25 April 2019, Volume 41 Issue 2
    

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  • The relationship between meteorological elements and ice core record forming process and its resolution on Glacier No.1 in headwater of Urumqi River, eastern Tianshan Mountains
    YOU Xiaoni, LI Zhongqin, WANG Lixia
    Journal of Glaciology and Geocryology. 2019, 41(2): 259-267. https://doi.org/10.7522/j.issn.1000-0240.2019.0065
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    To explore the effect of elution process on ion concentrations in snow and then interpret the ice core records, it is necessary to figure out the complete process of ice core record forming through tracking the Mg2+ concentration peaks in snow-firn packs. For the case of Glacier No.1 in headwater of Urumqi River, it is concluded that in the ice core record formed from Mg2+ ion with a resolution of one year, finally only 30% of the initial value can be preserved. In April, ion concentration in whole snow-firn layer will increase because of frequent dust events and precipitation. A temperature index elution model is constructed to describe the relationship between positive cumulative air temperatures and ion concentrations in ablation season. This conclusion shows that ion concentration decays exponentially with positive air temperatures. This model could reflect the elution process well.
  • Runoff variation and its influence factors in the Yanggong River basin of Mt.Yulong region due to climate change
    FANG Jinxin, PU Tao, SHI Xiaoyi, WANG Shijin, NIU Hewen
    Journal of Glaciology and Geocryology. 2019, 41(2): 268-274. https://doi.org/10.7522/j.issn.1000-0240.2019.0312
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    Based on the runoff data at Mujiaqiao hydrological station of Yanggong River basin and the meteorological data of Lijiang city during the period 1979-2016, this study analyzed the variation of the runoff and its main influencing factors. The results showed that the discharge of the Yanggong River basin exhibited an increasing trend and then decreasing trend during the study period. Though the discharge increased during 1980s, 1990s and 2000-2009, the discharge decreased during 2010-2016. The discharge during 2010-2016 decreased by 42% (0.88×108 m3) compared with the average discharge of 2000-2009. Moreover, the correlation analysis showed that precipitation and temperature were the main control factors for the Yanggong River runoff. The influence of precipitation on discharge mainly occurred in rainy season whereas the influence of temperature on discharge mainly occurred in melting season. The variation of snow and ice meltwater caused by the rising temperature resulted in the different change of runoff and precipitation.
  • Study on the restoration model of ecological environment in the northern part of the eastern end of the Altun Mountains
    NIU Zuirong, CHEN Xuelin, HUANG Weidong, WANG Yinong, WANG Yusen, WU Xue
    Journal of Glaciology and Geocryology. 2019, 41(2): 275-281. https://doi.org/10.7522/j.issn.1000-0240.2019.0105
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    Altun Mountains desertification control ecological function zone is an important ecological barrier in the western part of Gansu, Xinjiang and even the entire northwestern region. This study analyzes the current status and existing problems of the Xitugou watershed, which is a typical representation of the northern part of the eastern end of the Altun Mountains. The study conceives the notion of regional eco-environmental governance and puts forward a regional flood resource utilization model, which includes "situational flood control"-"desert control through flood"-"natural purification"-"comprehensive utilization". In addition, the study proposes a regional ecological environment and desert governance model in which the "flood" is utilized to treat the "desert", turning something bad into something good. Domestic and foreign scholars have carried out some research on desertification control and grassland ecological security evaluation in this region, but the research on the development and utilization of flood resources in desert areas is rare, and it is highly representative in the utilization of flood resources in desert areas. It is the protected area of Altun Mountain. Standardized management and sustainable countermeasures development provide a scientific basis for providing demonstration of ecological restoration in similar areas.
