There is significant evidence that seasonal snow mass, snow cover extent, and snow season duration are consistently decreasing in many lowland rivers in the Northern Hemisphere, often accompanied by a decrease in the magnitude of snowmelt floods (freshets). This paper explores to what extent snow accumulated in a river basin during winter affects subsequent freshet and if the ongoing decrease in runoff is due to a decrease in snow. We analysed maximum annual snow water equivalent (pre-melt SWE) and freshet runoff data for 20 river basins located in different physiographic conditions within the East European Plain in 1951-2019. For this analysis, we developed a new method for assessing the pre-melt SWE contribution to freshet runoff as a product of two physically meaningful indicators named 'variability ratio index' and 'elasticity index'. First, we demonstrated that downward trends in both pre-melt SWE and freshet runoff occurred and were more noticeable in the more southern, less forested, and mid-area basins. Then, using the developed method, we assessed to what extent the pre-melt SWE contributes to the detected runoff changes and how this contribution evolves in time. The main conclusions of our study are as follows. It was found that for the entire period, the pre-melt SWE variation was not the dominant freshet variance contributor (25% on average). Also, we revealed that in a half of the river basins, SWE contribution to runoff has decreased in the recent decades compared with the baseline period (1951-1990), and this decline is mostly associated with a decrease in the elasticity index. Overall, we found that the SWE variability was not the dominant factor in snowmelt runoff changes in the vast territory under consideration over a 69-year period. The result indicates the ambiguity of the relationship between the warming-induced reduction in SWE and decrease in snowmelt runoff.

Moscow megacity is experiencing the largest net population growth in Russia and across Europe, resulting in significant climatic and hydrological changes of the small rivers. High-frequency (30-min) automatic streamflow and sediment monitoring with turbidity sensors was performed in 2019-2024 across the Setun River-the major tributary of the Moskva River, with a 190 km2 catchment area. It was also enhanced with 8 detailed records by the in-situ LISST-200x laser diffractometer, spanning 49 h from February to April 2024. The geospatial analyses of the catchment revealed up to 40 % distribution of impervious surface types, which determines a novel streamflow regime. Its main features are frequent short-term peak flow events, up to 29 per year, and a short flood wave catchment response to rainstorms. Downstream increase in residential area density and impervious surface area from upstream to downstream areas does not affect the relative contribution of various water sources, whereas a 3-4-fold increase in suspended sediment transport conditions along the river is registered. Short-lived increases in suspended particulate matter (SPM) concentration and grain sizes are characterized by hysteresis effects due to hydraulic sorting of suspended sediments along the river channel downstream of the local pollution sources. Finally, we developed a robust and novel methodological approach for forecasting suspended sediment concentrations from water level and flow, precipitation, and air temperature in a fluvial urban system by adopting 5 machine learning models with a resolution of 30 min to 1 day. The best results were demonstrated by the recurrent neural network LSTM for daily water turbidity values with a root-mean-square error of 10.8 NTU.

Catchment erosion, channel erosion and sediment transport are connected processes within fluvial system forming a sediment cascade. Studies related to connectivity between a specific source and its multiple sinks within catchment, and rivers, and their multiple impacts have expanded in scope and sophistication during the last two decades, and were recently broadly presented at numerous international conferences and workshops. The International conference on transboundary catchment erosion and pollution problems was held in Belgrade, Serbia, in July 2023. The outcome of this conference as comprehensive literature review on the topic initiated this review which is aimed at classification the functional scheme of soil erosion, channel processes and sediment transport, and their impacts which include natural hazards, river pollution and hydrogeochemistry, catchment management, and hazards prevention, and technologies. We summarize established and emerging papers related to both regional studies on catchment erosion and management, as well as channel processes modelling and hydrogeochemical impact in streams and rivers. Finally, we discuss future directions and challenges to bridge scientific and management gaps by promoting a holistic understanding of river systems and catchment conditions.

