As a major source of freshwater in Central Asia,Tajikistan is endowed with abundant glaciers and water resources.However,the country faces multiple challenges,including accelerated glacier retreat,complex inter-govern...As a major source of freshwater in Central Asia,Tajikistan is endowed with abundant glaciers and water resources.However,the country faces multiple challenges,including accelerated glacier retreat,complex inter-government water resource management,and inefficient water use.Existing research has predominantly focused on individual hydrological processes,such as glacier retreat,snow cover change,or transboundary water issues,but it has yet to fully capture the overall complexity of water system.Tajikistan’s water system functions as an integrated whole from mountain runoff to downstream supply,but a comprehensive study of its water resource has yet to be conducted.To address this research gap,this study systematically examined the status,challenges,and sustainable management strategies of Tajikistan’s water resources based on a literature review,remote sensing data analysis,and case studies.Despite Tajikistan’s relative abundance of water resources,global warming is accelerating glacier melting and altering the hydrological cycles,which have resulted in unstable runoff patterns and heightened risks of extreme events.In Tajikistan,outdated infrastructure and poor management are primary causes of low water-use efficiency in the agricultural sector,which accounts for 85.00%of the total water withdrawals.At the governance level,Tajikistan faces challenges in balancing the water-energy-food nexus and transboundary water resource issues.To address these issues,this study proposes core paths for Tajikistan to achieve sustainable water resource management,such as accelerating technological innovation,promoting water-saving agricultural technologies,improving water resource utilization efficiency,and establishing a community participation-based comprehensive management framework.Additionally,strengthening cross-border cooperation and improving real-time monitoring systems have been identified as critical steps to advance sustainable water resource utilization and evidence-based decision-making in Tajikistan and across Central Asia.展开更多
Debris flow events are frequent in Tajikistan,yet comprehensive investigations at the regional scale are limited.This study integrates remote sensing,Geographic Information System,and machine learning techniques to ev...Debris flow events are frequent in Tajikistan,yet comprehensive investigations at the regional scale are limited.This study integrates remote sensing,Geographic Information System,and machine learning techniques to evaluate debris flow susceptibility and associated hazards across Tajikistan.A dataset comprising 405 documented debris flow points and 14 influencing factors,encompassing geological,climatic-hydrological,and anthropogenic variables,was established.Three machine learning algorithms—Random Forest,Support Vector Machine(SVM),and Multi-layer Perceptron—were applied to generate susceptibility maps and delineate debris flow risk zones.The results indicate that the areas of higher and high susceptibility accounted for 20.43%and 4.41%of the national area,respectively,and were predominantly concentrated along the Zeravshan and Vakhsh river basins.Among the evaluated models,SVM model demonstrated the highest predictive performance.Beyond conventional topographic and environmental controls,drought conditions were identified as a critical factor influencing debris flow occurrence within the arid and semi-arid mountainous regions of Tajikistan.These findings provide a scientific basis for regional debris flow risk management and disaster mitigation planning,and offer practical guidance for selecting conditioning factors in machine-learning-based susceptibility assessments in other dry mountainous environments.展开更多
Tajikistan contains the majority of Central Asia’s glaciers,which cover about 6.00%of the national territory;their rapid shrinkage poses a significant threat to regional water resource security.However,glacier monito...Tajikistan contains the majority of Central Asia’s glaciers,which cover about 6.00%of the national territory;their rapid shrinkage poses a significant threat to regional water resource security.However,glacier monitoring in Tajikistan was interrupted after 1991,creating a substantial gap in understanding the current state and temporal evolution of these glaciers.Based on glacier inventory data,in situ measurements,and published literature,this study examined the present status and recent variations of glaciers in Tajikistan through data integration and validation,literature collation and comparative analysis,and the application of Geographic Information System(GIS)spatial analysis techniques.As of 2023,Tajikistan possesses a total of 11,528 glaciers,encompassing an area of 7624.48(±305.58)km2.Small glaciers dominate in number,whereas large glaciers account for the majority of the total area.Over the past two decades,the glacier count has decreased by 2014,and the total area has decreased by 628.98 km2,corresponding to an average annual reduction rate of 0.33%.Regional shrinkage rates range from 4.10%to 22.28%.Glaciers have undergone accelerated mass loss during the past 20 a;only those on the northeastern Pamir Plateau exhibit a weak positive mass balance.Observations of typical monitored glaciers also reveal intensified melting and retreat,consistent with regional trends.In light of the recent acceleration of glacier shrinkage in Tajikistan,focused measures should be implemented to strengthen glacier monitoring,enhance public awareness of glacier preservation,and promote the sustainable development and utilization of glacier tourism.These findings bridge the knowledge gap regarding the spatiotemporal dynamics of Tajikistan’s glaciers over recent decades and provide essential data support for regional water resource management.展开更多
