Specific features of ice regime in rivers of the Northern Dvina basin

Variations in the characteristics of ice regime of rivers in the Northern Dvina basin over the last 125 years are analyzed. For the Northern Dvina lower course, potential changes in the dates of the appearance of floating ice and the breakup due to expected changes in the air temperature and the rate of streamflow in rivers are assessed. Special attention is paid to the factors that affect the formation of ice jams and their spatial and temporal variability. The prognostic relationship for the maximum ice-jam stage in the Sukhona River near the town of Velikii Ustyug is presented as an example.     

Oxygen regime of rivers in Volga,Ob, and Lena basins

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.     

Regional Retrospective Analysis of Water and Bottom Sediments in the Upper Volga

Water Resources - The dynamics of water quality in the Upper Volga was analyzed in the segment from the source to the Ivankovo Reservoir. It was found that the increase in anthropogenic stress in...     

Distribution and Activity of Bacteriobenthos in the Upper Volga Reservoirs

Regularities of bacteria distribution in the bottom sediments of the Upper Volga reservoirs are studied. Human-induced changes in the structure and activity of bacteriobenthos communities occurring in water body areas adjacent to towns and settlements are described. Reservoir zones subject to long-term human impact are distinguished.__________Translated from Vodnye Resursy, Vol. 32, No. 4, 2005, pp. 489–499.Original Russian Text Copyright © 2005 by Kosolapov, Krylova, Kopylov.     

Present-Day State of Zoobenthos in the Upper Volga Reservoirs

The state of zoobenthos in the Ivankovo, Uglich, Rybinsk, and Gor'kovskoe reservoirs in 1994–2000 is evaluated based on a number of characteristics. Wide seasonal and year-to-year variations are recorded in some characteristics. Groups of stations are distinguished based on a combination of characteristics and a combined index.     

Heavy Metals in Bottom Sediment in the Upper and Lower Volga

Heavy metal concentrations in bottom sediment in some reaches of the Upper (the Ivankovo Reservoir) and Lower Volga (from Volgograd to the mouth offshore area). The bottom sediment in the Ivankovo Reservoir are shown to be heavily polluted by Cu and Zn and to a lesser extent, by Co and Ni; heavy pollution with Ni and Cr and moderate pollution with Zn and Mn were recorded in the Lower Volga. Principal component procedure was used to assess bottom sediment pollution. The role of organic matter in the formation of the Ivankovo Reservoir bottom sediment pollution with heavy metals is shown to be moderate because of the weak correlation between heavy metal concentration and organic matter content of bottom sediment. The same is true for the Lower Volga because of low organic matter content of bottom sediment. The major role in the redox cycle of elements is shown to belong to Fe in the Ivankovo Reservoir and Mn in the Lower Volga.     

Concentrations of Heavy Metals in the Upper Volga Bottom Deposits

The distribution of heavy metals in the Volga bottom deposits is studied. According to the degree of pollution with heavy metals, three stretches are singled out within the river reach under consideration. A drastic increase in Cu and Cd concentrations in bottom deposits is established. A close statistical correlation between Cu and Pb accumulation and the organic matter content of bottom deposits is revealed.     

Discharge currents in shallow offshore mouth area of the Volga based on space photography data

The main results of studying discharge currents in the shallow offshore mouth area of the Volga River based on space photography materials collected during 1975–1997 are considered. The hydrographic zoning of the shallow offshore zone was elaborated taking into account the obtained data on the positions of discharge streams. The southern marine boundary of the region was established for the first time by the zone of convergence of river discharge streams and marine alongshore currents. A computer technique was developed for the compilation of discharge current maps in the shallow offshore zone of the Volga based on space photographs. An electronic atlas of discharge streams in the shallow offshore zone is created, and maps of discharge currents are compiled for different hydrological phases and stages of the Caspian Sea.     

Long-Term variations in water levels in the Volga mouth area and their dependence on the Caspian Sea level variations

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.     

Seasonal deformation regime of rifts in lowland rivers

Various schemes of within-year transformations of rifts from spring flood to low-water period and autumn freshets have been considered. Such transformations have been shown to manifest themselves in the displacement of rift trough from the upper to the lower point bars, accumulation of sediments in one phase of water regime and erosion of ridges in the other phase, as well as in the advancement of ridge-type micro- and meso-forms of channel relief onto rift saddle. Differences have been revealed between the regimes of rifts composed of sand and pebble-boulder sediments; specific features were identified in the regime of rifts in rivers in permafrost zones and rifts with rock protrusions on the bed.     

Hydrochemical Characteristics of the Upper Volga Reservoirs in the Low-Water Season of 1997

The results of studies of the Ivankovo, Uglich, Rybinsk, and Gorkii reservoirs are analyzed. The studies involved a wide range of hydrochemical (salt composition, biogenic elements, organic matter, oil products, and heavy metals) and hydrophysical characteristics in the summer low-water period. The concentrations of organic matter and major biogenic elements are shown to decrease downstream along the chain of reservoirs with a respective general decrease in the trophic status. Large built-up areas located downstream of the Rybinsk Hydroelectric Plant are shown to adversely affect the river water quality.     