  • Monthly variations of temperature gradient in glacierized and non-glacierized areas of the western Qilian Mountains
    JIN Zizhen, QIN Xiang, SUN Weijun, CHEN Jizu, ZHANG Xiaopeng, LIU Yushuo, LI Yanzhao
    Journal of Glaciology and Geocryology. 2019, 41(2): 282-292. https://doi.org/10.7522/j.issn.1000-0240.2019.0106
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    In order to study the effect of underlying surfaces on the temperature gradient in glacierized and non-glacierized areas, in this paper, the daily mean temperature data of three meteorological stations at 4 180 m, 4 550 m and 5 040 m in the Laohugou basin of Qilian Mountains, along with seven national meteorological stations (Sunan, Subei, Toler, Yumen, Jiuquan, Guazhou and Dunhuang) are used to analyze the characteristics of annual temperature gradient in glacierized area and non-glacierized area in the western Qilian Mountains, combined with precipitation and other meteorological data. It is found that:(1) in the non-glacierized area, the temperature gradient increases with elevation and with obvious monthly fluctuation. Temperature gradient presents the trend of decreasing firstly and then increasing, with a maximum in summer and a minimum in winter, and an annual mean temperature gradient of 0.50℃·(100m)-1. (2) In the glacierized area, the temperature gradient presents the trend of increasing first and then decreasing, with a minimum in summer, and a maximum in winter, and an annual mean temperature gradient of 0.61℃·(100m)-1. The variation of daily temperature gradient is large in daytime with an average temperature gradient of 0.49℃·(100m)-1 and stable at 0.83℃·(100m)-1 at night without obvious change. (3) The annual temperature gradient has opposite to the precipitation gradient in glacierized area and non-glacierized area, indicating that precipitation has a certain effect on the change of temperature gradient. (4) Due to the difference of underlying surface between the non-glacierized area and the glacierized area, the temperature gradient has the opposite variation trend in the year. The temperature jump must be considered when the temperature on the ice surface is calculated from the non-glacierized area. The annual average temperature jump on the Laohugou Glacier No.12 is 1.30℃.

  • Effect of snow cover on ground-air temperature difference observed by automatic weather stations in Liaoning Province

    ZHU Ling, GU Zhengqiang, GONG Qiang, CHAO Hua, LI Yang, XU Hong, ZHOU Xiaoyu, SHEN Lidu, LIN Na
    Journal of Glaciology and Geocryology. 2019, 41(2): 293-303. https://doi.org/10.7522/j.issn.1000-0240.2019.0066
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    Based on air temperature, ground temperature, snow cover duration and snow cover depth records from 61 weather stations in Liaoning Province from 1971 to 2016, the effect of snow cover on ground-air temperature difference were analyzed. The analyses show that the difference of ground temperature caused by different observation ways before and after replacement of automatic weather station plays a dominant role for ground-air temperature difference increasing significantly; ground-air temperature difference change was influenced by snow cover duration and snow cover depth obviously. In the area with long snow cover duration, snow cover increases the albedo, resulting in snow cover surface temperature decreasing and snow-air temperature difference increasing. Besides, due to the insulating effect of snow on the ground, ground-air temperature difference increases significantly. Therefore, ground (snow)-air temperature difference has a negative correlation with snow cover duration before replacement of automatic weather station, and ground-air temperature difference has a positive correlation with snow cover duration after the replacement. Variation coefficients of daily mean ground-air temperature difference with daily snow depth changes between 0.045-0.858 ℃·cm-1 from station to station. In the area where annual snow cover duration is less than 40 days and snow cover depth is below 10 cm, the heat preservation effect of snow increases significantly with the increase of snow depth. In the area where annual snow cover duration is more than 40 days and maximum snow cover depth is above 10 cm, when snow cover depth below 10 cm, the heat preservation effect of snow has increased significantly with the increase of snow depth, however, when snow cover depth above 10 cm, the heat preservation effect of snow has increased slowly with the increase of snow depth.

  • A comparison of sub-cloud secondary evaporation effect of precipitation isotope in Xinjiang based on the Stewart model improvement scheme
    ZHOU Su'e, ZHANG Mingjun, WANG Shengjie, MENG Hongfei, ZHANG Yaning, YU Xiuxiu
    Journal of Glaciology and Geocryology. 2019, 41(2): 304-315. https://doi.org/10.7522/j.issn.1000-0240.2019.0107
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    The sub-cloud secondary evaporation is easy to occur and change its isotope ratio in the arid and semi-arid areas with low precipitation and high evaporation. In the isotope hydrology study it is necessary to have a better understanding of variability in stable hydrogen and oxygen isotopes of raindrops from cloud base. The Stewart model is often used for evaluation the change in isotope ratios in raindrops. Temperature and relative humidity of raindrops falling under the cloud are the key input parameters of the model. Now, the widely used atmospheric mean hypothesis is different from natural conditions, the impact of which on the simulation results remains to be determined. Based on the hourly meteorological observations at surface as well as the daily radiosonde observation in Xinjiang from July 2016 to June 2017, the effect of sub-cloud secondary evaporation in Xinjiang was analyzed using the Stewart model improvement schemes (i.e., schemes ①, ② and ③). It is found that:(1) There are obvious seasonal variation of sub-cloud evaporation found by the three schemes, the trend of f is larger in autumn and winter and smaller in spring and summer, and ΔδD, Δδ18O and Δd is smaller in autumn and winter and larger in spring and summer. (2) Spatially, Δd is less in the western region of Junggar Basin and northern edge of Turpan-Hami Basin. In terms of f, ΔδD, Δδ18O and Δd, the differences among the three schemes are obvious in the Tarim Basin. (3) There is correlation between f and Δd. On the whole, the slopes of the three Stewart model improvement schemes are highest in Tarim Basin, following by the Altai region and the Junggar Basin, and then the Tianshan Mountains. It can be found that the linear relationship between f and Δd of the three Stewart model improvement schemes is larger than 1.0‰/% in Xinjiang, except the second scheme in the Tianshan Mountains, the slope of the third scheme in Tarim Basin reaches up to 1.496‰/%, which may be due to Xinjiang located in the arid and semi-arid climate zone. There is no doubt that schemes ③ is the research direction of sub-cloud secondary evaporation in the future.
