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Frost heaving in ballast railway tracks

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Research in Cold and Arid Regions 2015年第5期7卷 632-636页

作者： Satoshi Akagawa Michiaki Hori Cryosphere Engineering Laboratory Hokkaido Railway Campany

Frost heaving is a well-known phenomenon in cold regions, which may occur in wet clayey grounds during winter. Railway track upheaval occurring in cold regions during the winter is generally understood as frost heaving in the subgrade layer. However, it has been confirmed that upheaval due to frost heaving sometimes occurs in the ballast layer. This un- derstanding has been observed in active railways in northern Japan. The samples collected from ballast and subgrade layers have been examined for frost heave susceptibilities and confirmed that ballast layers which contain fines may heave.

关键词： frost heaving ballast layer subgrade layer railway track

Movement and variation of four typical glaciers in the Qilian Mountains,northwestern China

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Research in Cold and Arid Regions 2015年第3期7卷 206-211页

作者： ZheFan Jing Kun Wang Li Liu Key State laboratory of cryosphere Cold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

We selected four typical glaciers in the Qilian Mountains and investigated their movements and variation using advanced technologies such as remote sensing, photographic measurements, and global positioning systems. The velocity of glacier movements in the Qilian Mountains is relatively low, and there has been no significant variation during the past 50 years. Glacier motion has maintained a normal style. The movement velocity of Laohugou Glacier No. 12 presented a decreasing trend （by 48%） from 1960 to 2012. The movement velocity of the Qiyi Glacier also presented a decreasing trend （by 48.1%） from 1958 to 2012; it decreased by 29.4% from 1958 to 1977 and by 26.5% from 1977 to 2012. Therefore, the Qiyi Glacier＇s movement velocity varied greatly over the earlier 20 years （1958 1977）, but presented a small decreasing trend during the latter 30 years （1977-2012）. By comparing the movement velocity variation of these typical glaciers, we determined that the extent of variation was consistent among large glaciers （such as Laohugou Glacier No. 12） and small glaciers （such as the Qiyi Glacier and Yanglonghe Glacier No. 5）, despite their different sizes.

关键词： typical glaciers movement velocity variation extent Qilian Mountains

Modeling permafrost properties in the Qinghai-Xizang(Tibet) Plateau

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Science China Earth Sciences 2015年第12期58卷 2309-2326页

作者： HU GuoJie ZHAO Lin WU XiaoDong LI Ren WU TongHua XIE ChangWei PANG QiangQiang XIAO Yao LI WangPing QIAO YongPing SHI JianZong cryosphere Research Station on Qinghai-Xizang Plateau State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences

Water and heat dynamics in the active layer at a monitoring site in the Tanggula Mountains, located in the permafrost region of the Qinghai-Xizang(Tibet) Plateau(QXP), were studied using the physical-process-based COUPMODEL model, including the interaction between soil temperature and moisture under freeze-thaw cycles. Meteorological, ground temperature and moisture data from different depths within the active layer were used to calibrate and validate the model. The results indicate that the calibrated model satisfactorily simulates the soil temperatures from the top to the bottom of the soil layers as well as the moisture content of the active layer in permafrost regions. The simulated soil heat flux at depths of 0 to 20 cm was consistent with the monitoring data, and the simulations of the radiation balance components were reasonable. Energy consumed for phase change was estimated from the simulated ice content during the freeze/thaw processes from 2007 to 2008. Using this model, the active layer thickness and the energy consumed for phase change were predicted for future climate warming scenarios. The model predicts an increase of the active layer thickness from the current 330 cm to approximately 350–390 cm as a result of a 1–2°C warming. However, the effect active layer thickness of more precipitation is limited when the precipitation is increased by 20%–50%. The COUPMODEL provides a useful tool for predicting and understanding the fate of permafrost in the QXP under a warming climate.

关键词：高原冻土西藏青海 CoupModel 活动层厚度高原多年冻土区建模特性

An analytical model for estimating soil temperature profiles on the Qinghai-Tibet Plateau of China

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Journal of Arid Land 2016年第2期8卷 232-240页

作者： HU Guojie ZHAO Lin WU Xiaodong LI Ren WU Tonghua XIE Changwei QIAO Yongping SHI Jianzong CHENG Guodong cryosphere Research Station on Qinghai-Xizang Plateau State Key Laboratory of Cryospheric SciencesCold and Arid Regions Environmental and Engineering Research InstituteChinese Academy of Sciences

Soil temperature is a key variable in the control of underground hydro-thermal processes. To estimate soil temperature more accurately, this study proposed a solution method of the heat conduction equation of soil temperature （improved heat conduction model） by applying boundary conditions that incorporate the annual and diurnal variations of soil surface temperature and the temporal variation of daily temperature amplitude, as well as the temperature difference between two soil layers in the Tanggula observation site of the Qinghai-Tibet Plateau of China. We employed both the improved heat conduction model and the classical heat conduction model to fit soil temperature by using the 5 cm soil layer as the upper boundary for soil depth. The results indicated that the daily soil temperature amplitude can be better described by the sinusoidal function in the improved model, which then yielded more accurate soil temperature simulating effect at the depth of 5 cm. The simulated soil temperature values generated by the improved model and classical heat conduction model were then compared to the observed soil temperature values at different soil depths. Statistical analyses of the root mean square error （RMSE）, the normalized standard error （NSEE） and the bias demonstrated that the improved model showed higher accuracy, and the average values of RMSE, bias and NSEE at the soil depth of 10-105 cm were 1.41℃, 1.15℃ and 22.40%, respectively. These results indicated that the improved heat conduction model can better estimate soil temperature profiles compared to the traditional model.

