As significant evidence of permafrost degradation,thermokarst lakes play an important role in the permafrost regions by regulating hydrology,ecology,and biogeochemistry.In the Sources Area of the Yellow River(SAYR),pe...As significant evidence of permafrost degradation,thermokarst lakes play an important role in the permafrost regions by regulating hydrology,ecology,and biogeochemistry.In the Sources Area of the Yellow River(SAYR),permafrost degradation has accelerated since the 1980s,and numerous thermokarst lakes have been discovered.In this paper,we use Sentinel-2 images to extract thermokarst lake boundaries and perform a regional-scale study on their geometry across the permafrost region in the SAYR.We also explored the spatiotemporal variations and potential drivers from the perspectives of the permafrost,climate,terrain and vegetation conditions.The results showed that there were 47,518 thermokarst lakes in 2021 with a total area of 190.22×106 m^(2),with an average size of 4,003.3 m^(2).The 44,928 ponds(≤10,000 m^(2))predominated the whole lake number(94.1%)but contributed to a small portion of the total lake area(28.8%).With 2,590 features(5.9%),small-sized(10,000 to 100,000 m^(2))and large-sized lakes(>100,000 m^(2))constituted up to 71.2%of the total lake area.Thermokarst lakes developed more significantly in warm permafrost regions than in cold permafrost areas;74.1%of lakes with a total area of 119.6×106 m^(2)(62.9%),were distributed in warm permafrost regions.Most thermokarst lakes were likely to develop within the elevation range of 4,500~4,800 m,on flat terrain(slope<10°),on SE and S aspects and in alpine meadow areas.The thermokarst lakes in the study region experienced significant shrinkage between 1990 and 2021,characterized by obvious lake drainage;the lake numbers decreased by 5418(56.1%),with a decreasing area of 58.63×106 m^(2)(49.0%).This shrinkage of the thermokarst lake area was attributable mainly to the intensified degradation of rich-ice permafrost thawing arising from continued climate warming,despite the wetting climatic trend.展开更多
Permafrost thickness under identical climates in cold regions can vary significantly because it is severely affected by climate change, topography, soil physical and thermal properties, and geothermal conditions. This...Permafrost thickness under identical climates in cold regions can vary significantly because it is severely affected by climate change, topography, soil physical and thermal properties, and geothermal conditions. This study numerically in- vestigates the response of ground thermal regime and talik development processes to permafrost with different thicknesses under a thermokarst lake on the Qinghai-Tibet Plateau. On the basis of observed data and information from a representative monitored lake in the Beiluhe Basin, we used a heat transfer model with phase change under a cylindrical coordinate system to conduct three simulation cases with permafrost thicknesses of 45 m, 60 m, and 75 m, respectively. The simulated results indicate that increases in permafrost thickness not only strongly retarded the open talik formation time, but also delayed the permafrost lateral thaw process after the formation of open talik. Increasing the permafrost thickness by 33.3% and 66.7% led to open talik formation time increases of 83.66% and 207.43%, respectively, and resulted in increases in the lateral thaw duration of permafrost under the modeled thermokarst lake by 28.86% and 46.54%, respectively, after the formation of the open taliks.展开更多
Most of the thermokarst lakes are spread appreciably in Beiluhe Basin,Qinghai-Tibet Plateau,China,where ice-rich permafrost exists.Two typical thermokarst lakes with differing area and depth were examined to ascertain...Most of the thermokarst lakes are spread appreciably in Beiluhe Basin,Qinghai-Tibet Plateau,China,where ice-rich permafrost exists.Two typical thermokarst lakes with differing area and depth were examined to ascertain their age.We obtained lake-bottom samples of 50 cm length from lake BLH-A and 25 cm length from lake BLH-B.Environmental 137 Cs and 210 Pb and radiocarbon age dating techniques were applied to the 50 cm and 25 cm samples,respectively.The results indicate that the initiation of BLH-A is about 800-900 a B.P.,and approximately 1,450±30 a B.P.to 2,230±30 a B.P.for BLH-B.These results will provide scientific bases for sedimentological study and thermokarst activity in Beiluhe Basin.展开更多
