Vol 45, No Suppl 1 (2018)

The mathematical model for simulating deformations of river channels composed of heterogeneous alluvium has been developed. The combination of shallow water equations and a three-layer model is used to describe the fluid flow and non-uniform sediment transport in bed (layer II) and suspended (layer III) loads. Changes in the fractional composition of unerodible bottom sediments (layer I) are also considered. The algorithm provides mass conservation for each fraction. The comparison of calculations results and experimental data (hydraulic washing of a desilting basin from sediments and armoring processes in heterogeneous soils) confirms the operability of the model. The model is applied to calculate the silting and hydraulic washes of the reservoir of a hydroelectric power station on a mountain river.

Simulation models of river reservoir functioning in which dynamic volume nomograms are used to consider the non-horizontal nature of the reservoir water surface have not been so far applied due to the lack of accurate and fast-working computer realizations of such models. In 2015–2016, the authors of this paper developed such a program. In the periods of carrying out special-purpose spring water releases to the lower reaches of the Volga River in 2016 and in 2017, the developed model was used in a trial mode for a designing the reservoirs’ water regime. The results of water releases carried out under complicated hydrological and economic conditions proved the high performance of the model and confirmed the prospects of its application to solve the inverse problem.

The West Caucasus is the only Russian region where disastrous floods cause a great number of victims regularly. Developing the automated monitoring networks in the Kuban River Basin and Krasnodar Krai has improved the quality of hydrological information over the last years; however, its use for flood forecasting has to be more effective. The paper presents methods of short-term flood forecasting for West Caucasian rivers with rain floods prevalence during the warm season. They are based on applying the Flood Cycle Model (FCM), which has been tested for the first time in the region (the case study of the Tuapse, Psekups, and Pshish rivers). The presented forecasting methods, whose quality completely conforms to the criteria of the Russian Hydrometeorological Service, can enhance the existing hydrological forecasting systems. To further develop the flood forecasting methods for the West Caucasian rivers using physically based models, it is critically important to increase the precipitation measuring network density within the mountain parts of watersheds.

The decomposition of water quality formation of city watercourse was carried out. The ratio of natural and anthropogenic (local and transit) components of the watercourse water quality were determined in the case of the Belaya River. The mass of pollutants entering the water body from Ufa City territory through sources of different categories, including point and non-point, was estimated. It was established that the ratio of pollutant masses from point and non-point sources varies in different phases of water regime, depending on the pollutant type. In the study, it is shown that the system of river water quality monitoring should be improved taking into account the features of its formation within urban territory.

The study is aimed to evaluate a hydrological simulation model intended for assessing climate change impact. A new test was suggested and applied to evaluate the performance of a physically based model of Selenga River runoff generation. In this test, to calibrate the model, an enhanced Nash–and-Sutcliffe efficiency (NSE) criterion was used, including trend-oriented reference (benchmark) models instead of the simple reference model used in the original NSE criterion. Next, modifications were made in the Differential Split Sample test (DSS-test) of V. Klemeš (1986), focused on differences in the model performance criteria for climatically contrasting periods, and a new statistical measure was proposed to estimate the significance of these differences. After that, model performance was evaluated for four sites within the catchment, three indicators of interest (daily, monthly, and annual discharge series), and the model ability to reproduce the observed trends in annual and seasonal discharge values was assessed. The model proved robust enough to be applied to assessing climate change impact on the annual and monthly runoff in different parts of the Selenga River basin.

Water flow and sediment transport under the effect of hydrotechnical constructions on the Amur River near Blagoveshchensk and Heihe cities was analyzed based on two-dimensional hydrodynamic modeling using STREAM_2D software (the authors V. Belikov et al., Russia). Three modeling scenarios were considered: without constructions, with the embankment of Blagoveshchensk, with the embankment of Blagoveshchensk and a system of dams near the Chinese island of Big Heihe. Modeling results have shown that the embankment has only a local effect on the part of the Amur R. upstream from confluence with the Zeya R. The construction of dams in the side channels near the island of Big Heihe can lead to significant flow redistribution, providing the flow concentration in the main river channel and reduction of the water flow, entering the island system. An increase in erosion in the main channel downstream of the confluence near the left bank and a simultaneous increase in accumulation near the right bank of the Amur R. below the island system can take place as the result of side channels shutting by dams from the right bank.

A physically based model of runoff formation with daily resolution has been developed for the upper part of the Ussuri basin with an area of 24400 km² based on ECOMAG hydrological modeling platform. Two versions of the hydrological model have been studied: (1) a crude version with the spatial schematization of the drainage area and river network based on DEM 1 × 1 km with the use of soil and landscape maps at a scale of 1: 2500000 and (2) a detailed version with DEM 80 × 80 m and soil and landscape maps of the scale of 1: 100000. Each version of the model has been tested for two variants of meteorological inputs: (1) meteorological forcing data (temperature, air humidity, precipitation) at eight weather stations and (2) with the involvement of additional data on precipitation collected at 15 gages in the basin. The model has been calibrated and validated over a 34-year period (1979–2012) with the use of runoff data for the Ussuri R. and its tributaries. The results of numerical experiments for assessing the sensitivity of model hydrological response to the spatial resolution of land surface characteristics and the density of precipitation gaging stations are discussed.