Tajikistan,a mountainous country and a vital water tower for Central Asia,is becoming increasingly vulnerable to snow drought under climate change,threatening its snow-and glacier-fed streamflow.Yet,the impacts of sno...Tajikistan,a mountainous country and a vital water tower for Central Asia,is becoming increasingly vulnerable to snow drought under climate change,threatening its snow-and glacier-fed streamflow.Yet,the impacts of snow drought on the regional hydrology remain insufficiently understood.In this study,we integrated multisource data,including the Fifth Generation European Centre for Medium-Range Weather Forecasts Atmospheric Reanalysis for Land Applications(ERA5-Land)data and hydrological station data,to systematically assess the snow drought patterns and their impacts on streamflow during 1950–2023.We identified snow drought events based on precipitation and snow fraction anomalies relative to climatological means and classified them into warm snow drought,dry snow drought,and warm&dry snow drought.The results revealed that snow drought was a recurrent phenomenon,occurring in 51.70%of the years during the study period,with warm&dry snow drought accounting for 21.90%of the total events.Both the frequency and severity exhibited pronounced spatial variability,largely governed by the elevation and snowfall fraction.Specifically,the frequency of warm snow drought was negatively correlated with the snowfall fraction,decreasing on average by 0.20 per unit increase in snowfall fraction,whereas the frequency of dry snow drought was positively correlated,increasing by 0.07 per unit increase.The streamflow analysis results demonstrated that snow drought typically reduced the warm-season discharge by 5.00%–18.00%in certain rivers,thereby exacerbating the water stress during the dry season.The results of this study advance our understanding by explicitly linking the types of snow drought to hydrological responses in Central Asia’s high mountains,providing a scientific basis for climate adaptation and sustainable water resource management in Tajikistan.展开更多
This study aimed to elucidate the influence of inflow water on the salinity concentration process of a saline lake and the mass balance of Lake Issyk-Kul,a tectonic saltwater lake in Kyrgyzstan.Based on the survey res...This study aimed to elucidate the influence of inflow water on the salinity concentration process of a saline lake and the mass balance of Lake Issyk-Kul,a tectonic saltwater lake in Kyrgyzstan.Based on the survey results and meteorological data from 2012 to 2015,we analyzed the dissolved chemical composition loads due to water inflow.Then,we discussed the relationship between the increase in salinity and water inflow into the lake.Through the water quality analysis data,we used the tank model to estimate the river inflow and analyze the loads by the L-Q curve.The groundwater loads were then estimated from the average annual increase in salinity of the lake over a period of 30 a.The results suggest that Lake Issyk-Kul was temporarily freshened between about AD 1500 and 1800 when an outflowing river existed,and thereafter,it became a closed lake in AD 1800 and continued to remain a saline lake until present.The chemical components that cause salinization are supplied from the rivers and groundwater in the catchment area,and when they flow into the lake,Ca^(2+),HCO_(3)−and Mg^(2+)precipitate as CaCO_(3) and MgCO_(3).These compounds were confirmed to have been left on the lakeshore as evaporite.The model analysis showed that 1.67 mg/L of Ca^(2+)and Mg^(2+)supplied from rivers and groundwater are precipitated as evaporite and in other forms per year.On the other hand,salinity continues to remain in the lake water at a rate of 27.5 mg/L per year.These are the main causes of increased salinity in Lake Issyk-Kul.Since Na^(+)and Cl^(-)are considered to be derived from geothermal water,they will continue to flow in regardless of the effects of human activities.Therefore,as long as these components are accumulated in Lake Issyk-Kul as a closed lake,the salinity will continue to increase in the future.展开更多
The paper is concerned with the development of a comprehensive methodology to establish a MPAs （marine protected areas） network in the Black Sea and Azov Sea region. Scientific basis to rationale establish that the ...The paper is concerned with the development of a comprehensive methodology to establish a MPAs （marine protected areas） network in the Black Sea and Azov Sea region. Scientific basis to rationale establish that the MPAs network is a complex system of landscape zoning and mapping, defining their variability, sustainability, and geo-ecological condition, and taking into account evaluation of degradation of the underwater landscape over the past 100 years.展开更多
In recent years,mudflows have emerged as a significant threat to infrastructure and lives,exhibiting increased frequency and severity.This study collectively addresses the rising threat of natural hazards,specifically...In recent years,mudflows have emerged as a significant threat to infrastructure and lives,exhibiting increased frequency and severity.This study collectively addresses the rising threat of natural hazards,specifically mudflows in mountain-foothill zones in Tajikistan,utilizing UAV and remote sensing technologies to monitor their impact.From 2020 to 2023,we employed a QC-2 Micro UAV and a DJI Phantom 4 quadcopter to capture high-resolution aerial imagery across multiple affected districts,supplemented by pre-and post-event Sentinel-2 images analyzed using the Normalized Difference Water Index(NDWI)and Normalized Difference Vegetation Index(NDVI).Our analysis revealed that 49 districts and cities experienced significant mudflow events,resulting in estimated damages and economic losses of 30.2 million USD,with particularly severe impacts noted in the Khuroson,Tojikobod,Vakhsh,Panjakent,Lakhsh,and Varzob.The composition of mudflows in the six studied areas predominantly consisted of clay,with some regions featuring mudstone and a few exhibiting a mixture of both materials.Our findings indicate the predominance of rain-induced mudflows in foothill areas,contrasting with rain-snow,glacial,and lake-outburst-induced mudflows in mountainous regions.This underscores the urgent need for effective disaster risk management strategies in vulnerable locations.Integrating UAV and remote sensing technologies provides crucial information for analyzing damages,identifying vulnerable areas,and advising emergency response efforts,thereby enhancing disaster risk management in Tajikistan.展开更多
The study investigated the trend of extreme flood events in the Pearl River basin during 1951-2010. Stream flow data at 23 gauging stations were used for the study. The Pearson type III distribution was selected for t...The study investigated the trend of extreme flood events in the Pearl River basin during 1951-2010. Stream flow data at 23 gauging stations were used for the study. The Pearson type III distribution was selected for the flood frequency analysis. Results indicate that extreme flood events increase significantly in the Pearl River Basin since 1980. At the 23 gauging stations, there are 16 (70%) stations show positive (increasing) trends in 1981-2010. Most of the 16 stations are located along the West River and North River. While 7 (30%) stations show negative (decreasing) trends, and are found in the East River and the southeast region of the West River Basin.展开更多
