Rivers Of Central Asia Research Articles

River flow in the near future: a global perspective in the context of a high-emission climate change scenario

Abstract. There is high confidence that global warming intensifies all components of the global water cycle. This work investigates the possible effects of global warming on river flows worldwide in the coming decades. We conducted 18 global hydrological simulations to assess how river flows are projected to change in the near future (2015–2050) compared to the recent past (1950–2014). The simulations are forced by runoff from the High Resolution Model Intercomparison Project (HighResMIP) CMIP6 global climate models (GCMs), which assume a high-emission scenario for the projections. The assessment includes estimating the signal-to-noise (S/N) ratio and the time of emergence (ToE) of all the rivers in the world. Consistently with the water cycle intensification, the hydrological simulations project a clear positive global river discharge trend from ∼2000 that emerges beyond the levels of natural variability and becomes “unfamiliar” by 2017 and “unusual” by 2033. Simulations agree that the climate change signal is dominated by strong increases in the flows of rivers originating in central Africa and South Asia and those discharging into the Arctic Ocean, partially compensated for by the reduced flow projected for Patagonian rivers. The potential implications of such changes may include more frequent floods in central African and South Asian rivers, driven by the projected magnification of the annual cycles with unprecedented peaks, a freshening of the Arctic Ocean from extra freshwater release, and limited water availability in Patagonia given the projected drier conditions of its rivers. This underscores the critical need for a paradigm shift in prioritizing water-related concerns amidst the challenges of global warming.

Comparative analysis of information products of land cover types
 of high spatial resolution in mapping floodplain landscapes

Intrazonal floodplain landscapes in the southern Russia remain relatively unaffected by the direct impact of anthropogenic activity, while zonal steppe landscapes are almost completely plowed, and semi-desert and desert are subject to high pasture loads. At the same time, climatic changes and the regulation of river flow by hydroelectric dams lead to the redistribution of river flow, which leads to the degradation of floodplain ecosystems due to a decrease in the duration and height of the flood. The construction of hydraulic structures, including shafts, dams, and arrays of irrigated lands, contributes to the withdrawal of significant areas from the floodplain regime. Reducing the duration of high water and the areas of flooding during them entails an increase in the mineralization of groundwater and stabilization of their level, which negatively affects natural floodplain ecosystems. Similar trends of hydrological and climatic changes are characteristic of floodplain landscapes of rivers in the zone of insufficient moisture, for example, the Don and its tributaries, the Volga in its lower reaches, the rivers of Central Asia. For these reasons, it is important to monitor the condition of floodplain landscapes, one of the tools of which is mapping based on remote sensing data. The purpose of this work is to map the types of land cover of floodplain landscapes of the Lower Volga on the basis of thematic information products ESA GlobCover, ESRI WorldCover, FROM-GLC10 with a spatial resolution of 10 m and GlobCover30 (GLC30) with a resolution of 30 m. It has been established that the actual area of wetlands regularly flooded during floods is 48% of the area of the entire territory. The most accurate estimates of the areas of wetlands, reservoirs, meadows and forests were obtained from the data of the ESA GlobCover information product, which is associated with the use of not only Sentinel-2 optical satellite images, but also Sentinel-1 radar. ESA data is recommended for analyzing the state of floodplain landscapes in the zone of insufficient moisture.

CA-discharge: Geo-Located Discharge Time Series for Mountainous Rivers in Central Asia

We present a collection of 295 gauge locations in mountainous Central Asia with norm discharge as well as time series of river discharge from 135 of these locations collected from hydrological yearbooks in Central Asia. Time series have monthly, 10-day and daily temporal resolution and are available for different duration. A collection of third-party data allows basin characterization for all gauges. The time series data is validated using standard quality checks. Norm discharge is validated against literature values and by using a water balance approach. The novelty of the data consists in the combination of discharge time series and gauge locations for mountainous rivers in Central Asia which is not available anywhere else. The geo-located discharge time series can be used for water balance modelling and training of forecast models for river runoff in mountainous Central Asia.