A thermokarst lake is defined as a lake occupying a closed depression formed by ground settlement following thawing of ice-rich permafrost or the melting of massive ice. As it is the most visible morphologic landscape...A thermokarst lake is defined as a lake occupying a closed depression formed by ground settlement following thawing of ice-rich permafrost or the melting of massive ice. As it is the most visible morphologic landscape developed during the process of permafrost degradation, we reviewed recent literature on thermokarst studies, and summarized the main study topics as： development and temporal evolution, carbon release, and ecological and engineering influence of thermokarst lakes. The climate warming, forest fires, surface water pooling, geotectonic fault and anthropogenic activity are the main influencing factors that cause an increase of ground temperatures and melting of ice-rich permafrost, resulting in thermokarst lake formation. Normally a thermokarst lake develops in 3–5 stages from initiation to permafrost recovery. Geo-rectified aerial photographs and remote sensing images show that thermokarst lakes have been mainly experiencing the process of shrinkage or disappearance in most regions of the Arctic, while both lake numbers and areas on the Qinghai-Tibet Plateau have increased. Field studies and modeling indicates that carbon release from thermokarst lakes can feedback significantly to global warming, thus enhancing our understanding of the influences of thermokarst lakes on the ecological environment, and on regional groundwater through drainage. Based on field monitoring and numerical simulations, infrastructure stability can be affected by thermal erosion of nearby thermokarst lakes. This review was undertaken to enhance our understanding of thermokarst lakes, and providing references for future comprehensive studies on thermokarst lakes.展开更多
This study presents thermokarst lake changes at seven different sites in the continuous and isolated permafrost zones in Mongolia. Lakes larger than 0.1 ha were analyzed using Corona KH-4, KH-4A and KH-4B (1962-1968),...This study presents thermokarst lake changes at seven different sites in the continuous and isolated permafrost zones in Mongolia. Lakes larger than 0.1 ha were analyzed using Corona KH-4, KH-4A and KH-4B (1962-1968), Landsat ETM + (1999-2001), and ALOS/AVNIR-2 (2006-2007) satellite imagery. Between 1962 and 2007, the total number and area of lakes increased by +21% (347 to 420), and +7% (3680 ha to 3936 ha) in the continuous permafrost zone, respectively. These changes correspond to the appearance of 85 new lakes (166 ha) during the last 45 years. In contrast, lakes in the isolated permafrost zone have decreased by –42% (118 to 68) in number and –12% (422 ha to 371 ha) in area from 1962 to 2007. The changes in lake area and number are likely attributed to shifts in climate regimes and local permafrost conditions. Since 1962, the mean annual air temperature and potential evapotranspiration have increased significantly in the northern continuous permafrost zone compared to the southern isolated permafrost zone. Due to ongoing atmospheric warming without any significant trend in annual precipitation, patches of ice-rich subsurface have thawed, and the number and area of lakes have accordingly developed in the continuous permafrost zone. Shrinking of thermokarst lakes in the isolated permafrost zone may be due to disappearing permafrost, deepening of the active layer, and increased water loss through surface evaporation and subsurface drainage.展开更多
In permafrost regions of the Qinghai-Tibet Plateau,road disaster caused by permafrost degradation cannot be ignored.As a common thermal disaster in permafrost regions,thermokarst lake has serious thermal erosion on pe...In permafrost regions of the Qinghai-Tibet Plateau,road disaster caused by permafrost degradation cannot be ignored.As a common thermal disaster in permafrost regions,thermokarst lake has serious thermal erosion on permafrost and results in permafrost degradation aggravating.This study focused on two subgrade cross-sections of Gonghe-Yushu Highway in the Qinghai-Tibet Plateau to analyze thermal effect of thermokarst lake on the permafrost under embankment.The analysis infers that thermokarst lake can transfer heat to permafrost under the embankment,as a heat resource,and the heat flux decreases with the distance away from thermokarst lake in horizontal and vertical direction.Thermokarst lake can cause average ground temperature of permafrost under the embankment increasing,and with less distance from the thermokarst lake the temperature increases more severely.Thermokarst lake results in 14 m thickness melting interlayer in soil under lake and change shape of melting area.展开更多
