Dmitriy Sokolov

Relevance. Current data on the chemical composition of river water is a crucial foundation for addressing water management challenges and serves as input information for global climate modeling. This article provides an overview of monitoring systems for the chemical composition WATER RESOURCES STUDIES 67 № 3, 2026 ВОДНОЕ ХОЗЯЙСТВО РОССИИ: ПРОБЛЕМЫ, ТЕХНОЛОГИИ, УПРАВЛЕНИЕ of river water in major Russian rivers (Northern Dvina, Ob, Yenisei, Lena, Don) within the observation network of Roshydromet, at departmental stations, and as part of scientific research programs. Methods.Information sources providing data and their accessibility are examined. The results of long-term network observations at the downstream Roshydromet stations on the rivers under consideration are summarized. The programs and data of the ArcticGRO (Ob, Yenisei, Lena, Kolyma) and Arctic FLUX (Ob, Yenisei, Lena, Kolyma) projects, as well as monitoring at the Samoylovsky Island Research Station (Lena), are reviewed. The monitoring of the chemical composition of river water in the lower reaches of the Moskva, Oka, Don, Northern Dvina, Ob, Yenisei, and Lena rivers is discussed. This monitoring was established in 2024 with the support of a mega-grant from the Ministry of Education and Science of the Russian Federation titled “Flows of potentially toxic elements and compounds in river basins: study technologies, quantitative assessment, and forecast.” Within this monitoring, more than 150 suspended and dissolved forms of chemical elements, nutrients, and organic substances are measured weekly, year-round. This represents a qualitatively new type of monitoring of the chemical composition of water in major Russian rivers, both in terms of detail and the scope of observations. Results. First estimates of seasonal transport forms of nutrients are presented, along with assessments of the input of suspended forms of trace elements into the receiving seas. The prospects for implementing remote and automated methods for monitoring the chemical composition of river water in Russian rivers are discussed.

This study aims to identify the main patterns of distribution and sources of pollutants in the Moskva River and their influence on river water quality under different levels of anthropogenic stress caused by the largest megacity in Europe – Moscow. For this study, we determined concentrations of 18 trace elements, nutrient elements and major ions, chemical and biochemical oxygen demand, and physical parameters of water at 45 stations on the Moskva River and 20 stations on its tributaries during spring flood and low water of 2019 and 2020 to identify the extent and mechanisms of urban impact on its water chemistry. Chemical elements concentrations have been determined using ICP–MS and ICP–AES methods. Mn, Al, Cu, Sr, Zn, B, Mo, and inorganic nitrogen were outlined as key pollutants according to various drinking water and environmental guidelines. Using correlation and factor analysis, five groups of elements were identified, corresponding to different drivers controlling their unequal distribution within the watershed: mineral sources (Sr, Li, B, Mo, Ca), sewage and road runoff (TN, TP, Sb, Ni, N–NO₂, BOD₅, COD, V, Zn), impact of acidic wetlands (Al, COD, Zr, Bi), groundwater and landfills leachate (V, As, Pb, U, Sb), and industrial activities (Zn, Cu). Water quality in the Moskva Basin on the whole is good according to the CCME Water Quality Index. Local deterioration of water quality to marginal and even fair (depending on the reference water quality guideline) is confined to the Moskva River part downstream from the Kuryanovo aeration station to the Moskva mouth and to the mouths of several heavily contaminated tributaries.

According to the results of 2019-2020 studies, we considered the features of hydrological, thermal, ice regime and water turbidity of the small urban Setun River, one of the largest right tributaries of the Moscow River, flowing in the western part of the city of Moscow. The specific discharge from the Setun watershed is 1.5-2 times and the turbidity is 3 times higher than in natural conditions in the upper Moscow River basin. Due to thermal pollution by wastewater, ice cover forms only in the upper reaches of the river during sustained frosts, and water temperature within the city is 1.5-2.5 degrees higher (up to 6 degrees in winter).

In 2019, we conducted an integrated study on the Moskva River and its tributaries during the low summer season with a focus on organic matter content (OM) assessment in river waters. The maximum OM content was measured at the river headwaters and related to natural sources. The Mozhaysk Reservoir regulation in the summer had the effect of increased organic load below the dam due to a rise in the allochthonous labile OM. Upstream from the Moscow City, the OM content was relatively low, despite wastewater inflow from several densely populated areas and polluted river inflow. Within the city, organic matter concentration increased by a factor of 1.5 due to an inflow from the Volga River via the Moskva-Volga Canal, whereas the release of treated sewage from the Moscow City wastewater treatment facilities did not have a significant effect. Below the city, the OM content increased again by a factor of 1.5 due to the inflow of urban and industrial wastewater and polluted tributaries. The observations in the lower reaches of the Moskva River indicate a high degree of anthropogenic euthrophication.

The development and deployment of new operational runoff forecasting systems are a strong focus of the scientific community due to the crucial importance of reliable and timely runoff predictions for early warnings of floods and flashfloods for local businesses and communities. OpenForecast, the first operational runoff forecasting system in Russia, open for public use, is presented in this study. We developed OpenForecast based only on open-source software and data—GR4J hydrological model, ERA-Interim meteorological reanalysis, and ICON deterministic short-range meteorological forecasts. Daily forecasts were generated for two basins in the European part of Russia. Simulation results showed a limited efficiency in reproducing the spring flood of 2019. Although the simulations managed to capture the timing of flood peaks, they failed in estimating flood volume. However, further implementation of the parsimonious data assimilation technique significantly alleviates simulation errors. The revealed limitations of the proposed operational runoff forecasting system provided a foundation to outline its further development and improvement.

По результатам детальных экспедиционных исследований 2012, 2016 и 2017 гг. выявлены закономерности современного режима содержания органических веществ в воде основных притоков Можайского и Рузского водохранилищ. Получены прямые связи содержания органических веществ с расходом воды, в половодье имеющие форму петли, а в остальную часть года близкие к линейным. Найденные зависимости существенно зависят от гидрометеорологических условий и отсутствуют для зарегулированных водосборов. В паводки концентрация органических веществ выше, чем в половодье. В многоводные периоды при преобладании поверхностного стока до 45% органических веществ находится во взвешенном состоянии, а при превалировании внутрипочвенного стока — до 95–100% в растворенном. Показана принципиальная возможность параметризации содержания органических веществ в речных водах для обеспечения диагностических и прогнозных расчетов качества воды Москворецкого водоисточника при отсутствии мониторинговых данных.