The diversity of natural conditions of the Crimean Peninsula determines different regimes of the main meteorological characteristics that determine the water availability for the territory. The estimation of the spatiotemporal heterogeneity of these characteristics and the solution of the problem of gaps in the ground-based observation data can be based on the results of calculations by general circulation models of the Earth’s atmosphere with assimilation of ground-based observation data, also known as atmospheric reanalysis. Estimates of the quality of reproduction of the surface air temperature and the total precipitation by atmospheric reanalysis models EWEMBI, ERA5-Land, and MSWEP are given and compared with data from ground-based meteorological observations. The main characteristics of the data sets used (both observational and calculated), the main verification methods, the results of estimates and the conclusions regarding the applicability of the data used in simulation problems are given. The mean errors of the models in air temperature and the amount of precipitation over various averaging periods (day, month, year) are given. Thus, the mean coefficients of correlation over different averaging periods vary within 0.74–0.97 for temperature and 0.52–0.79 for precipitation. The results show that all model reproduce the values of the temperature and total precipitation over different averaging periods with an acceptable accuracy; however, all of them show a tendency toward underestimation of the daily sums of precipitation along with an overestimation of the number of days with precipitation.

The results of generalization of field studies of the ionic composition of natural waters in the river basins of the Crimean Mountains during hydrological and hydrochemical expedition surveys in 2021–2022 are presented. The boundaries of catchment areas and their recharge areas have been estimated and five main types of water circulating in the river basins have been identified. The main patterns of change in ion concentrations in the water with change in runoff in the outlet sections of the Kuchuk-Uzenbash and Tonas rivers and karst aquifer systems (Karstovyi and Ayan springs and Kizil-Koba Cave (Red Cave)) have been identified. The typification of underground spring waters by chemical composition and altitudinal position of their discharge onto the surface of the catchment areas demonstrates their vertical hydrochemical zonality on the scale of a small river basin.

Размыв обнажений многолетнемерзлых пород (едома) в бортах долин крупных рек Арктики рассматривается как важный источник поступления взвешенных наносов и углерода в природные воды рек Лена, Колыма, Яна, Индигирка и далее в Северный ледовитый океан. В ходе экспедиционных исследований ледового комплекса едомы Дуванный Яр – крупнейшего внутри­материкового обнажения многолетнемерзлых пород, расположенного в нижнем течении реки Колыма – в период с 2019 по 2021 год проведены оценки его влияния на сток речных взвешенных наносов. Для оценки дальности распространения шлейфа мутности от ледового комплекса анализировались данные дистанционного зондирования со съемочной системы Landsat за период с 1995 по 2021 год (обработано более 60 снимков за период открытой воды с июня по сентябрь). Для оценки баланса взвешенных наносов использовались натурные измерения мутности, в том числе с использованием акустического доплеровского профилографа течений. Благодаря этим измерениям впервые удалось количественно оценить баланс взвешенных наносов на участке между впадением крупных притоков реки Колыма – рек Омолон и Большой Анюй. Выявлено увеличение мутности воды реки Колыма в пределах 20% в период летней межени на нижерасположенном бесприточном участке. Проведена оценка поступления взвеси за счет таяния склонов ледового комплекса в жаркие летние дни в формирующейся сети мутьевых водотоков – величиной более 5 кг/с. Эффект термического разрушения ледового комплекса подтверждает статистически значимая связь между длиной шлейфа мутности, распространяющегося от едомы Дуванный Яр вниз по течению реки Колыма, с температурой воздуха в этом районе. Таким образом, впервые получены количественные данные, подтверждающие роль активизации разрушения многолетнемерзлых пород в формировании стока наносов. The erosion of permafrost outcrops (yedoma) in the valleys of large Arctic rivers is considered as an important source of suspended sediment and carbon inflow into the natural waters of the Lena, Kolyma, Yana, Indigirka Rivers and further into the Arctic Ocean. In the course of expeditionary studies of the Duvanny Yar Yedoma ice complex, the largest inland outcrop of permafrost, located in the lower reaches of the Kolyma river in 2019–2021 the assessments of its influence on the suspended sediments’ runoff were carried out. To analyze the scale of the turbidity plume from the ice complex and suspended sediments’ balance on the adjacent river reach we used remote sensing methods, and field measurements of turbidity, including using an acoustic Doppler current profiler. An increase of around 20% in the turbidity of the Kolyma River was revealed during the summer low-flows in the reach downstream of the yedoma. The influx of suspended matter due to the melting of the slopes of the ice complex on hot summer days in the emerging network of turbidity streams was estimated at a value of more than 5 kg/s. The effect of thermal destruction of the ice complex is confirmed by a statistically significant relationship between the length of the turbidity plume propagating from Duvanny Yar Yedoma downstream the Kolyma river and the air temperature in this area. Thus, for the first time, quantitative data have been obtained confirming the role of activation of destruction of permafrost in the formation of sediment runoff.