СЫРДАРИЯ ӨЗЕНІ АҒЫНДЫСЫНЫҢ ЖЫЛІШІЛІК ҮЛЕСТІРІМІНІҢ ӨЗГЕРІСІН БАҒАЛАУ

The Syrdarya River is the second largest river in the Aral-Syrdarya basin. It flows through the densely populated southern region of Kazakhstan and flows into the Aral Sea. The available water resources of the river are mainly used for irrigation of agricultural land. The main obstacle to the development of this branch of the economy is the lack of water in some parts of the massif, especially in its lower reaches. The article is devoted to the water regime currently forming in the lower reaches of the Syrdarya River, and the assessment of the change in runoff over the year. In modern conditions, as a result of the influence of economic activity on the flow of the Syrdarya River, it is difficult to clearly determine the type of river nutrition. It follows from the analysis that in all seasons of medium and low (low) water content, the values of the flow volume are close to each other. Also, the intra-annual flow distribution differs from the Central Asian rivers of a natural nature. For example, if in the natural conditions of the river the greatest Runoff is observed in March-July, then in modern conditions the period of abundant water falls on the winter period – November-February. The average monthly minimum water flows occur during surface irrigation of cultivated areas, that is, in the summer months, and in the fall there is abundant irrigation of rivers. The large Toktagul and Andijan reservoirs built in the upper reaches of the river for irrigation purposes also have a great influence on the intra-network distribution of runoff and the dynamics of its fluctuations. This is due to the fact that currently these reservoirs are actually used for energy purposes. In addition, in recent years, the Koksarai counterregulator has been built along the Syr Darya River in Kazakhstan.The main purpose of the study is to clarify the intracellular distribution of runoff in the lower reaches of the river in such difficult hydrological conditions in the river basin.

Comparative analysis and human health risk assessment of contamination with heavy metals of Central Asian rivers

The study focuses on heavy metals contamination, drinking water quality, and associated health risks for adults and children by consuming water from Central Asian Rivers (Syr-Darya, Nura, and Ili Rivers). Water samples were collected from three rivers within the 2014–2019 period by the RMS “Kazhydromet” and analyzed for various physicochemical parameters. The study revealed that the concentrations of Fe, Cd, Cr (VI), Hg, Mn, and As significantly exceeded local and international drinking water standards in at least one water body. The lowest total water quality index (55.1%) was observed in the Nura River (“marginal water category”). Coal, soil, non-ferrous metals, and iron ore industries were found to be the major sources of heavy metals in the regions. Deterministic risk assessment revealed serious cancer risks (>1E−5) in rivers due to As and Cr (VI) exposure by oral and dermal contact for adults and children. Stochastic risk assessment confirmed high cancer risks (>1E−4) due to Cr (VI) contamination of the Syr-Darya River. The study results indicate the serious lifetime cancer risk to the residents due to the use of river water for drinking and household activities. Therefore, the study area urgently and continuously requires heavy metal removal, effective monitoring, and good quality drinking water supply.

The Status and Influencing Factors of Surface Water Dynamics on the Qinghai-Tibet Plateau During 2000–2020

The Qinghai–Tibet Plateau is rich in water resources with numerous lakes, rivers, and glaciers, and, as a source of many rivers in Central Asia, it is known as the Asian Water Tower. Under global climate change, it is critical to understand the current influencing factors on surface water area in this region. Although there are numerous studies on surface water mapping, they are still limited by temporal/spatial resolution and record length. Moreover, the complicated topographic condition makes it challenging to map the surface water accurately. Here, we proposed an automatic two-step annual surface water classification framework using long time-series Landsat images and topographic information based on the Google Earth Engine (GEE) platform. The results showed that the producer accuracy (PA) and user accuracy (UA) of the surface water map in the Qinghai–Tibet Plateau in 2020 were 99% and 90%, respectively, and the Kappa coefficient reached 0.87. Our dataset showed high consistency with high-resolution images, indicating that the proposed large-scale water mapping method has great application potential. Furthermore, a new annual surface water area dataset on the Qinghai–Tibet Plateau from 2000 to 2020 was generated, and its relationship with climate, vegetation, permafrost, and glacier factors was explored. We found that the mean surface water area was about 59 481 km2, and there was a significant increasing trend (=322 km2/year, <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$p &lt; 0.01$ </tex-math></inline-formula> ) during 2000–2020 in the plateau. Greening, warming, and wetting climate conditions contributed to the increase of surface water area. Active layer thickness and permafrost types may be the most related to the decrease of surface water area. This study provides important information for ecological assessment and protection of the plateau and promotes the implementation of sustainable development goals related to surface water resources.

