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.

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.

The features of the suspended sediment load along the 200-km braided channel of the Lena River from the city of Pokrovsk to the Aldan River mouth (upstream of the Aldan braiding) are described in detail (30-m resolution) based on water-sediment concentration modeling, using the collection of Landsat images for the period of 1992–2018. It is shown that large anabranching river reaches correspond to changes of the system of sediment transport and accumulation, manifesting themselves as the predominance of the occurrences of positive (increase) or negative (decrease) ΔS0 values (where ΔS0 stands for suspended sediment-concentration budget). The conditions of a longitudinal decrease in suspended-sediment concentration along the braided reach of the Lena River are characterized by high water discharges (>20 000 m3/s) and are associated with sediment accumulation in riffles and floodplain areas. It has been revealed that a significant role in the longitudinal decrease in water-sediment concentration is played by lateral floodplain branches, which accumulate a part of the incoming suspended sediments and exert a dilution effect on the sediment flow downstream of the confluence with the main channel. Cases of a longitudinal increase in the water-suspended sediment concentration are typical for lower water flow rates (<20 000 m3/s) and are related to increased bank thermal erosion in summer and erosion of riffles during a low-water period. A combination of the grid of suspended-sediment concentration, velocities, and channel depths with a 30 × 30-m resolution (more than 20 000 cells) for low-water conditions revealed a dependence of the local suspended-sediment concentration on the transporting capacity of the flow, which was determined for particular verticals. A correspondence between the regime of certain reaches in different phases of water regime is observed. It indicates the mutual influence of the directedness of mass exchange and channel morphology. The transformation of distribution systems of suspended sediments may be interpreted as one of the self-regulation mechanisms in the channel system. Complex systems of sediment flow distribution along the channel of a large river reflect the opposite directions of erosion-accumulation processes caused by bends in the longitudinal profile.

Braided river channels are very diverse both morphologically (in terms of the number and water content of channel branches, size and shape of islands, their position, ratios, evolution, etc.), and in the mode of channel changes. Nevertheless, both in Russian and foreign literature, when describing them, there are different points of view on terms and classifications that define them, which make it difficult to analyze types of braided channels and regimes of channel changes, possible reactions of channels to changes in factors due to too much generalization. The classification of Moscow State University is considered to be an exception. It is constantly being improved as new data are obtained based on scientific research. Braided channel reaches are formed at several structural levels – point, midchannel bars, channel (island), floodplain-channel and floodplain (split channels). Each higher level of braided channels includes channel types of the previous levels. The main channel patterns that determine channel regime of braided rivers are island-braided channels, along which there are distinguished morphological homogeneous reaches or single patterns of channels or certain channel branches. In turn, in island-braided channels each of their types has several varieties depending on the number and morphology of islands, channel stability, water content of channel branches and peculiarities of water and sediment runoff dispersion along them. Braided channel types and their varieties are characterized by certain values of the flow quasi-uniformity indicator of I.F. Karasev and special coefficients in hydrological and morphological relationships linking morphological parameters of channels with characteristics of determining factors. The article provides a detailed, most complete classification of braided channels and substantiates the use of terms and concepts that characterize each type or braided channel reaches and their elements.

A quantitative assessment of channel planform changes on the 600-km channel of the Kamchatka River was carried out. Possibilities of semi-automatic GIS-interpretation of satellite images were used for retrospective analysis of such an extended section of a large river. It was estimated that 37% of the left bank length and 44% of the right bank length are eroded. The amount of material coming into the channel due to riverbanks erosion significantly exceeds the sediment runoff, which determines channel type and regime of channel changes. Processes of bank erosion vary on the scale of the longitudinal profile and different channel types. Downstream according to decrease of channel slope, a decrease of bank erosion intensity is observed. The most important factor of bank erosion on the river local section is the volume of material coming from the upstream sections. A quantitative analysis and forecast of planform changes of a river section requires a differential assessment for different morphodynamic channel types, taking into account characteristics of channel processes in the upstream river sections. The bank erosion prognostic equations obtained for the meandering channel and the floodplain-channel multiple branches of the Kamchatka River are discussed.