In this study, tree-ring width data of Schrenk spruce (Picea schrenkiana) from the upper timberline of the Tien Shan (Kyrgyzstan) were analyzed to investigate the effect of climate change. Growtheclimate response anal...In this study, tree-ring width data of Schrenk spruce (Picea schrenkiana) from the upper timberline of the Tien Shan (Kyrgyzstan) were analyzed to investigate the effect of climate change. Growtheclimate response analyses revealed that the tree rings of spruce at the upper timberline of the Tien Shan also can provide hydrometeorological (precipitation and streamflow) signals. Tree-ring records from both Kyrgyzstan and Xinjiang exhibited similar tree-growth variability at both annual and decadal time scales during the common period 1457e2009. In Xinjiang and Kyrgyzstan, tree growth was reduced during the Little Ice Age (LIA); however, the timing and magnitude of LIA differ between the two regions. During 1470e1660, the two chronologies diverged, and this phenomenon is considered to be caused by a different response to the harsh climate of the LIA. In this study, the tree-ring width series from the upper tree line of the Tien Shan is negatively associated with temperature. As opposed to previous studies, the tree-ring width series from the upper timberline of the Tien Shan appears to respond well to hydrometeorological factors. Therefore, we highlight the need for more detailed ecophysiological response studies for spruce trees at the upper timberline of the Tien Shan, in particular, with regard to the role of water availability and temperature during the growth season.展开更多
A 606 year runoff reconstruction of the Kara Darya River was developed, based on the tree-ring width chronology of Turkestan juniper(Juniperus turkestanica) from the Pamir-Alai Mountains of Kyrgyzstan. Preliminary com...A 606 year runoff reconstruction of the Kara Darya River was developed, based on the tree-ring width chronology of Turkestan juniper(Juniperus turkestanica) from the Pamir-Alai Mountains of Kyrgyzstan. Preliminary comparison between the snow cover variation and these climate/runoff reconstructions found that Central Asian snow cover may have strong associations with large-scale ocean-atmosphere-land circulations. The runoff reconstruction demonstrated that instrumental runoff was not representative of runoff over the past 606 years. The drought of the 1960 s-1990 s resulted in low runoff levels during the past 50 years;however, this probably does not represent a worst-case scenario for the Kara Darya because the runoff reconstruction showed additional extremely low runoff prior to the 20 th century. The reconstruction will provide a long-term perspective on runoff variation in the Kara Darya River basin, aid sustainable water resource management and be useful in guiding expectations of future variations and water resource planning.展开更多
Based on ASTER （Advanced Spaceborne Thermal Emission and Reflection Radiometer） remote sensing data, bare soil evaporation was estimated with the Penman-Monteith model, the Priestley-Taylor model, and the aerodynami...Based on ASTER （Advanced Spaceborne Thermal Emission and Reflection Radiometer） remote sensing data, bare soil evaporation was estimated with the Penman-Monteith model, the Priestley-Taylor model, and the aerodynamics model. Evaporation estimated by each of the three models was compared with actual evaporation, and error sources of the three models were analyzed. The mean absolute relative error was 9% for the Penman-Monteith model, 14% for the Priestley-Taylor model, and 32% for the aerodynamics model; the Penman-Monteith model was the best of these three models for estimating bare soil evaporation. The error source of the Penman-Monteith model is the neglect of the advection estimation. The error source of the Priestley-Taylor model is the simplification of the component of aerodynamics as 0.72 times the net radiation. The error source of the aerodynamics model is the difference of vapor pressure and neglect of the radiometric component. The spatial distribution of bare soil evaporation is evident, and its main factors are soil water content and elevation.展开更多
This article presents a summary of our studies of Holocene moraines and glaciers of the Tien-Shan, Pamir, and Himalaya moun- mills with the purpose of providing pattern regularity of the Holocene glaciation decomposit...This article presents a summary of our studies of Holocene moraines and glaciers of the Tien-Shan, Pamir, and Himalaya moun- mills with the purpose of providing pattern regularity of the Holocene glaciation decomposition. We developed a method for ob- taining reliable radiocarbon dating of moraines with the use of autochthonous organic matter dispersed in fine-grained morainic material, as well there were shown new possibilities of isotope-oxygen and isotope-uranium analysis for the Holocene glaciations dynamics. We found that Holocene glaciations disintegrate stadiaUy according to the decaying principle, and seven main stages may be distinguished. We achieved the absolute dating of the first three stages, identifying these periods as 8,000, 5,000, and 3,400 years ago. The application of the above-mentioned isotope methods of the Holocene glaciations and moraines study will allow re- searchers to improve the offered model of the Holocene glaciations disintegration; it will be great contribution to salvation of the problem of long-term climatic and glaciations forecast.展开更多
In this study, the goal is to increase the efficiency of a high-pressure hydraulic turbine. The goal is achieved by numerical flow simulation using CFX-TASCflow. This approach reduces costs and time compared to the ex...In this study, the goal is to increase the efficiency of a high-pressure hydraulic turbine. The goal is achieved by numerical flow simulation using CFX-TASCflow. This approach reduces costs and time compared to the experimental approach and allows for improving the turbine productivity and its design. The analysis of energy losses in the flow part of the turbine Fr500, as well as the analysis of the influence of the opening of the guide vanes on changes in energy losses. The results showed that the greatest losses occur in the guide vane 3.02% based on the two-dimensional model and 2.5% based on the 3D model, which significantly affects the efficiency. The analysis was carried out using programs for calculating fluid flow in two-dimensional and three-dimensional formulations. With the help of the study, the main energy problem is solved—increasing efficiency.展开更多
