Large Transboundary River Research Articles

A Retrospective Hydrological Uncertainty Analysis Using Precipitation Estimation Ensembles for a Poorly Gauged Basin in High Mountain Asia

Abstract We study the impact of uncertain precipitation estimates on simulated streamflows for the poorly gauged Yarlung Tsangpo basin (YTB), high mountain Asia (HMA). A process-based hydrological model at 0.5-km resolution is driven by an ensemble of precipitation estimation products (PEPs), including analyzed ground observations, high-resolution precipitation estimates, climate data records, and reanalyses over the 2008–15 control period. The model is then forced retrospectively from 1983 onward to obtain seamless discharge estimates till 2007, a period for which there is very sparse flow data coverage. Whereas temperature forcing is considered deterministic, precipitation is sampled from the predictive distribution, which is obtained through processing PEPs by means of a probabilistic processor of uncertainty. The employed Bayesian processor combines the PEPs and outputs the predictive densities of daily precipitation depth accumulation as well as the probability of precipitation occurrence, from which random precipitation fields for probabilistic model forcing are sampled. The predictive density of precipitation is conditional on the precipitation estimation predictors that are bias corrected and variance adjusted. For the selected HMA study site, discharges simulated from reanalysis and climate data records score lowest against observations at three flow gauging points, whereas high-resolution satellite estimates perform better, but are still outperformed by precipitation fields obtained from analyzed observed precipitation and merged products, which were corrected against ground observations. The applied methodology indicates how missing flows for poorly gauged sites can be retrieved and is further extendable to hydrological projections of climate. Significance Statement We show how to use different precipitation estimates, like computer simulations of weather or satellite observations, in conjunction with all available ground measurements in regions with generally poor meteorological and flow measurement infrastructure. We demonstrate how it is possible to retrieve past unobserved river flows using these estimates in combination with a hydrological computer model for streamflow simulations. The method can help us to better understand the hydrology of poorly gauged regions that play an important role in the distribution of water resources and can be affected by future changes. We applied the method to a large transboundary river basin in China. This basin holds water needed by large, densely populated regions of India that may become water constrained by warmer climate.

Analysis of Meteorological Element Variation Characteristics in the Heilongjiang (Amur) River Basin

Located in the Heilongjiang (Amur) River in north-east Asia, spanning four countries, plays a crucial role as an international border river, and its meteorological changes significantly impact the variation in water resources in the basin. This study utilizes daily average temperature and precipitation data from 282 meteorological stations in the Heilongjiang (Amur) River Basin and its surrounding areas for the period 1980–2022. The analysis employs spatial interpolation, change point testing, and model construction prediction methods. The results indicate a significant increasing trend in both overall temperature and precipitation changes within the Heilongjiang (Amur) River Basin. At the spatial scale, the annual warming rate increases gradually from the southeastern coastal region to the northwestern plateau region, while the rate of precipitation increase decreases from the southern area towards its surroundings. Temporally, the warming amplitude during the growing season decreases gradually from east to west, and the trend in precipitation changes during the growing season aligns with the overall annual precipitation trend. During the non-growing season, the warming trend shows a decrease in the plains and an increase in the plateau, while precipitation increase concentrates in the central and southern plains, and precipitation decrease predominantly occurs in the northwestern plateau region. Temperature and precipitation change points occurred in the years 2001 and 2012, respectively. In precipitation prediction, the Long Short-Term Memory (LSTM) model exhibits higher accuracy, with R (Pearson correlation coefficient) and NSE (Nash-Sutcliffe efficiency coefficient) values approaching 1 and lower NRSME values. This study provides a research foundation for the rational development and utilization of water resources in the Heilongjiang (Amur) River Basin and offers valuable insights for research on climate change characteristics in large transboundary river systems.