Changes in the hydrological processes in alpine soil constitute one of the several key problems encountered with studying watershed hydrology and ecosystem stability against the background of global warming. A typical...Changes in the hydrological processes in alpine soil constitute one of the several key problems encountered with studying watershed hydrology and ecosystem stability against the background of global warming. A typically developing thermokarst lake was chosen as a subject for a study using model simulation based on observations of soil physical properties, infiltration processes, and soil moisture. The results showed that the selected thermokarst lake imposed certain changes on the soil infiltration processes and, with the degree of impact intensifying, the initial infiltration rate decreased. The greatest reduction was achieved in the area of moderate impact. However, the stable infiltration rate and cumulative infiltration gradually increased in the surface layer at a depth of 10 and 20 cm, both decreasing initially and then increasing, which is correlated significantly with soil textures. Moreover, the cumulative infiltration changed in line with steady infiltration rate. Based on a comparative analysis, the Horton model helps better understand the effect on the soil infiltration processes of the cold alpine meadow close to the chosen thermokarst lake. In conclusion, the formation of the thermokarst lake reduced the water holding capacity of the alpine meadow soil and caused the hydraulic conductivity to increase, resulting in the reduction of runoff capacity in the area of the thermokarst lake.展开更多
Under the rapidly warming climate in the Arctic and high mountain areas,permafrost is thawing,leading to various hazards at a global scale.One common permafrost hazard termed retrogressive thaw slump(RTS)occurs extens...Under the rapidly warming climate in the Arctic and high mountain areas,permafrost is thawing,leading to various hazards at a global scale.One common permafrost hazard termed retrogressive thaw slump(RTS)occurs extensively in ice-rich permafrost areas.Understanding the spatial and temporal distributive features of RTSs in a changing climate is crucial to assessing the damage to infrastructure and decision-making.To this end,we used a machine learning-based model to investigate the environmental factors that could lead to RTS occurrence and create a susceptibility map for RTS along the Qinghai-Tibet Engineering Corridor(QTEC)at a local scale.The results indicate that extreme summer climate events(e.g.,maximum air temperature and rainfall)contributes the most to the RTS occurrence over the flat areas with fine-grained soils.The model predicts that 13%(ca.22,948 km^(2))of the QTEC falls into high to very high susceptibility categories under the current climate over the permafrost areas with mean annual ground temperature at 10 m depth ranging from-3 to-1℃.This study provides insights into the impacts of permafrost thaw on the stability of landscape,carbon stock,and infrastructure,and the results are of value for engineering planning and maintenance.展开更多
基金supported by the Natural Science Foundation of Qinghai Province,China(No.2021-ZJ940Q)the Open Project of State Key Laboratory of Plateau Ecology and Agriculture,Qinghai University(No.2022-ZZ-02)。
文摘As significant evidence of permafrost degradation,thermokarst lakes play an important role in the permafrost regions by regulating hydrology,ecology,and biogeochemistry.In the Sources Area of the Yellow River(SAYR),permafrost degradation has accelerated since the 1980s,and numerous thermokarst lakes have been discovered.In this paper,we use Sentinel-2 images to extract thermokarst lake boundaries and perform a regional-scale study on their geometry across the permafrost region in the SAYR.We also explored the spatiotemporal variations and potential drivers from the perspectives of the permafrost,climate,terrain and vegetation conditions.The results showed that there were 47,518 thermokarst lakes in 2021 with a total area of 190.22×106 m^(2),with an average size of 4,003.3 m^(2).The 44,928 ponds(≤10,000 m^(2))predominated the whole lake number(94.1%)but contributed to a small portion of the total lake area(28.8%).With 2,590 features(5.9%),small-sized(10,000 to 100,000 m^(2))and large-sized lakes(>100,000 m^(2))constituted up to 71.2%of the total lake area.Thermokarst lakes developed more significantly in warm permafrost regions than in cold permafrost areas;74.1%of lakes with a total area of 119.6×106 m^(2)(62.9%),were distributed in warm permafrost regions.Most thermokarst lakes were likely to develop within the elevation range of 4,500~4,800 m,on flat terrain(slope<10°),on SE and S aspects and in alpine meadow areas.The thermokarst lakes in the study region experienced significant shrinkage between 1990 and 2021,characterized by obvious lake drainage;the lake numbers decreased by 5418(56.1%),with a decreasing area of 58.63×106 m^(2)(49.0%).This shrinkage of the thermokarst lake area was attributable mainly to the intensified degradation of rich-ice permafrost thawing arising from continued climate warming,despite the wetting climatic trend.
