Vol 46, No Suppl 1 (2019)

The formation and distribution of river flow characteristics in the Don basin have been catholically analyzed, depending on the present-day climatic conditions in the central European Russia. The recent global warming is shown to have resulted in a change in the river flow formation conditions and water resources, as well as in a substantial transformation of the river water regime in the basin. The river water and groundwater chemistry in the basin in 1990–2015 has been considered at the main observation points. The dynamics of river water quality pollution level during the long period is presented. Water pollution characteristics, which make it possible to identify the water quality class and pollution level, have been used to give a generalized estimate of the water quality in the chosen river areas.

A number of requirements for sediment transport formulas are considered for using in mathematical and physical models of alluvial channels. Some formulas (Bagnold, Petrov, Kopaliani) are analyzed and compared. It is demonstrated that the universal bed load transport formula should implicitly contain the Froude number. At the same time, the dependence of bed load discharge on the hydraulic resistance coefficient and the non-moving flow velocity increases the calculation error. However, these parameters, must be taken into account in simulating bed deformations for non-uniform sediments.

The objective of this study was to provide the most accurate presentation of the behavior of a disastrous rain flood, which had resulted in destruction of a dam, casualties, and significant material damage. The problems set were solved by methods of numerical modeling in the two-dimensional setting applying the STREAM 2D CUDA software package. To calculate the rain flood, a catchment model of the Durso River was developed on a triangular non-uniform mesh, adapted to the river channel and the main inflows. To ensure direct numerical modeling of the dam’s destruction, a model was developed, which included the water area of the reservoir, the dam, composed of non-homogeneous earth material, and a downstream section of the river from the dam to the river mouth. The main results of the study were: the hydrograph of the water discharge of the rain flood, calculated by the actual precipitation data; a description of the washout of the earth dam composed of non-homogeneous materials, resulting from water spill over the dam crest, and a desctiption of the downstream spread of the breach wave.

The study focuses on the specific features of the justice dealing with the results of measuring the characteristics of safety and quality of production, works, or services. It is shown that the error (uncertainty) that appears in such situations is a measure of data scatter and a source of legal uncertainty, which causes a risk of judicial errors. The level of such risk increases with increasing demands of economy to the standardization of the ever-decreasing values of characteristics evaluated with higher uncertainty. The study shows that a necessary condition for the rule of law in such cases is the risk-oriented approach to resolving arbitration cases.

The article discusses the role of sulfite-reducing clostridia in methane and hydrogen oxide formation in bottom sediments. The examined materials have been accumulated in the course of expeditions carried out at 25 water objects and streams of the subarid zone of the Southern ETR with different mineralization and the degree of anthropogenic stress, as well as via an experiment aimed at detection of the ability of sulfite-reducing clostridia to produce reduced gases. In the majority of samples of bottom sediments in water objects of the Southern ETR, including mud sediments of lakes that are used for therapeutic purposes, the amount of sulfite-reducing clostridia exceeds the normative levels by an order of magnitude. The maximum abundance (10⁶–10⁷ CFU/g) was recorded in the nearshore zone of the southeastern part of the Taganrog Bay, thus implying fecal pollution. As a rule, the highest abundance is restricted to the higher (0–2 and/or 2–5 cm) layers. A close relationship was found to exist between the concentrations of methane and hydrogen sulfide, as well as the abundance of sulfite-reducing clostridia in the bottom sediments. The results of the laboratory experiment imply the ability of sulfite-reducing clostridia to produce methane and hydrogen sulfide. It is supposed that sulfite-reducing clostridia, as well as methanogens and sulfate-reducing microorganisms, participate in the generation of methane and hydrogen sulfide in situ in bottom sediments and therapeutic muds.

The article presents the results of studying the water chemistry and the species structure of phytoplankton and higher aquatic vegetation of the cooling reservoir at the Kalinin Nuclear Power Plant (NPP), the lakes Pesvo and Udomlya being its components. It was established that the inflow of heated waters from the Kalinin Nuclear Power Plant to the lakes Pesvo and Udomlya had resulted in a significant change in the temperature conditions of the water bodies, an increase in water mineralization and the concentrations of hydrocarbonates, sulfates, calcium, and magnesium, as well as рН. The role of cryptophytae algae (Cryptophyta) has increased, and species of higher aquatic vegetation, unusual for this area have appeared.

For 11 large river basins (the Rhine, Tagus, Ganges, Lena, Upper Yellow, Upper Yangtze, Niger, Mackenzie, Upper Mississippi, Upper Amazon and Darling) located on different continents under a wide variety of natural conditions, series of annual river runoff were calculated by means of the land surface model SWAP for the period of 1962–2099. For the historical (base) period (1962–2005), meteorological forcing data were taken from the global WATCH data set. For the projection period (2006–2099), the results of simulations from five Atmosphere and Ocean General Circulation Models (AOGCMs: HadGEM2-ES, IPSL-CM5A -LR, MIROC-ESM-CHEM, GFDL-ESM2M, and NorESM1-M) obtained for four climate change scenarios of the RCP-family were applied. The obtained series of annual runoff for each river basin were used to calculate climatic values and standard deviations of annual runoff for four climatic periods (1962–2005, 2006–2035, 2036–2065 and 2066–2099), which were then averaged over all AOGCMs and RCP-scenarios and used to construct distribution functions of annual runoff (for each river basin and climatic period) approximated by the lognormal distribution function of random variables. The constructed annual runoff distribution functions were applied for estimating the probabilities of occurrence of extremely high and extremely low values of annual runoff for each river and climatic period.

Projected changes in river runoff due to possible climate change during the 21st century were simulated with making use of a physically-based land surface model SWAP and meteorological projections simulated by five Global Climate Models (GCMs) for each of four RCP scenarios. The Northern Dvina, Indigirka, and Taz river basins were used in the study. For each basin, 20 projections of changes in climatic river runoff were obtained for three climatic periods of the 21st century. The projected changes in climatic river runoff were analyzed together with the projected changes in climatic precipitation, incoming shortwave and longwave radiation, and evapotranspiration. The obtained hydrological projections were used to estimate their uncertainties resulting from the application of different GCMs and RCP scenarios.