  • Analyses on the characteristics of seasonally frozen ground under snow cover and forest/grassland in Kunes Valley, western Tianshan, Xinjiang
    ZHANG Feiyun, GUO Lingpeng, HAO Jiansheng, YANG Tao
    Journal of Glaciology and Geocryology. 2019, 41(2): 316-323. https://doi.org/10.7522/j.issn.1000-0240.2019.0020
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    The characteristics of seasonally frozen ground are different under snow cover, forest and grassland. In order to analyze the differences of seasonally frozen ground under snow cover, forest and grassland, in this study, the seasonally frozen ground depth under forest and snow cover, grass and snow cover, and grassland were observed in Tianshan Station for Snow Cover and Avalanche Research, Chinese Academy of Sciences, in the upstream of Kunes River, western Tianshan, Xinjiang. The variations of soil temperature and soil moisture were observed under grassland & snow cover and grassland conditions. The results indicated that the frozen depth under grassland was the deepest while that under forest and snow cover condition was the shallowest. Snow cover influences not only the frozen depth, but also the soil temperature and soil moisture. In the seasonally frozen ground development period, the soil temperature and soil moisture increased due to the insulation effect of snow cover. During the thawing period, the soil moisture increased due to supply of snow melt water firstly and then decreased due to evaporation.
  • Daily variation of soil freezing-thawing and its relationship with air and soil temperature in Jilin Province
    REN Jingquan, WANG Dongni, LIU Yuxi, LI Jianping, GUO Chunming, LI Qi
    Journal of Glaciology and Geocryology. 2019, 41(2): 324-333. https://doi.org/10.7522/j.issn.1000-0240.2019.0108
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    The process of soil freezing and thawing has an important influence on the evolution of climate and ecological environment. In order to study the soil freezing and thawing process and its response to climate change in the seasonal frozen soil region, the daily variation of soil freezing and thawing process and its relationship with air temperature and soil temperature were analyzed based on the observation data of frozen soil, air temperature and soil temperature of the four typical representative stations from 2014 to 2017 in Jilin Province. The results showed that the upper limit of frozen soil showed a linear upward trend, and the lower limit value showed a trend of three times curve in the whole process of soil freezing and thawing. From the beginning of stable freezing, the lower limit of frozen soil increased gradually, and it decreased slowly after reached the maximum. The process of soil thawing include the lower and upper soil thawing. The upper limit of frozen soil have thawed at the same time or later than lower limit, but the daily variation of soil thawing of the upper limit was greater than the lower limit. During the soil freezing process, the accumulated air temperature, accumulated soil temperature at 0 cm, accumulated soil temperature at 10 cm and the depth of freezing had three times curve relationship, with the increase of negative accumulated temperature, the depth of freezing increased. The accumulated air temperature, accumulated soil temperature at 0 cm, accumulated soil temperature at 10 cm and the depth of upper limit of frozen soil had three times curve relationship in the process of upper limit of soil thawing, with the increase of positive accumulated temperature, the depth of upper limit of frozen soil increased. During the process of lower limit of soil thawing, the accumulated air temperature, accumulated soil temperature at 0 cm, accumulated soil temperature at 160 cm and the depth of lower limit of frozen soil showed a linear trend significantly. The depth of lower limit of frozen soil decreased with the increase of positive accumulated air temperature, the depth of frozen soil was shallower.