Роль водохранилищ в формировании гидроэкологической ситуации центрально-азиатского региона

As you know, the basins of more than 260 of the world's rivers are divided between two or more countries. River basins are home to about 40% of the world's population, occupy approximately half of the land surface, and account for about 60% of the globe's fresh water. Therefore, in modern times, one of the important regional and international problems is the establishment of friendly relations between the countries of transboundary river basins, the rational use of transboundary water resources, the correct distribution of water between countries, the resolution of conflicts in the use of transboundary water resources and other similar issues. The Aral Sea basin has two large transboundary rivers that are used by all countries in the region. Thus, this article examines the role of reservoirs in the regulation of water resources and their effective use in the process of climate change. In particular, this article analyzes the role of the Tajik Sea reservoir in regulating river flow, sedimentation of pollutants in river water and a decrease in the degree of salinity, as well as the impact on the formation of the climate of adjacent areas and use in various industries.

Satellite-based soil moisture enhances the reliability of agro-hydrological modeling in large transboundary river basins

Satellite-based observations of soil moisture, leaf area index, precipitation, and evapotranspiration facilitate agro-hydrological modeling thanks to the spatially distributed information. In this study, the Climate Change Initiative Soil Moisture dataset (CCI SM, a product of the European Space Agency (ESA)) adjusted based on Soil Water Index (SWI) was used as an additional (in relation to discharge) observed dataset in agro-hydrological modeling over a large-scale transboundary river basin (Odra River Basin) in the Baltic Sea region. This basin is located in Central Europe within Poland, Czech Republic, and Germany and drains into the Baltic Sea. The Soil and Water Assessment Tool+ (SWAT+) model was selected for agro-hydrological modeling, and measured data from 26 river discharge stations and soil moisture from CCI SM (for topsoil and entire soil profile) over 1476 sub-basins were used in model calibration for the period 1997–2019. Kling–Gupta efficiency (KGE) and SPAtial EFficiency (SPAEF) indices were chosen as objective functions for runoff and soil moisture calibration, respectively. Two calibration strategies were compared: one involving only river discharge data (single-objective - SO), and the second one involving river discharge and satellite-based soil moisture (multi-objective – MO). In the SO approach, the average KGE for discharge was above 0.60, whereas in the MO approach, it increased to 0.67. The SPAEF values showed that SWAT+ has acceptable accuracy in soil moisture simulations. Moreover, crop yield assessments showed that MO calibration also increases the crop yield simulation accuracy. The results show that in this transboundary river basin, adding satellite-based soil moisture into the calibration process could improve the accuracy and consistency of agro-hydrological modeling.

Satellite-based Soil Moisture Could Enhance the Reliability of Agro-hydrological Modeling in Large Transboundary River Basins

Satellite-based Soil Moisture Could Enhance the Reliability of Agro-hydrological Modeling in Large Transboundary River Basins

Exploring spatio-temporal patterns of sediment load and driving factors in Lancang-Mekong River basin before operation of mega-dams (1968–2002)

Sediment is of great importance for the Lancang-Mekong River (LMR) ecosystem, providing essential ecological services for local communities. Understanding sediment change and its driving factors are critical to the sustainable management of this large transboundary river system. Insufficient background knowledge of sediment dynamics driven by climate change and land cover change hinders our understanding of sediment change in the long term. In this study, a distributed hydrological model coupled with a sediment module was developed to address the sediment dynamics and its driving factors of the LMR basin from 1968 to 2002, i.e., the pre-dam period. A new index was also proposed to quantify the regional sediment composition by considering riverbed deposition. The major results are: 1) the leading factor influencing the suspended sediment concentration has changed over the study period, i.e., from rainfall before the 1980s to land cover change after the 1980s; 2) from 1968 to 2002, the land cover change had the greatest impact on the suspended sediment load followed by rainfall; 3) the contribution ratio of the upstream area could be overestimated without considering sediment deposition onto riverbed. The approach presented here provides additional insights into quantifying the regional sediment composition for the dynamic Lancang-Mekong River basin experiencing rapid anthropogenic stresses.