High-altitude glacier-lake systems in the eastern Pamir Plateau,Tajikistan,are highly sensitive elements of Central Asia’s cryosphere and are vital for sustaining regional water resources.The Yashilkul Lake is locate...High-altitude glacier-lake systems in the eastern Pamir Plateau,Tajikistan,are highly sensitive elements of Central Asia’s cryosphere and are vital for sustaining regional water resources.The Yashilkul Lake is located within a tectonic depression dammed by an ancient rockslide,forming a large alpine lake.This lake is currently impacted by intensified warming,glacier retreat,and poorly quantified hydrological shift.The primary objective of this study is to assess multi-decadal changes in the Yashilkul and Bulunkul lakes and their surrounding cryosphere between 1994 and 2024.The changes were analyzed using multitemporal Landsat imagery and unmanned aerial vehicle (UAV) surveys,complemented by in situ meteorological observations from the Bulunkul meteorological station spanning the period from 1990 to 2024.Glacier and lake boundaries were extracted from Landsat data,primarily by applying the normalized difference water index,supplemented by manual delineation.UAV photogrammetry characterized dam morphology and adjacent ponds,and climate trends were evaluated with the modified Mann-Kendall test.A significant warming trend of 0.096℃/a and pronounced interannual precipitation variability have driven persistent glacier retreat and lake surface area fluctuations.The Yashilkul Lake’s surface area decreased from 36.40 (±1.15) km^(2) in 2010 to 31.94 (±0.54) km^(2) in 2020 and partially rebounded to 33.99 (±0.60) km^(2) in 2024,while the Bulunkul Lake’s surface area remained nearly stable owing to limited glacial influence.Additionally,UAV surveys conducted in 2022 and 2024 revealed main features of the Yashilkul Lake:rockslidedammed origin,perched ponds along the dam body,and an artificial canal regulating its outflow.Nearby glaciers,particularly Glacier No.369,exhibited strong frontal retreat and proglacial lake expansion.The proglacial lake expanded nearly fourfold from 0.08 (±0.01)km^(2) in 2000 to 0.33 (±0.02) km^(2) in 2024,raising concerns about potential glacial lake outburst floods that could impact the Yashilkul Lake and compromise the integrity of its natural dam.The findings highlight accelerating hydrological and cryospheric transformations in the Pamir Plateau,emphasizing the need for sustained monitoring of glacier-lake systems owing to their critical implications for water security,ecological stability,and downstream hazard management.展开更多
Glaciers in the Pamir region are experiencing rapid melting and receding due to climate change,which has a significant implication for the Amu Darya river basin.Predominantly,surging glaciers,which undergo unpredictab...Glaciers in the Pamir region are experiencing rapid melting and receding due to climate change,which has a significant implication for the Amu Darya river basin.Predominantly,surging glaciers,which undergo unpredictable advances,are potentially leading to the obstruction of high-altitude river channels and also glacial lake outburst floods.decrease of-703.5±30.0 m.There is a substantial increase in the number(from 19 to 75)and area(from 4889.7±0.6 m2 to 15345.5±0.6 m2)of RGS lakes along with supra-glacier ponds based on a comparison of ArcGIS base map in 2011 and high-resolution UAV data in 2023.For M glacier,number of lakes increased from 4 to 22 but the lake area declined from 10715.2±0.6 to 365.6±0.6 m2.It was noted that the largest lake in 2011 with an area of 10406.4±0.6 m2 at the southeastern portion of the glacier was not observed in 2023 due to outburst.Both the glaciers have substantially impacted the river flow(Abdukahor river)by obstructing a significant proportion of river channel in recent years and might cause outburst floods.These findings enhance the understanding of glacier dynamics and their impacts on the surrounding areas,emphasizing the urgent need for continued monitoring and appropriate management strategies,with a specific focus on surging glaciers and the associated risks.展开更多
Recent climate dynamics denote patterns and variations in climatic conditions and associated cryospheric changes in the Pamir region,affecting downstream ecosystems and communities.The present investigation describes ...Recent climate dynamics denote patterns and variations in climatic conditions and associated cryospheric changes in the Pamir region,affecting downstream ecosystems and communities.The present investigation describes changes in Baralmos glacier and supraglacial lakes,along with related hazards,using meteorological observations,reanalysis products,and high-resolution satellite imagery from 2002 to 2022.Moreover,observations using Unmanned Aerial Vehicles(UAVs)were conducted between 2020 and 2022 to document recent variations.Reanalysis data suggested that there are no obvious trends in annual air temperature and precipitation except for a significant temperature rise in July(the warmest month)of about 1.34°C/decade(p<0.05)and precipitation decrease in December(p<0.05).During the last two decades of investigation,lake areas expanded from 20500 to 62800±21 m2,representing an approximately threefold increase,leading to increased mudflows in the Surkhob river and causing severe damage to property and infrastructures,most prominently during 2020 and 2022.The UAV data reveal an average decrease of-2.7±0.5 m in surface elevation downstream of Baralmos glacier between 2020 and 2022.This study is vital for implementing more intensive measures of the glacial environment and defining suitable mitigation strategies in the Pamir region.展开更多
Uncertainties in modern assessments of the impact of long-term climatic variations on the characteristics of groundwater discharge and groundwater resources are considered.The authors show that when assessing groundwa...Uncertainties in modern assessments of the impact of long-term climatic variations on the characteristics of groundwater discharge and groundwater resources are considered.The authors show that when assessing groundwater resources and especially forecasting groundwater resources,the main calculated hydrogeological parameters are insufficiently reliable and estimates of possible changes of main meteorological characteristics should be considered.Therefore,it is currently almost impossible to forecast the impacts of climate change on groundwater resources and regime for the coming decades.A scenario-based approach is the most promising for studying the potential effects of climate change on groundwater.展开更多
基金supported by the National Natural Science Foundation of China(W2412135)the Youth Innovation Promotion Association of the Chinese Academy of Sciences.
