首页 | 本学科首页   官方微博 | 高级检索  
相似文献
 共查询到20条相似文献,搜索用时 31 毫秒
1.
The author examines the problem of the present state of the environment in the desert irrigation districts of southern Kazakhstan and Central Asia. A drop of the level of the Aral Sea and the formation of new land on the exposed seabed, the desiccation and desertification of the Amudarya and Syrdarya deltas caused by an intensification of agriculture have been proceeding against the background of a series of dry years. Irreversible environmental changes are having a negative impact on the socioeconomic conditions of the Aral region. The author, basing himself on the results of scientific investigations related to the Aral Sea problem, proposes a number of measures designed to moderate this negative impact.  相似文献   

2.
A specialist in loess geomorphology and arid-zone hydrology distinguishes three categories of factors accounting for waterlevel changes in the Aral Sea. She judges the most significant to be changes in inflow resulting from changes in the course of the Amudarya, the more important of the two tributary streams. The Amudarya at various times emptied into the Sarykamysh depression, southwest of the Aral Sea, giving rise to a flow of water through the now dry Uzboy channel to the Caspian Sea. Climatic change, involving alternations of wet and dry cycles, is said to have accounted for only minor water level fluctuations, of the order of 4 to 6 m, against the background of the major fluctuations produced by the Amudarya course migrations. Human activity, notably irrigation, is regarded as having become significant only in modern times as a result of an expansion of irrigation works. The present abrupt decline in the Aral waterlevel (6 m from 1960 to 1977, including 2 m in the last three years) is attributed to the combination of a dry climatic cycle and greatly increased use of water for irrigation.  相似文献   

3.
In view of the declining inflow into the Aral Sea, alternative proposals are advanced to save this inland sea by reducing its area as well as its salinity levels. The proposals involve the closing off of some portions of the sea, notably the Little Aral in the northeast and the Western Aral, from the large shallow eastern portion. Some portions of this fragmented sea would then be treated as active bodies of water with a throughflow regime, discharging surplus waters of high salinity into other portions, which would be allowed to become salt marshes. Various combinations of active water areas and residual water areas are examined, and possible trends in waterlevel and salinity are projected to the middle of the 21st century.  相似文献   

4.
Although both the Caspian and Aral Sea basins are affected by fluctuations in the general moisture conditions affecting the Northern Hemisphere, the two drainage basins react differently to identical moisture changes both over the long term and over the short term. Over the short term, a shift in wet periods has been observed between the European part of the USSR, which contains the Volga basin draining into the Caspian, and western Asia, which contains the Aral Sea drainage basin. Since there is a direct relationship between general moisture conditions and level changes, the short-term level fluctuations would be heterochronous (out of phase) in the two seas. Over the long term, the comparison is complicated by the fact that Caspian drainage derives mainly from snow meltwater in the Russian plain while Aral Sea drainage derives from a combination of snow and glacier meltwater. Glacier runoff tends to increase in dry, warm periods and to decrease in wet, cold periods of glacier growth, while snow is related directly to general moisture conditions.  相似文献   

5.
The article examines the prospects of using runoff characteristics and changes in runoff composition as a basis for predicting environmental modification. The technique is employed to assess changes in the circulation of matter that are taking place in the drainage basin of the Aral Sea as a result of the intensification of irrigation. Overall runoff, including its liquid, solid (suspended sediment) and chemical phases, is analyzed in connection with a shift in the deposition of material from the Aral Sea to the irrigated plains.  相似文献   

6.
The history of variations of the level of the Aral Sea from the most ancient times is reviewed and much useful information presented on natural regimes of the Aral's tributary rivers, the Amudar'ya and Syrdar'ya; the natural high- and low-water cycles of the Aral; and historical episodes where natural or human events diverted the Amudar'ya's flow westward into Lake Sarykamysh, which served as a kind of “alternative Aral” during these situations. Thus, the present decline of the Aral and growth of Sarykamysh can be viewed as just one cycle (albeit man-modified) of an Amudar'ya-Aral-Sarykamysh drainage system. Translated by Edward Torrey, Alexandria, VA 22308 from: Izvestiya Akademii Nauk SSSR, seriya geograficheskaya, 1990, No. 1, pp. 78-86.  相似文献   