Provisión y disposición de agua en 243 ciudades argentinas: Servicios ecosistémicos en el continuo territorio-ecosistema acuático-centro urbano

Cities depend on different ecosystems that provide them with services. In the case of water supply and effluent disposal in Argentine cities, its recognition is still incomplete and fragmented. Here is presented a first database that maps and classifies the water supply sources and effluent destinations of all Argentine cities >20000 inhabitants (in 2010). Utilizing existing reports, journalistic news and satellite information, water intake and discharge points were recorded, along with other associated infrastructure in 243 cities. It was found that 30.5, 17.5 and 12.6% of the population is exclusively supplied by large transboundary rivers, groundwater and internal rivers and streams, respectively, with 25.2% supplied by mixed sources. The cities that are connected to the public sanitation networks resort mainly to internal rivers and streams (26.6%) for their disposal; however, of the urban population that is not connected to the sewage network, a high proportion discharges into free aquifers. Most Argentine cities do not return sewage water to the same system that supplies it, predominantly transfers from underground sources to internal rivers and streams. The database evidences the contrasting ‘effluent pressure’ (population/flow rate of the receiving system) between cities linked to large rivers (e.g., Paraná basin, 273 inhabitants.m-3.s-1) and internal basins (e.g., Mar Chiquita, 16141 inhabitants.m-3.s-1). This database, open for consultation and updating, makes visible the spatial and hydrological connection between cities and the hydrographic network, helping to improve water security and prioritize efforts to protect aquatic ecosystems that guarantee it from all levels of management.

Assessments and Corrections of GLDAS2.0 Forcing Data in Four Large Transboundary Rivers in the Tibetan Plateau and Northeast China

AbstractGLDAS2.0 provides long‐term fine resolution gridded hydrometeorological data sets, which are necessary for water‐related studies, particularly in some transboundary rivers that are partially without observation. Yet, GLDAS2.0 has only been validated at limited locations, and few studies have been conducted to develop approaches to correct the GLDAS2.0 data for transboundary rivers. This work assessed the GLDAS2.0 data and developed approaches to correct their uncertainties for studies in large transboundary rivers in the Tibetan Plateau and Northeast China (NC). To achieve these goals, observational data from 1982 to 2010 and a water and energy budget‐based distributed hydrological model including biosphere after calibration and validation were employed. We find that the GLDAS2.0 data (except for wind speed) can reasonably replicate observed seasonal variations. However, its specific humidity and wind speed have large uncertainty, and precipitation has large uncertainty in summer. In NC, the trends of its precipitation, air temperature, downward longwave radiation, and wind speed are consistent with the observations. In the Yarlung Tsangpo, Lancang, and Nu Rivers, the trends of all GLDAS2.0 data reproduce the observation very well, that is, wetting, warming, and dimming trends. Validations show that the corrections are effective and the corrected forcing data can be successfully used in hydrological simulation with improved performance than the raw GLDAS2.0 data, which demonstrates the usefulness of the methodology and corrected forcing data to hydrometeorological studies in transboundary rivers in China as well as in other nearby regions/countries.

Meander reshaping – the formation process of a wintering riverbed depression of fish

The study of the spatiotemporal distribution of fish is an important and poorly studied aspect of the ecology of aquatic organisms. The research work was performed using the modern hydroacoustic method and geographic information systems. A section in the lower reaches of the Irtysh, a large transboundary Siberian river (in Western Siberia, Russian Federation), was studied. It has a strong development of meandering. The merging (i.e., reshaping of closely spaced meanders and erosion-accumulating channel processes) results in development of wintering riverbed depression, which is a critical “temporal bottleneck” during the winter period of the fish life cycle. The average density of fish in the study area in summer and autumn was 8,031 and 9,194 individuals per ha, respectively. Analysis of the distribution of fish showed that the distribution in the horizontal aspect had a more aggregated character in the autumn. In the vertical aspect, it had a more surface (pelagic) character. The ichthyofauna in the water area of the riverbed depression is mainly represented by cyprinids. The loop-shaped evolution of the channel formed a section of the river with multidirectional, circulating, and counter-current flows. It also created zones with depths exceeding 20 m and aggregations of fish. These features characterize the studied water area as a wintering riverbed depression of the fish of the Lower Irtysh. This section of the river should be included in the list of protected wintering biotopes of fish in the West Siberian fishery basin, which will ensure the conservation of fish at the critical stage of the life cycle.

