Water Resources

Reconstruction of variations in the Caspian Sea level is proposed based on the results of investigations of deposits in the Agrakhan sand bar and bays (or former bays) of the eastern sea coast. The history of sedimentation in particular regions is reconstructed by the radiocarbon dating. Generalized data on the age of deposits are used to construct the most likely temporal course of variations in the sea level within the historic epoch.

In the study, multivariate statistical methods including principal component analysis (PCA)/factor analysis (FA) and cluster analysis (CA) were applied to analyze surface water quality data sets obtained from the Huaihe River segment of Bengbu (HRSB) and generated during 2 years (2011–2012) monitoring of 19 parameters at 7 sampling sites. The results of PCA for 7 sampling sites revealed that the first four components of PCA showed 94.89% of the total variance in the data sets of HRSB. The Principal components (Factors) obtained from FA indicated that the parameters for water quality variations were mainly related to heavy metals (Pb, Mn, Zn and Fe) and organic related parameters (COD, PI and DO). The results revealed that the major causes of water quality deterioration were related to inflow of industrial, domestic and agricultural effluents into the Huaihe River. Three significant sampling locations—(sites 2, 3 and 4), (sites 1 and 5) and (sites 6 and 7)—were detected on the basis of similarity of their water quality. Thus, these methods were believed to be valuable to help water resources managers understand complex nature of water quality issues and determine the priorities to improve water quality.

Variations in the concentrations of dissolved organic and biogenic substances in waters of natural watercourses under the effect of natural and anthropogenic factors are considered. Seasonal and long-term dynamics of these concentrations in 1990–2001 are analyzed. The causes of an improvement in surface water quality are established, and the role of some changes in the agricultural production in the forest–steppe zone of the Central Black Earth Region of Russia is assessed.

This work analyses the state of water resources in six Mediterranean islands: Corsica, Crete, Cyprus, Mallorca, Malta and Sicily. The analysis is focused on the prevailing social, economic and hydroclimatological characteristics of these islands in order to identify the main common features affecting water availability, demand and use. A detailed analysis of the state of water resources in all the considered islands has been carried out. A background of current conditions relating to freshwater availability, quality and use has been established. Different strategies to face water scarcity and enhance water quality in theislands have been assessed in a context of climate change which is a common threat. The identification of similar problems for all the islands highlights the importance of strengthening inter-islands co-operation in the field of sustainable water resources management.

The results of studies of water bodies in the Amur R. basin in 2011–2017 have been used to characterize the space and time variations of the concentrations of dissolved microelement forms. They have been found to vary widely in some areas, because of either the diverse natural conditions and the anthropogenic effect in areas near cities (Chita, Sretensk, Khabarovsk) and populated localities (Nizhneleninskoe V.), as well as the transboundary transport from Chinese territory. The character of the time variations of the concentrations of dissolved forms of metals in water in the Amur basin have been shown to be diverse and to demonstrate a complex combination of the factors that determine this variability. The time variations of dissolved matter concentrations are more pronounced in watercourses where runoff is not regulated (the Ussuri, Amurskaya branch).

The lack of long term observed data is the main challenge in many simulation-based studies for identification of nutrient critical source areas (CSAs). This study explored the effect of calibration of the Soil and Water Assessment Tool (SWAT) on identification of nutrient CSAs and evaluated capability of this model for finding CSAs under the limited data condition. For this purpose, the Zrebar Lake watershed in Iran was used to assess the variations in total phosphorus and total nitrogen CSAs identified by both calibrated and uncalibrated SWAT models. In this study, a modified version of SWAT model was used for calibration the model considering observed lake water quality data and also for simulation of lake water quality and quantity interactions with the watershed management practices. The nutrient CSAs identified by calibrated and uncalibrated models showed that the irrigated farmlands were the main sources of nutrients discharged into the lake in which alfalfa, apple and tobacco were marked as the most polluting cultivations. It was also concluded that CSAs were not considerably different based on the calibrated and uncalibrated models. This validates the capabilities of SWAT on marking CSAs for areas with lack of long term observed data.

Elision and infiltration groundwater of the Northern Caspian basin are described. It is shown that a zone of elision brines with a high formation pressure exists under the Caspian Sea. These brines are shown to penetrate from below the Caspian Sea into the underground beds, carry fluids, and facilitate the formation of hydrocarbon fields.

Statistical methods for assessing the spatial distribution of benthic communities in different parts of watercourses have been considered as applied to lowland rivers of the Lower Volga region. The applicability domains are described for different response models, gradient analysis, and random skewers methods, which are used to analyze the distribution of aquatic organisms in bottom sediments. Stationarity and autocorrelation criteria for the description of generalized characteristics of macrozoobenthos communities are analyzed. The problems of identification of statistically significant isolated zones at whose boundaries the succession change of the species composition of aquatic organisms are discussed. The results of nonparametric dispersion analysis of species similarity matrices, the formation of dendrites, and the search for barriers between individual areas are given (based on Delaunay triangulation and Monmonier’s maximal-diversity algorithm).

The space and time distribution of reservoirs over the drainage basins of Arctic seas within Russian Federation territory and the main rivers flowing into the Arctic Ocean is analyzed. The Ob River is considered along with the Kazakh part of the Irtysh Basin. The stages of the hydroengineering development of water resources are identified and characterized. The effect of reservoirs on the water regime and the annual runoff of major rivers is determined. The perspectives of the construction of reservoirs are demonstrated.

The first, theoretical part of the study presents a mathematical formulation of the problem of background flow over a two-stage elevation and the derivation of a criterion of bifurcation of a topographic vortex generated by this elevation. The spectral problem of the search for bifurcation points is solved numerically by the inverse iteration method. The second part presents the results of laboratory experiments aimed to simulate topographic vortices. The main attention is focused on the process of bifurcation of a topographic vortex and the formation of secondary toroidal vortices over a two-stage axisymmetric elevation of the bed in the form of two coaxial solid cylinders of different diameters, located one on top of the other. The bottom cylinder has a larger diameter. The input characteristics for the laboratory experiments are data derived from numerical solutions of the appropriate spectral problem.