Vol 43, No 1 (2016)

The presented results have been obtained in a study of the concentrations and composition of aliphatic and polycyclic hydrocarbons in bottom sediments of Volga delta branches and in its shallow zone (2009–2010), as well as the Caspian Sea proper (2010–2013). Oil hydrocarbon pollution has been found to manifest itself mostly in Volga delta branches, which, despite the low concentrations (up to 54.5 μg/g), showed higher hydrocarbons share in C_org (up to 33.8%), while the composition of alkanes suggested their oil genesis. The geochemical barrier the Volga–the Caspian Sea prevents anthropogenic hydrocarbons from entering the open parts of the Caspian. Bottom sediments in the shallow zone of the Northern Caspian, represented by coarse-grained material, are now polluted by oil hydrocarbons to a lesser extent compared with other areas. The highest concentrations of aliphatic hydrocarbons (up to 178 μg/g) were recorded in the deepsea bottom sediments of Derbent Depression and in depressions of the Middle and Southern Caspian. These areas show a higher concentration of C_org (up to 9.884%) and a low concentration of hydrocarbons in C_org (up to 0.16%), while odd high-molecular homologues (n-C₂₅–C₃₁) dominate in the composition of alkanes.

The results of studies of the hydrobiological regime of three sapropel lakes in Novosibirsk region in 2012 are presented. The biological production of the examined lakes, the composition and biomass of dominating species–producers of organic matter (phyto- and zooplankton, macrophytes) is determined, and the sedimentation rate of plankton and phytodetritus is estimated. The obtained results provide improved estimates of the contribution of aquatic organisms of different trophic levels to the processes of sedimentation and formation of sapropel in different types of lakes.

In the article, the results of field observations of the chemical composition of the small river basin waters obtained during warm periods in 2011–2012 are presented. Seven basic geographical types of water were investigated, namely, cyclonic rainfall, rainstorm, throughfall, subsurface soil flow, low water flow (specific discharges of waters do not exceed 2.5 L/s km²), low floods (peak specific discharges are from 2.5 to 16 L/s km²) and medium floods (peak specific discharges are from 16 to about 100 L/s km²). A result of the interaction between the rain water and landscape constituents is that all examined natural waters differ to the maximum extent in the anionic composition. A chemical type of stream waters is sufficiently stable; it is formed predominantly within the soil-ground cover and does not change with increase in flow rate.

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.

The Eskisehir province is well-known due to its industrial and agricultural activities, which are a threat for the aquatic environment. Hence, monitoring of water quality in the area is of vital importance because of an excess heavy metal contents, especially As. The Porsuk River is heavily polluted by industrial activities from Kutahya city. It discharges into the Porsuk Dam and from there it flows relatively clean to Eskisehir city center, but beyond this point it increasingly deteriorates due to the negative impact of industrial and agricultural activities up to the junction point of Porsuk and Sakarya rivers. Heavy metal concentrations and As contents in surface and ground waters were selected as pollution indicators to examine pollution level and compare an interaction between river and groundwater. For this purpose, water samples taken between 2008 and 2010 from the Porsuk River along the section from the west of Kutahya to the discharge point into the Sakarya River, as well as groundwater samples from the wells located close to or far of the Porsuk River, were evaluated. Based on the obtained results, we found that the Porsuk River, especially at the locations close to the Sakarya River, and groundwater are polluted in terms of heavy metals and As compounds. In conclusion, the heavy metal and As pollution is also observed in the wells close to the locations in which groundwater is fed by the Porsuk River since it acts as an influent river. Thus, surface water is considered as a polluting source of groundwater.

Inundatios on the Black Sea coast of Krasnodar krai between 1945 and 2013 have been analyzed. The main genetic types of inundations on the coast have been identified. The specific features and regularities of inundation wave transformation along the rivers and over time have been studied. Seasonal and maximal runoff of Black Sea rivers has been analyzed over a long-term period. Regularities in the variations of the number of inundatios and their characteristics over the coastal area have been revealed both at the annual and long-term scales. Quantitative estimates are given to the hazard and damage to the population and economic activity due to inundations in the valleys of Black Sea rivers.

The applicability of a procedure, developed previously for evaluating runoff hydrographs of northern rivers, to the largest Russian river—the Lena—which flows under severe conditions of the Northeastern Siberia, is examined. The procedure is based on the land surface model SWAP in combination with input data derived from global databases of land surface parameters and meteorological forcing data derived from observations at meteorological stations located in the basins of the rivers or near them. Also studied was the ability of the model SWAP to reproduce the many-year dynamics of the values of snow water equivalent averaged over the Lena basin and their distribution over the basin area.