В статье приводятся результаты высокочастотного мониторинга стока наносов крупнейшего правого притока р. Москвы в пределах города – р. Сетуни, осуществлявшегося в 2020–2021 гг. автоматическими регистраторами оптической мутности и уровня воды. Задействованы 2 ряда записи с 16 ноября 2019 г. по 19 марта 2020 г. (частота записи 10 минут) и с 1 марта 2021 г. по апрель 2021 г. и с июля 2021 г. по октябрь 2021 г. (частота записи 1 минута). В условиях высокой антропогенной нагрузки средняя мутность воды р. Сетунь достигает 100 мг/л, что в 3–4 раза выше фоновых значений. Отмечается корреляция мутности с расходами воды, которая возрастает при увеличении лага по времени от 0 до 50 часов. На основе совмещения измерений мутности воды с характеристиками уровня и расхода воды, атмосферных осадков и температуры воздуха, а также производных от них, проведена настройка 5 моделей машинного обучения для прогнозирования стока наносов с разрешением 1 час и 1 сутки. Наилучшие результаты продемонстрировала рекуррентная нейросеть LSTM RNN для прогноза суточных значений мутности воды: при среднеквадратической ошибке 10,8 NTU были верно определены время и величина локальных увеличений пика мутности. The article presents the results of high-frequency monitoring of sediment flow of the largest right tributary of the Moscow River within the city – the Setun River, carried out in 2020–2021 by automatic recorders of optical turbidity and water level. Several recordings were involved from November 16, 2019 to March 19, 2020 (recording frequency 10 minutes) and from March 1, 2021 to April 2021 and from July 2021 to October 2021 (recording frequency 1 minute). Under conditions of high anthropogenic load, the average turbidity of the Setun River water reaches 100 mg/l, which is 3–4 times higher than background values. There is a correlation between turbidity and water flow rates, which increases with increasing time lag from 0 to 50 hours. Based on combining measurements of water turbidity with characteristics of water level and flow, precipitation, and air temperature, as well as derivatives from them, 5 machine learning models were configured to predict sediment runoff with a resolution of 1 hour and 1 day. The best results were demonstrated by the recurrent neural network LSTM RNN for forecasting daily values of water turbidity: with a root-mean-square error of 10.8 NTU, the time and magnitude of local increases in the turbidity peak were correctly determined.

Климатические изменения в Арктике сопровождаются интенсификацией эрозионных и русловых процессов, частично обусловленной таянием многолетней мерзлоты. В статье представлены результаты гидрологических исследований, которые были организованы в 2022 году в южной части Ямало-Ненецкого автономного округа. Дается анализ современных трендов гидроклиматических изменений, приводятся результаты комплексного гидрогеохимического обследования 41 водотока на субширотном участке Салехард – Надым – Уренгой, использованного для обоснования водосборов стационарного мониторинга эрозионных процессов. Обсужаются особенности организованных стационарных наблюдений скорости отступания берегов, интенсивности овражной эрозии, уровенного и ледового режима на реки Васъёган в бассейне Нижней Оби, на двух смежных водосборах рек Маханад-Пусъяха и Выеръяха в бассейне реки Надым и на водосборе реки Седэ-Яха в бассейне реки Пур. Приводится анализ первичных результатов мониторинга.