文摘As a major source of freshwater in Central Asia,Tajikistan is endowed with abundant glaciers and water resources.However,the country faces multiple challenges,including accelerated glacier retreat,complex inter-government water resource management,and inefficient water use.Existing research has predominantly focused on individual hydrological processes,such as glacier retreat,snow cover change,or transboundary water issues,but it has yet to fully capture the overall complexity of water system.Tajikistan’s water system functions as an integrated whole from mountain runoff to downstream supply,but a comprehensive study of its water resource has yet to be conducted.To address this research gap,this study systematically examined the status,challenges,and sustainable management strategies of Tajikistan’s water resources based on a literature review,remote sensing data analysis,and case studies.Despite Tajikistan’s relative abundance of water resources,global warming is accelerating glacier melting and altering the hydrological cycles,which have resulted in unstable runoff patterns and heightened risks of extreme events.In Tajikistan,outdated infrastructure and poor management are primary causes of low water-use efficiency in the agricultural sector,which accounts for 85.00%of the total water withdrawals.At the governance level,Tajikistan faces challenges in balancing the water-energy-food nexus and transboundary water resource issues.To address these issues,this study proposes core paths for Tajikistan to achieve sustainable water resource management,such as accelerating technological innovation,promoting water-saving agricultural technologies,improving water resource utilization efficiency,and establishing a community participation-based comprehensive management framework.Additionally,strengthening cross-border cooperation and improving real-time monitoring systems have been identified as critical steps to advance sustainable water resource utilization and evidence-based decision-making in Tajikistan and across Central Asia.
基金supported by the National Natural Science Foundation of China(42361144880)the Science and Technology Program of Xizang Autonomous Region,China(XZ202402ZD0001)the Qinghai Province Basic Research Program Project,China(2024-ZJ-904).
文摘Debris flow events are frequent in Tajikistan,yet comprehensive investigations at the regional scale are limited.This study integrates remote sensing,Geographic Information System,and machine learning techniques to evaluate debris flow susceptibility and associated hazards across Tajikistan.A dataset comprising 405 documented debris flow points and 14 influencing factors,encompassing geological,climatic-hydrological,and anthropogenic variables,was established.Three machine learning algorithms—Random Forest,Support Vector Machine(SVM),and Multi-layer Perceptron—were applied to generate susceptibility maps and delineate debris flow risk zones.The results indicate that the areas of higher and high susceptibility accounted for 20.43%and 4.41%of the national area,respectively,and were predominantly concentrated along the Zeravshan and Vakhsh river basins.Among the evaluated models,SVM model demonstrated the highest predictive performance.Beyond conventional topographic and environmental controls,drought conditions were identified as a critical factor influencing debris flow occurrence within the arid and semi-arid mountainous regions of Tajikistan.These findings provide a scientific basis for regional debris flow risk management and disaster mitigation planning,and offer practical guidance for selecting conditioning factors in machine-learning-based susceptibility assessments in other dry mountainous environments.
基金supported by the National Key R&D Plan“Inter-governmental International Science&Technology Innovation Cooperation”Key Specialized Program,China(2025YFE0102800)the Program of the State Key Laboratory of Cryospheric Science and Frozen Soil Engineering,Chinese Academy of Sciences(CSFSE-ZZ-2403).
文摘Tajikistan contains the majority of Central Asia’s glaciers,which cover about 6.00%of the national territory;their rapid shrinkage poses a significant threat to regional water resource security.However,glacier monitoring in Tajikistan was interrupted after 1991,creating a substantial gap in understanding the current state and temporal evolution of these glaciers.Based on glacier inventory data,in situ measurements,and published literature,this study examined the present status and recent variations of glaciers in Tajikistan through data integration and validation,literature collation and comparative analysis,and the application of Geographic Information System(GIS)spatial analysis techniques.As of 2023,Tajikistan possesses a total of 11,528 glaciers,encompassing an area of 7624.48(±305.58)km2.Small glaciers dominate in number,whereas large glaciers account for the majority of the total area.Over the past two decades,the glacier count has decreased by 2014,and the total area has decreased by 628.98 km2,corresponding to an average annual reduction rate of 0.33%.Regional shrinkage rates range from 4.10%to 22.28%.Glaciers have undergone accelerated mass loss during the past 20 a;only those on the northeastern Pamir Plateau exhibit a weak positive mass balance.Observations of typical monitored glaciers also reveal intensified melting and retreat,consistent with regional trends.In light of the recent acceleration of glacier shrinkage in Tajikistan,focused measures should be implemented to strengthen glacier monitoring,enhance public awareness of glacier preservation,and promote the sustainable development and utilization of glacier tourism.These findings bridge the knowledge gap regarding the spatiotemporal dynamics of Tajikistan’s glaciers over recent decades and provide essential data support for regional water resource management.
基金supported by the National Key Research and Development Project of China(2025YFE0103300)the National Natural Science Foundation of China(W2412135)+2 种基金the Natural Science Foundation of Xinjiang Uygur Autonomous Region(2024D01A143,2025D01B165)the China Postdoctoral Science Foundation(GZC20250226)the S&T Innovation and Development Project of Information Institution of Ministry of Emergency Management,China(2024506).
