Vol 46, No 3 (2019)

The balance structure of the pumpage sourses of riverside water-intakes, developing a subsoil aquifer or intermediate water that hydraulically interacts with it, can show the effect of the processes of water balance adjustment in the unsaturated zone to the accompanying subsoil water level drawdown. In this case, because of the shallow depth to subsoil water, its level drop due to water withdrawal causes a decrease in evapotranspiration and an increase in groundwater infiltration recharge. These processes have their effect on the balance structure of usable water resources as components of natural and involved resources and reduce the impact of groundwater pumping on river flow. Analysis of the operational data of the Sudogda waterintake in Vladimir oblast and geohydrological modeling were used to evaluate variations of the groundwater evaportanspiration losses and infiltration recharge and their role in the water balance structure of reserves of a field and in the impact of groundwater withdrawal on river flow.

Data of long-term measurements of under-ice solar radiation, water temperature, and chlorophyll a are analyzed in four phytoplankton groups (green, diatoms, blue-green, and cryptophyte algae) in a small mesotrophic Vendyurskoe Lake (Karelia) in the period of spring under-ice convection. It is shown that, after thawing away of snow cover from lake surface, under-ice illumination increases, water temperature rises, the depth of convectively mixed layer (CML) increases, and microalga photosynthesis intensifies. In the daytime, chlorophyll a extremums appear in the CML, and, unlike the homogeneous characteristics (water electric conductivity, mineralization, etc.), the cells of different phytoplankton species can be used as tracers in studying convective mixing. A prognostic equation is obtained, reflecting an inverse dependence of the coefficients of variation of chlorophyll a concentration in CML on solar radiation fluxes, penetrating under ice bottom surface. A direct relationship was shown to exist between the increase in chlorophyll concentration in CML and its thickness.

The values of Clark W-statistics, ∆-Shannon-Weaver, and an average individual mass of specimen were used to characterize the spatial distribution of zooplankton in the Kolsay lakes. With a relatively constant species composition, the interannual dynamics of the size and quantity variables of zooplankton testified to an increase in the eutrophication processes of three of the four Kolsay lakes. Interannual changes in the structure of the zooplankton community were mostly determined by the introduction of allochthonous species of fish, reduction of the water level, and enhancement of biogenic load due to recreational use of the lakes. The effect of very low concentrations of heavy metals on the dimensional variables of zooplankton can be connected with the oligotrophic status of Kolsaiskie lakes.

The content of the man-made radioactive nuclide 137Cs was investigated in different groups of the salt lakes of Crimea peninsula. One of the main sources of 137Cs was determined to be the North-Crimea channel, which supplied the Dnepr water to Crimea until 2014 with a high content of radioactive nuclides of Chernobyl origin. The other source of 137Cs is the Black Sea water owing to its drainage and direct connection with the coastal salt lakes of Crimea, which demonstrates a positive correlation between 137Cs concentration and water salinity.

Data on the Cd, Cu, Pb, and Zn contents in the bottom sediments of Amur Bay are presented. Contamination of bottom sediments is particularly heavy near the central part of Vladivostok, where the concentration of all metals, except for Cd, exceeds the threshold levels, at which negative biological effects are possible. Biological tests of marine crustaceans were conducted between 2003 and 2014 on water toxicity in this most contaminated bay water area. However, only in August 2003, September 2003, and July 2007, the survival rate of mysids in the surface water of the entire inner area was credibly lower than that in the outer part of the bay. In the following years, the ecotoxicological condition of the bay water improved owing to the decrease in contamination.

The interaction between hydrological cycle components in the ocean–atmosphere–land system was considered. Calculations were made with the use of various reanalysis archives, and regularities in the interannual variability of evaporation and precipitation in the North Atlantic and their effect on the zonal transport of water vapor onto the European continent were considered. Statistical models of the annual average total moisture flow at the meridional section 5° E as a function of evaporation in the North Atlantic were constructed. The contribution of the zonal transport of water vapor at the meridian 5° E to the variance of the total precipitation over cold and warm seasons in the Volga basin was determined. Models with a small number of parameters were constructed for forecasting the annual runoff of the Volga as a function of precipitation by methods of multiple regression and decision trees.

The discussion on developing new computer technologies for problems analysis and support of decision-making is continued regarding water resources available for the users of the water utilization system of the Lower Volga and the entire Volga–Kama reservoirs cascade. Thus, this second part examines the objectives of the tactic planning to determine augmentation to the downstream water of Volgograd hydropower installation (special augmentation) and develops an algorithm for defining special augmentation based on the inflow forecast in the spring high water (April–June). This algorithm will aid in the operating management of the reservoirs for implementing the already set strategic goals.