  • Study on drought monitoring in northwestern Tibet by remote sensing based on FY-3A/VIRR data

    ZENG Lin, Zhaxi Yangzong, FENG Wenlan, NIU Xiaojun, Zhaxi Ouzhu, Laba Zhuoma
    Journal of Glaciology and Geocryology. 2019, 41(2): 334-341. https://doi.org/10.7522/j.issn.1000-0240.2019.0064
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    Because of complicated landform and harsh climate, the meteorological observation data were very scarce in northwestern Tibet, which is characterized by vulnerable ecological environment. Drought monitoring by remote sensing could obtain drought conditions with continuous changes on the surface, which was of great significance for the arrangement of agricultural and husbandry production in this area. In this paper, we try to reveal the drought in northwestern Tibet based on primary data, standard products (surface temperature, vegetation index) of FY-3A/VIRR and drought monitoring and TVDI (temperature vegetation drought index). Then, the monitoring results has been compared, respectively, the results of the EOS/MODIS data monitoring, field measured soil moisture data during this period, and the precipitation data from weather stations. The results were compared with those monitoring results based on MODIS data, measured soil moisture, the meteorological observation data. It is found that the TVDI calculated by FY-3A/VIRR showing a significant negative correlation with the measured soil moisture and accumulated precipitation, which had passed the remarkable test of the 0.01 level; they were basically the same that the spatial distribution characteristics of TVDI drought grades estimated by remote sensing using FY-3A/VIRR data and EOS/MODIS data. Therefore, the FY-3A/VIRR data could be used to carry out drought monitoring by remote sensing in northwestern Tibet instead of EOS/MODIS data, also available for providing data support for guiding agricultural and husbandry production in northwestern Tibet.

  • Study on surface evaporation of Pingdingshan expansive soil under atmospheric effect

    ZHAI Juyun, HAO Xiao, MA Mingjiang, GAO Yanke, ZHANG Gonghui, LI Yapeng
    Journal of Glaciology and Geocryology. 2019, 41(2): 342-349. https://doi.org/10.7522/j.issn.1000-0240.2019.0061
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    The expansive soil is sensitive to climate. In this study, the indoor and outdoor evaporation experiments on Pingdingshan expansive soil with various initial water content have been studied. The variation of soil water content with depth in the evaporation process has been obtained. The evaporation intensity is different between indoor and outdoor soil specimens, but their evaporation coefficient is less different. The evaporation coefficient has correlation with soil water content and water content gradient. When the surface soil is close to saturation, the evaporation coefficient fluctuates around one. With continuous evaporation, the evaporation coefficient decreases with the surface water content, and the water content gradient increases with the decrease of surface water content. When the surface water content reaches the residual water content, the water content gradient reaches the maximum. The continuous evaporation water content gradient will gradually decrease. A good logarithmic relationship between the evaporation coefficient of soil and the evaporation duration can be seen.
  • Analysis of the influence of groundwater seepage on the mechanical properties of model piles in frozen soil region
    ZHANG Lei, WU Yaping, WANG Ning, WANG Haixin, HUANG Huanan, CHEN Kun, SUN Anyuan
    Journal of Glaciology and Geocryology. 2019, 41(2): 350-356. https://doi.org/10.7522/j.issn.1000-0240.2019.0059
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    In order to understand the effect of the groundwater seepage on pile foundation in permafrost, considering the axial force and lateral frozen stress of pile, and soil temperature affecting the bearing capacity of pile foundation, a simulation test have carried out. The effects of groundwater on the bearing capacity of permafrost pile foundation under five different working conditions have been simulated, respectively, including there is no groundwater, the pile bottom water has temperature effect only and the pile bottom water has temperature effect and seepage effect both, the pile top water has temperature effect only and the pile top water has temperature effect and seepage effect both. The following conclusions can be drawn:Under the five working conditions, the axial force of the pile is the maximum when there is no groundwater and the axial force decreases downward, when the condition of temperature effect and seepage effect is less than that under the condition of temperature effect only. Compared with no groundwater, the effect of groundwater on frozen stress is more obvious; the water at the top of the pile has a great influence on the lateral frozen stress of the upper half of the pile and the water at the bottom of the pile has a great influence on the lateral frozen stress on the lower half of the pile. As a whole, the variation range of the lateral frozen stress caused by the ground water is larger than that caused by the top water. The temperature effect of water at the pile bottom only is more significant than that the temperature effect together with seepage effect, and the temperature effect and seepage effect of water at the pile top both result in frozen stress on the pile side more serious than that with temperature effect only. At the same depth, groundwater temperature and seepage effect together result soil temperature rise more than only groundwater temperature effect, making frozen stress acting on the pile rapidly decrease, at the same time, the temperature effect of groundwater makes the adjacent frozen soil warm and thawing, and the seepage effect also makes a wider range of frozen soil warm and thawing, the mechanical properties of pile foundation changed, resulting in changing bearing capacity of pile foundation.