Размыв обнажений многолетнемерзлых пород (едома) в бортах долин крупных рек Арктики рассматривается как важный источник поступления взвешенных наносов и углерода в природные воды рек Лена, Колыма, Яна, Индигирка и далее в Северный ледовитый океан. В ходе экспедиционных исследований ледового комплекса едомы Дуванный Яр – крупнейшего внутри­материкового обнажения многолетнемерзлых пород, расположенного в нижнем течении реки Колыма – в период с 2019 по 2021 год проведены оценки его влияния на сток речных взвешенных наносов. Для оценки дальности распространения шлейфа мутности от ледового комплекса анализировались данные дистанционного зондирования со съемочной системы Landsat за период с 1995 по 2021 год (обработано более 60 снимков за период открытой воды с июня по сентябрь). Для оценки баланса взвешенных наносов использовались натурные измерения мутности, в том числе с использованием акустического доплеровского профилографа течений. Благодаря этим измерениям впервые удалось количественно оценить баланс взвешенных наносов на участке между впадением крупных притоков реки Колыма – рек Омолон и Большой Анюй. Выявлено увеличение мутности воды реки Колыма в пределах 20% в период летней межени на нижерасположенном бесприточном участке. Проведена оценка поступления взвеси за счет таяния склонов ледового комплекса в жаркие летние дни в формирующейся сети мутьевых водотоков – величиной более 5 кг/с. Эффект термического разрушения ледового комплекса подтверждает статистически значимая связь между длиной шлейфа мутности, распространяющегося от едомы Дуванный Яр вниз по течению реки Колыма, с температурой воздуха в этом районе. Таким образом, впервые получены количественные данные, подтверждающие роль активизации разрушения многолетнемерзлых пород в формировании стока наносов.

An important trend of modern development is the concentration of population in urban agglomerations, where a specific meso- and micro-climate is created under conditions of dramatically transformed natural landscapes. In the present paper, the long-term statistical analysis of intense rainfalls and annual daily precipitation maxima was carried out based on the Moscow region weather stations timeseries for the period of 1966-2021. An increase in the variability of intense precipitation over the Moscow region corresponding to the formation of significant floods was revealed in some years. The COSMO-CLM model simulated extreme precipitation for the basin of the Setun' River (190 km2), the largest right-bank tributary of the Moskva River within the Moscow city, which was recorded over Moscow in May 2020 and June 2021. Maximum precipitation was registered over the Setun' River basin during 45-90 minutes and induced rainfall floods that exceeded the spring flood by two times. The estimated basin travel time was 6-8 hours. Rainfalls form a multistep hydrograph inheriting the shower precipitation structure on small rivers.

Применения модели формирования речного стока ECOMAG в Байкальском регионеМорейдо В.М.(vsevolod.moreydo

В статье приведены оценки влияния каскада вилюйских водохранилищ на трансформацию расходов воды и взвешенных наносов реки Вилюй. Оценки получены на основе данных многолетних сетевых наблюдений, а также экспедиционных измерений в августе – сентябре 2021 года и материалов спутниковой съемки. В ходе экспедиционных исследований оценено распределение мутности воды по акватории и глубине Вилюйского водохранилища, исследована продольная трансформация мутности воды – вдоль руслового Светлинского водохранилища и его нижнего бьефа вплоть до поселка Сунтар. Показано, что в результате подпора Вилюйским водохранилищем, бóльшая часть речных наносов откладывается в приустьевых зонах крупных притоков этого водоема. Здесь также наблюдается и наибольшая мутность воды по данным отбора проб воды и спутникового зондирования. По итогам георадарной съемки дна установлено, что осаждение значительной части речных наносов в верхних отсеках Вилюйского водохранилища объясняет практически отсутствие современных речных отложений в его приплотинной части. Составлен баланс наносов Вилюйского водохранилища с оценкой сбрасываемых в нижний бьеф наносов. По всем собранным данным описан характер продольной трансформации воздействий водохранилищ на расходы и уровни воды, расходы наносов и мутность воды по длине среднего и нижнего течения реки Вилюй. Показано, что не только на зарегулированной реке Вилюй, но и почти на всех ее притоках доминирует тенденция к снижению стока наносов. При этом обнаружены аномалии величин стока и гидрофизических показателей в некоторых притоках реки Вилюй, подверженных сильному антропогенному воздействию. Estimates of the influence of the Vilyuy river reservoir cascade on the transformation of river streamflow discharges and suspended sediments load are presented in the article. The estimates are based on long-term network observations, field measurements in August-September 2021, and satellite imagery. During the fieldwork studies, the horizontal and vertical distribution of water turbidity in the headwaters of the Vilyuy reservoir was estimated, the longitudinal transformation of turbidity patterns in the Svetlinskoe reservoir and downstream Vilyuy river to the Suntar village was assessed. It is shown that due to the backwater from the Vilyuy HPP-1,2 dams, most of the river sediments are deposited in the estuarine zones of large tributaries of the reservoir. The highest water turbidity is also observed here according to sampling and satellite imagery data. Based on the results of ground-penetrating radar survey of the reservoir bottom, it was revealed that the deposition of a significant part of river sediments in the upper compartments of the Vilyuy reservoir explains the absence of contemporary river sediments in this part near the dam. The sediment balance of the Vilyuy reservoir was calculated, accounting for the sediments released downstream of the dam. Based on all the collected data, the nature of the longitudinal transformation of the impacts of reservoirs on water discharges and levels, sediment discharges and water turbidity along the entire length of the middle and lower Vilyuy is discussed. It is shown that almost all the rivers of the Vilyuy basin show a tendency towards a decrease in their sediment runoff. At the same time, anomalies in the runoff and electrical conductivity of water were found in some tributaries of the river Vilyuy, subject to strong anthropogenic impact.

