Lake Baikal: Extreme level as a rare hydrological event

The optimal boundaries of water level variation range in Lake Baikal have been determined under the conditions of runoff regulation at the Irkutsk HPP and the extremely low water abundance in lake basin in recent years. The properties of the time series of level regime and the characteristics of runoff from its drainage basin have been studied. The formation of long-term dry periods in the region has been studied, and the regularities in level regime variations in the lake have been estimated for both natural and runoff-regulation conditions, and the specifics of runoff regulation and level drawdown in dry years have been considered.     

Transformation of estimated characteristics of the annual and maximal runoff in the major tributaries of Lake Baikal

Hydrometric data of recent years were used to evaluate the parameters of distribution of the annual and maximal runoff in the major tributaries of Lake Baikal: the Selenga, Upper Angara, and Barguzin. The estimates of the mean water content, maximal water discharges of spring flood and rain freshets were obtained. The comparison with analogous data of an earlier period often shows significant difference. Variations of the characteristics under consideration are taking place against the background of warming in the region since the early 1970s. The results of the current transformation of river runoff variations is a change in Baikal water regime, which determines the restructuring of hydrological processes in the lake.     

Long-term and seasonal water level fluctuations of the Rybinsk Reservoir and their role in the functioning of its ecosystem

Seasonal and long-term variability of the Rybinsk Reservoir level regime over the period of its operation was analyzed. Changes in the level regime at different phases of water content were shown together with the data on mean monthly and extreme level values and the rates of the reservoir filling and drawdown. The level regime impact on the functioning of individual components of the reservoir ecosystem was discussed. Due consideration was given to the assessment of changes in the reservoir environmental situation under the condition of the normal impounded water level drop by 1 m.     

Hydrological and morphological features of the Upper Angara mouth area

The hydrological and morphological processes in the mouth area of the Upper Angara (which ranks second in terms of water abundance among Baikal Lake tributaries) are considered. The major external factors that determine those processes have been revealed. The main features of the delta??s water regime, including the effect of anthropogenic level rise in the lake, are described. Specific attention is paid to morphological processes in the delta and on the barrier bar, separating a large mouth lagoon from the lake.     

Dynamic-stochastical modeling of long-term fluctuations in Lake Baykal levels and Angara River runoff

The results of modeling of the long-term fluctuations in Lake Baikal levels and Angara River runoff are presented. The dynamic-stochastical model was developed and used to obtain analytical relationships between the statistic characteristics of the Baikal levels fluctuations and the parameters of forcing processes, including water inflow into the lake and the effective evaporation from its surface. The parameter λ determining the inertia of the Baikal levels fluctuations, decreased by about three times after Irkutsk Reservoir filling, resulting in an increase in the variance of the lake levels fluctuations. The dependence of variances of the Baikal levels fluctuations and Angara runoff on parameter λ was studied. It is shown that the decreasing in the variance of the Baikal levels fluctuations corresponds to increasing in the variance of Angara river runoff and vice versa. The results of numerical modeling of Baikal levels fluctuations show that water withdrawal from inflow into the lake has an adverse effect on Angara runoff regime.     

Lake Baikal and the Angara River before and after the Construction of Reservoirs

Variations in the regime of the Angara River flow fluctuations and in the components of the water balance of Lake Baikal are discussed.     

Assessing the state of water masses of the Southern Baikal in the zone of influence of Baikal PPM by many-year microbiological characteristics

Results of many-year (1990–2009) microbiological studies of waters in different parts of Southern Baikal subject to different anthropogenic load are presented. Long-term observation series made it possible to establish tendencies in variations of the structure and functional activity of microbiocenoses as the result of natural evolution and anthropogenic impact. The obtained microbiological data characterizes water quality and the level of technogenic disturbances near Baikal Pulp-and-Paper Mill. Water quality assessment by sanitary-bacteriological characteristics suggests that the water area near the discharge site of effluents from Baikal PPM chronically experiences bacterial pollution. No significant changes in the technogenic stress on Southern Baikal ecosystem have taken place since the 1990s.     

The Effect of the Development of Groundwater Deposits on Its Fluorine Content

Synthesis of regime observations of groundwater quality at deposits under operation and thermodynamic modeling of the geochemical interaction processes that govern the groundwater chemistry were used to recognize the geochemical causes and processes that bring about an increase in the groundwater fluorine content during water withdrawal accompanied by groundwater level drop and partial drying of the aquifer. The causes of the invalidity of previous forecasts are established.     

Lake Water Resources in the Asian Part of the Russian Federation

Water resources of lakes with natural and regulated hydrological regime are evaluated, and estimates are given to the water resources of artificial water bodies in three federal districts in the Asian part of RF (Ural, Siberian, and Far-Eastern) and the constituent entities of the Federation they contain. The estimates were made by a new procedure, incorporating up-to-date satellite data and functions of Google Earth project. In the Asian part of RF, ~3140000 natural water bodies were analyzed, including ~1170000 lakes >1 ha in area and ~6000 artificial water bodies. Lake water resources in the Asian part of RF amount to 24537 km³, of which ~96% are contained in Lake Baikal. Other 638 km³ are contained in artificial water bodies.     

