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 46 毫秒
1.
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   

2.
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   

3.
The proposed dam across the Kerch' Strait is opposed both on econonic grounds and because it is unlikely to achieve its basic purpose of reducing the salinity level in the Sea of Azov and restoring earlier fish productivity. Calculations are presented to show that the additional streamflow into the Sea of Azov needed to reduce salinity from the present 15 per thousand to 10 per thousand would be far more costly than the revenue that could be derived from fisheries. It is proposed that the loss in fish productivity in the Sea of Azov might be compensated for far more economically by developing pond fisheries in the drainage basin and by introducing brackish-water and marine species into the sea.  相似文献   

4.
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   

5.
The government committee charged by the former USSR Supreme Soviet with formulating measures for resolving the Aral Sea crisis presents a list of basic recommendations for ameliorating public health and economic problems in the Aral Region and reversing the decline of the sea. Considerable emphasis is placed on basic structural change in the regional economy and water budget. A staged procedure is outlined for the gradual transformation of the water balance and economic structure while maintaining the Aral Sea as a single (unified) water body.  相似文献   

6.
In an effort to stabilize the declining level of the Caspian Sea, it has been proposed that evaporation from the water surface be reduced by decreasing the size of the sea through construction of a dam in the northern portion. Data on the geology and hydrology of the Caspian Sea bed suggest that the construction of a dam might have undesirable consequences not only for the northern fisheries basin but for the sea as a whole. The findings are based on the presence of salt domes on the bottom of the northern Caspian Sea. An influx of highly mineralized subsurface waters along faults associated with the salt domes as well as leaching of salt from the structures themselves may threaten to raise the salinity of the northern fisheries basin to intolerable magnitudes. The presence of a man-made dam, in the author's view, would also interfere with the natural circulation of water, threatening contamination of deeper layers of the Caspian Sea with hydrogen sulfide, as has happened in the case of the Black Sea. [For a discussion of the Caspian Sea problem, see Soviet Geography, November 1972.]  相似文献   

7.
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   

8.
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   

9.
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   

10.
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   

11.
The economics of Central Asian transportation are such that railroads are more economical than waterways if they run parallel, but water transport is considerably more economical than motor transport in the absence of railroads. This explains why shipping was never significant along the Syrdarya, one of the two major streams of Central Asia, which has been paralleled by a railroad (from Orenburg to Tashkent) since 1906. The situation was different in the case of the Amudarya, which was paralleled by a railroad in its lower reaches only since 1955. The significance of shipping on the Aral Sea is declining rapidly as more water is being withdrawn from its tributary streams for irrigation and the sea level is dropping. The author sees a future for water transportation on a southern east-west route made up by the upper reaches of the Amudarya and the Karakum Canal. However, such a route would require considerably additional capital investment on the canal to make it accessible to larger barges.  相似文献   

12.
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   

13.
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   

14.
刘桂春  韩增林 《人文地理》2007,22(3):51-55,27
随着社会生产力的提高,人类认识和干预自然的能力逐渐增强,人地关系也随之向广度和深度发展。在人地关系发展初期,人与陆地之间的相互作用强度远大于人与海洋之间的相互作用,而人地关系发展至今天,"地"的概念已经扩展到陆地和海洋的总体。本文首先阐述海陆复合生态系统理论,在此基础上分析海洋功能介入到原本主要以陆地为基地的人地关系系统中的机制问题。文章认为,海陆生态系统的进化、系统开放性所决定的物质能量和信息的交流以及人类需求的拉动都可能解释海洋功能对人地关系系统的介入。  相似文献   

15.
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   

16.
从地理学角度看,湖泊都有自然沼泽化的趋势。人类活动可以加剧或者减缓这种趋势。杭州西湖就是由于人们古往今来的长期良性开发,才得以保存至今而且成为著名风景胜地的。在阐明这一原理的基础上,本文分析评价了近20余年来人们对此湖的开发行为,结论是:良性和非良性开发都在持续。这一结论对国内许多同类湖泊而言具有一定普遍性或代表性。  相似文献   

17.
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   

18.
Vertical and lateral variations in lithology, salinity, temperature, and pressure determined from wireline LAS logs, produced water samples, and seismic data on the south flank of a salt structure on the continental shelf, offshore Louisiana indicate three hydrogeologic zones in the study area: a shallow region from 0 to 1.1 km depth with hydrostatically pressured, shale‐dominated Pleistocene age sediments containing pore waters with sea water (35 g l?1) or slightly above sea water salinity; a middle region from 1.1 to 3.2 km depth with near hydrostatically pressured, sand‐dominated Pliocene age sediments that contain pore waters that range from seawater salinity to up to 5 times sea water salinity (180 g l?1); and a deep section below 3.2 km depth with geopressured, shale‐dominated Miocene age sediments containing pore waters that range from sea water salinity to 125 g l?1. Salt dissolution has generated dense, saline waters that appear to be migrating down dip preferentially through the thick Pliocene sandy section. Sand layers that come in contact with salt contain pore waters with high salinity. Isolated sands have near sea water salinity. Salinity information in conjunction with seismic data is used to infer fluid compartmentalization. Both vertical and lateral lithologic barriers to fluid flow at tens to hundreds of meters scale are observed. Fluid compartmentalization is also evident across a supradomal normal fault. Offset of salinity contours are consistent with the throw of the fault, which suggests that saline fluids migrated before fault formation.  相似文献   

19.
方嘉雯 《人文地理》2013,28(3):64-69
秦腔起源于古代陕甘一带民间歌舞,流行于陕、甘、青、宁、新等地。本文从文化地理学的角度,采用文化扩散和整合的思维着重分析了秦腔文化形成的自然地理与社会原因,系统探讨了不同时期和地区秦腔文化的扩散类型、传播路径与整合特征。结果认为,秦腔文化扩散的主要方式是人口迁移与艺人游走,特点是多级化。秦腔文化景观反映当地发展史,是多种地域文化要素相互作用的产物,传播时的屏障作用具有正负双重影响。未来秦腔文化的发展要根植于群众并植入现代元素,以实现秦腔文化新的繁荣。  相似文献   

20.
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   

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