In 2020 and 2021, the city of Moscow, Russia, has experienced two historical rainfall events that had caused major flooding of small rivers. Based on long-term observation datasets from the surrounding weather stations, regional mesoscale COSMO-CLM climate model results, and a detailed hydrological and water quality monitoring data, we performed a pioneer assessment of climate change and urbanization impact on flooding hazard and water quality of the urban Setun River as a case study. Statistically significant rise of some moderate ETCCDI climate change indices (R20mm and R95pTOT) was revealed for the 1966–2020 period, while no significant trends were observed for more extreme indices. The combined impact of climate change and increased urbanization is highly non-linear and results in as much as a fourfold increase in frequency of extreme floods and shift of water regime features which lead to formation of specific seasonal flow patterns. The rainstorm flood wave response time, involving infiltrated and hillslope-routed fraction of rainfall, is accounted as 6 to 11 h, which is more than twice as rapid as compared to the non-urbanized nearby catchments. Based on temporal trends before and after rainfall flood peak, four groups of dissolved chemicals were identified: soluble elements whose concentrations decrease with an increase in water discharge; mostly insoluble and well-sorted elements whose concentrations increase with discharge (Mn, Cs, Cd, Al); elements negatively related to water discharge during flood events (Li, B, Cr, As, Br and Sr); and a wide range of dissolved elements (Cu, Zn, Mo, Sn, Pb, Ba, La, Cs, U) which concentrations remain stable during rainfall floods. Our study identifies that lack of research focused on the combined impacts of climate change and urbanization on flooding and water quality in the Moscow urban area is a key problem in water management advances.

В статье приведены оценки влияния каскада вилюйских водохранилищ на трансформацию расходов воды и взвешенных наносов реки Вилюй. Оценки получены на основе данных многолетних сетевых наблюдений, а также экспедиционных измерений в августе – сентябре 2021 года и материалов спутниковой съемки. В ходе экспедиционных исследований оценено распределение мутности воды по акватории и глубине Вилюйского водохранилища, исследована продольная трансформация мутности воды – вдоль руслового Светлинского водохранилища и его нижнего бьефа вплоть до поселка Сунтар. Показано, что в результате подпора Вилюйским водохранилищем, бóльшая часть речных наносов откладывается в приустьевых зонах крупных притоков этого водоема. Здесь также наблюдается и наибольшая мутность воды по данным отбора проб воды и спутникового зондирования. По итогам георадарной съемки дна установлено, что осаждение значительной части речных наносов в верхних отсеках Вилюйского водохранилища объясняет практически отсутствие современных речных отложений в его приплотинной части. Составлен баланс наносов Вилюйского водохранилища с оценкой сбрасываемых в нижний бьеф наносов. По всем собранным данным описан характер продольной трансформации воздействий водохранилищ на расходы и уровни воды, расходы наносов и мутность воды по длине среднего и нижнего течения реки Вилюй. Показано, что не только на зарегулированной реке Вилюй, но и почти на всех ее притоках доминирует тенденция к снижению стока наносов. При этом обнаружены аномалии величин стока и гидрофизических показателей в некоторых притоках реки Вилюй, подверженных сильному антропогенному воздействию.