  • Development and application of a confined compression apparatus for frozen soil
    YAN Xu, KONG Lingming, YANG Xiao, YAO Xiaoliang, QI Jilin
    Journal of Glaciology and Geocryology. 2019, 41(2): 357-363. https://doi.org/10.7522/j.issn.1000-0240.2019.0021
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    The compressibility of frozen soil should be considered in high-grade highway engineering and other infrastructure construction in permafrost regions. As an important parameter, the coefficient of lateral earth pressure at rest (i.e., K0) for frozen soil and its changes with temperature need to be investigated. However, the related studies are inadequate so far because of a lack of the confined compression apparatus applicable to frozen soil. In order to accurately and quickly measure the above-mentioned mechanical properties of frozen soil, this paper developed a confined compression apparatus exclusively for frozen soil, which is in light of the experimental principle of the unfrozen soil compression and takes into account the characteristics of the mechanical properties of frozen soil which are dominated by temperature. In the new apparatus, the second-level temperature control is realized by adopting both a cold circulation in the cooling tank and a thermostat outside the cooling tank, which makes the control accuracy of temperature reach ±0.1℃. Besides, the apparatus can achieve the closed-loop temperature control by using a full digital servo controller and can run smoothly under heavy loads by adopting a high-performance load framework with strong stiffness. The reliability of the apparatuses was verified through a series of confined compression tests on frozen standard sand. It was found that the self-developed apparatus can provide reliable compressibility parameters and K0 for practical engineering involving frozen soil materials.
  • Spatial distribution of bedrock rebound value (Schmidt Hammer) across the Heihe River basin and its implication
    CHEN Liping, GENG Haopeng, ZHANG Jian, ZHAO Qiming, PAN Baotian
    Journal of Glaciology and Geocryology. 2019, 41(2): 364-373. https://doi.org/10.7522/j.issn.1000-0240.2019.0302
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    The weathering of bedrock reflects the combined influence of tectonics and climate on landscape. The intense tectonic movement since the late Cenozoic and the arid climatic conditions make the Qilian Mountains an ideal location to study the weathering processes and landscape evolution. In this paper, Schmidt Hammer is used to study the spatial variation of bedrock rebound value (R) at various altitudes over the Heihe River basin. The results show that there is a good correlation between the catchment-averaged value R and the erosion rate, which means that the value R can be used as a substitute index for the spatial variation of weathering intensity. The mean value R within same rocks shows a little difference, which indicates that lithology has limited influence on value R. The value R is further compared with climatic and topographic factors. The results show that value R has strongly correlated with climatic factors (temperature, precipitation and NDVI) rather than any topographic factors. The value R is negatively correlated with altitude as it below 3 800 m a.s.l. However, the value R is positively correlated with altitude as it above 3 800 m a.s.l.
  • Study on structural improvement of railway subgrade transition section in permafrost region based on thermal stability
    LUO Tao, LÜ Mengfei, WU Yaping, PAN Gaofeng, SUN Jianzhong
    Journal of Glaciology and Geocryology. 2019, 41(2): 374-383. https://doi.org/10.7522/j.issn.1000-0240.2019.0015
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    Since the Qinghai-Tibet Railway was brought into use, the problem of frost heaving and thaw which is on the permafrost railway subgrade has come out in an endless stream, and differential settlement of transition section on railway subgrade is particularly serious. This paper takes the exploratory improvement research on construction structure of railway subgrade transition section in the frozen soil area, at the same time, it takes the analysis of the long-term thermal stability of the transition section of improved railway subgrade. However the premise is that they are based on the governance method of differential settlement of railway subgrade transition section, and combined with active cooling measures of railway subgrade in frozen soil area. The results show that in the satisfying mechanical stability proposition, railway subgrade can achieve the maximum natural-convection heat transfer effect by replacing the filling of the upper layer of the subgrade named traditional block gravel with single particle size gravel for a certain height; Through numerical simulation and analysis, it is found that the structure of improved railway subgrade transition section under the environment of warmer temperature has obvious effect on active cooling, and the long-term thermal stability is well. The influence of abutment on the temperature field of railway subgrade transition section is great. It is suggested that the abutment which is strongly irradiated by the sun should be heat preservation treatment.