HYDROCHEMISTRY OF HIGH-MOUNTAIN PAMIR RIVERS: FORMATION, CHANGES AND INFLUENCE ON THE CHEMICAL COMPOSITION OF IRRIGATION WATER

The purpose of the research is to analyze the prospects for the agriculture development in the Central Asian region and Tajikistan in particular, in terms of identifying the main favorable and constraining factors for the further agriculture development. The Pyanj river is one of the main tributaries of the Transboundary Amu Darya River in the Central Asian region, whose waters are a source of drinking water supply for the population and 80% used for irrigation of agricultural land. The trend of deteriorating water quality of Central Asian River systems recently has been increasing, and monitoring water quality from the formation zone to the downstream of the rivers is a problem in the region. The statistical methods and Pearson correlation to the meteorological conditions monitoring of the river basins were used. In the Laboratory of Environment and Geology of the Department of Geological Sciences of the University of Colorado at Boulder (USA), as well as in the Laboratory of Moisture Chemistry of the Institute of Arctic and Alpine Research (USA) by use of an inductively coupled plasma mass spectrometer (ICP-MS) and ion chromatography was conducted the element analyses of waters. The physical and chemical analyses of water samples was conducted using the “TaLab” spectrophotometer following the relevant state standards. The suitability of water for irrigation were determined by the calculation of the coefficients of sodium adsorption (SAR), the percentage of sodium (Na%), the percentage of sodium solubility (SSP), and the percentage of exchangeable sodium (ESP). The contribution of the Gunt River to the enrichment of the main Pyanj River with Fe, Co, Ni, Sr, Ca, Mg, Na, and K elements are established. The assessment of the natural water quality of the Pyanj and Gunt rivers for irrigation was carried out using various index methods, such as SAR, ESP, SSP and %Na.

About the Mechanisms of Formation of the Chemical Composition of the High-Mountain Rivers of Central Asia: The Shakhdara River and its Contribution to the Hydrochemistry of the Transboundary Panj River

About the Mechanisms of Formation of the Chemical Composition of the High-Mountain Rivers of Central Asia: The Shakhdara River and its Contribution to the Hydrochemistry of the Transboundary Panj River

УЧАСТИЕ ТУРКЕСТАНСКОГО ОТДЕЛА РУССКОГО ГЕОГРАФИЧЕСКОГО ОБЩЕСТВА В ПРАВИТЕЛЬСТВЕННЫХ ПРОГРАММАХ ПО ВОПРОСАМ ВОДОПОЛЬЗОВАНИЯ И ЗЕМЛЕУСТРОЙСТВА В ТУРКЕСТАНСКОМ КРАЕ В XIX-XX ВВ.

The article studies the role of the Turkestan Branch of the Russian Geographical Society in organizing the research of the hydrology and geology of the Turkestan Territory in the context of the colonial policy of the Russian Empire in the Central Asian region at the turn of the 19th–20th centuries. The Turkestan Branch of the Russian Geographical Society considered the organization of permanent hydrometric observation of the Aral Sea and the Central Asian rivers – the Amu Darya and Syr Darya as the most important direction of its activity. Organized and systematic study of the water areas in the Turkestan Territory should have contributed to erecting the irrigation and road structures, construction of canals and aryks (ditches), development of agriculture and farming that served the economic interests of the Russian government in the Turkestan Territory. In addition to the study of water and land use in Turkestan Territory, the article also analyses the issue of the development of the Hungry Steppe. A separate direction of scientific activity of the Turkestan Branch of the Russian Geographical Society was a series of expeditions aimed at studying biological properties of soil, locust control and mono-cultivation of cotton crops in Turkestan Territory. The author concludes that the systematic study of water and land resources of the Turkestan Territory was of practical importance in the development of Central Asia. The Russian government implemented long-term projects on erecting irrigation systems and a canal in the Hungry Steppe, and partially solved the issues of land use in the Turkestan Territory.