水位变化对河流、湖泊湿地植被的影响

水位是湿地生态水文过程的关键因素之一,其改变将影响湿地植被覆盖度和物种组成,最终产生群落演替.从水位梯度,水位波动和人工控湖、控河工程3方面论述水位变化对湿地植被的影响:由于对水位选择的不同及彼此竞争力的差异,湿地植物种沿水位具有梯度分布现象,同时形态可塑性能对其分布范围产生一定影响;水位波动的频率和淹没持续时间对于植被演替具有基础性的作用,水位波动幅度的影响则相对较小,周期性波动能维持以草本植物为主的湿地植被的物种多样性和稳定性,非周期性波动以洪水、干旱为主,易促进湿地植被向固定的水生或陆生方向演替;人工控湖、控河的影响在机理上并无特殊之处,但保证物种多样性和生态系统稳定性的各种缓解措施具有较高的参考价值.基于机理的量化模型,自然、人为因素驱动下水位变化对湿地植被影响的差别研究,模拟水位波动实验以及人工控湖、控河工程的跟踪观测将是今后该领域研究的热点.     

Methane and the Microbiological Processes of Its Transformations in the Water of the Upper Volga Reservoirs

Specific features of CH₄ distribution and the extent of its transformations in the water of reservoirs in the Upper Volga basin are considered. Methanogenesis was detected in water at some stations. The quantitative characteristics of CH₄ and methane oxidation are shown to correlate with the environmental conditions of the reservoir.     

Assessing the Abundance,Biomass, and Production of Heterotrophic Bacteria in Upper Volga Reservoirs

Water Resources - Two reservoirs in the Upper Volga were studied to determine the abundance, biomass, and production of planktonic, epiphyte, and benthos bacterial communities and to assess their...     

Year to year variations in water balance components in the Volga Basin and their interaction

A method for the assessment of water balance components in a large water basin is discussed. The assessment is based on data on atmospheric precipitation and river runoff. The major components of annual water balance are determined for the Volga Basin for a period of 109 years (from 1892/1893 to 2000/2001). The main statistical characteristics of time series of water balance elements are estimated and their correlation is calculated.     

The Regime of Water and Chemical Runoff in the Upper Volga Basin under Global Warming

Water Resources - The present-day conditions of the formation and distribution of the water resources and chemistry under global warming during the recent decades have been considered. The...     

The regime of dissolved gases and organic matter in Selenga basin rivers

The gas regime and active reaction of water in Selenga basin rivers are analyzed. It is shown that, in the lower reaches of the Selenga and Uda rivers, which experience the highest anthropogenic impact, the minimal values of hydrogen index were recorded in under-ice period, while in the rivers of Chikoi, Khilok, Dzhida, and Temnik, during spring flood and summer freshets. The concentrations of organic substances are heterogeneous and vary widely under the effect of matter input with major tributaries and wastewater discharge from GOS. It has been established that the concentrations of readily oxidizable organic substances in 28–33% of the taken samples are above the established standards on maximal allowable concentrations in the period of open river channels. In spring and autumn, the organic matter in the rivers of the basin is mostly represented by soil terrigenous material.     

Comparative hydrochemical assessment of the current state of some water bodies in the Upper Volga

Results of field studies of water chemistry in the Upper Volga and some its tributaries in the reach between the Volga source and Tver City, as well as in lakes Sterzh, Vselug, Peno, and Volgo, which are constituent parts of the Verkhnevolzhskoe Reservoir, as well as Selizharovskii Pool of Lake Seliger. The year-to-year and season-to-season dynamics of the hydrochemical regime of the examined water bodies and their variations downstream the Volga under the effect of natural and anthropogenic factors are analyzed.     

Space and time variations of the runoff of Kamchatka Krai rivers

The current features of the space and time variations of river runoff in Kamchatka Krai have been considered. Two relatively long cycles have been shown to exist in water runoff variations in the major portion of the examined rivers. The renewable water resources were increasing until 1970–1980, while in the following years (up to 2010), they were gradually decreasing. Current data on river runoff were used to prove the existence of three zonal types of water regime in Kamchatka Krai; five azonal types of annual runoff distribution are characterized. One of them (nearly uniform annual distribution caused by the predominance of groundwater recharge) has been theoretically predicted in the classification proposed by M.I. L’vovich, though without factual confirmation. The specific features of water regime of rivers whose basins lie on the slopes of active volcanoes are considered for the first time. This type of regime typically shows alternating periods of the presence and absence of surface runoff in river channels, corresponding to the inflow of snowmelt or rainfall runoff at high level of subsoil water (when channel deposits are fully saturated with water) or at its low position (when moisture is deficient).     

Chemical stratification and stability of meromictic lakes in the Upper Romerike district

A number of lakes in Southeast Norway have developed biogenic meromixis and have typically also considerable concentrations of dissolved iron and manganese in the bottom waters. Eight such lakes are described. Products of biological decomposition like carbon dioxide, methane and some inorganic salts gave a difference in density between mixo- and monimolimnion and hence chemical stability to the lakes. The concentration of iron and manganese gave minor contributions to the density gradients, and these substances are regarded as less important for the stability because of their reduced solubility under oxic conditions. Quantitative expressions of wind influence on lake surfaces were obtained by calculation of the work of the wind during the heating season. These values were low compared with a more exposed lake in the same region. Water movements generated by the wind have eroding effects on the chemical stratification only during short periods of homothermy before icelaying. During the rest of the year the monimolimnion is protected by either thermal stratification or ice cover. During the autumnal partial circulation a substantial reduction in chemical stability took place. For some of the lakes it is assumed that full circulation may take place in years with favourable weather conditions.