文摘Tajikistan,a mountainous country and a vital water tower for Central Asia,is becoming increasingly vulnerable to snow drought under climate change,threatening its snow-and glacier-fed streamflow.Yet,the impacts of snow drought on the regional hydrology remain insufficiently understood.In this study,we integrated multisource data,including the Fifth Generation European Centre for Medium-Range Weather Forecasts Atmospheric Reanalysis for Land Applications(ERA5-Land)data and hydrological station data,to systematically assess the snow drought patterns and their impacts on streamflow during 1950–2023.We identified snow drought events based on precipitation and snow fraction anomalies relative to climatological means and classified them into warm snow drought,dry snow drought,and warm&dry snow drought.The results revealed that snow drought was a recurrent phenomenon,occurring in 51.70%of the years during the study period,with warm&dry snow drought accounting for 21.90%of the total events.Both the frequency and severity exhibited pronounced spatial variability,largely governed by the elevation and snowfall fraction.Specifically,the frequency of warm snow drought was negatively correlated with the snowfall fraction,decreasing on average by 0.20 per unit increase in snowfall fraction,whereas the frequency of dry snow drought was positively correlated,increasing by 0.07 per unit increase.The streamflow analysis results demonstrated that snow drought typically reduced the warm-season discharge by 5.00%–18.00%in certain rivers,thereby exacerbating the water stress during the dry season.The results of this study advance our understanding by explicitly linking the types of snow drought to hydrological responses in Central Asia’s high mountains,providing a scientific basis for climate adaptation and sustainable water resource management in Tajikistan.
基金This study was supported in part by a research grant from the Graduate School of Humanities,Hosei University and Japan Society for the Promotion of Science(JSPS,JP21K13150).
文摘This study aimed to elucidate the influence of inflow water on the salinity concentration process of a saline lake and the mass balance of Lake Issyk-Kul,a tectonic saltwater lake in Kyrgyzstan.Based on the survey results and meteorological data from 2012 to 2015,we analyzed the dissolved chemical composition loads due to water inflow.Then,we discussed the relationship between the increase in salinity and water inflow into the lake.Through the water quality analysis data,we used the tank model to estimate the river inflow and analyze the loads by the L-Q curve.The groundwater loads were then estimated from the average annual increase in salinity of the lake over a period of 30 a.The results suggest that Lake Issyk-Kul was temporarily freshened between about AD 1500 and 1800 when an outflowing river existed,and thereafter,it became a closed lake in AD 1800 and continued to remain a saline lake until present.The chemical components that cause salinization are supplied from the rivers and groundwater in the catchment area,and when they flow into the lake,Ca^(2+),HCO_(3)−and Mg^(2+)precipitate as CaCO_(3) and MgCO_(3).These compounds were confirmed to have been left on the lakeshore as evaporite.The model analysis showed that 1.67 mg/L of Ca^(2+)and Mg^(2+)supplied from rivers and groundwater are precipitated as evaporite and in other forms per year.On the other hand,salinity continues to remain in the lake water at a rate of 27.5 mg/L per year.These are the main causes of increased salinity in Lake Issyk-Kul.Since Na^(+)and Cl^(-)are considered to be derived from geothermal water,they will continue to flow in regardless of the effects of human activities.Therefore,as long as these components are accumulated in Lake Issyk-Kul as a closed lake,the salinity will continue to increase in the future.
文摘The paper is concerned with the development of a comprehensive methodology to establish a MPAs （marine protected areas） network in the Black Sea and Azov Sea region. Scientific basis to rationale establish that the MPAs network is a complex system of landscape zoning and mapping, defining their variability, sustainability, and geo-ecological condition, and taking into account evaluation of degradation of the underwater landscape over the past 100 years.
基金funded by the Gansu Provincial Science and Technology Program(22ZD6FA005)Gansu Postdoctoral Science Foundation(Grant number E339880204)。
文摘In recent years,mudflows have emerged as a significant threat to infrastructure and lives,exhibiting increased frequency and severity.This study collectively addresses the rising threat of natural hazards,specifically mudflows in mountain-foothill zones in Tajikistan,utilizing UAV and remote sensing technologies to monitor their impact.From 2020 to 2023,we employed a QC-2 Micro UAV and a DJI Phantom 4 quadcopter to capture high-resolution aerial imagery across multiple affected districts,supplemented by pre-and post-event Sentinel-2 images analyzed using the Normalized Difference Water Index(NDWI)and Normalized Difference Vegetation Index(NDVI).Our analysis revealed that 49 districts and cities experienced significant mudflow events,resulting in estimated damages and economic losses of 30.2 million USD,with particularly severe impacts noted in the Khuroson,Tojikobod,Vakhsh,Panjakent,Lakhsh,and Varzob.The composition of mudflows in the six studied areas predominantly consisted of clay,with some regions featuring mudstone and a few exhibiting a mixture of both materials.Our findings indicate the predominance of rain-induced mudflows in foothill areas,contrasting with rain-snow,glacial,and lake-outburst-induced mudflows in mountainous regions.This underscores the urgent need for effective disaster risk management strategies in vulnerable locations.Integrating UAV and remote sensing technologies provides crucial information for analyzing damages,identifying vulnerable areas,and advising emergency response efforts,thereby enhancing disaster risk management in Tajikistan.
