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Human driving forces
A number of human factors have interacted to create the widespread environmental changes described above.
First, population changes are clearly important. Between 1950 and 1988, the population of the Aral Sea basin grew dramatically - from 13.8 to 33.2 million people, comprising increases from 8.1 to 19.9 million in Uzbekistan, 1.0 to 2.2 million in Kirghizstan, 2.0 to 5.1 million in Tadzhikistan, 1.5 to 3.5 million in Turkmenistan, and 1.2 to 2.4 million in Kazakhstan (all within the sea-basin limits).
In 1990, the population of the Aral Sea basin numbered 34 million. Very high natural population increases typify this region. This was true throughout the period 1950-1989. Mean annual rates of population increase in the late 1980s amounted to 2.85 per cent in Uzbekistan, 2.60 per cent in Kirghizstan, 3.2 per cent in Tadzhikistan, 2.65 per cent in Turkmenistan, and 1.06 per cent in southern Kazakhstan (as compared with 0.95 per cent in the USSR as a whole).
Table 3.4 Average content, expressed as fractions of maximum permissible concentration (MPC), of DDT and hexachlorocyclohexane (HCCH)*
|Republic area||DDT (MPC = 0.1)a||HCCH (MPC = 0.1)a|
|Gorno-Badakhshan autonomous area||1.28||0.03|
|Kazakhstan(Chimkent and Kzyl Orda)||0.10||0.07|
Source: Unpublished data provided by Republican Agricultural
a. Numerator refers to the spring levels; the denominator to autumn levels. MPC expressed as mg/kg.
Population growth is connected not with immigration but with natural increase, which amounted to 18.1 per cent in the Kazakhstan part of the basin, less than 5.5 per cent in Kirghizstan, less than 8.5 per cent in Turkmenistan, 30.8 per cent in Uzbekistan, and 35.2 per cent in Tadzhikistan (as compared with 6.8 per cent in Russia). The inhabitants of the Aral Sea basin have the largest families - ranging from 5.51 members for Kazakhs to 6.48 for Tadzhiks in the former USSR (where the mean figure in 1990 was 3.51).
Children and young people occupy a significant place in the age structure owing to the high natural increase of population. Children and teenagers up to 15 years of age comprise 42.5 per cent of the population in the Aral region (as compared with 26.8 per cent in the former USSR). Therefore, there are fewer people of working age here than in the USSR (49.2 per cent against 56.7 per cent). Thus more than half of the population is outside the age-limits of an able-bodied population. This circumstance aggravates the complex social situation in the region.
This age structure of the population also has a partial bearing on some of the medical problems. Because schoolchildren were extensively involved in cotton raising, environmental risks associated with the use of herbicides and defoliants affected children more than might ordinarily be expected.
Most of those professing religious belief are adherents of Islam, chiefly of Aryan and (to a lesser extent) of Shiite persuasion. Believers among the Pamir belong mainly to the Shiite group of Ismailites. In addition, other religions exist within the region. The multinational and multireligious character of the Aral Sea basin population needs to be taken into account when considering impacts and potential solutions.
Over the same period, both industrial and agricultural production also increased. Variations in river runoff and environmental pollution caused the principal environmental changes in the Aral region. Though water consumption in industry and municipal economies increased during this period, water consumption in these branches of the economy never exceeded 4-5 km³ per year (table 3.5). Clearly, the development of agriculture and, more specifically, the growth of irrigation have been the main engines of environmental change.
The area of irrigated land has increased since the early 1960s by 1.5 times in Uzbekistan and Tadzhikistan, 1.7 times in Kazakhstan, and 2.4 times in Turkmenistan. Significant capital investment in agriculture has accompanied this growth in irrigation. Thus, the funds to support agricultural production have increased 5-7 times, power generation capacities in agriculture have grown by up to 6 times, the number of tractors by 3.2 times, and tractor engine power by 7.6 times. Meanwhile, use of chemical fertilizers has grown two- to sixfold (table 3.6). Particularly noteworthy is the fact that fertilizer consumption per hectare is 2-3 times higher in the Central Asian republics than in the Russian republics. Thus, the growth of irrigation in the Aral Sea basin has been accompanied by enormous investments in agricultural production (table 3.7). At the same time, one should note that the basic capital investments were made almost solely for water-reclamation projects.
Table 3.5 Use of the water resources of the Aral Sea basin at the level of the mid(km³/year)
|Economic sector||Water intake||Water diversion||Water consumption|
|Industry and power generation||8.3||6.4||1.9|
|Agricultural water supply||0.86||no data||no data|
Whereas irrigation is generally necessary in arid regions, the design, construction, and exploitation of irrigation systems in the Aral Sea basin have involved far-reaching and serious drawbacks. The extensive development of irrigation paid attention primarily not to increasing productive output on existing land but to expanding irrigated areas. Frequent cultivation of severely salinized lands required substantial reclamation efforts but yielded only very modest harvests. All too often, unprepared land was used for irrigation. At the same time, the quality of many irrigation systems was very poor. Irrigation canals and drainage collectors, for example, were often constructed without filtration linings. Thus, the efficiency of irrigation systems is extremely low; some 30-45 per cent of all water is estimated to be lost.
