral Sea Basin during 1960-2000¹

Indicator	Unit	1960	1970	1980	1990	2000
Population	Million	14,1	20,0	26,8	33,6	41,5
Area under irrigation	million ha	4,31	5,15	6,92	7,60	7,99
Irrigated area per person	ha/person	0,32	0,27	0,26	0,23	0,19
Total draw-off	km^3/year	60,61	94,56	120,69	116,27	105,0
Draw-off for irrigation	km^3/year	56,15	86,84	106,79	106,40	94,66
Unit draw-off per ha under irrigation	m^3/ha	12,450	16,860	15,430	14,000	11,850
Unit draw-off per capita	m^3/person	4,270	4,730	4,500	3,460	2,530

Source: (ICWC/SIC 2002)

¹ Excludes part of basin that lies in Iran and Afghanistan

From table 1 it can be analyzed that the population in Central Asia increased threefold in the period of 1960-2000. Moreover, the area under irrigation has almost doubled in the same period of time whereas the irrigated area per person has decreased from 0,32 ha/person to 0,19. Total draw-off, including draw-off for irrigation also increased significantly by 2000 (ICWC/SIC 2002).
The dramatic drying out of the Aral Sea has resulted in severe environmental, economic and social consequences. Roll and Alexeeva state that the Aral crisis has led to environmental degradation, including land and water salinization in the region. Besides, the adverse problems of salinization threatening the entire economy of the Central Asia gave rise to other problems such as:

• 
  Increasing erosion and sedimentation that, in turn, alter the basin water regulation infrastructure;
  
• 
  Soil contamination;
  
• 
  Diminishing wetlands and biodiversity;
  
• 
  Environmental issues in mountain regions, i.e. preservation of the glaciers, sustainability of mountain forests, and erosion of mountain slopes (Roll and Alexeeva 2005).
  

Roll and Alexeeva (2005) also add that human-induced desiccation of the Aral Sea has brought about some negative problems, such as desertification, dust and salt winds, changes in the regional climate, health problems of the population.
Generally speaking, the Aral Sea catastrophe primarily relates to the sharp shrinking of the Aral Sea, but meantime, we also should take into consideration a crucial issue: If the Syrdarya and Amudarya water does not reach the Aral Sea where this water is distributed?

CEU eTD Collection
It is widely known, that the drying out of the Aral Sea is mainly determined by human factors which contribute 80% to the shrinking of the Aral Sea. The remaining 20% is due to a natural factor, i.e. change of the regional climate. The human-induced factor primarily implies an excessive use of Syrdarya and Amudarya water for irrigation purposes (Mamatkanov 2001).
Apart from this, an inadequate efficiency of water resources for use in irrigation farming is an important issue for discussion. ICWC (2002) indicates that water losses occur in the on-farm delivery networks and directly in the fields. According to WUFMAS, water losses in these two cases can amount to 40% of the total supplies coming to the irrigation areas (ICWC/SIC 2002).
Additionally, due to obsolete condition of the irrigation channels and collector-drainage systems, a significant amount of water is discharged into the nearest depressions and lowlands. The Aydar-Arnasay lakes system, originally formed as a result of water discharges from the Chardara reservoir and fed by collector-drainage water from the Golodnaya Steppe irrigation area for a long period of time, is a distinct example of Aral water redistribution (Severskiy 2004). Summarizing, Severskiy emphasizes that namely insufficient use of water resources and very old collector-drainage network have resulted in shrinking of the Aral Sea and formation of the new artificial system such as the Aydar-Arnasay lakes in Uzbekistan.

2.