Statistical analysis of daily observation series at 1719 weather stations in Russia in the period from 1966 to 2014 was used to derive an approximate formula for calculating mean daily vapor pressure deficit by the mean daily air temperature and daily precipitation totals. The formula was proposed to reduce the number of meteorological characteristics, required for regional runoff formation models in the estimation of total evaporation, by excluding data on measured vapor pressure deficit, which are more difficult to determine. Testing the proposed formula for problems of hydrological calculations was illustrated by comparing runoff hydrographs over long periods, calculated using two versions of the hydrological model, one with the actual deficit and the other with those calculated by the proposed empirical formula, for a series of regional runoff formation models developed for largest river basins in Russia based on ECOMAG model system. Statistical criteria were used to show that the calculations made with the use of the approximate formula for the majority of compared watersheds yield about the same simulation accuracy as calculations made with the use of actual vapor pressure deficit.

Surrogate measures are becoming increasingly used to measure suspended sediment flux, but only few particular computer techniques of data processing are recently developed. This study demonstrates capabilities of acoustic Doppler current profilers (ADCPs) to infer information regarding suspended-sand concentrations in river systems and calculate suspended sediment flux via big data analytics which includes process of analyzing and data mining of measurements based on ADCP signal backscatter intensity data. We present here specific codes done by R language using RStudio software with open-source tidyverse and plotly packages aimed to generate tables containing data of suspended load for cells, verticals and whole cross-section based on backscattering values from 600 kH Teledyne RDInstruments RioGrande WorkHorse ADCP unit, as well perform estimates of morphometric, suspended sediment concentration (SSC) and velocity characteristics of the flow. The developed tools enabled to process large data array consisting of over 56,526,480 geo-referenced values of river depth, streamflow velocity, and backscatter intensity for each river cross-section measured at six case study sites in Russia.

Significant degradation of the Agrakhan Bay on the eastern coast of the Terek River delta has occurred in the course of the 20th century as a result of the combined action of natural and anthropogenic factors. Comprehensive studies conducted by the authors in 2018–2020 have made it possible to describe the main causes of this degradation, characterize the current state of the reservoir, and establish scientific bases under recommendations for its improvement. It has been demonstrated that as a result of partial drying and reduction of water surface area the bay has lost its former importance as a spawning and rearing water body providing the West Caspian region with the younglings of valuable commercial fish species. By 2018, the catches decreased by ten times compared to the early 20th century with sturgeons having almost totally disappeared. The state of the northern part of the bay, which has transformed into a group of shallow water bodies almost entirely separated from each other and from the sea is particularly unfavourable. The study of hydrological and morphological, hydrobiological, fishery-related and hydrochemical parameters has shown that the improvement of the wetlands at the former bay site is possible. Detailed analysis of the water balance using multivariate limnological calculations has shown that there is enough water for watering and partial restoration of the water bodies of the Agrakhan Bay hydrographic system. Clearing of silted and overgrown canals, deepening and berming of the remaining water bodies, and directing the necessary amounts of river water into Northern and Southern Agrakhan Bay (in accordance with the calculated delivery schedule) will allow reduction of the overgrowing and siltation of water bodies, restore the water exchange between them, improve water quality, revive the fishery industry in the region, improve the habitats of many rare and protected animal species, and increase the recreational attractiveness of the region.

В статье исследуются возможности краткосрочного (от 1 до 7 суток) прогнозирования расходов воды на основе нескольких методов машинного обучения: модели множественной линейной регрессии (LM), искусственной нейронной сети по типу многослойного перцептрона (MLP) и рекуррентной искусственной нейронной сети с долгосрочной кратковременной памятью (LSTM). Предлагаются методы расширения набора предикторов для построения моделей и исследуется возможность случайного перемешивания хронологического ряда предикторов для калибровки и верификации моделей как повышающая устойчивость результатов прогноза. В качестве объекта исследования используется малая река Средней полосы России – р. Протва (г/п Спас-Загорье). На конкретном примере показана возможность построения эффективной оперативной прогностической системы для краткосрочного прогнозирования стока. Исследование выявило приемлемую для оперативной практики применимость моделей искусственных нейронных сетей, использующих всю доступную гидрометеорологическую информацию на водосборе, как показавших наиболее устойчивые результаты на всех заблаговременностях от 1 до 7 суток.