Table 3.6 Use of chemical fertilizers in the Aral Sea basin, 1960-1985 (calculated for 100% of nutrients; kg/ha)
Table 3.7 Capital investment in agriculture in Uzbekistan, 1956- 1987 (million roubles)
|Period||For agriculture as a whole (excluding forestry and timber)||Including reclamation construction|
|1956 - 1960||1,729||459a|
|1961 - 1965||3,120||1,091a|
|1966 - 1970||5,441||2,042a|
Source: Uzbekistan (1988).
a. For construction of the water economy only.
Irrigation techniques are also extremely primitive. Thus, in Uzbekistan, 89.5 per cent of the irrigated area in 1977 was watered by means of furrows and only 1.5 per cent by means of sprinklers (USSR 1984). In the Tashauz area of Turkmenistan, 95 per cent of land was irrigated manually along furrows in 1984 (Batyrov et al. 1984). Systems of continuous control of soil and air humidity and plants are virtually non-existent.
Increased water saving could be achieved by instituting changes in rice cultivation. Irrigation levels for rice in the Aral region amount to 26,00034,000 m³/ha (USSR 1984), and water intake has reached at least 80,000 m³/ha in the lower reaches of the Syr Darya (Voropayev, Ismaiylov, and Fedorov 1984). A primary reason for this large discharge of water is the irrational choice of rice cultivation, with its numerous embayments and operational losses of water.
Water demands for irrigation currently take little or no account of soil attributes. Water budget and water thermobudget methods take into account only the thermal-physical properties of soil (USSR 1984). The possibility of short-term droughts, mineralization, and the composition of irrigation waters have also not usually been considered. Indeed, irrigation practices were developed assuming maximum possible harvests (USSR 1984); this is often unreasonable both economically and ecologically.
Current water demand for cotton in the Aral region amounts to 7,50012,500 m³ per hectare. At the same time, farming data in the Karakalpak Republic suggest that optimal irrigation standards for cotton may be 3,5004,400 m³/ha (with yields of 2.5-3.0 tonnes/ha). One species cultivated requires 2,500-3,000 m³/ha of water for the growing period, with a yield of 2.2 tonnes/ha. An irrationality attendant on water use is also apparent in the fact that the growth in water consumption in irrigated farming has greatly outstripped the increments to irrigated areas (fig. 3.4). Comparison of human-induced (anthropogenic) runoff expenditures with natural expenditures (evaporation and transpiration in river-beds, flood plains, and deltas) shows that the former are largely responsible for water deficits in the region (table 3.8).
As mentioned above, large amounts of fertilizers and herbicides have been used on irrigated land. In fact, fertilizer use in the Aral basin exceeds the average use in Russia by 10-15 times, and the amount of herbicides, defoliants, and other pesticides applied reaches 54 kg/ha (whereas, in the former USSR, 3 kg/ha was the average). These fertilizers eventually reach the rivers through drainage runoff, which is often used for the drinking-water supply. Many food products are also contaminated with pesticides, and their concentrations sometimes exceed the maximum permissible concentration for air.
The use of drainage runoff also reflects irrationality. In the first half of the 1980s, the drainage runoff (i.e. the runoff of drainage and discharge waters) amounted to 29-46 km³ per year. It should be emphasized that the existing accounting system does not allow a precise determination of the volume of drainage runoff, part of which is discharged by relatively small drains to the desert and is not taken into account. Also, diversions in large main drains are not measured adequately. Part of the drainage waters, for example, is secretly pumped to irrigation canals. All figures for drainage runoff, therefore, need to be more precise. In recent years, drainage runoff has increased owing to the expansion of irrigation areas; it apparently now amounts to at least 45-50 km³ per year, of which 25-26 km³ is discharged into rivers, 10-12 km³ to lakes, and 10-15 km³ to the desert.
Table 3.8 Changes In runoff, caused by natural and anthropogenic effect, from the main rivers of the Aral Sea basin, 1932-1985 (km³/year)
|Syr Darya basin||Amu Darya basin|
Source: Data provided by the State Hydrological Institute.
A solution to the drainage runoff problem is needed for several reasons. First, drainage runoff is one type of water resource that could contribute to reducing water deficits. Second, drainage waters in a desert often result in salinization of soils and groundwater, whereas discharges to rivers often produce increased mineralization and toxicity of river water.
Growth of water consumption for irrigated farmimg in the Aral Sea basin, 1930-1990
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