We substantiate the use of the previously developed methods to classify sections of the largest river (Lena) from the types of channel processes and special aspects of their management, i. e. water resource use, exploitation of the river as the water transport way, development of riverine areas and construction of river crossings for service lines. For assessing the complexity of river channel reconfguration and implementing regulatory measures we use certain indicators of channel stability, the channel pattern, river runoff, conditions of effective discharge, composition of bed-material load, occurrence of riffes and characteristics of their regime. It is shown that the indicator of complexity of channel processes management is represented by the amount of channel dredging performed to ensure normal navigation conditions. On the Lena river (from the Osetrovo port to the estuary) there are 10 reaches which differ both in the features and the degree of complexity of channel processes and, accordingly, in the conditions for their management. The study identifed the most diffcult (for channel management) sections; for the broad foodplain, unstable and compound braided channel we determined the main water management and water transport problems associated with channel processes.

Widely-spread small rivers are very poorly studied in relation to channel processes. The influence of local factors, high sensitivity to human impact, close connection with basin processes, and relatively low rates of channel changes distinguish them from medium and large ones and make it necessary to form a special approach to studies. Based on collection of long-term maps and local residents’ interviews, we reconstructed the transformation of channels in the Kudma River basin (the Volga Upland) for the last 200 years. Based on the bank erosion monitoring during 2011-2019 the modern rates of channel changes were revealed. We found that significant human impact is associated with the artificial channels cutoffs and draining of ponds which led to channel incision of the Kudma and Ozerka Rivers in the middle reaches and the transformation of floodplain into terrace. Agriculture development caused siltation of the upper reaches of rivers. The rivers of the forested part of the basin experienced the least human changes. From 2011 to 2019 the maximum rates of bank erosion were found to be within range of 0.3 to 2.7 m/year and supposed to be driven by peak water discharge.

Abstract. Geography and associated hydrological, hydroclimate and land-use conditions and their changes determine the states and dynamics of wetlands and their ecosystem services. The influences of these controls are not limited to just the local scale of each individual wetland but extend over larger landscape areas that integrate multiple wetlands and their total hydrological catchment – the wetlandscape. However, the data and knowledge of conditions and changes over entire wetlandscapes are still scarce, limiting the capacity to accurately understand and manage critical wetland ecosystems and their services under global change. We present a new Wetlandscape Change Information Database (WetCID), consisting of geographic, hydrological, hydroclimate and land-use information and data for 27 wetlandscapes around the world. This combines survey-based local information with geographic shapefiles and gridded datasets of large-scale hydroclimate and land-use conditions and their changes over whole wetlandscapes. Temporally, WetCID contains 30-year time series of data for mean monthly precipitation and temperature and annual land-use conditions. The survey-based site information includes local knowledge on the wetlands, hydrology, hydroclimate and land uses within each wetlandscape and on the availability and accessibility of associated local data. This novel database (available through PANGAEA https://doi.org/10.1594/PANGAEA.907398; Ghajarnia et al., 2019) can support site assessments; cross-regional comparisons; and scenario analyses of the roles and impacts of land use, hydroclimatic and wetland conditions, and changes in whole-wetlandscape functions and ecosystem services.