Meander reshaping – the formation process of a wintering riverbed depression of fish

The study of the spatiotemporal distribution of fish is an important and poorly studied aspect of the ecology of aquatic organisms. The research work was performed using the modern hydroacoustic method and geographic information systems. A section in the lower reaches of the Irtysh, a large transboundary Siberian river (in Western Siberia, Russian Federation), was studied. It has a strong development of meandering. The merging (i.e., reshaping of closely spaced meanders and erosion-accumulating channel processes) results in development of wintering riverbed depression, which is a critical “temporal bottleneck” during the winter period of the fish life cycle. The average density of fish in the study area in summer and autumn was 8,031 and 9,194 individuals per ha, respectively. Analysis of the distribution of fish showed that the distribution in the horizontal aspect had a more aggregated character in the autumn. In the vertical aspect, it had a more surface (pelagic) character. The ichthyofauna in the water area of the riverbed depression is mainly represented by cyprinids. The loop-shaped evolution of the channel formed a section of the river with multidirectional, circulating, and counter-current flows. It also created zones with depths exceeding 20 m and aggregations of fish. These features characterize the studied water area as a wintering riverbed depression of the fish of the Lower Irtysh. This section of the river should be included in the list of protected wintering biotopes of fish in the West Siberian fishery basin, which will ensure the conservation of fish at the critical stage of the life cycle.

Modelling framework for flow, sediments and nutrient loads in a large transboundary river watershed: A climate change impact assessment of the Nemunas River watershed

This study provides an in-depth analysis of the Nemunas River watershed, situated in the Baltic Sea basin, and possible future changes to the stream flow, hydrologic regime, sediment (SS), Total Nitrogen (TN) and Total Phosphorus (TP) load from the river to the Curonian Lagoon under different climate change scenarios using high-resolution modelling. The sub-regions of the watershed, represented by sub-basins of the Nemunas River tributaries and the main river branch, were modelled using the Soil and Water Assessment Tool (SWAT). The model setup was performed using the developed customizable MATLAB scripts for an advance Hydrologic Response Unit configuration and a hillslope delineation procedure. The modelling framework was used to assess the climate changes in the watershed under two future scenarios: RCP4.5 and RCP8.5, using the projected changes to precipitation, temperature, and carbon dioxide concentrations for the near-term (up to 2050) and long-term period (up to 2100) compared to the baseline period (1995–2010). The projections show that the annual long-term trends for flow, depending on the scenario, are small or not existing. Even if there is no visible change in trends over the years, inter-annual changes on flow, sediment and nutrient load will occur. The findings of the study suggest that the conditions of the RCP4.5 are likely to be more “wet”, whereas RCP8.5 will likely be “drier”. Most shifts will occur in the winter season, especially in January and February. A decrease in snow cover across the watershed, together with the greater frequency of soil freeze-thaw cycles can weaken the nutrient retention of soils and increase nitrogen and phosphorus losses. Coupled with the increased flows in winter, the projected nutrient load changes during winter season indicate a two-fold increase in sediment, up to 42% and 62% in TN and TP load to the Nemunas River and subsequently, to the Curonian lagoon.

Flood modeling of a large transboundary river using WRF-Hydro and microwave remote sensing