关键词： soil temperature heat conduction equation daily amplitude boundary condition

Modeling Hydrothermal Transfer Processes in Permafrost Regions of Qinghai-Tibet Plateau in China

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Chinese Geographical Science 2015年第6期25卷 713-727页

作者： HU Guojie ZHAO Lin LI Ren WU Tonghua WU Xiaodong PANG Qiangqiang XIAO Yao QIAO Yongping SHI Jianzong cryosphere Research Station on Qinghai-Xizang Plateau State Key Laboratory of Cryospheric Sciences Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences

Hydrothermal processes are key components in permafrost dynamics; these processes are integral to global warming. In this study the coupled heat and mass transfer model for(Coup Model) the soil-plant-atmosphere-system is applied in high-altitude permafrost regions and to model hydrothermal transfer processes in freeze-thaw cycles. Measured meteorological forcing and soil and vegetation properties are used in the Coup Model for the period from January 1, 2009 to December 31, 2012 at the Tanggula observation site in the Qinghai-Tibet Plateau. A 24-h time step is used in the model simulation. The results show that the simulated soil temperature and water content, as well as the frozen depth compare well with the measured data. The coefficient of determination(R2) is 0.97 for the mean soil temperature and 0.73 for the mean soil water content, respectively. The simulated soil heat flux at a depth of 0–20 cm is also consistent with the monitored data. An analysis is performed on the simulated hydrothermal transfer processes from the deep soil layer to the upper one during the freezing and thawing period. At the beginning of the freezing period, the water in the deep soil layer moves upward to the freezing front and releases heat during the freezing process. When the soil layer is completely frozen, there are no vertical water exchanges between the soil layers, and the heat exchange process is controlled by the vertical soil temperature gradient. During the thawing period, the downward heat process becomes more active due to increased incoming shortwave radiation at the ground surface. The melt water is quickly dissolved in the soil, and the soil water movement only changes in the shallow soil layer. Subsequently, the model was used to provide an evaluation of the potential response of the active layer to different scenarios of initial water content and climate warming at the Tanggula site. The results reveal that the soil water content and the organic layer provide protection against active layer deepening in summer, s

关键词：过程模拟西藏高原高原多年冻土区土壤-植物-大气系统 CoupModel 青海传热传质模型垂直温度梯度

Variation of Thornthwaite Moisture Index in Hengduan Mountains, China

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Chinese Geographical Science 2016年第5期26卷 687-702页

作者： ZHU Guofeng QIN Dahe TONG Huali LIU Yuanfeng LI Jiafang CHEN Dongdong WANG Kai HU Pengfei College of Geography and Environment Science Northwest Normal University State Key laboratory of cryosphere Sciences Cold and Arid Regions Environmental and Engineering Research Institute Chinese Academy of Sciences

The Thornthwaite moisture index, an index of the supply of water(precipitation) in an area relative to the climatic demand for water(potential evapotranspiration), was used to examine the spatial and temporal variation of drought and to verify the influence of environmental factors on the drought in the Hengduan Mountains, China. Results indicate that the Thornthwaite moisture index in the Hengduan Mountains had been increasing since 1960 with a rate of 0.1938/yr. Annual Thornthwaite moisture index in Hengduan Mountains was between –97.47 and 67.43 and the spatial heterogeneity was obvious in different seasons. Thornthwaite moisture index was high in the north and low in the south, and the monsoon rainfall had a significant impact on its spatial distribution. The tendency rate of Thornthwaite moisture index variation varied in different seasons, and the increasing trends in spring were greater than that in summer and autumn. However, the Thornthwaite moisture index decreased in winter. Thornthwaite moisture index increased greatly in the north and there was a small growth in the south of Hengduan Mountains. The increase of precipitation and decrease of evaporation lead to the increase of Thornthwaite moisture index. Thornthwaite moisture index has strong correlation with vegetation coverage. It can be seen that the correlation between Normalized Difference Vegetation Index(NDVI) and Thornthwaite moisture index was positive in spring and summer, but negative in autumn and winter. Correlation between Thornthwaite moisture index and relative soil relative moisture content was positive in spring, summer and autumn, but negative in winter. The typical mountainous terrain affect the distribution of temperature, precipitation, wind speed and other meteorological factors in this region, and then affect the spatial distribution of Thornthwaite moisture index. The unique ridge-gorge terrain caused the continuity of water-heat distribution from the north to south, and the water-heat was stronger than that from the east to w

