卷 46, 编号 1 (2019)

The results of long-term field studies are used to consider in detail the issues of hydrological regime formation in a lagoon–channel estuary of the Bol’shaya R. in Kamchatka krai, one of the most remote and poorly know Russian regions. A vast body of factual data is given to characterize the estuary and the processes taking place in it, as well as the natural conditions under which it exists.

Formulation of rainfall runoff models and identification of their parameters is difficult step especially for catchments having scanty or no data. Parameters of geomorphic instantaneous unit hydrograph (GIUH) models have been investigated in this research. Recorded data of Shahpur Dam Catchment, Pakistan was used for developing direct runoff hydrograph model. Satellite imageries of the catchment were processed using ArcGIS 10.1 to estimate geomorphologic parameters. The rainfall and runoff data for 10 events was collected from Meteorological Department Lahore and from Small Dam Organization, Rawalpindi, Pakistan. Rainfall data was analyzed and excess rainfall was estimated using Percent Runoff Method. Using estimated geomorphologic parameters the ordinates of GIUH- Nash Model were obtained by standard equations of Nash instantaneous unit hydrograph (IUH). These ordinates of Nash-IUH, were converted into the ordinates of direct runoff hydrographs through their convolution with the excess rainfall. The results of model were evaluated on the basis of their deviation from the observed runoff data. Statistical parameter Nash-Sutcliffe Coefficient and percent error between observed and simulated direct runoff were used for this purpose. The impact of using digital elevation models (DEM) of two different resolutions; 30 and 90 m, was then investigated. It is observed that the geomorphic parameters are affected due to DEM’s resolution. Hence the resolution of DEM impacts the direct runoff as well.

Field studies of the seasonal and daily dynamics of the mixing zone were carried out in the microtidal estuary of the Partizanskaya River. The position of the mixing zone was determined by river runoff volume. The upstream boundary of the mixing zone was located at a distance from 5 (at river discharge of 73.67 m³/s) to 12.5 km (at 7.7 m³/s) from the mouth bar. The estuary features a two-layer water circulation, resulting in the formation of halocline with a gradient of water salinity of up to 30‰ per 1 m. Salinity variations at rifts, caused by tides, reach 27‰ over a 3-hour period.

Two reservoirs in the Upper Volga were studied to determine the abundance, biomass, and production of planktonic, epiphyte, and benthos bacterial communities and to assess their contribution to the formation of the total abundance and productivity of bacteria. The abundance and production of heterotrophic bacteria per 1 cm³ of bottom sediments were 10–10² times greater than those in epibioses of higher aquatic plants and 10³–10⁴ times greater than those in water mass. In the mesoeutrophic Rybinsk Reservoir and eutrophic Ivan’kovo Reservoir, bacteriobenthos accounts for 90.4 and 98.8% of the total biomass and 95.8 and 99.5% of the total production of heterotrophic bacteria; bacterioplankton, for 9.55 and 1.19% of biomass and 4.12 and 0.45% of production; and bacterioepiphyton, for 0.05 and 0.03% of biomass and 0.03 and 0.02% of production. The obtained data demonstrate the important role of benthic bacterial communities in the Upper Volga reservoirs.

The processes of possible long-term variations of pH in Caucasian lakes were analyzed based on a study of lacustrine sediments from five small lakes of the Western and Central Caucasus. The study was focused on diatom complexes examined in core columns of bottom sediments. The values of pH were reconstructed using the authors’ principle of unification of hydrological characteristics. The study used the results of isotopic dating. Series of numerical values of pH with lengths from 2000 to 130 years were constructed for the examined lakes. The reconstructed series of pH values show no appreciable changes in the lakes of the Western Caucasus and suggest pronounced processes of alkalinization in the lakes of the Central Caucasus.

The analysis of data on the space and time variations of the concentrations and element composition of organic matter dissolved in Caspian Sea water over 2010–2015 showed that the average concentrations of C_org and N_org did not changed over the last 5 years of sea level drop relative to the period of level rise, while the concentrations of P_org decreased more than three times, i.e., qualitative changes had taken place in the organic matter. According to the average data, the concentrations of C_org, N_org, and P_org in the southern waters were slightly higher than those in the Northern and Middle Caspian waters. In deep-water regions, the concentrations of С_org, N_org, and Р_org increase at the boundary of hydrogen sulfide appearance. The presence of hydrogen sulfide in deep waters of the Derbentskaya and Southern Caspian depressions, accompanied by an increase in OM, suggests that no radical increase in vertical seawater mixing took place in these regions during the eight-year regression. The distribution of carbohydrates demonstrates a considerable contribution of petroleum hydrocarbon OM to the total pool.

External water exchange of bays of the lakes Onega (Kondopoga and Petrozavodsk bays) and Ladoga (Hiidenselkä Bay), considering the exchange with the lake water, was assessed by water chemistry of the bays and inflowing waters, as well as by the volume of water inflow into the bays. The periods of water exchange were found to be 0.13 for Petrozavodsk Bay, 1.02 for Kondopoga Bay, and 1.15 year for Hiidenselkä Bay. Their water exchange periods are 2–3 times greater if water exchange with the lake was not considered. Data on water exchange in Petrozavodsk Bay were confirmed by seasonal variations of water isotopic composition.

The objectives of this study were to predict the water quality index using Support Vector Machine (SVM) model and to identify the most important attributes affecting the variability of the water quality index in the Sefidrud basin which is located in the northern part of Iran. Water samples at each site have been collected monthly from December 2007 to November 2008. At each station, water samples were collected from inside the middle of the river by means of a plastic bucket and were transported to the laboratory. Water quality parameters were measured, calculated and classified according to the standard methods. Prediction of the SVM models in the study area resulted in determination coefficient and root mean square error of 0.87 and 0.061 for the water quality index, respectively. The nitrate was identified as the most important attribute influencing the water quality index. Overall, our results indicated that the SVM models could explain 87% of the total variability in water quality index. Besides, the predictability of water quality index could be improved by other statistical and intelligent models. These predictions help us to improve river management, regarding water quality.

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.

The study is focused on the step-by-step development of the modern system of legal rules and principles used at the international level to regulate the use of transboundary watercourses in the course of their hydropower, water-management, and fishery development and for their protection and preservation. Analysis is given to the main tendencies in the development of the newly forming branch of the international public law aimed to regulate the international cooperation in the use, protection, and maintenance of transboundary water resources.