卷 50, 编号 3 (2023)

The study is focused on variations of air temperature in the basin of the Volga reservoirs, the total inflow into the water bodies, their water exchange, water level and temperature, and the heat content of water mass in open-water period under various climate conditions. The object of the analysis is the long-term series of hydrometeorological data processed by statistical methods. It is shown that the present-day air temperature has increased by 1.3‒1.8°C compared with the period before 1976. The rate of warming was on the average 0.50°C/10 years. The volume of annual inflow increased by 12.4%. Three low-water and 4 high-water phases were identified in the reservoirs of the Upper Volga, including 29–31 low-water, 25–31 high-water, and 8–16 medium-water years. During the low-water phases, the volume of inflow into the reservoirs is 10–28% less than the long-term average, while in high-water years, it is 4–20% higher. The coefficient of water exchange in the reservoirs decreased or increased by 5–13% relative to the values obtained earlier. An increase in the winter and a decrease in the spring inflow were recorded in the reservoirs of the Upper Volga and in the Kuibyshev Reservoir. A tendency toward an increase in the normal annual water level was observed in the reservoirs in the upper part of the Volga and in the Kuibyshev Reservoir, while in the lower Volga, the normal annual level somewhat decreased. In low-water phases, the reservoir levels were on the average 17 cm below and in the high-water phases, 10 cm above the normal annual value. An increase in air temperature during the warm season in the reservoir water areas, on the average by 1.2°C, led to a synchronous increase in the temperature of the water mass by 1.1°C. At the same time, the heat content of the water mass of the reservoirs increased, on the average, by 24% in the upper part of the Volga and by as little as 2–11% in its lower part

The first full morphological–hydrological characteristic is given to complex parallel-branch bifurcations of the lower Lena, which have formed at the total (taken with islands) channel width in individual links from 12.6 to 28 km and their length from 36 to 45 km. The number of islands in the branching links is 29 in the Upper Monastyrskii and more than 40 in the Cherpalskii bifurcations. It is shown that, all over the length, two branches with largest water abundance can be identified—the left and the right—of which the latter, navigable in all links and more abundant in water, runs along or near the right, bedrock bank. The left branch concentrates the runoff of water and sediments from the Vilyui, the left tributary of the Lena; this, along with the sediment-removing role, determines its shallowness and higher secondary branching. The links of the branches are separated by short segments of channel narrowing down to 5–8 km, in which two-midstream flow persists. It is shown that groups of islands (archipelagoes) in the middle of the river between the main branches are separated by relatively low-flow central branches subparallel to them (overall, within 10–15% of river flow), numerous transverse channels between islands and divided into into two parts (upstream and downstream) by diagonal branches, through which water partly redistributes between the main branches. It was shown that, at many-year scale and at seasonal runoff variations, the water abundance in the main and subparallel branches is practically constant, while the discharge in diagonal branches varies periodically from 10–15 to 30–35%, depending on channel transformations in the right main branch. This coincides with the periodic redistribution of water discharges, the development and shallowing of channels in secondary branching of the main channel, which lie near the sites of separation of diagonal branches from them. The revealed regularities for the first time give data on the channel regime of parallel-branch bifurcation of the channel of a large river, which is of great importance for the improvement of navigation in the Lower Lena

The earlier solutions of the problem of groundwater flow in an inundated rock massif with vertically drains (drain trenches) are represented by extremely complex mathematical relationships in complex variables which make them difficult to use in applied problems. A new approximate-hydromechanical solution of the problem was obtained with the use of velocity hodograph and the presentation of model relationships in elementary functions, which coincides with the exact data in boundary points and which are in almost complete agreement (⪡1%) with the results of exact calculations by V.V. Vedernikov for special cases. For the first time, a picture of the field of full flow velocities was analytically constructed in the form of an isotach family for the given inundated massif with drains, showing the heterogeneous character of velocity distribution in it at the presence of water in the drain. Groundwater flow diagrams are also presented for boundary lines (in particular, in comparison with the case when there is no water in the drain), along with plots of flow functions and heads.