The Brahmaputra River, a trans-boundary river between India and Bangladesh experiences large scale floods with frequent inundation events affecting millions of people annually. An integrated approach for quantitative understanding of flood wave characteristics and real time flood modeling framework can be helpful for effective decision making and planning of flood risk management strategies. In this study, we have characterized the flood wave propagation in the Brahmaputra River using gauge observations and model simulations. The spatio-temporal variation of flood lift is estimated using stage hydrograph of different gauge stations along the river. The temporal variation in flood hydrograph is characterized by different flood wave parameters for a gauge station which govern the flood condition in the Brahmaputra River. These flood wave characteristics are used in the categorization of different intensity of flood events. To estimate the river discharge, the WRF-Hydro model was set-up over the Brahmaputra river basin for hourly discharge estimation. The satellite observations form altimeter and Synthetic Aperture Radar (SAR) are used to estimate river flood-plain elevation and inundation. Altimetry data from Jason-3 satellite was used for water level retrieval and compared with gauge and simulated discharge time-series for further validation of model capabilities. Sentinel-1 satellite SAR images are used to assess the flood inundation extent and probability based on flood wave characteristics in the downstream flood-plain region of Guwahati. Finally, we have integrated these data-sets for a flood modeling and forecasting framework for a braided transboundary river system. This integrated system is studied in detail for an extreme event that occurred during July 2019 in the Brahmaputra River. An hourly estimate of each event for the flood period proved the capability of this system for operational deployment in near real-time flood assessment and forecasting purposes for the flood-prone region of South Asia.

The efficacy of DNA barcoding in the classification, genetic differentiation, and biodiversity assessment of benthic macroinvertebrates.

Macroinvertebrates have been recognized as key ecological indicators of aquatic environment and are the most commonly used approaches for water quality assessment. However, species identification of macroinvertebrates (especially of aquatic insects) proves to be very difficult due to the lack of taxonomic expertise in some regions and can become time‐consuming. In this study, we evaluated the feasibility of DNA barcoding for the classification of benthic macroinvertebrates and investigated the genetic differentiation in seven orders (Insecta: Ephemeroptera, Plecoptera, Trichoptera, Diptera, Hemiptera, Coleoptera, and Odonata) from four large transboundary rivers of northwest China and further explored its potential application to biodiversity assessment. A total of 1,144 COI sequences, belonging to 176 species, 112 genera, and 53 families were obtained and analyzed. The barcoding gap analysis showed that COI gene fragment yielded significant intra‐ and interspecific divergences and obvious barcoding gaps. NJ phylogenetic trees showed that all species group into monophyletic species clusters whether from the same population or not, except two species (Polypedilum. laetum and Polypedilum. bullum). The distance‐based (ABGD) and tree‐based (PTP and MPTP) methods were utilized for grouping specimens into Operational Taxonomic Units (OTUs) and delimiting species. The ABGD, PTP, and MPTP analysis were divided into 177 (p = .0599), 197, and 195 OTUs, respectively. The BIN analysis generated 186 different BINs. Overall, our study showed that DNA barcoding offers an effective framework for macroinvertebrate species identification and sheds new light on the biodiversity assessment of local macroinvertebrates. Also, the construction of DNA barcode reference library of benthic macroinvertebrates in Eurasian transboundary rivers provides a solid backup for bioassessment studies of freshwater habitats using modern high‐throughput technologies in the near future.

Transboundary rivers of Ukraine: perspectives for sustainable development and clean water

ABSTRACT Transboundary river basins are responsible for over half of the global river discharges and accommodate 40% of the global population. Ukraine is part of the four large transboundary rivers that flow through more than ten European countries and experience pollution problems because of human activities in up-and downstream areas. The Ukrainian government calls for actions to achieve Sustainable Development Goal 6 (SDG6) and integrate the European Union water legislation. This paper discusses five sustainable development perspectives for Ukraine to reduce pollution in transboundary rivers. These perspectives relate to (1) transitions from administrative river management (before 2017) to river basin management (after 2017) to enhance cooperation between countries, (2) interdisciplinary and (3) transdisciplinary research to better understand the causes and effects of river pollution and explore solutions, (4) innovation and modernization of water-related infrastructures and (5) the societal awareness. Future research could focus on the example of Ukraine and the adoption of these five perspectives to support the formulation of solutions to achieve SDG6 and support the sustainable basin management of transboundary rivers and the integration of European Union water legislation.

