Vol 44, No 2 (2017)

The potentialities of artificial neural networks are studied as applied to estimating key model parameters required for calculating river runoff by SWAP model in the case of ungauged watersheds. The examined geographic objects were 323 experimental watersheds of MOPEX project. The quality of model parameter estimates based on ANNs with different architecture was analyzed.

The morphometric and anthropogenic risk factors of floods in a typical lowland Lower Kura R. are studied. The isolation of the channel from the floodplain is the major cause of floods in the river. The high channel tortuosity makes the flow turbulent. In addition, the high sediment concentration, the turbid and disperse character of the liquid, the gentle bed slope, and the alluvial character of the soil underlying the bed and embankments contribute to the vertical and horizontal dynamics of the channel.

Remote-sensing images of Ebinur Lake Basin including six years (1960, 1972, 1990, 2000, 2005 and 2010) were interpreted through RS and GIS. Land use changes in Ebinur Lake Basin during the past five decades were analyzed according to interpretation results. On this basis, effect of land use changes on hydrology and water resources was analyzed. Results show that the land use pattern in Ebinur Lake Basin changed greatly from 1960 to 2010. Cultivated Land and Urban-Rural Construction Land increased, while other landuse types decreased. Most areas were Unused Land. Generally, oasis expanded continuously, but oasis in Ganjiahu Zone at downstream of the Kuitun River Basin reduced to some extent. Runoff of the Kuitun River and Jinghe River increased gradually, but runoff of the Bortala River reduced continuously. Both inflows and lake area declined year by year. The groundwater level dropped significantly and water deteriorated continuously. Due to the decelerating wind blowing, evaporation in the basin reduced accordingly. Hydrology and water resources changes in Ebinur Lake Basin in past five decades were mainly caused by continuous expansion of Cultivated Land and oasis, continuous population growth and hydraulic engineering constructions. However, oasis expansion shall be limited within the carrying capacity of water resources. To maintain ecological security in the basin, it is necessary to determine reasonable oasis area, optimize river system structure, and improve utilization efficiency of water resources.

Active bed forms of three major classes are formed in Terek lower reaches during summer floods. They include ripples, dunes of the first order, and dunes of the second order (from smaller to larger), which commonly form an incomplete hierarchy. The morphology of the bed forms is essentially stochastic and can be adequately described by probability distribution functions of bed form characteristics for some narrow ranges of hydraulic flow characteristics. At the same time, the mean values of bed form morphometric characteristics (length, height, and asymmetry) show stable relationships with flow velocity and depth. The celerity of active dunes can be adequately described by a modified Snishchenko–Kopaliani formula. The channelforming sediments that move as bed forms in Terek lower reaches account for 7% of sediment transport rate of all channel-forming sediments, a value near the lower limit for rivers with sand alluvium.

Groundwater chemistry in the northwestern Bol’shekhetskaya Megasyneclise is considered, and the predominance of inversion hydrogeochemical zonality is identified. The analysis of the hydrogeochemistry and genetic coefficients enabled the tentative identification of infiltrogenic, sedimentogenic, lithogenic, and condensatogenic types of waters. The implemented paleohydrogeochemical reconstructions confirmed the predominance in the cross-section of ancient infiltrogenic and slightly saline sedimentogenic water at all development stages of the sedimentary basin.

The results of studying the hydrocarbon composition of organogenic bottom sediments of oil-polluted lakes and lakes of similar types remote from centers of anthropogenic activity are given. To correctly assess the oil pollution of organogenic materials one has to take into account the presence of native hydrocarbons in their composition and to choose the main criterion of oil pollution based on the presence of specific oil components not characteristic of aquatic ecosystems in their natural state. The most promising among such components are alkylbenzenes С₁₅–С₂₅, which slowly degrade under the conditions typical of northern aquatic ecosystems and can be retained for a long time by organogenic matrix.

The distribution and fractionation of rare-earth elements (REE) are studied in the surface and subsurface waters and rocks of the Albynskoe Gold-Bearing Placer. The obtained data show the rocks of the placer to be enriched with rare-earth elements and to feature the predominance of light lanthanides over heavy ones. Groundwater show an equality between the groups of light and heavy lanthanides, while in the surface waters the concentration of light REE is much higher than that of heavy ones, thus reflecting the composition of the drained ore rocks. The leaching of rare-earth elements from rocks by atmospheric water is intensified by agents produced by microorganisms in their vital activity.

The three-dimensional hydrodynamic and eutrophication model was implemented based on EFDC to help eutrophication control decision making of Shenzhen Reservoir. Model calibration and validation were conducted with two set of independent observed data in 2009 and 2010–2011. The model represented the hydrodynamic process and the spatial and temporal distribution of water quality well. Subsequently, three eutrophication control scenarios were configured, included removing 100% nutrients from all tributaries, increasing by 50% of water flows, and removing 50% nutrients from Dongjiang. As results shown, the maximum chlorophyll-a concentrations were decreased by 1, 16.4 and 46.3%, the average chlorophyll-a concentrations were decreased by 1.3, 29.8 and 29.9%. Increasing water flows and removing nutrients from Dongjiang can significantly improve water quality and effectively reduce risk of water bloom.

Due to scarcity of local data on stormwater pollution levels and rainfall-runoff generation process, very few attempts have been made towards the management of stormwater in sub-tropical rural catchments. An attempt has been made in the present study to characterize and predict the stormwater runoff characteristics using regression modeling from five rural catchments in north-west India. Stormwater samples and flow data were collected from 75 storm events. Samples were analyzed for pH, total suspended solids (TSS), 5-day biochemical oxygen demand (BOD₅), chemical oxygen demand (COD), total kjeldhal nitrogen (TKN), total phosphorous (TP), nitrate-nitrogen (NO₃^-–N), total coliform count (TC), fecal coliform count (FC), Zn, Cu and Fe. It was found that size of the catchment and the land use practices influenced the stormwater quality even in predominantly rural areas, otherwise thought to be homogeneous. The results obtained were related with the antecedent dry days (ADD) and average rainfall. ADD was found to be positively correlated with pollutant loads whereas average rainfall showed negative correlation. The study highlights the importance of ADD in causing greater mean pollutant concentrations except for TKN, TP and NO₃^-–N. Regression models were developed for the studied catchments to estimate mean pollutant concentrations as a function of rainfall variables. Results revealed that measured pollutant concentrations demonstrated high variability with ADD and average rainfall in small rural catchments, whereas in large catchments, factors like land use, extent of imperviousness etc. resulted in low predictability of measured parameters.

The expedition for studying the Volga R. was organized by the Institute of Oceanology, Russian Academy of Sciences and the Institute of Inland Water Biology, Russian Academy of Sciences, with the participation of the Institute of Geochemistry and Analytical Chemistry on the r/v Akademik Topchiev (June 2–18, 2016). The main objective of the expedition studies of the Institute of Oceanology, Russian Academy of Sciences, was to examine the sedimentation and biogeochemical processes in the mixing zone of the Volga and its tributaries with the aim to assess the present-day water quality and trends in its changes in the recent years. In this context, the study was focused on the aerosols of near-water layer, surface water, and bottom sediments along the route the Rybinsk Reservoir (Borok Settl.)–Lower Volga (Astrakhan C.). The methodology was based on a multidisciplinary study of dissolved compounds and suspended particles (<1 μm). The main attention was focused on studying the spatial variations of biogenic substances, organic compounds (Corg in suspension and solution), the suspension itself, and hydrcarbons.