Том 46, № 5 (2019)

Four global climate scenarios of the family “Special Report on Emissions Scenarios” of the Intergovernmental Panel on Climate Change, which correspond to the specified scenarios of economic, technological, political, and demographic development of the human civilization were used to develop forecast versions of meteorological forcing data dynamics in the Ob–Irtysh basin in the XXI century. The obtained data were used to simulate the variants of possible changes in water balance components in this river basin up to mid-XXI century. The calculation technique is based on the use of land surface model SWAP and a generator of climate scenarios MAGICC/SCENGEN. The changes in the annual runoff of the Ob, governed by possible global climate change are compared with its natural variations caused by weather noise.

In the present study, long-term monitoring data were collected from the study area of the Kaoping River Basin, Taiwan. Specifically, data from six selected groundwater level stations and six precipitation stations in the vicinity were collected between 1997 and 2014. The standardized groundwater index (SGI) and standardized precipitation index (SPI) were then used to analyze the region’s drought characteristics. The results revealed that continuous droughts occurred in the river basin from 2003 to 2005. The trend for 2014 further indicated that the drought situation in the region would worsen in terms of severity. After calculation and analysis of the cross correlation function between the SGI and the SPI, a positive correlation was identified between the maximum cross correlation function (q_max) and the duration of the drought event. The larger the q_max value, the longer was the duration of the drought, and vice versa. The study also found that the q_max value varied with geographical locations: it was smaller for the various measuring stations located along the Qishan and Laonong rivers, but it tended to be larger for stations located beyond the Ailiao River. Thus, this study reckoned that if a drought event were to occur in the latter area in the future, its duration would be relatively longer. The findings of this study could also serve as future reference for the water resources management of the Kaoping River Basin.

The experimental data given in the article show a perturbation of currents in the northeastern Caspian Sea near Peschanomysskoe uplift, which is caused by the interaction between cyclonic circulation and the southern slope of the uplift. This interaction results in that the water of the cyclonic circulation forks into lower and upper branches. The lower, bottom branch is reflected southwestward by the uplift, where, at the head of the uplift, it meets water flowing southeastward over the bed of the Yuzhno-Buzachinskii depression, while the upper branch, consisting of the surface and intermediate cold water, is pushed upward and flows over the uplift. The rise of cold water forms upwelling in the top layer, which extends over the entire northeastern part of the sea.

Data of field measurements of water level variations and current velocities in Petrozavodsk Bay, Lake Onega, made in 2016–2017, are analyzed. Water level variations were carried out with a step of 10 s by two instruments TDR-2050 (RBR Ltd., Canada). Spectral analysis was made by simple Fourier transformation after one-minute averaging of data to reduce instrumental noise. Energy-bearing periods corresponding to the modes of seiches of Petrozavodsk Bay and Lake Onega were identified. Flow velocities were measured by instruments Aquadopp HR-Profiler (Nortek, Norway). A linear approximation of the theory of long waves was used to analyze seiche oscillations in a model bay approximating Petrozavodsk Bay with the Ivanovskie Islands taken into account. An analytical solution was used to evaluate the periods of larger modes of the seiches and the corresponding maximal velocities of wave currents for Petrozavodsk Bay. Theoretical estimates were compared with field data and showed a satisfactory agreement.

The distribution of methane concentration measured in 2014 and 2015 in different parts of Lake Baikal has been analyzed. In the period of expedition studies, methane concentration in lake water and bottom sediments varied from <0.1 to 13.9 µL/dm³ (on the average, 0.7 µL/dm³) and from <0.01 to 3.69 µg/g dry residue (on the average, 0.34 µg/g). The maximal concentrations of methane in water and bottom sediments of the lake were typical of the northern area, which receives waters of the Upper Angara and Kichera, and at some stations on a profile running along the mouth area of the Selenga R., as well as stations in the zone of underwater discharge of wastewater from Baikal’sk City and the Baikal Pulp and Paper Plant (BPPP), which was closed down in 2013. The presence of higher or lower methane concentrations in the examined upper horizons of Lake Baikal deposits is due to the differences in the level of anthropogenic impact; variations in sedimentation conditions, which determine the grain-size distribution and the concentration of organic matter, and, as a consequence, the rate of methanogenesis.