Distribution of sturgeon in the River Irtysh

Using the modern hydroacoustic methods and the computerized software and hardware complex “AsCor”, the features of the distribution of fish of the Acipenseridae family in the lower reaches of the large transboundary river the Irtysh (Western Siberia) have been investigated: in the water area of the riverbed depression (turbulent flow) and control sections (laminar flow). The identification of sturgeon was carried out by the echometric method according to the shape of the swim bladder. It is shown that in the water area of the riverbed depression, increased density of fish is formed, the share of sturgeons being 4.9–5.8%. Among other fish species, the group of cyprinids always dominates. The significant excess of the average fish density in the riverbed depression, in contrast to the control, was 6–30 times. In the water area of the riverbed depression, the average fish density was 4,524, in the control sections 245–2,091 individuals/ha. The size structure of the group of sturgeon in the control sections was represented by individuals with body sizes less than 25–30 cm, and in the riverbed depression – by individuals of different sizes and ages with a body length to 35 cm. The water area of the riverbed depression is located in the meandering section of the river and is characterized by intense vertical vortex structures (whirlpools) and the presence of malfunctioning currents. Features of the hydrological characteristics of the riverbed depression are factors in the formation of aggregations of fish, since fish can use the energy of discrete vortices, low-velocity areas, and as a result, show preference for certain turbulence regimes.

Simulation of streamflow and instream loads of total suspended solids and nitrate in a large transboundary river basin using Source model and geospatial analysis

The management of LULC changes in transboundary river basins continues to challenge water resources managers due to the differences in development and conservation priorities of the countries sharing the basin. While various watershed models (WMs) exist to support decision making, basin-wide sustainable application of the instituted WM depends on the management priorities, resources, data availability, and knowledge gaps at national and sub-basin levels. Building on the results of our prior comparative analysis of WMs for a large transboundary river basin, we applied the ‘Source’ model to the Lower Mekong Basin (LMB). The constructed LMB-Source model was evaluated based on its streamflow and instream total suspended solids (TSS) and nitrate loads simulative performances. A combination of predictive performance metrics (PPMs) and sophisticated hydrologic signatures were used to calibrate model parameters and diagnose the model performance. Calibration results indicated strong similarity between the simulated and observed time series data and were further confirmed by the validation results. The successful model calibration generated parameters that represent hydrologic response characteristics (HRCs) and overland TSS and nitrate generation and removal dynamics (GRDs) previously not available for the LMB. The HRCs and GRDs can be regionalised with physical attributes of the LMB in future studies which can be used to support the management of ungauged sub-basins. This study confirms Source's capability as a decision support tool for the management of transboundary river basins, and provides basin-specific values of HRCs and GRDs that can be used for a better evaluation of the potential effects of LULC changes.

The height of a damless water intake structure threshold

More than 80% of the annual water consumption in Uzbekistan comes from large transboundary rivers such as the Amu Darya and Syr Darya. The rest of the water is formed on the territory of the Republic. Almost all year round, the turbidity of the Amu Darya and Zaravshan rivers is 3÷5 g/l, reaching 15÷18 g/l during flood periods.in most cases, water from the rivers is taken into irrigation channels using damless water intake structures. In order to prevent the ingress of bottom sediments from rivers into channels, thresholds have been constructed at water intake structures, the height of which is set constructively. As a result, bottom sediments pass through thresholds and move along the bottom of channels, reducing their cross-sections, as well as filling the chambers of pumping stations and pressure basins of hydroelectric power plants with sediments. After getting into the flow parts of pipelines and hydraulic machines (pumps and hydraulic turbines), they lead to abrasive wear, as well as other negative consequences. A lot of work has been done to prevent sediment from entering through water intake structures, but so far none of these proposals has provided an effective solution. In the laboratory of the Tashkent Institute of irrigation and agricultural mechanization engineers, a series of experiments were conducted on a glass hydraulic tray to determine the height of bottom sediments, taking into account their heterogeneity. Based on experiments, the dependence on determining the height of the ridge is derived. Based on the obtained dependence, a method for determining the height of the threshold of a damless water intake structure is proposed. This technique was experimentally tested on a laboratory tray. Specifying the threshold height will lead to optimization of capital costs for the construction of the threshold of the water intake structure, as well as reduction of operating costs for cleaning channels from sediment and repair work of hydraulic machines from hydroabrasive wear.