Environmental flows in integrated sustainable water resource management in Tuyamuyin water reservoir, Uzbekistan

Climate change is causing extreme recession of the mountain glaciers in Central Asia. Also increased evapotranspiration from higher temperatures in arid and semi-arid zones in Uzbekistan. Additionally, climate change has an effect increased exceptional water deficits. In such scenarios Environmental despite for a more sustainable water supply system, available reservoir capacity. Central Asia unlock watershed region, its main rivers are the Amu Darya and the Syr Darya, and its key problems of the region the efficient use of water from these rivers. Supplying water to the Khorezm oasis and Karakalpakstan, Tuyamuyin reservoir is the main water resource. With an increasing population of the region and Aral Sea ecological problems, mounting demand exists for a more sustainable water supply system. Water reservoirs of Central Asian river contribute to the improvement of water resources management in the lower part of the region and thus, play a strategic role in regional water supplication. 70% of Central Asia is arid and semi-arid regions and therefore, water supply for irrigation and population purposes is the main water sector of all Central Asian countries.

Features of Water Diplomacy in Central Asia

Water issues are traditionally one of the most complex and controversial issues in Central Asia. Over the 30 years since independence, the five republics have not been able to come to a single agreement on the use of water resources. Mainly because their interests do not coincide. The region is conventionally divided into agricultural and energy republics. Some need to irrigate their lands, others are interested in producing electricity. Each of the five republics strives to take into account primarily its own interests, sometimes disregarding the interests of its neighbors. The article deals with the problems of the development of water diplomacy between the states of Central Asia. It is noted that this problem is relevant for the region due to the peculiarities of the position and legal regime of transboundary rivers in Central Asia.

TOURISM IN UZBEKISTAN

A tourist who is at least a little familiar with the history of mankind does not need to ask questions: what is so attractive about tourism in Uzbekistan and what makes it stand out among hundreds of other tourist destinations. Because the answer is obvious. In the same way that this land, called by the ancient Greeks Transoxiana, attracted Alexander the Great almost two and a half millennia ago. What fascinated the Arabs with the land they called Maverannahr - the land of two great Central Asian rivers - the Amu Darya and the Syr Darya, mighty oasis cities inhabited by skilled artisans, the land of generous fields and gardens, giving sun-drenched harvests. The article describes the main sites of tourism in Uzbeksitan.

Hot Spots of Glacier Mass Balance Variability in Central Asia.

The Tien Shan and Pamir mountains host over 28,000 glaciers providing essential water resources for increasing water demand in Central Asia. A disequilibrium between glaciers and climate affects meltwater release to Central Asian rivers, challenging the region's water availability. Previous research has neglected temporal variability. We present glacier mass balance estimates based on transient snowline and geodetic surveys with unprecedented spatiotemporal resolution from 1999/00 to 2017/18. Our results reveal spatiotemporal heterogeneity characterized by two mass balance clusters: (a) positive, low variability, and (b) negative, high variability. This translates into variable glacial meltwater release (≈1–16%) of annual river runoff for two watersheds. Our study reveals more complex climate forcing‐runoff responses and importance of glacial meltwater variability for the region than suggested previously.

Agricultural impacts drive longitudinal variations of riverine water quality of the Aral Sea basin (Amu Darya and Syr Darya Rivers), Central Asia

River ecosystems are under increasing stress in the background of global change and ever-growing anthropogenic impacts in Central Asia. However, available water quality data in this region are insufficient for a reliable assessment of the current status, which come as no surprise that the limited knowledge of regulating processes for further prediction of solute variations hinders the development of sustainable management strategies. Here, we analyzed a dataset of various water quality variables from two sampling campaigns in 2019 in the catchments of two major rivers in Central Asia—the Amu Darya and Syr Darya Rivers. Our results suggested high spatial heterogeneity of salinity and major ion components along the longitudinal directions in both river catchments, pointing to an increasing influence of human activities toward downstream areas. We linked the modeling outputs from the global nutrient model (IMAGE-GNM) to riverine nutrients to elucidate the effect of different natural and anthropogenic sources in dictating the longitudinal variations of the riverine nutrient concentrations (N and P). Diffuse nutrient loadings dominated the export flux into the rivers, whereas leaching and surface runoff constituted the major fractions for N and P, respectively. Discharge of agricultural irrigation water into the rivers was the major cause of the increases in nutrients and salinity. Given that the conditions in Central Asia are highly susceptible to climate change, our findings call for more efforts to establish holistic management of water quality.