基金supported by National Basic Research Program of China (No. 2010CB428405)Special Public Sector Research Program of Ministry of Water Resources(No.201301040 and 201301070)+2 种基金National Natural Science Foundation of China (No. 41001012)Foundation forthe Author of National Excellent Doctoral Dissertation of China (No. 201161)Qing Lan Project and Program for New Century Excellent Talents in University
文摘The study investigated the trend of extreme flood events in the Pearl River basin during 1951-2010. Stream flow data at 23 gauging stations were used for the study. The Pearson type III distribution was selected for the flood frequency analysis. Results indicate that extreme flood events increase significantly in the Pearl River Basin since 1980. At the 23 gauging stations, there are 16 (70%) stations show positive (increasing) trends in 1981-2010. Most of the 16 stations are located along the West River and North River. While 7 (30%) stations show negative (decreasing) trends, and are found in the East River and the southeast region of the West River Basin.
文摘In this study, tree-ring width data of Schrenk spruce (Picea schrenkiana) from the upper timberline of the Tien Shan (Kyrgyzstan) were analyzed to investigate the effect of climate change. Growtheclimate response analyses revealed that the tree rings of spruce at the upper timberline of the Tien Shan also can provide hydrometeorological (precipitation and streamflow) signals. Tree-ring records from both Kyrgyzstan and Xinjiang exhibited similar tree-growth variability at both annual and decadal time scales during the common period 1457e2009. In Xinjiang and Kyrgyzstan, tree growth was reduced during the Little Ice Age (LIA); however, the timing and magnitude of LIA differ between the two regions. During 1470e1660, the two chronologies diverged, and this phenomenon is considered to be caused by a different response to the harsh climate of the LIA. In this study, the tree-ring width series from the upper tree line of the Tien Shan is negatively associated with temperature. As opposed to previous studies, the tree-ring width series from the upper timberline of the Tien Shan appears to respond well to hydrometeorological factors. Therefore, we highlight the need for more detailed ecophysiological response studies for spruce trees at the upper timberline of the Tien Shan, in particular, with regard to the role of water availability and temperature during the growth season.
基金This work was supported by the National Key R&D Program of China (2018YFA0606401)NSFC (U1803341)+1 种基金the 2nd Scientific Expedition to the Qinghai-Tibet Plateau (No. 2019QZKK0102)the national youth talent support program
文摘A 606 year runoff reconstruction of the Kara Darya River was developed, based on the tree-ring width chronology of Turkestan juniper(Juniperus turkestanica) from the Pamir-Alai Mountains of Kyrgyzstan. Preliminary comparison between the snow cover variation and these climate/runoff reconstructions found that Central Asian snow cover may have strong associations with large-scale ocean-atmosphere-land circulations. The runoff reconstruction demonstrated that instrumental runoff was not representative of runoff over the past 606 years. The drought of the 1960 s-1990 s resulted in low runoff levels during the past 50 years;however, this probably does not represent a worst-case scenario for the Kara Darya because the runoff reconstruction showed additional extremely low runoff prior to the 20 th century. The reconstruction will provide a long-term perspective on runoff variation in the Kara Darya River basin, aid sustainable water resource management and be useful in guiding expectations of future variations and water resource planning.
基金supported by the Ministry of Water Resources (Grants No. 200701039 and 200801001)the National Technology Supporting Program (Grants No. 2006BAC05B02 and 2007BAC03A060301)
文摘Based on ASTER （Advanced Spaceborne Thermal Emission and Reflection Radiometer） remote sensing data, bare soil evaporation was estimated with the Penman-Monteith model, the Priestley-Taylor model, and the aerodynamics model. Evaporation estimated by each of the three models was compared with actual evaporation, and error sources of the three models were analyzed. The mean absolute relative error was 9% for the Penman-Monteith model, 14% for the Priestley-Taylor model, and 32% for the aerodynamics model; the Penman-Monteith model was the best of these three models for estimating bare soil evaporation. The error source of the Penman-Monteith model is the neglect of the advection estimation. The error source of the Priestley-Taylor model is the simplification of the component of aerodynamics as 0.72 times the net radiation. The error source of the aerodynamics model is the difference of vapor pressure and neglect of the radiometric component. The spatial distribution of bare soil evaporation is evident, and its main factors are soil water content and elevation.
基金the program of the Institute of Water Problems and Hydro Power of National Academy of Sciences of the Kyrgyz Republic
文摘This article presents a summary of our studies of Holocene moraines and glaciers of the Tien-Shan, Pamir, and Himalaya moun- mills with the purpose of providing pattern regularity of the Holocene glaciation decomposition. We developed a method for ob- taining reliable radiocarbon dating of moraines with the use of autochthonous organic matter dispersed in fine-grained morainic material, as well there were shown new possibilities of isotope-oxygen and isotope-uranium analysis for the Holocene glaciations dynamics. We found that Holocene glaciations disintegrate stadiaUy according to the decaying principle, and seven main stages may be distinguished. We achieved the absolute dating of the first three stages, identifying these periods as 8,000, 5,000, and 3,400 years ago. The application of the above-mentioned isotope methods of the Holocene glaciations and moraines study will allow re- searchers to improve the offered model of the Holocene glaciations disintegration; it will be great contribution to salvation of the problem of long-term climatic and glaciations forecast.
文摘In this study, the goal is to increase the efficiency of a high-pressure hydraulic turbine. The goal is achieved by numerical flow simulation using CFX-TASCflow. This approach reduces costs and time compared to the experimental approach and allows for improving the turbine productivity and its design. The analysis of energy losses in the flow part of the turbine Fr500, as well as the analysis of the influence of the opening of the guide vanes on changes in energy losses. The results showed that the greatest losses occur in the guide vane 3.02% based on the two-dimensional model and 2.5% based on the 3D model, which significantly affects the efficiency. The analysis was carried out using programs for calculating fluid flow in two-dimensional and three-dimensional formulations. With the help of the study, the main energy problem is solved—increasing efficiency.