  • Calculation and analysis of freezing time of frozen soil model test specimen
    ZHANG Wenqiang, WANG Yi, NIU Yonghong
    Journal of Glaciology and Geocryology. 2019, 41(2): 384-391. https://doi.org/10.7522/j.issn.1000-0240.2019.0109
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    Quick and easy determination of the freezing time of a specimen is of great significance for the design of model test. Firstly, the freezing test of frozen soil specimens with different dry densities was carried out. It was found that the freezing time increases slightly with the increase of dry density. Then the freezing time of silty sand specimens with different dry densities and sub-clay cube specimens with different scales was simulated by COMSOL Multiphysics software without considering water migration. Comparing with the test results, it was found that the numerical simulation results of silty sand specimens with different dry densities under the simplified conditions can reflect the main characteristics of temperature change during freezing process, and the calculated time for the specimen to reach the preset negative temperature is basically consistent with the measured results. The results of numerical simulation of cubic specimen also show that the time when the specimen drops to the preset negative temperature increases with increase of volume under the same dry density and water content, and follow a power function. Therefore, in the process of model test design, a simple numerical analysis can be carried out according to the test conditions, in order to arrange the test time reasonably and economically, while ensuring the freezing quality of the specimen.
  • Characteristics and causes of the landslide outbreaking in Yongguangcun, Minxian County, Gansu Province
    WANG Guoya, REN Lubin, WU Weijiang, SU Xing, FENG Letao, YAO Zhengxue
    Journal of Glaciology and Geocryology. 2019, 41(2): 392-399. https://doi.org/10.7522/j.issn.1000-0240.2019.0110
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    In addition to the general conditions of landslides, the conditions for the occurrence of mud-flow loess landslides should include special state factors, triggering factors and corresponding driving shear stress conditions. Through on-site investigation and field investigation of Yongguangcun landslide in Minxian County, Gansu Province, the results show that although the plane shape of Yongguangcun landslide is similar to that of mud flow, it has the special landform, geomorphology, rock and soil properties and hydrogeological conditions needed for landslide formation and occurrence. Yongguangcun landslide develops in the Loess Plateau area upstream of the ditch. It has large free surface, high shear outlet position and high potential energy. Malan loess is the main rock and soil body of the landslide. Loess has large pore structure and vertical joint development, which is conducive to the infiltration of surface water. The lower part is Neogene mudstone with low permeability coefficient, which is a relative aquifer. Long-term irrigation results in higher groundwater level, weak interlayer in loess layer and rising groundwater level, which leads to softening and saturation, rapid reduction of strength and formation of potential sliding surface. Yongguangcun landslide also has an arc-shaped back wall of the landslide. There are many tension cracks on the top of the back edge of the landslide. In the absence of rainfall, under the external conditions of Minxian "7·22" earthquake, a low-angle, fast and long-distance mud-flow loess landslide occurred. The sliding body formed a fan-shaped accumulation area after it washed out of the ditch. Yongguangcun landslide is a special kind of mud-flow loess landslide caused by earthquake. At present, the research of mud-flow loess landslide is still in the exploratory stage, which is a supplement to the classification of Loess landslide. It is suggested that further study on the mechanism of such disasters and the calculation method of their stability should be strengthened.
  • Risk assessment of glacial debris flow along the Tianshan Highway based on geomorphic information entropy
    XIE Tao, YIN Qianfeng, GAO He, GUO Feng, LIN Daming
    Journal of Glaciology and Geocryology. 2019, 41(2): 400-406. https://doi.org/10.7522/j.issn.1000-0240.2018.0408
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    Glacial debris flow is widely distributed in western China, where the special landform conditions have significantly impacted the development of glacial debris flow hazards. Geomorphic information entropy theory is applied to quantify the development stages of geomorphology. In this paper, the application of geomorphic information entropy theory to glacial geomorphic condition is discussed and the corresponding correction coefficients under various glacial geomorphic conditions are proposed. Thirteen debris flow gullies along the Tianshan Highway were selected for risk assessment based on the ArcGIS platform. As a result, it is found that the corrected geomorphic information entropy value is able to judge the risk of glacial debris flow.
