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1.
M. V. Isupova 《Water Resources》2008,35(6):615-634
Long-term water level variations in the Volga mouth area and the effect exerted on them by the river’s flow and the Caspian Sea’s level variations are considered. Quantitative relationships were identified between the mean annual water levels at different gages in the mouth and the sea level. A backwater component was isolated in the long-term variations in water level in the Volga mouth area. Relationships between the daily water levels in the mouth and the Caspian Sea’s level at fixed water flow in the delta apex are presented. The magnitude and the propagation distance of backwater from the sea into the delta are specified. The responses of the mouth areas of rivers emptying into the Caspian Sea to sea level variations in the past century are compared. 相似文献
2.
The regularities of surge-induced water level variations in the Danube mouth are considered. The recurrence of level rises and drops in the near-shore mouth zone is evaluated. The regularities of the propagation of surge-induced level variations into the delta and over the near-delta reach of the Danube are established. The magnitude of positive and negative surges in the delta and the extent of their propagation are shown to depend on the surge phenomena in the offshore zone and the Danube water discharge.Translated from Vodnye Resursy, Vol. 32, No. 1, 2005, pp. 35–47.Original Russian Text Copyright © 2005 by Isupova, Mikhailov, Morozov. 相似文献
3.
A. M. Nikanorov L. I. Minina V. A. Bruzgalo L. S. Kosmenko M. Yu. Kondakova O. S. Reshetnyak A. O. Danilenko 《Water Resources》2016,43(5):791-802
Many-year variations of water pollution and the state of more than two hundred of rivers (or their segments) in different latitudinal zones in European Russia are estimated. In accordance with latitudinal zonality, space and time trends in variations of water quality and the state of rivers are identified. By the level of water pollution, most river ecosystems (or their segments) were classified as polluted and very polluted, very polluted and dirty, dirty and very dirty. A tendency toward water quality improvement could be seen in the recent decade. More than 50% of the examined river ecosystems are at the transitional state of passing from natural (and/or equilibrium) to crisis state. 相似文献
4.
V. N. Mikhailov D. V. Magritsky V. I. Kravtsova M. V. Mikhailova M. V. Isupova 《Water Resources》2012,39(1):11-43
Regularities in the response of the mouths of major rivers, flowing into the Caspian Sea, to large-scale variations in its
level and river water runoff and sediment yield are considered. Changes in the morphological structure and hydrological regime
of the Volga, Terek, Sulak, Ural, and Kura mouths have been analyzed in both geological past and separately for three modern
periods: a considerable drop in Caspian Sea level before 1978, its abrupt rise in 1978–1995, and a relative stabilization
in the subsequent years. Specific features were identified in the hydrological-morphological processes in different mouths,
caused by the differences in river sediment yields, and the slopes of delta surface and mouth nearshore beds. Some theoretical
and methodological approaches were verified in the analysis and evaluation of the processes under consideration. The obtained
results of studies of the mouths of rivers flowing into the Caspian Sea can be regarded as examples and analogues in the assessment
of processes, which take place at the mouths of other Russian and world rivers at present and can take place in the future
under anticipated natural and anthropogenic variations in sea level and river runoff. 相似文献
5.
Variations in the mouth areas of the Yenisei and Pur rivers over the period of 50 years were revealed on the basis of comparison of topographic maps prepared in the 1950s and space images made from the Landsat satellite in 1973 (MSS System) and 1999, 2000 (ETM System). Maps of the drainage network dynamics were compiled; they show that, over a period of many years, mouth areas of northern rivers undergo slow but steady changes, which are indicative of the continuing protrusion of deltas into bays at a rate up to 20 m/year, the increment in mouth areas reaching 0.05–0.07% a year. As noted, secondary water streams die off under the condition of flow concentration in main branches, and small islands get integrated. It was found that, over the period under study, natural variations in the level of the receiving water body and human-induced changes in river basins (construction of a chain of reservoirs) did not have considerable impact on dynamic processes occurring in deltas. 相似文献
6.
M. V. Mikhailova 《Water Resources》2016,43(5):766-778
Data on several river deltas are used to analyze the regularities in their dynamics in the context of variations of water and sediment runoff, sea level, and hydroengineering activities in delta areas. The basis for this analysis includes the results of many-year studies of river deltas in Russia and the world. The specific features of the evolution of the structure and morphometry of bayhead deltas, forming in bays, lagoons, and estuaries are shown in the case of the Alikazgan delta in the Terek mouth area and the deltas of two watercourses in the Mississippi mouth area. Data on many-year variations of the morphometric characteristics of modern protruding deltas in open coastal zones are systematized, and the factors that have an effect on these changes are analyzed. The types of delta formation processes and the types of deltas are considered with regard to the factors involved. The majority of modern river deltas are found to slow down their progradation into seas under the effect of anthropogenic runoff decline; moreover, some deltas have started retreating and degrading. 相似文献
7.