Assessment of impacts of utilization on water resources in the basin of trans-boundary Red river system

The Red river system is the large trans-boundary river system, there has been no united system of hydrology stations as well as integrated plan for the water use and management in the whole basin. The trend of water resources change in the Red river system basin has been assessed on the basic of statistic analyses of data observed during the studies, especially in the time when the exploitation of water resources has been intensified for the multisectoral development. This paper shows some of the results from considerations of the water use in the highlands that is influential in water resources in the Red river system basin and the planned reservoirs which are built in the basin of Red river system. The results include the assessment of the state and trend of water resources in the Red river system basin, the trend of water level lowering in the lowlands and its impacts.

ГОЛОВНИЙ ЄВРОПЕЙСЬКИЙ ВОДОДІЛ В УКРАЇНІ ТА ЙОГО ТУРИСТИЧНЕ ЗНАЧЕННЯ

Objective: On the basis of general geographical analysis to reveal the tourist potential of the Main European watershed on the territory of Ukraine. Method. General scientific methods of analysis, synthesis and generalization as well as cartographic methods by the means of GIS have been used. Results:The peculiarities of the geographical location of the Main European Watershed on a European scale have been analyzed. New facts from the history of its research have been presented. A hypsometric profile along the watershed line has been constructed, its morphometric parameters have been determined. With the help of detailed cartographic analysis, the Ukrainian section of the Main European Watershed line has been identified. Its location in relation to the physical and geographical zoning has been determined. A regional analysis of tourist facilities attractiveness on the watershed line has been conducted. Cross-border and domestic transport opportunities for access to the watershed line have been assessed. The coordinate reference of the most important orohydrographic elements - the points of watersheds intersection of large transboundary rivers basins: Danube, Vistula, Dniester, Dnieper, as well as their tourist significance have been specified. Possibilities of tourist use of nature reserve fund objects which are located on the watershed line have been revealed, in particular of such national natural parks, as Uzhanian National Nature Park, Boikivschyna National Nature Park, Yavorivskyi National Park, Northern Podillia, Shatsk National Natural Park. The importance of the watershed for sustainable (ecologically oriented) tourism development in international biosphere reserves: "The Eastern Carpathians" (Slovak-Ukrainian-Polish), "Roztochia" (Ukrainian-Polish), "Western Polissya" (Polish-Ukrainian-Belarusian) has been demonstrated. Touristic assessment of historical and cultural sites located on the watershed line has been conducted. The importance of the city of Lviv as a separate tourist destination has been emphasized. Environmental problems related to the development of tourist resources have been outlined. Selected tourist clusters of the destination have been identified, the possibilities of their use have been revealed. The Main European Watershed specifics in general tourist resources classification have been emphasized. Scientific novelty: For the first time, the Main European Watershed has been considered as a separate integrated tourist destination, its detailed geographical analysis has been performed, and a cluster approach has been used to assess the tourist resources located on the watershed line. Practical significance. The results of the study will contribute to the integration process of Ukraine into the European tourist area, give impetus to new tourist routes planning, promote the development of tourist resources of national natural and regional landscape parks, support tourist clusters planning and developing.

Influence of the saline waters of the flowing well on the chemical composition of water and bottom sediments in the Irtysh river and its tributary (Aremzyanka river)

The article presents data on the influence of waters from the self-flowing wells in the floodplain of the Aremzyanka river of the first order inflow on the chemical composition of the water in the large transboundary Irtysh river in the south of the Tyumen region (Tobolsk District). The article shows the excess of the background of various elements in the bottom sediments of the studied rivers. The number of ions in the water of the Aramzyanka river is 2 times higher in comparison with the main river. The paper discusses the impact of saline water from a flowing well on a freshwater ecosystem, its components.