  • Experimental study of salt-frost heave characteristics of fine-grained sodium sulfate saline soil
    YU Tianyou, WU Yaping, SI Peiguo, ZHANG Lei, KONG Lingnan, PU Zenggang
    Journal of Glaciology and Geocryology. 2019, 41(2): 407-415. https://doi.org/10.7522/j.issn.1000-0240.2019.0060
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    In order to explore the influence of temperature and sodium sulfate content on the salt-frost heave ratio and proportion of salt heave in fine-grained sodium sulfate saline soil, Lanzhou loess was taken as plain soil to prepare specimens mixed salt artificially for testing. The results showed that when the compaction degree is 92% and the moisture content is the optimal moisture content of 16.8%, with the increase of the salt content, the freezing temperature of the fine-grained saline soil decreases with the increase of the sodium sulfate content, and with the decrease of the temperature, the change trend of salt heave ratio is basically consistent with the salt-frost heave ratio. From freezing temperature to -5 ℃, the salt heave ratio is significant, and below -5 ℃ salt heave ratio less increases; when the compaction degree is 92% and the moisture content is 16.8%, the lower the temperature is, the larger the salt heave ratio will be when the sodium sulfate content is constant. At constant temperature, the higher the content of sodium sulfate, the more the salt heave ratio; above the freezing temperature the salt heave ratio will be 100%; As the freezing temperature drops to -3 - -4 ℃, the salt heave ratio will drop to 50%, and salt heave ratio will be constant as the freezing temperature lower than -10 ℃.
  • Significant analysis of the influence factors on strength of frozen soil base on multivariable linear regression model
    BAI Ruiqiang, XU Xiangtian, HUA Shuguang, WANG Jiwei
    Journal of Glaciology and Geocryology. 2019, 41(2): 416-423. https://doi.org/10.7522/j.issn.1000-0240.2019.0111
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    To quantitative analyze the impact of soil type, moisture content, temperature and strain rate, etc. on strength of frozen soil, a significance analysis of influence factors on strength of frozen soil was carried out with multiple linear regression models based on the published experimental data in this study. The results show that the main factors influencing the strength of frozen soil are temperature and soil property, with the impact intensity of 0.632 and 0.193, respectively, when considering linear effect only. Moisture content also has significant effect with the intensity of -0.577. In order to investigate the nonlinear effect of the impact factors on strength of frozen soil, the nonlinear term is linearized by variable substitution under the condition of retaining second order of Taylor expansion of strength, and the multiple linear regression model is used to analyze furtherly. The analytical results show that the impacts of moisture content and temperature on the strength of frozen soil include linear, nonlinear and cross impacts, while the strain rate on strength contains only nonlinear and cross impacts. The impact intensity of the factors on the strength of frozen soil could be quantitatively described by partial regression coefficient.

  • Analyses of evaporation (dish evaporation), precipitation and runoff depth in Diqing Prefecture on the Qinghai-Tibet Plateau, China

    WANG Dongsheng, DUAN Chaoxiong, YUAN Shutang, HU Guandong
    Journal of Glaciology and Geocryology. 2019, 41(2): 424-433. https://doi.org/10.7522/j.issn.1000-0240.2019.0045
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    In this study, the evaporation (dish evaporation), precipitation and runoff depth in Diqing Prefecture in the southeastern margin of the Qinghai-Tibet Plateau were studied. The annual and inter-annual evolution of each element were analyzed. The mutation points were examined and the correlation among regional evaporation, precipitation and runoff depth were discussed. The results showed that: (1) The evaporation in the study area was relatively equilibrium in the four seasons, as well as runoff depth and precipitation; the interannual dispersion coefficient of runoff depth was low, as well as precipitation and evaporation; the interannual dispersion coefficient of runoff was low also, as well as evaporation and Precipitation. (2) The annual evaporation increasing in the study area was mainly due to the evaporation increasing in spring. The decrease of annual precipitation was mainly due to the decrease of precipitation in winter. The increase of annual runoff depth was mainly due to the increase of runoff depth in summer, autumn and winter. The increase of runoff depth in summer was mainly due to summer evaporation decreasing, and the increase in runoff depth in autumn was mainly caused by precipitation increase in autumn, evaporation decreasing in autumn; the increase in runoff depth in winter was mainly due to runoff increase in autumn. (3) The annual and spring evaporation declines in the study area were significant, and the annual drought and spring drought risks were decreasing. The annual precipitation tended to concentrate in summer and autumn, and the runoff increased in deep summer and autumn; the risk of flood disasters in this region  increased. Since 2000, annual evaporation has increased significantly and precipitation and runoff have decreased significantly in the study area. This trend has deviated from the linear trend. In addition, the annual and seasonal precipitation and runoff depth have detected some mutation signals showing a decreasing around 2014, which may have a great impact on regional ecological environment and water resources.