Data on the distribution of methane concentration in water in the open water area and the northern end of Lake Baikal and in the source of the Angara R. collected in September 2016 and 2019 are analyzed. To apply correlation analysis, in addition to methane, various hydrochemical characteristics were also determined, including the temperature, pH, the concentrations of О2, suspended matter, Corg, Norg, Porg, mineral compounds of nitrogen and phosphorus. Methane concentration in Baikal water in 2016 varied within 0.44–3.41 µL/dm3 (on the average, 0.80 µL/dm3); in 2019, within 0.20–5.19 µL/dm3 (on the average, 1.22 µL/dm3). The maximal methane concentration was recorded in the water mass of the deepest central depression of the lake, and the minimal, in its southern depression. Among shallow areas, minimal methane concentrations were recorded in the coastal zone of Listvenichnyi Bay, and its maximal concentrations, in the northern part of the lake, into which many rivers empty, as well as in Selenginskoe shallows. Most stations, either deep-water or shallow, showed a peak of subsurface maximum of methane concentration at depths of 25–50 m (thermocline zone), after which its concentrations commonly dropped, reaching their minimal values either in the intermediate water mass or in bottom layers. Shallow areas, in addition to higher methane concentrations compared to deep-water areas, also featured a higher contrast in its vertical distribution in the water mass. The analysis of correlation relationships between the examined hydrochemical characteristics revealed significant direct correlations of methane concentration with the concentrations of Corg and Norg and an inverse correlation with O2 concentrations.

Water management statistics of the state water cadaster of the Republic of Belarus was used to analyze the dynamics of water use over 2000–2019. The study is based on the statistical methods for the analysis of time series and the relative characteristics of water use dynamics. Trends and priorities were revealed in water use in the country as a whole and at the level of administrative regions. It is shown that in 2000–2019, water intake in the country decreased by 28%, and the use of water for drinking and industrial needs dropped by more than 30%. Comparative analysis revealed differences in water use between regions expressed in the relative characteristics: total water intake, the volume of groundwater development and surface water extraction, the amounts of water use for different purposes. In the majority of administrative regions of the country (102 out of 118), the main source of water supply is groundwater, the development of which exceeds the extraction of surface water, and in 36 regions, water supply relies completely on groundwater. The administrative regions are grouped by the priority objectives of water use. It is found that two water use objectives are of priority in 78 regions; these are household and agricultural needs, met by groundwater. The differentiation of the volumes of water withdrawal and water use priorities at the regional level is determined by population size, the development level of material production branches, and their water demand.

The article considers neural-network methods and technologies, which are relatively new even for many researchers and experts, as applied to water–environmental regulation. The efficiency of neural networks in this line of studies is due to their self-training, and the ensuing ability to reveal complex nonlinear relationships between the characteristics under control by data processing instruments, consisting of interrelated neurons. The methodology of artificial neural networks and the features of their functioning are described. Training and methodological examples are given to illustrate their potential use. A practical problem, considered as an example of ANN application, is the potential for improving the efficiency of identification of large enterprises polluting natural water among many water users in an industrial region. This is made with the use of data on the concentrations of some priority water-polluting metals at the hydrochemical gages in the Iset river near Ekaterinburg City. The neural-network analysis is shown to detect relationships between individual water quality characteristics at nearby gages. This allowed the conclusion that there exist close logistic economic relationships between water users, which help revealing water pollutants by the water footprint produced by plants working in the same branch. It is also shown that the use of ANN opens new ways for determining the contribution of industrial waste discharges to the level of water pollution by substances of dual genesis (natural and technogenic). The reliability of the conclusions is confirmed by the possibility to use the data on a given hydrochemical gage to satisfactorily predict water quality at a gage further downstream.