The main results obtained by processing satellite photographs of the delta and the shallow offshore mouth area of the Volga made from 1975 to 1997. The study includes electronic treatment of the photographs, zoning of the delta and shallow offshore mouth area, and the evaluation of their main quantitative characteristics. Space and time variations in the boundaries of zones, main landscape components, and the hydrological characteristics (higher aquatic plants, currents, water flow, sediments, etc.). The environmental state of the identified zones and the role of anthropogenic load are estimated. 相似文献
8.
The dynamic type of ice drift development is found to dominate in the mouth zones of the Northern Dvina and Pechora rivers in the period of spring ice break. The ice drift is accompanied by the formation of ice jams in the mouth, the most common among them being jams of arched and wedge type. The jams are a common cause of flooding of towns and settlements in the region. The particular features of ice breaking in the mouths of northern rivers are discussed along with the regularities of ice jam formation during ice drift. The formation of jams is shown to be associated with stable retardation of ice in the sites of river channels that have specific morphological characteristics or to be caused by drifting ice mass running into solid ice fields in lower parts of river delta arms. 相似文献
9.
青海湖水位变化与湖区气候要素的相关分析 总被引：9，自引：2，他引：7
对湖区现有气象和水文资料作相关分析后得出,影响青海湖水位或水量的主要气象因子是前期降水量、当年蒸发量、水汽压饱和差及融冰期开始后的气温。影响湖周水系流量的气象因子则视发源地远近而异：源于近处的短程河溪的流量受制于当时降水量;源于冰山雪岭的较长河流的流量,由发源地及其流域的固态水储量和当时热状况而定。 相似文献
10.
1996年 1 1月 9日长江口以东海域发生 MS6.1地震 ,震前巢湖地下水动态观测网中 3口深水井所记录到的水位经标准差、剩余值数据处理得到前兆异常。其异常时间以中短期为主 ,不同步。本文还对如何提高地震预报的准确性及降水对井水位的影响等问题进行了讨论。 相似文献
11.
The formation of the runoff of small rivers in different natural zones of the cis-Urals Region is analyzed. Correlation between variations in the flood flow of small rivers and changes in the system of agricultural land use in 1936–1995 in the Southern cis-Urals is shown. The dependence of the balance of melt water on the topography and type of farming lands on the slope is discussed. The effect of fall plowing on the coefficient of snowmelt runoff is assessed. 相似文献
12.
E. N. Dolgopolova 《Water Resources》2017,44(6):808-819
The factors that govern the distribution and transformation of tidal waves in the macrotidal estuary of the Mezen River have been considered, including tide range in the mouth section, water discharge in the river’s lower reaches, estuary shape, and bed resistance coefficient. Data on variations of water discharge over period 1920–2008 are given. The parameters of estuary channel narrowing in horizontal and vertical sections have been considered. The effect of narrowing and bed hydraulic friction on tide wave amplitude has been evaluated. Froude number values for the tidal estuary suggest that tidal bore can form at the Mezen mouth. The conditions of the propagation of tidal waves to the mouths of different rivers and tidal bore formation in them are considered. 相似文献
13.
气候变化对湖库水环境的潜在影响研究进展 总被引：4，自引：3，他引：1
本文着重归纳气候变化对湖库热力特性、冰期、溶解氧、营养盐、浮游植物和水生植物等方面的影响规律,探讨气候变化对湖库水环境潜在影响的区域差异,讨论现有研究方法的优缺点和发展前景.研究表明,气候变暖对湖库物理过程的影响最为显著;热带草原气候和温带海洋性气候对于气候变暖和降雨变化的响应较其他气候类型突出;气候变化对湖库水环境的影响效果具有两面性.通过分析各气候类型中气候变暖对磷水平的潜在影响差异表明,亚热带季风气候的湖库更可能受气候变暖的影响趋于富营养状态.在今后研究中,建议深入开展各气候类型中区域性气候变化对湖库水环境影响的实例研究. 相似文献
14.