The paper deals with comparative summary of sediment loads and particulate trace metals (V, Cr, Co, Cu, Zn, Cd, Pb) transport in the largest Asian rivers of Russia and China. Environmental conditions and human interventions in the selected catchments (Lena, Ob, Enisey, Selenga, Kolyma, Amur, Yellow, Yangtze, Pearl) are analyzed with respect to the rate and composition of suspended sediment loads. The paper presents calculations of sediment load changes at the downstream sections of the rivers and new database of the chemical composition of suspended matter which involves all recent studies of the last decade for the sediment geochemistry. The results indicate that fluvial system and its human modifications are the most significant drivers of sediment load. Fluvial erosion in the unconfined channels exerts a significant control on the sediment load changes due to observed permafrost melting. We concluded that construction of reservoirs has the most important influence on land–ocean sediment fluxes in the largest rivers of Asia but plays relatively weak role in heavy metal composition in suspended particulate matter (SPM) due to lowest sedimentation rates of the fine clay particles, which are mostly enriched with heavy metals. The paper also presents novel mapping approaches related to cartographic recognition of the fluvial system and its human modification and sediment transfer processes in the largest Asian rivers of Russia and China, linked with a specific legend. Finally, analysis of uncertainties associated with estimating the SPM composition in the rivers was done with respect to spatial and temporal variability. It was shown that the main error occurs due to incorporation of data only from particular hydrological seasons which usually ignore high flood conditions.

Surface mining can contribute to increasing riverine loads of potentially metal-enriched sediments. However, the related human disturbances and natural processes reflect a great complexity, which hinders quantitative understanding. We here consider the Zaamar Goldfield in Mongolia, one of the world's largest placer mining sites, located in the Tuul River basin (upper Lake Baikal basin). A main study aim is to investigate relations between patterns of increased sediment loads along the Tuul River and the (spatially variable) area coverage of active or recently abandoned placer mines in the river vicinity. Specifically, we compare observed loads derived from nested catchment areas with the output from spatially distributed soil erosion modelling. Results showed that riverine sediment loads in mining areas reflect soil losses both from soil erosion and direct human impacts (e.g. waste water discharge), which are two to three orders of magnitude higher than the input from natural areas dominated by soil erosion alone. Notably, the sediment load contributions from the mining areas were insensitive to changes in hydrometeorological conditions, whereas contributions from natural areas were much lower during drier periods (as expected when governed by soil erosion by water). Accordingly, the relative contribution to the total sediment load (TSL) of metal-enriched soil from mining areas is likely to be particularly pronounced (with estimated values of about 80% of TSL) under drier hydrometeorological conditions. This is consistent with observations of considerably elevated metal concentrations under low flow conditions and implies that if annual average discharge continues to decrease in the Tuul River as well as the entire Selenga River system, increased metal concentrations may be one of the consequences.

Due to specific environmental conditions, headwater catchments located on volcanic slopes and valleys are characterized by distinctive hydrology and sediment transport patterns. However, lack of sufficient monitoring causes that the governing processes and patterns in these areas are rarely well understood. In this study, spatiotemporal water discharge and sediment transport from upstream sources was investigated in one of the numerous headwater catchments located in the lahar valleys of the Kamchatka Peninsula Sukhaya Elizovskaya River near Avachinskii and Koryakskii volcanoes. Three different subcatchments and corresponding channel types (wandering rivers within lahar valleys, mountain rivers within volcanic slopes and rivers within submountain terrains) were identified in the studied area. Our measurements from different periods of observations between years 2012–2014 showed that the studied catchment was characterized by extreme diurnal fluctuation of water discharges and sediment loads that were influenced by snowmelt patterns and high infiltration rates of the easily erodible lahar deposits. The highest recorded sediment loads were up to 9·104 mg/L which was related to an increase of two orders of magnitude within a one day of observations. Additionally, to get a quantitative estimate of the spatial distribution of the eroded material in the volcanic substrates we applied an empirical soil erosion and sediment yield model – modified universal soil loss equation (MUSLE). The modeling results showed that even if the applications of the universal erosion model to different non-agricultural areas (e.g., volcanic catchments) can lead to irrelevant results, the MUSLE model delivered might be acceptable for non-lahar areas of the studied volcanic catchment. Overall the results of our study increase our understanding of the hydrology and associated sediment transport for prediction of risk management within headwater volcanic catchments.