7.
An analysis of evaporation changes in the Central Asian plain in connection with the drop of the Aral Sea level beginning in 1961 shows that there has been a reduction in evaporation from stream valleys and deltas and an increase in evaporation from irrigated land and newly formed evaporating surfaces. These new entities are primarily the Arnasay depression (west of the Golodnaya Steppe irrigation district) and the Sarykamysh depression (west of the lower reaches of the Amudarya), which have become filled with spent irrigation water draining from the irrigated land. Another new source of evaporation associated with human activity are the lakes and wetlands formed along the Kara Kum Canal as a result of the filtration of canal water. It turns out, furthermore, that irrigation on sloping piedomon plains, such as those watered by the Kara Kum Canal, requires more water than in old irrigated alluvial plains because of the additional water needed to flush salt out of the soil and to fill subsoil cavities and raise the watertable.  相似文献   

8.
The author, an expert in Central Asian toponymy, culture, and physical geography, examines major trends in research on the Aral region's geography by focusing on major themes of paleogeography, bottom and shoreline morphology, hydroclimatic conditions, migration of salts, and forecasting negative impacts of hydrological engineering projects on the region's environment. In the process he presents much interesting material on the early history of the sea and its hinterland (most notably, the deltas of the Syr Dar'ya and Amu Dar'ya) and about differences in the interpretation of quantitative information about the sea by scholars at different times and using different methodologies.  相似文献   

9.
The Sarykamysh depression of Soviet Central Asia, southwest of the Aral Sea, has begun to fill with water since around 1960 after having lain dry for 350 years. As of 1976, the lake, fed mainly by irrigation drainage water from the nearby Khorezm (Khiva) oasis, had grown to 2,000 km2, with a depth of at least 40 m. The depression was receiving 4 to 4.5 km3 of water a year and continued to fill. While the appearance of such a large body of water in the desert would appear in itself to be a positive development, the question is raised whether the water would not be put to better use by being directed toward the Aral Sea.  相似文献   

10.
The increasing demand on water in the Soviet Union and the problem of assuring water quality require the construction of long-term water-management balances by drainage basins. These balances, based on predicted demand and water availability, would suggest the need for water-management projects within basins and interbasin transfers. Water needs would be evaluated both in terms of water requirements by categories of users and in terms of water quality. The most crucial regional problems involve the increasing shortage of water in Central Asia (with the prospect of interbasin transfer from Siberia) and in southern regions of the European USSR (with the problem of diverting water southward from the northern runoff slope). The Caspian Sea is expected to require a supplementary inflow of 80 to 100 cubic kilometers a year by the end of the century if the decline of its waterlevel is to be arrested. But southward diversion of northern waters is not expected to add more than 50 to 70 km3 at best, with a possible saving of an additional 10 to 20 km3 through decline of evaporation from a reduced Caspian Sea surface. The preservation of conditions in the Sea of Azov, the Aral Sea and Lake Balkhash pose additional water problems. [The senior author died in October, 1974].  相似文献   

11.
An analysis of water-balance components over the 45-year period 1926–1970 seeks to establish their relative significance in the marked decline of the Aral Sea level since 1961. Long-term fluctuations in the sea level are found to reflect both natural fluctuations in the water resources available to the drainage basin and the steady growth of human activity in the watershed area. An increase in water withdrawals for irrigation in the 1950s did not appreciably affect the Aral Sea level because of generally large water resources during those years. The intensive decline of the water level since 1961 is attributed mainly to a growth of consumptive withdrawals from the Syrdarya and Amudarya, the two main tributaries of the Aral Sea. The position of the sea level also depends on the annual fluctuations of evaporation from the sea surface, which tends to be more variable than the annual streamflow to the sea. The subsurface component of Aral Sea inflow, contrary to previous studies, is found to be a negligible factor.  相似文献   

12.
The haunting picture of a disappearing Aral Sea is just part of an overall environmental crisis in the Aral Sea Basin, where millions of people are dependent on agricultural production around the flows of two main rivers, the Amu Darya and Syr Darya. Forced cotton cultivation in the former Soviet Union, in the context of inefficient agricultural organization and production, caused water mismanagement, salinization, water and soil contamination, erosion and the desiccation of the Aral Sea. In the post-Soviet era of ‘transition’, the governments of the Central Asian states and international donors have tried to mitigate the impact of the crisis and contain its scope. Resource-based tensions in the region reflect national (and sometimes ethnic) interests vested in the crucial agricultural sectors that provide foreign exchange and food. Although the Central Asian governments are gradually formulating regional water, land and salt management strategies, the room for manoeuvre that exists to implement policies which would immediately improve the environment, such as efficient water management and sustainable land use, is not being sufficiently utilized.  相似文献   