Signatures of human intervention – or not? Downstream intensification of hydrological drought along a large Central Asian river: the individual roles of climate variability and land use change

Abstract. The transboundary Helmand River basin (HRB) is the main drainage system for large parts of Afghanistan and the Sistan region of Iran. Due to the reliance of this arid region on water from the Helmand River, a better understanding of hydrological-drought pattern and the underlying drivers in the region is critically required for effective management of the available water. The objective of this paper is therefore to analyze and quantify spatiotemporal pattern of drought and the underlying processes in the study region. More specifically we test for the Helmand River basin the following hypotheses for the 1970–2006 period: (1) drought characteristics, including frequency and severity, systematically changed over the study period; (2) the spatial pattern and processes of drought propagation through the Helmand River basin also changed; and (3) the relative roles of climate variability and human influence on changes in hydrological droughts can be quantified. It was found that drought characteristics varied throughout the study period but largely showed no systematic trends. The same was observed for the time series of drought indices SPI (standard precipitation index) and SPEI (standardized precipitation evapotranspiration index), which exhibited considerable spatial coherence and synchronicity throughout the basin, indicating that, overall, droughts similarly affect the entire HRB with few regional or local differences. In contrast, analysis of the SDI (streamflow drought index) exhibited significant negative trends in the lower parts of the basin, indicating an intensification of hydrological droughts. It could be shown that with a mean annual precipitation of ∼ 250 mm yr−1, streamflow deficits and thus hydrological drought throughout the HRB are largely controlled by precipitation deficits, whose annual anomalies on average account for ±50 mm yr−1, or ∼ 20 % of the water balance of the HRB, while anomalies of total evaporative fluxes on average only account for ±20 mm yr−1. Assuming no changes in the reservoir management practices over the study period, the results suggest that the two reservoirs in the HRB only played a minor role for the downstream propagation of streamflow deficits, as indicated by the mean difference between inflow and outflow during drought periods, which did not exceed ∼ 0.5 % of the water balance of the HRB. Irrigation water abstraction had a similarly limited effect on the magnitude of streamflow deficits, accounting for ∼ 10 % of the water balance of the HRB. However, the downstream parts of the HRB moderated the further propagation of streamflow deficits and associated droughts because of the minor effects of reservoir operation and very limited agricultural water in the early decades of the study period. This drought moderation function of the lower basin was gradually and systematically inverted by the end of the study period, when the lower basin eventually amplified the downstream propagation of flow deficits and droughts. Our results provide plausible evidence that this shift from drought moderation to drought amplification in the lower basin is likely a consequence of increased agricultural activity and the associated increases in irrigation water demand, from ∼ 13 mm yr−1 at the beginning of the study period to ∼ 23 mm yr−1 at the end, and thus in spite of being only a minor fraction of the water balance. Overall the results of this study illustrate that flow deficits and the associated droughts in the HRB clearly reflect the dynamic interplay between temporally varying regional differences in hydro-meteorological variables together with subtle and temporally varying effects linked to direct human intervention.

Central Asian rivers under climate change: Impacts assessment in eight representative catchments

Study regionEight river catchments within Central Asia. Study focusThe limited amount of water resources is already an issue in the Central Asian region, and climate change may be crucial for water availability and development of countries in the region. This study investigates potential climate change impacts on water resources in Central Asia to the end of the century by focusing on eight river catchments with diverse natural conditions located in different countries. The eco-hydrological model SWIM was setup, calibrated and validated for all selected catchments under study. Scenarios from five bias-corrected GCMs under Representative Concentration Pathways 4.5 and 8.5 were used to drive the hydrological model. New hydrological insights for the regionThe results show an increase of mean annual temperature in all catchments for both RCPs to the end of the century. The projected changes in annual precipitation indicate a clear trend to increase in the Zhabay and to decrease in the Murghab catchments, and for other catchments, they were smaller.The projected trends for river discharge are similar to those of precipitation, with an increase in the north and decrease in the south of the study region. Seasonal changes are characterized by a shift in the peak of river discharge up to one month, shortage of snow accumulation period, and reduction of discharge in summer months.