Relationships between Water Flow and Dissolved Solids Discharge in the Major Tributaries of Lake Baikal

Data of long-term observations of water and hydrochemical regimes were used to characterize relationships between water flow and dissolved solids discharge in the three major tributaries of Lake Baikal, which account for about two-thirds of the total water inflow into the lake. The total dissolved solids content (TDS) of these rivers' water and the concentrations of the principal ions are classified taking into account the relationships between the sources of alimentation.     

Seasonal and year-to-year dynamics of phytoplankton in connection with the level regime of the Kuibyshev Reservoir

The results of long-term observations are used to analyze the seasonal and year-to-year variations of the abundance and biomass of planktonic algae in connection with the seasonal dynamics of water level in the Kuibyshev Reservoir. The dynamics of level regime in the reservoir in combination with climate conditions are a determining factor for phytoplankton development. The adverse effects of eutrophication (in particular, water blooming) can be reduced by maintaining an optimal water level in the reservoir—not below the normal water level (53 m BS) in the summer.     

Combining the management of water level regimes and plant structures for waterbird habitat provision in wetlands

The survival of waterbirds depends heavily on habitat, particularly aquatic plants. For each kind of aquatic plant, there are specific water level regime requirements to meet its germination and growth. Previous studies usually focused on the use of water level management to achieve protection and restoration of aquatic plants. However, the water level regimes in many wetlands have been greatly changed and their ecological objectives usually cannot be achieved by water level management alone. Accordingly, this study combined water level management and artificial planting for waterbird habitat provision in wetlands. The Hongze Lake National Wetland Nature Reserve was taken as the research area. In this study, we considered the needs of waterbirds for nesting and foraging, and determined the aquatic plant species to be planted. According to the seasonal water level requirements of these plants, we simulated the plantable areas of different aquatic plants under different water level regimes. We then further optimized the water level regimes according to the needs of waterbirds, and determined the optimal water level management scheme. In addition, we formulated planting principles, explored the planting structure under each water level regime, so that the plant structure can better serve the waterbirds. The results showed that the current water level regime of Hongze Lake is not consistent with the growth rhythm of aquatic plants. Because of the human regulation, the water level of the wetland is high in winter and low in summer, which is contrary to the requirements of aquatic plant growth. A combination of water level regimes and plant structure management, however, could effectively expand the area for waterbird habitat. The results of this study will help wetland managers to make informed decisions about how to restore the waterbird habitat in other similar regulated wetlands.     

Toxic (mercury,berillium) and biogenic (selenium,fluorine) elements in aquatic ecosystems of Baikal Natural Territory

Up-to-date analytical methods are used to collect data on the concentrations of toxic (mercury, beryllium) and biogenic (selenium, fluorine) elements in various aquatic landscape-geochemical systems of Baikal Natural Territory, including the central, buffer zone, and the zone of atmospheric influence. The concentrations of selenium and fluorine were found to far below (with rare exceptions) their hygienic standards for drinking water. By this characteristic, the Baikal Natural Territory is classified as a deficient biogeochemical province. The low concentrations (up to nanograms) of highly toxic elements—mercury and beryllium—in surface and subsurface waters of aquatic landscapes show that the considered ecological zones are quite favorable for human life. Studying microelements in landscape-geochemical zones opens the way for environmentally safe nature management in the territory and enables one to forecast variations in the quality of water resources under growing anthropogenic load.     

Estimation of coseismic deformation, poroelasticity, and fracturing of rocks from the data on water level in a borehole

Variations in the water level in boreholes emerge in response to tidal, baric, and tectonic forcing. We analyze the data on atmospheric pressure and water level recorded in the boreholes located in the mid-latitude Eurasia (45°?C55°N) from Western Europe (Belgium, Uccle), Siberia (coastal area of Lake Baikal, Talaya River) to Far Eastern Russia (the Bychikha borehole near Khabarovsk and the boreholes on the Kamchatka Peninsula and Kurils). The response of the water level in a borehole to periodic tidal and baric impacts is investigated. In this case, water level variations reflect areal (lateral) and vertical deformations, which allows estimating the elastic moduli and porosity of the confined aquifer in a static model. Measurements in the boreholes drilled in the fractured solid rock enable determining the geometric parameters of the fractures. The possibility to apply the method for evaluating tectonic deformations is discussed. Application of tidal coefficients of boreholes for determining the coseismic deformation is demonstrated by the example of the Kultuk earthquake (Lake Baikal, August 27, 2008, M = 6.3).     