基金supported by the National Natural Science Foundation of China (NSFC) (No.41271076)the National Key Basic Research Program of China (No.2010CB951402)the Open Fund Project of the Institute of Plateau Meteorology, China Meteorological Administration (No.LPM2008019)
文摘Permafrost thickness under identical climates in cold regions can vary significantly because it is severely affected by climate change, topography, soil physical and thermal properties, and geothermal conditions. This study numerically in- vestigates the response of ground thermal regime and talik development processes to permafrost with different thicknesses under a thermokarst lake on the Qinghai-Tibet Plateau. On the basis of observed data and information from a representative monitored lake in the Beiluhe Basin, we used a heat transfer model with phase change under a cylindrical coordinate system to conduct three simulation cases with permafrost thicknesses of 45 m, 60 m, and 75 m, respectively. The simulated results indicate that increases in permafrost thickness not only strongly retarded the open talik formation time, but also delayed the permafrost lateral thaw process after the formation of open talik. Increasing the permafrost thickness by 33.3% and 66.7% led to open talik formation time increases of 83.66% and 207.43%, respectively, and resulted in increases in the lateral thaw duration of permafrost under the modeled thermokarst lake by 28.86% and 46.54%, respectively, after the formation of the open taliks.
基金supported by the State Key Development Program of Basic Research of China (973 Plan,2012CB026101)the Open Foundation of Key Laboratory of Highway Construction & Maintenance Technology in Permafrost Region,CCCC First Highway Consultants Co.Ltd.the Independent Project of State Key Laboratory of Frozen Soil Engineering,CAS (Grant No.SKLFSE-ZY-14)
文摘Most of the thermokarst lakes are spread appreciably in Beiluhe Basin,Qinghai-Tibet Plateau,China,where ice-rich permafrost exists.Two typical thermokarst lakes with differing area and depth were examined to ascertain their age.We obtained lake-bottom samples of 50 cm length from lake BLH-A and 25 cm length from lake BLH-B.Environmental 137 Cs and 210 Pb and radiocarbon age dating techniques were applied to the 50 cm and 25 cm samples,respectively.The results indicate that the initiation of BLH-A is about 800-900 a B.P.,and approximately 1,450±30 a B.P.to 2,230±30 a B.P.for BLH-B.These results will provide scientific bases for sedimentological study and thermokarst activity in Beiluhe Basin.
基金support from the State Key Development Program of Basic Research of China(973 Plan,2012CB026101)the Western Project Program of theChinese Academy of Sciences(KZCX2-XB3-19)+1 种基金the Foundation for Innovative Research Groups of the National Natural Science Foundation of China(GrantNo.41121061)the National Sci-Tech Support Plan(2014BAG05B05)
文摘A thermokarst lake is defined as a lake occupying a closed depression formed by ground settlement following thawing of ice-rich permafrost or the melting of massive ice. As it is the most visible morphologic landscape developed during the process of permafrost degradation, we reviewed recent literature on thermokarst studies, and summarized the main study topics as： development and temporal evolution, carbon release, and ecological and engineering influence of thermokarst lakes. The climate warming, forest fires, surface water pooling, geotectonic fault and anthropogenic activity are the main influencing factors that cause an increase of ground temperatures and melting of ice-rich permafrost, resulting in thermokarst lake formation. Normally a thermokarst lake develops in 3–5 stages from initiation to permafrost recovery. Geo-rectified aerial photographs and remote sensing images show that thermokarst lakes have been mainly experiencing the process of shrinkage or disappearance in most regions of the Arctic, while both lake numbers and areas on the Qinghai-Tibet Plateau have increased. Field studies and modeling indicates that carbon release from thermokarst lakes can feedback significantly to global warming, thus enhancing our understanding of the influences of thermokarst lakes on the ecological environment, and on regional groundwater through drainage. Based on field monitoring and numerical simulations, infrastructure stability can be affected by thermal erosion of nearby thermokarst lakes. This review was undertaken to enhance our understanding of thermokarst lakes, and providing references for future comprehensive studies on thermokarst lakes.
文摘This study presents thermokarst lake changes at seven different sites in the continuous and isolated permafrost zones in Mongolia. Lakes larger than 0.1 ha were analyzed using Corona KH-4, KH-4A and KH-4B (1962-1968), Landsat ETM + (1999-2001), and ALOS/AVNIR-2 (2006-2007) satellite imagery. Between 1962 and 2007, the total number and area of lakes increased by +21% (347 to 420), and +7% (3680 ha to 3936 ha) in the continuous permafrost zone, respectively. These changes correspond to the appearance of 85 new lakes (166 ha) during the last 45 years. In contrast, lakes in the isolated permafrost zone have decreased by –42% (118 to 68) in number and –12% (422 ha to 371 ha) in area from 1962 to 2007. The changes in lake area and number are likely attributed to shifts in climate regimes and local permafrost conditions. Since 1962, the mean annual air temperature and potential evapotranspiration have increased significantly in the northern continuous permafrost zone compared to the southern isolated permafrost zone. Due to ongoing atmospheric warming without any significant trend in annual precipitation, patches of ice-rich subsurface have thawed, and the number and area of lakes have accordingly developed in the continuous permafrost zone. Shrinking of thermokarst lakes in the isolated permafrost zone may be due to disappearing permafrost, deepening of the active layer, and increased water loss through surface evaporation and subsurface drainage.