Taking into account the fact that during the last decades domestic readers were poorly familiar with the hydrology of this region, it was considered appropriate to study the extreme situations within the Prut basin. By means of very simple mathematical calculation we have highlighted the role of reservoirs in change of relationships between extreme rainfall and floods/droughts, estimate the confidence degree of these estimations, etc. The Prut watershed is characterized by a temperate-continental climate with excessive influences in the middle and lower parts. Probabilistic analysis of the annual maximum flow indicates high values in the summer. The high flows recorded in 2005, 2008, and 2010 were caused by the most serious floods for the last 35 years. The maximum flow values had an exceeding probability of 2–10%, which explained the frequency of the phenomenon. Only the historical value (4240 m³ s^–1) at Radauti-Prut exceeded the flow rate with 1% probability. The results obtained for the hydrometric station located downstream underlined the role of Stanca–Costesti Accumulation Lake in flood protection. Simple linear regression identified the strength of the relationship between the predictor variable (total monthly rainfall) and the criterion variable (average monthly flow). The indicator used in this study to highlight the size effect, R² (the regression coefficient), is based on the degree of association between variables and describes the percentage of variability explained by each variable in relation to the other. The results indicated a large effect size at the Radauti–Prut station that decreased gradually downstream, as a result of the flow regularization function played by the reservoir. The minimum flow study revealed 7 consecutive years with drought, from 1982–1988. In the current period, the extremely severe drought began in the late autumn of 2011 and was maintained at the end of the winter, summer, and autumn of 2012.

Innovative water management is the first priority for the Saemangeum Project, a national project for a building global city as a frontrunner of green growth because there has been a big debate concerning the environmental problems (water quality, destruction of mud flats and so on). This study aims at identifying the change of water quality with time and analyzing the cause of its tendency. Results of this study verify that the importance of water quality is required when preparing water infrastructure for smart water use and may use for establishing a proper management plan in the Mangyeong River basins of the Saemangeum.

An ensemble of cold thermals in a convective layer of a fresh or salt water body is considered. The probability distribution density of the vertical velocities of thermals is assumed to satisfy the K-form of Fokker−Planck equation. The K-form of the Fokker−Planck equation is shown to have a steady-state solution in the form of a generalized Maxwell distribution. Natural and numerical experiments were carried out to demonstrate the existence of such distribution. Lyapunov functional in the form of Kullback relationship was used to establish the nonlinear instability of this distribution with respect to small perturbations in the Hilbert space norm.

Experimental investigation on fluvial hydraulics needs a correct and accurate estimation of bed shear stress, which governs the hydrodynamics of the sediment transport. Present work compares bed shear stress estimated from the reach-averaged bed shear stress, Log profile, Quadratic stress law, Prandtl’s seventh power law, Reynolds shear stress, turbulent kinetic energy and graphical method approaches by doing experimentation on plane bed and curvilinear bed channel. On plane bed condition, the bed shear estimated from Reynolds stresses and Graphical methods are comparable to the reach-averaged bed shear stress (the difference is within 10%). However, all approaches estimate approximately less than 10% from reach-averaged bed shear stress in curvilinear bed channel.

This paper presents a dual-percolation model coupling the percolation theory and the fracture percolation theory to study the conductivity of the fractured porous media. The Monte-Carlo method is used in the numerical simulation. First an appropriate computing scale by considering the calculation precision and elapsed time together is validated. Then, two parameters, A₀ and D are presented in this model to determine the conductivity of the media. Generally the media can be blocked by itself in the condition of D > 2. However, the increase of pore connection and the randomness of fracture direction may release the selfblockage, increase the conductivity and make the dual porous media dissipated. A few long fractures can play a great role in the connection of media.

There are two significant reasons for the uncertainties of water demand. On one hand, an evolving technological world is plagued with accelerated change in lifestyles and consumption patterns; and on the other hand, intensifying climate change. Therefore, with an uncertain future, what enables policy-makers to define the state of water resources, which are affected by withdrawals and demands? Through a case study based on thirteen years of observation data in the Zayandeh Rud River basin in Isfahan province located in Iran, this paper forecasts a wide range of urban water demand possibilities in order to create a portfolio of plans which could be utilized by different water managers. A comparison and contrast of two existing methods are discussed, demonstrating the Random Walk Methodology, which will be referred to as the “On-uncertainty path”, because it takes the uncertainties into account and can be recommended to managers. This OnUncertainty Path is composed of both dynamic forecasting method and system simulation. The outcomes show the advantage of such methods particularly for places that climate change will aggravate their water scarcity, such as Iran.

Soil physical properties and hydrological processes were analyzed in two experimental catchments with different forest types: one catchment is covered mostly with conifer type trees and the other catchment is covered with conifer and broad leaf trees. To analyze the effects of forest type on soil physical properties, we applied an hourly time step lumped conceptual model, which includes a physically-based infiltration submodel and an evapotranspiration sub-model, to simulate long term discharge. The estimated model parameters and some measured soil characteristics were compared for the two catchments to reveal the differences in soil physical properties. The differences in hydrological processes were compared through observed hydrological factors (rainfall, discharge and meteorological data) between the two catchments.