Seismicity of the Baikal rift zone for the digital recording period of earthquake observation (2001–2006)

Some characteristics of the seismic regime of the Baikal rift zone for the analogue (1960–2000) and digital (2001–2006) registration modes are considered. It was ascertained that the general number of seismic events recorded by digital equipment increased by two times in comparison with the analogue observation period and the catalog completeness level was lowered to K _P = 7.0 as well. The focal mechanisms of 110 earth-quakes with K _P ≥ 8.0 were examined. The overwhelming majority of them during 2001–2006 were due to normal faulting and normal faulting with strike-slip components. Special attention was given to study of the strong events (K _P ≥ 13.5 and MPSP ≥ 4.7), whose focal solutions reveal the regional stress field.     

Specific features of cold bottom intrusion in Baikal according to observations in 1993–2009

The specific features of cold bottom intrusion in Baikal are considered based on the results of observations of 1993–2009. It is shown that the intrusion-related renewal of bottom water takes place not regularly and not simultaneously in different hollows. Its maximums were recorded in Southern Baikal in 1997 and 2007, in Middle Baikal in 1995, 2006, and 2009, and in Northern Baikal in 1997 and 2009. In these years, the volume of cold bottom layer in some hollows reached 200–470 km³ and its total cooling reached −20 to −60 MJ 10⁹. Cold intrusions were more frequent and had greater effect on the bottom layer in Southern Baikal than in other parts of the lake. The intrusions, especially in the years of their active development, are shown to cause water cooling in both the bottom layer and the major part of the deep-water zone of all hollows.     

Toxicity and Accumulation of Al in the Acid Water of Small Lakes and Watercourses in Finnish Lapland

On the basis of a study of the hydrochemical regime and the status of benthic acidophobic species in the acidified watercourses and small lakes of Finnish Lapland, humic compounds are demonstrated to be the principal factors controlling both pH and the proportions of different forms of Al in water. It is found that the concentration of labile aluminum, i.e., that form of aluminum which is most toxic for aquatic organisms, increases only in acid water (pH 4.8–6.5) with a low and extremely low humic content of water (with a color of 5–60 mg Pt/l). Humic and other organic substances that fix Al in an inert or another stable form are demonstrated to be able to decrease the toxic properties of aluminum for acidophobic species and the capacity of aluminum to be accumulated in the bodies of aquatic organisms. Aluminum is shown to have no tendency to an increased rate of accumulation in the bodies of aquatic organisms that form the highest trophic level of secondary predators.     

三峡工程蓄水对洞庭湖水情的影响格局及其作用机制

三峡工程建成投入运行后,汛末蓄水将使坝下河湖水情发生变化,长江中下游秋季来水减少成为常态.为客观分析三峡蓄水对洞庭湖水情的影响分量、空间格局及其作用机制,选取三峡工程典型的蓄水过程,运用长江中游江湖耦合水动力学模型计算了因上游来水变化引起的洞庭湖水情时空变化.结果表明:1)三峡汛末蓄水对洞庭湖水位影响具有明显的"北高南低,东强西弱"的格局,即东洞庭湖最为显著、南洞庭湖东部和西洞庭湖北部次之,南洞庭湖西部和西洞庭湖南部最小.2)洲滩湿地受蓄水影响最明显的主要为东洞庭湖、南洞庭湖和湖泊洪道两侧的条带状洲滩.3)三峡蓄水对洞庭湖水位的影响机制有二:长江干流水位快速消落加速湖泊水体下泄以及削减长江三口分流补给湖泊的水量.     

Assessing possible changes in Selenga R. water regime in the XXI century based on a runoff formation model

The runoff of the Selenga R., the largest tributary of Lake Baikal, in recent two decades corresponds to a low-water period. Such decrease can be due to the global climate processes, which have an effect on the amounts of precipitation onto and evaporation from Selenga drainage basin, which is located in arid climate zone. The adaptation of Ecomag software complex to simulating river runoff in the Selenga Basin based on global databases (relief, soils, vegetation, and weather information) is described. The model was calibrated and verified, and the statistical estimates of calculation efficiency were constructed. The obtained model of runoff formation in the Selenga Basin was used to assess the possible changes in the climate and water regime in the XXI century with the use of data of global climate models under different scenarios of greenhouse gas emissions. Throughout the XXI century, the Selenga R. runoff may decrease by 10–40%, depending on the forecasted climate conditions.     

Search for anomalous effects in geophysical fields in relation to earthquakes in the Baikal rift zone

The paper presents data of electrical conductivity monitoring for the upper crust obtained with the use of a controllable electromagnetic source by the dipole, vertical electromagnetic, and transient electromagnetic sounding methods, as well as variations in the geomagnetic field and the Lake Baikal water level. With the help of spectral, spectral time, and multivariate analyses, main spatial and temporal patterns of variations in geophysical parameters are determined. The present study revealed anomalous effects in the behavior of the canonical coherence (parameter K) and aggregated signal (parameter A) and other anomalous variations in geophysical parameters related to earthquakes in the Baikal rift zone.