基金supported by Independent Research Project of State Key Laboratory of Frozen Soil Engineering(SKLFSE-ZQ-50)CAS Youth talent growth fund(Y9510608)+1 种基金National Key R&D(2017YFC0405101)National Natural Science Foundation of China(41901079).
文摘In permafrost regions of the Qinghai-Tibet Plateau,road disaster caused by permafrost degradation cannot be ignored.As a common thermal disaster in permafrost regions,thermokarst lake has serious thermal erosion on permafrost and results in permafrost degradation aggravating.This study focused on two subgrade cross-sections of Gonghe-Yushu Highway in the Qinghai-Tibet Plateau to analyze thermal effect of thermokarst lake on the permafrost under embankment.The analysis infers that thermokarst lake can transfer heat to permafrost under the embankment,as a heat resource,and the heat flux decreases with the distance away from thermokarst lake in horizontal and vertical direction.Thermokarst lake can cause average ground temperature of permafrost under the embankment increasing,and with less distance from the thermokarst lake the temperature increases more severely.Thermokarst lake results in 14 m thickness melting interlayer in soil under lake and change shape of melting area.
基金supported by the National Natural Science Foundation of China(Grant No.41271092)the National Basic Research Program of China(Grant Nos.2010CB951402,2012CB026101)the Key Project of the National Natural Science Foundation of China(Grant No.D010102-91125010)
文摘Changes in the hydrological processes in alpine soil constitute one of the several key problems encountered with studying watershed hydrology and ecosystem stability against the background of global warming. A typically developing thermokarst lake was chosen as a subject for a study using model simulation based on observations of soil physical properties, infiltration processes, and soil moisture. The results showed that the selected thermokarst lake imposed certain changes on the soil infiltration processes and, with the degree of impact intensifying, the initial infiltration rate decreased. The greatest reduction was achieved in the area of moderate impact. However, the stable infiltration rate and cumulative infiltration gradually increased in the surface layer at a depth of 10 and 20 cm, both decreasing initially and then increasing, which is correlated significantly with soil textures. Moreover, the cumulative infiltration changed in line with steady infiltration rate. Based on a comparative analysis, the Horton model helps better understand the effect on the soil infiltration processes of the cold alpine meadow close to the chosen thermokarst lake. In conclusion, the formation of the thermokarst lake reduced the water holding capacity of the alpine meadow soil and caused the hydraulic conductivity to increase, resulting in the reduction of runoff capacity in the area of the thermokarst lake.
基金funded by the National Natural Science Foundation of China(42372334)the Science and Technology Research and Development Program of the Qinghai-Tibet Group Corporation(Grant No.QZ2022-G05)。
文摘Under the rapidly warming climate in the Arctic and high mountain areas,permafrost is thawing,leading to various hazards at a global scale.One common permafrost hazard termed retrogressive thaw slump(RTS)occurs extensively in ice-rich permafrost areas.Understanding the spatial and temporal distributive features of RTSs in a changing climate is crucial to assessing the damage to infrastructure and decision-making.To this end,we used a machine learning-based model to investigate the environmental factors that could lead to RTS occurrence and create a susceptibility map for RTS along the Qinghai-Tibet Engineering Corridor(QTEC)at a local scale.The results indicate that extreme summer climate events(e.g.,maximum air temperature and rainfall)contributes the most to the RTS occurrence over the flat areas with fine-grained soils.The model predicts that 13%(ca.22,948 km^(2))of the QTEC falls into high to very high susceptibility categories under the current climate over the permafrost areas with mean annual ground temperature at 10 m depth ranging from-3 to-1℃.This study provides insights into the impacts of permafrost thaw on the stability of landscape,carbon stock,and infrastructure,and the results are of value for engineering planning and maintenance.