Regularities in processes of seawater intrusion into the rivers of Senegal, Saloum, Gambia, and Casamance in West Africa are analyzed. The seawater intrusion during the low-flow period, which is a common phenomenon for the lower reaches of these rivers, has taken on extreme features in the course of the severe drought that occurred in West Africa in the 1970s–1980s. The processes of progressing water salinization in estuaries under the impact of drastic reduction of atmospheric precipitation and river runoff, considerable evaporation water losses, and tides are described. Due consideration is given to the unique hydrological phenomenon, i.e., the so-called reverse estuary. The Senegal River mouth is taken as a case study of cyclic variations in runoff, water salinity, and distance of saltwater penetration into the river. Certain environmental consequences of water salinization are discussed using the Casamance River estuary as an example. Methods used in Africa to prevent seawater intrusion and salinization of estuaries harmful for the environment and economy are described in this article. 相似文献
15.
The basic peculiarities of the hydrological regime of one of the largest mouth areas of the world, i.e., the common mouth of the rivers of Ganges and Brahmaputra, are discussed. The main features of natural conditions (including climatic) of the mouth of these rivers and the delta drainage system are characterized. The hydrological regime of the Ganges and Brahmaputra rivers, the largest rivers of South Asia, is studied in greater detail; the quantitative assessments of the water and sediment runoff of these rivers are specified. Provision is made for revealing the basic peculiarities of river flow distribution among numerous delta branches, annual floods during southwest monsoons, tidal phenomena in the maritime zone of the delta, and disastrous storm surges and inundations in the period of tropical cyclones. Flood control measures taken in Bangladesh to protect the population and lands are described. 相似文献
16.
Michael Mutz Herve Pigay Kenneth J. Gregory Dietrich Borchardt Michael Reich Klaus Schmieder 《Limnologica》2006,36(2):110-118
Dead wood is a significant element of natural streams and rivers in temperate climate zones. Established stream management removes wood, whereas some scientists recently promoted the reintroduction of wood in stream rehabilitation and restoration. It is desirable to know if wood in streams and rivers would be accepted. A survey was therefore conducted in order to assess the spontaneous visual perception of 10 stream and 10 river scenes with and without wood in terms of naturalness, risk, aesthetics and need for improvement using visual analog scales. Three hundred and sixty-five German students from five subjects related to water management and from one subject without any professional association to running waters were surveyed before their first contact to teaching of aquatic ecology. They clearly perceived wood in streams and rivers as natural. Scenes with wood were most frequently associated with danger for sport activities while scenes without wood were most frequently associated with danger by flooding. When comparing scenes with and without wood, scenes with wood were clearly considered more positive as significantly more aesthetic, less dangerous and needing less improvement. The disciplinary groups showed variations in the absolute evaluation scores but the relative evaluation of scenes with wood versus scenes without wood was similar among all groups. The results indicate an acceptance for the reintroduction of wood in stream rehabilitation and restoration by young students who are potential future players in water management. 相似文献
17.
The hydroclimatic conditions of water runoff formation and the hydrography of Parana and Uruguay river basins in the South America are considered. A survey of the recent studies of the hydrological regime of these rivers is given. Observation data are used to evaluate the long-term average values of water runoff and suspended sediment yield in the Parana and Uruguay and their variations along the rivers. Characteristics of many-year runoff variations in the rivers were evaluated. A climate-induced increase was identified in the Parana and Uruguay water runoff, and the corresponding present-day trends in river runoff variations in both rivers were evaluated. The total water runoff and suspended sediment yield of the Parana and Uruguay into La Plata estuary were calculated. Water balance of the drainage basin of La Plata estuary was characterized. 相似文献
18.
19.
A close negative correlation was found to exist between oxygen concentration in winter and the latitude in rivers in the basins
of the Ob and Volga. This can be explained by an increase in the duration of the freeze-up period (during which oxygen is
consumed for oxidation of organic matter (OM) in water and bottom sediments) in the direction from the south to the north,
while the input from oxygen from the atmosphere and photosynthesis is practically zero. No inverse relationship was found
to exist between dissolved oxygen and the latitude, because in rivers of mountain and semimountain types, typical of this
basin, organic matter (OM) does not accumulate in bottom sediments and the conditions of atmospheric circulation are better
than in lowland rivers. The magnitude of seasonal variations in oxygen in lowland rivers is greater than in mountain ones
because of an abrupt drop in oxygen concentration in slowly flowing rivers in winter and the saturation of their water by
oxygen from photosynthesis in summer. 相似文献
20.
A study on 3-D velocity structure of crust and upper mantle in Sichuan -Yunnan region, China 总被引：1，自引：0，他引：1
Many evidences indicate that the collision of two plates deformed strongly the crust of the SYR, and the deformation has been continued up to the present. In addition, the SYR is in the south segment of the South-North Seismic Zone of China, which is one of the regions in the Chinese mainland, where the seismic activity is very high, and the strong earthquakes frequently occurred. Since the 1970s, a series of large earthquakes with magnitude M>7.0 occurred in SYR, such as the 1970 Tongha… 相似文献