关键词：横断山地区水分指数中国归一化植被指数土壤相对含水率空间分布季风降水季节变化

Lakes in the Qinghai-Tibet Plateau are conducive to regional permafrost development

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Journal of Mountain Science 2023年第3期20卷 738-749页

作者： XIE Chang-wei YANG Gui-qian WANG Wu ZHANG Yu-xin LIU Wen-hui LIU Guang-yue WU Ji-chun PANG Qiang-qiang cryosphere Research Station on the Qinghai-Tibet Plateau State Key Laboratory of Cryosphere SciencesNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 730000China University of Chinese Academy of Sciences Beijing 101408China Department of Geological engineering Qinghai UniversityXining 810016China

The Qinghai-Tibet Plateau(QTP)possesses the largest areas of permafrost in the midand low latitude regions on the earth and many large lakes in the permafrost area.Based on a comprehensive investigation around certain typical lakes,this study found that although the presence of lakes formed different ranges of unfrozen zones in permafrost,the heating effect of lake water on surrounding permafrost is limited to a small extent.The temperature of permafrost around the lake is closely related to the distance to the lake and the ice content of the permafrost.Around lakes are ice-rich permafrost zones and permafrost temperature in this area is significantly lower than that far away from the lake,which indicates that the existence of lakes in the QTP has special effect on the permafrost distribution.Based on the monitoring results,this study presents the typical distribution pattern of the permafrost around large lakes and discusses the reasons for the distribution pattern.Due to the huge area of lakes and the significant impact of lakes on permafrost distribution,it is suggested to re-estimate the total permafrost area and underground ice storage in the QTP.

关键词： Heating effect So1il water content Permafrost distribution Lakes Qinghai-Tibet Plateau

Large-scale characteristics of thermokarst lakes across the source area of the Yellow River on the Qinghai-Tibetan Plateau

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Journal of Mountain Science 2023年第6期20卷 1589-1604页

作者： LIU Wen-hui ZHOU Guang-hao LIU Hai-rui LI Qing-peng XIE Chang-wei LI Qing ZHAO Jian-yun ZHANG Qi State Key laboratory of Plateau Ecology and Agriculture Qinghai UniversityXining 810016China Department of Geological engineering Qinghai UniversityXining 810016China College of Eco-Environmental engineering Qinghai UniversityXining 810016China cryosphere Research Station on the Qinghai-Tibet Plateau State Key Laboratory of Cryosphere SciencesNorthwest Institute of Eco-Environment and ResourcesChinese Academy of SciencesLanzhou 73ooooChina

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.

关键词： Thermokarst lake Spatial characteristic Influencing factor Source area of the Yellow River

Hydrological processes of glacier and snow melting and runoff in the Urumqi River source region, eastern Tianshan Mountains, China

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Journal of Geographical Sciences 2015年第2期25卷 149-164页

作者： SUN Meiping YAO Xiaojun LI Zhongqin ZHANG Mingjun College of Geography and Environment Science Northwest Normal University Lanzhou 730070 China State Key laboratory of cryosphere Sciences Cold and Arid Region Environment and Engineering Research Institute CAS Lanzhou 730000 China

Hydrological processes were compared, with and without the influence of precipita- tion on discharge, to identify the differences between glacierized and non-glacierized catchments in the Urumqi River source region, on the northern slope of the eastern Tianshan Mountains, during the melting season （May-September） in 2011. The study was based on hydrological data observed at 10-min intervals, meteorological data observed at 15-min intervals, and glacier melting and snow observations from the Empty Cirque, Zongkong, and Urumqi Glacier No.1 gauging stations. The results indicated that the discharge differed markedly among the three gauging stations. The daily discharge was more than the nightly discharge at the Glacier No.1 gauging station, which contrasted with the patterns observed at the Zongkong and Empty Cirque gauging stations. There was a clear daily variation in the discharge at the three gauging stations, with differences in the magnitude and duration of the peak discharge. When precipitation was not considered, the time-lags between the maximum discharge and the highest temperature were 1-3 h, 10-16 h, and 5-11 h at the Glacier No.l, Empty Cirque, and Zongkong gauging stations, respectively. When precipitation was taken into consideration, the corresponding time-lags were 0-1 h, 13 h, and 6-7 h, respectively. Therefore, the duration from the generation of discharge to confluence was the shortest in the glacierized catchment and the longest in the catchment where was mainly covered by snow. It was also shown that the hydrological process from the generation of discharge to confluence shortened when precipitation was considered. The factors influencing changes in the discharge among the three gauging stations were different. For Glacier No.1 station, the discharge was mainly controlled by heat conditions in the glacierized region, and the discharge displayed an accelerated growth when the temperature exceeded 5℃ in the melt season. It was found that the englacial and subglacial drainage channel of Glacier No

关键词： glacier and snow melting runoff generation and confluence hydrological process Urumqi Riversource region Tianshan Mountains