13.
An American specialist on the water resources of the republics of the former USSR, and especially those in Central Asia, reviews the current state of the Aral Sea Basin water resource with respect to supply, consumption, and the legal/institutional framework governing its use. More specifically, he examines water resources and management in the Aral Sea Basin for the purpose of assessing the potential for either interstate conflict or cooperation among the basin states (including Afghanistan and Iran). The author explores actions that could be taken to enhance water availability in the basin and the status of current structures for interstate management of key shared water resources. Journal of Economic Literature, Classification Numbers: Q15, Q25, R14. 2 figures, 2 tables, 49 references.  相似文献   

14.
An advocate of the diversion of Siberian water to Central Asia presents the latest thinking on such a project and recommends a combination of the diversion of water from the upper Ob' for irrigation of Northern Kazakhstan and the diversion of water from a small lower Ob' reservoir southward across the Turgay divide into the Aral Sea basin.  相似文献   

15.
The delta of the Volga River on the Caspian Sea is a highly dynamic form, whose growth has been affected by a combination of physical and human factors. Rapid delta growth in recent years has resulted in a deterioration of both physical and economic conditions (navigation problems, inadequate moisture supply, overgrowing of shallows with vegetation, loss of spawning grounds). Regression analysis yields a number of relationships between the inflow of water and suspended sediments, on the one hand, and delta growth, on the other hand, with a distinction between periods of a lowering of the Caspian Sea level and relative stability. The regression equations are used to project the likely future evolution of the delta. The only combination of conditions that is likely to limit further delta growth by the year 2000 is the stability of the Caspian Sea level and a period of average moisture supply. In all other cases, the delta is likely to continue its undesirable advance.  相似文献   

16.
An authoritative U.S. analyst of Central Asian water management problems, and former advisor to the Uzbek government on water management issues, surveys the nature and effectiveness of international and regional programs to mitigate the Aral Sea crisis. After first reviewing the history and magnitude of the crisis, the author assesses international and regional assistance programs during the late Soviet period and subsequent initial years of independence for the Central Asian republics within the Aral Basin. A concluding section includes policy recommendations based on the author's extensive experience in the field and familiarity with many of the principal organizations involved. Journal of Economic Literature, Classification Numbers: F35, Q15, Q25. 2 figures, 1 table, 32 references.  相似文献   

17.
A hydrogeologist suggests that nine-tenths of the present stream flow into the Aral Sea can be diverted for other purposes without causing the sea to dry up. The diversion would cause the sea level to drop by 12 meters, where it would stabilize because of a greater intake of subsurface runoff resulting from an increased artesian pressure differential, and because the draining of flooded shore areas and the drying up of reed growths will make more water available through savings in evaporation and transpiration.  相似文献   

18.
An American geographer and noted international authority on water management problems in Russia and Central Asia presents an account of an expedition, in late 2005 (under the sponsorship of the National Geographic Society) to Kazakhstan and Uzbekistan, focused on the Aral Sea. The steadily drying inland sea, with a surface area of 67,500 km2 in 1960, had split into two parts and shrunk to 17,380 km2 in 2006. The paper provides an up-to-date overview of the crisis and presents an optimistic scenario of the sea's future, noting development of economic activities (particularly fisheries) in its surrounding settlements. Journal of Economic Literature, Classification Numbers: O13, Q15, Q25. 6 figures, 1 table, 55 references.  相似文献   

19.
试论环渤海物流网络的形成与运作   总被引:11,自引:2,他引:9  
在简述物流发展背景与研究现状的基础上,作者界定了物流网络的概念与研究地域的范围,并且分析了环渤海物流网络的构成。同时作者仔细探讨了环渤海物流网络的形成机制和运作模式,通过分析,作者认为网络轮廓-海陆地域形状、网络节点-城市、网络联线-运输通道、网络能量-区域经济和运作主体-物流企业等五个要素共同作用而形成了物流网络,其运作由运作模块、驱动模块和调控模块组成。最后作者提出了相应的发展对策。  相似文献   

20.
Summary.   This paper will explore the role of the Isle of Man in the prehistory of the Irish Sea area through an examination of its changing islandscape from the Neolithic through the Iron Age. It was far from insular during prehistory, but the social and economic interactions of prehistoric Manx people around the Irish Sea and beyond were heavily affected by their water-bound environment. The way that the prehistoric Manx perceived their boundaries and their coastal situation is reflected in their ritual and social landscape, their preferential use of coastal areas for monumental architecture, and in the choices they made with regard to the island landscape they inhabited. This culturally constructed sense of islandness allowed the prehistoric Manx people to maintain distinctive local cultures while still playing an active role in the larger Irish Sea region.  相似文献   

设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号