Tradition Formation of Water Civilization in Uzbekistan

This article summarizes issues related to water civilization, irrigation thinking and centuries-old traditions of our people on irrigation, agriculture and land reclamation as the basis for the formation of the Tashkent Institute of Irrigation and Agricultural Mechanization Engineers at the beginning of the 20th century. It is known that the natural foundations of the water civilization of our region are inextricably linked with the history and development of the largest rivers in Central Asia, the Syrdarya and Amudarya, life in their basins, human activities and society in this region.

Molecular characterization of European Pygorchis Looss, 1899.

Adult trematodes of the genus Pygorchis Looss, 1899 (Trematoda: Philophthalmidae) parasitize the cloaca of birds. The genus contains three species, all of which are rarely reported and molecular phylogenetics of which have not been applied. The absence of reference DNA sequences limit studies of their indistinct larval forms. Based on the materials that were obtained from birds of the Czech origin, we performed a molecular characterization of both currently known Pygorchis spp., which are known from the Palearctic, the type species Pygorchis affixus Looss, 1899 and Pygorchis alakolensis Zhatkanbaeva, 1967, and provided morphological description of the examined P. alakolensis specimen. We found that the two species were of similar dimensions; the only difference was in the position of testes and in the extent of vitelline follicles. However, the position of testes in P. affixus was variable, and approximately 10% of examined P. affixus individuals had testes positioned obliquely. The second feature that allows differential diagnostic, the extent of vitelline follicles, was more reproducible as the vitelline follicles of P. affixus did not extend beyond the intestinal caeca, or, in exceptional cases, they extended them at only one side. In the examined P. alakolensis individual, the testes were positioned obliquely, and the vitelline follicles extended beyond the intestinal caeca. We reported P. alakolensis for the first time from Europe; previously, it was known only from Central Asian lakes and rivers. We confirmed the classification of Pygorchis into Philophtalmidae.

Методика прогноза водности высокогорных рек Центральной Азии на основе снимков MODIS

The article investigates the possibility of using snow cover satellite data for short-term hydrological forecasting for Central Asian rivers with high-altitude catchments. The research aimed to elaborate a methodology for forecasting mean 10-day (decadal) river discharge (MDD) of the Varzob and Tar Rivers based on MODSNOW-processed MODIS satellite imagery. The objectives of the study were to calculate the snow cover index (SCI) for high-altitude zones in 200 m increments for selected river basins, and to analyze the closeness of dependency between the corresponding SCIs and MDDs. The research resulted in equations applicable for producing operational river water content forecasts. Timely and reliable information on expected river water content during the forthcoming 10-day period allows decision makers (water management and hydropower agencies, emergency authorities) plan water supply for various economic sectors, as well as take measures to prevent hazardous hydrological phenomena on the rivers of Tajikistan and Kyrgyzstan.

Legacy and current pesticide residues in Syr Darya, Kazakhstan: Contamination status, seasonal variation and preliminary ecological risk assessment

The Syr Darya is one of two major rivers in Central Asia supplying critical fresh water to the Aral Sea. In spite of the river’s importance and agriculturally-intensive history, few studies have provided a modern evaluation of and the occurrence of pesticide residues potential effects to aquatic life. The primary goal of this investigation was to determine seasonal variations in ambient concentrations of modern and legacy pesticides in bottom sediment and water of the Syr Darya in Kazakhstan (KZ) downstream from an agriculturally-intensive watershed in Uzbekistan. Grab samples and passive samplers were used at five remote sampling stations during June 2015 to provide a baseline for ecotoxicological evaluation. Results were compared with samples collected during and after the agricultural growing season. Polar organic chemical integrative samplers (POCIS) were used in June and calibrated for time-weighted average concentrations of current use pesticides. Among legacy chlorinated pesticides measured in grab samples from the river, lindane (γ-HCH) was detected most frequently with the highest concentrations occurring during June. For all the sampling events, residues of lindane (γ-HCH) ranged from 0.014 to 0.24 μg/L detected in water samples, are among the highest concentrations reported for rivers globally. Concentrations of γ-HCH, p,p’-DDE and dieldrin were highest in October when dieldrin concentrations approached 0.4 μg/L. Sources of legacy pesticides may be either illicit upstream use or evidence of previous atmospheric contamination of glacial meltwater. Chronic exposure to these residues may lead to ecological risk to lower order organisms in both the sediment and water column.