A sanitary–bacteriological and hydrochemical survey of rivers flowing into Lake Baikal near Listvyanka Settl. was carried out in period from 2014 to 2015. Water quality at the mouths of the rivers of Bol’shaya Cheremshanka, Malaya Cheremshanka, and Kamenushka was found not to meet the standards of the normative and technical documentation introduced in Russia and abroad (in the United States and Europe) in terms of thermotolerant coliform bacteria, thermotolerant E. coli, and enterococci. In terms of hydrochemical characteristics, such as phosphates, water quality at the mouths of the Bol’shaya Cheremshanka, Malaya Cheremshanka, and Kamenushka rivers also failed to meet Russian standards. The coastal water of Lake Baikal at the mouth of the Bol’shaya Cheremshanka in July (at the peak of tourist season) 2015 showed the abundance of the group of thermotolerant coliform bacteria (TCB) more than 10 times in excess of the standard. Therefore, the study suggests the conclusion that the quality of water sampled at river mouths is much poorer than that in river reaches upstream of the settlement. Moreover, in July, when the recreational load increases appreciably, the abundance of the analyzed bacteria in water in river reaches within the settlement and in water samples taken upstream of it (background points) is found to differ radically. Hydrochemical and sanitary–bacteriological analysis of the coastal water of Lake Baikal was carried out at the mouths of the rivers flowing into it and revealed an effect of river water on the quality of coastal Baikal water.

The short-term, seasonal, and interannual variations in the abundance and species composition of the Black Sea metazoan microzooplankton have been analyzed at the open coastal area and the mouth of Sevastopol Bay in 2009–2015. Whatever the time scale, the temperature factor played the main role in abundance variations. In particular, the coincidence of two-year periodicities in the sum of active temperatures and the abundance of copepod-invader Oithona davisae at the year-to-year scale have been demonstrated. Variations of wind speed and direction have been shown to be significant factors in the short-term variations of microzooplankton abundance. The general species diversity of the community was found to depend significantly on the abundance of the invader species.

The present study is an attempt to apply principal component analysis (PCA) for spatial assessment of water quality parameters that are responsible for water quality deterioration in the Ganga river at four cities of Uttar Pradesh. 48 water samples of the Ganga river from Allahabad, Mirzapur, Shahzadpur and Varanasi in Uttar Pradesh were collected during January to December in 2013. Data were analyzed for assessment of 18 different physicochemical and biological water quality parameters. These variables were examined using PCA to define and standardize the parameters mainly responsible for water quality variance in Ganga river at four selected cities. PCA highlighted anthropogenic effect and industrial effect as two main significant components which explain more than 99.32% of the variance, accounting for 64.47 and 34.85% respectively of the total variance of Ganga water quality at the four cities. Results revealed that total dissolved solids, total alkalinity, total hardness were the important parameters in assessing variations in Ganga water quality during October to April (post-monsoon months) and turbidity, suspended solids are the important parameters in assessing variations in Ganga water quality during June to September (monsoon months). Ca²⁺, Cl^–, \({\text{SO}}_{4}^{{2 - }}\), temperature, fluoride, pH, Fe, Cl^–, were found to be non-principal water quality parameters. Principal component analysis produced three significant main components explaining more than 82.9% of the variance (anthropogenic and industrial effect) that present 57.1, 13.8 and 12% respectively of the total variance of water quality in Ganga river at the four selected cities. The result reveals that turbidity, dissolved oxygen and biochemical oxygen demand are the parameters that are most important in assessing variations of water quality. Water quality index based on eight parameters (turbidity, DO, BOD, COD, pH, TS, TSS and TDS) calculated for all four cities were found to range from medium to bad. Thus, this study illustrates the usefulness of multivariate statistical techniques for analysis, interpretation of complex data sets and understanding spatial variations in water quality for effective river water quality management.