基金funded by the Key Program of National Natural Science Foundation of China (42230708,42361144887)the Tianshan Talent Project of Xinjiang Uygur Autonomous Region,China (2022TSYCLJ0056)。
文摘High-altitude glacier-lake systems in the eastern Pamir Plateau,Tajikistan,are highly sensitive elements of Central Asia’s cryosphere and are vital for sustaining regional water resources.The Yashilkul Lake is located within a tectonic depression dammed by an ancient rockslide,forming a large alpine lake.This lake is currently impacted by intensified warming,glacier retreat,and poorly quantified hydrological shift.The primary objective of this study is to assess multi-decadal changes in the Yashilkul and Bulunkul lakes and their surrounding cryosphere between 1994 and 2024.The changes were analyzed using multitemporal Landsat imagery and unmanned aerial vehicle (UAV) surveys,complemented by in situ meteorological observations from the Bulunkul meteorological station spanning the period from 1990 to 2024.Glacier and lake boundaries were extracted from Landsat data,primarily by applying the normalized difference water index,supplemented by manual delineation.UAV photogrammetry characterized dam morphology and adjacent ponds,and climate trends were evaluated with the modified Mann-Kendall test.A significant warming trend of 0.096℃/a and pronounced interannual precipitation variability have driven persistent glacier retreat and lake surface area fluctuations.The Yashilkul Lake’s surface area decreased from 36.40 (±1.15) km^(2) in 2010 to 31.94 (±0.54) km^(2) in 2020 and partially rebounded to 33.99 (±0.60) km^(2) in 2024,while the Bulunkul Lake’s surface area remained nearly stable owing to limited glacial influence.Additionally,UAV surveys conducted in 2022 and 2024 revealed main features of the Yashilkul Lake:rockslidedammed origin,perched ponds along the dam body,and an artificial canal regulating its outflow.Nearby glaciers,particularly Glacier No.369,exhibited strong frontal retreat and proglacial lake expansion.The proglacial lake expanded nearly fourfold from 0.08 (±0.01)km^(2) in 2000 to 0.33 (±0.02) km^(2) in 2024,raising concerns about potential glacial lake outburst floods that could impact the Yashilkul Lake and compromise the integrity of its natural dam.The findings highlight accelerating hydrological and cryospheric transformations in the Pamir Plateau,emphasizing the need for sustained monitoring of glacier-lake systems owing to their critical implications for water security,ecological stability,and downstream hazard management.
基金funded by the Gansu Provincial Science and Technology Program(22ZD6FA005)Gansu Postdoctoral Science Foundation(Grant number-E339880204)。
文摘Glaciers in the Pamir region are experiencing rapid melting and receding due to climate change,which has a significant implication for the Amu Darya river basin.Predominantly,surging glaciers,which undergo unpredictable advances,are potentially leading to the obstruction of high-altitude river channels and also glacial lake outburst floods.decrease of-703.5±30.0 m.There is a substantial increase in the number(from 19 to 75)and area(from 4889.7±0.6 m2 to 15345.5±0.6 m2)of RGS lakes along with supra-glacier ponds based on a comparison of ArcGIS base map in 2011 and high-resolution UAV data in 2023.For M glacier,number of lakes increased from 4 to 22 but the lake area declined from 10715.2±0.6 to 365.6±0.6 m2.It was noted that the largest lake in 2011 with an area of 10406.4±0.6 m2 at the southeastern portion of the glacier was not observed in 2023 due to outburst.Both the glaciers have substantially impacted the river flow(Abdukahor river)by obstructing a significant proportion of river channel in recent years and might cause outburst floods.These findings enhance the understanding of glacier dynamics and their impacts on the surrounding areas,emphasizing the urgent need for continued monitoring and appropriate management strategies,with a specific focus on surging glaciers and the associated risks.
基金funded by the Gansu Provincial Science and Technology Program(22ZD6FA005)Gansu Postdoctoral Science Foundation(Grant number-E339880204)。
文摘Recent climate dynamics denote patterns and variations in climatic conditions and associated cryospheric changes in the Pamir region,affecting downstream ecosystems and communities.The present investigation describes changes in Baralmos glacier and supraglacial lakes,along with related hazards,using meteorological observations,reanalysis products,and high-resolution satellite imagery from 2002 to 2022.Moreover,observations using Unmanned Aerial Vehicles(UAVs)were conducted between 2020 and 2022 to document recent variations.Reanalysis data suggested that there are no obvious trends in annual air temperature and precipitation except for a significant temperature rise in July(the warmest month)of about 1.34°C/decade(p<0.05)and precipitation decrease in December(p<0.05).During the last two decades of investigation,lake areas expanded from 20500 to 62800±21 m2,representing an approximately threefold increase,leading to increased mudflows in the Surkhob river and causing severe damage to property and infrastructures,most prominently during 2020 and 2022.The UAV data reveal an average decrease of-2.7±0.5 m in surface elevation downstream of Baralmos glacier between 2020 and 2022.This study is vital for implementing more intensive measures of the glacial environment and defining suitable mitigation strategies in the Pamir region.
基金Russian Scientific Foundation for financial support of the investigations by the project#14-17-00791.
文摘Uncertainties in modern assessments of the impact of long-term climatic variations on the characteristics of groundwater discharge and groundwater resources are considered.The authors show that when assessing groundwater resources and especially forecasting groundwater resources,the main calculated hydrogeological parameters are insufficiently reliable and estimates of possible changes of main meteorological characteristics should be considered.Therefore,it is currently almost impossible to forecast the impacts of climate change on groundwater resources and regime for the coming decades.A scenario-based approach is the most promising for studying the potential effects of climate change on groundwater.