  • Cloud characteristic parameters and artificial precipitation in the Qilian Mountains: research progress and prospect

    WANG Yanfeng, WANG Jujie, YIN Xianzhi, WANG Rong
    Journal of Glaciology and Geocryology. 2019, 41(2): 434-443. https://doi.org/10.7522/j.issn.1000-0240.2019.0063
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    In this paper, the present research achievement on cloud characteristic parameters and artificial precipitation in the Qilian Mountains is reviewed, including the variation of cloud characteristic parameters, the characteristics of water vapor content, cloudiness distribution, cloud system distribution characteristics, cloud optical property, cloud and precipitation mechanisms, rainfall distribution, the weather systems in favour of artificial precipitation, catalytic mechanisms of artificial precipitation, as well as the comprehensive benefits of artificial precipitation. The foundation has been established for comprehensive and further understanding the cloud physics and precipitation as well as artificial precipitation mechanisms. Furthermore, the problems in the study of topographic cloud structures and precipitation mechanisms, quantitative artificial precipitation operation scientific indexes and cloud seeding optimization technology, and the interaction between topography and vertical airflow on the weather system in the Qilian Mountains are prospected.
  • Temporal and spatial characteristics of different classes and various durations of precipitation in Sichuan Province from 1961 to 2016
    ZENG Bo, CHEN Yun, WANG Qin, XU Jinxia
    Journal of Glaciology and Geocryology. 2019, 41(2): 444-456. https://doi.org/10.7522/j.issn.1000-0240.2019.0012
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    Based on the daily precipitation data from 122 stations in Sichuan Province, the spatial and temporal variations of different classes and duration rainfall from 1961 to 2016 are analyzed by using various statistics methods, such as mean, climate trend coefficient and so on. The results show that the proportion of light rain, moderate rain, heavy rain and all kinds of rainstorm was similar to each other in the basin and Panxi area. But in plateau region, the light rain accounts for more than 50% of the amount of precipitation, and the moderate rain for 40%, heavy rain for 10%. In the whole Sichuan Province the days of light rain account for more than 75% of the total rainy days, and the proportion was decreased as the magnitude increase. The annual precipitation mainly had decreased in the basin and Panxi, increased in plateau region. While the annual rainy days had decreased in any other regions except the fraction of the plateau, and in the main region they had passed the 99% significant level test. The characteristic trend of annual rainy days was mainly reflected in the light rain. As the magnitude of rainfall increasing, the amount and days of precipitation in the plateau, Panxi, northeast and southeast of the basin showed an increase trend, which may indicate that the increase of annual precipitation in the plateau was caused by the precipitation efficiency of the light rain and the increasing times of moderate and heavy rain, the increase of the annual precipitation in part of the basin and Panxi area was mainly caused by the increasing times of the large magnitude rainfall.
  • Prediction of flood disasters in Tibet based on grey theory
    XIONG Junnan, GONG Ying, LIU Zhiqi, FAN Chunkun, ZHU Jilong
    Journal of Glaciology and Geocryology. 2019, 41(2): 457-469. https://doi.org/10.7522/j.issn.1000-0240.2019.0112
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    Precipitation is a principal condition for flood. In this paper, based on precipitation data from 38 meteorological stations in Tibet, 1985-2014, as the basal forecast data, the grey model and the long sequence trend fitting are utilized to predict the yearly and seasonal precipitation in 2015-2019. It was verified by the measured precipitation from 2015 to 2017 that the result is good. Finally, the adjusted precipitation anomaly percentage was used as a flood index to analyze the flood forecast in 2018 and 2019. It is found that in 2018 precipitation concentrated in Nyingchi, Mainling, Bomê and Zayü in southeastern Tibet. Precipitation will mainly concentrate in Markam in 2019. And rainfall mainly occurs in the Great Canyon region of the Yalung Zangbo River in spring, the upper reaches of the Suoqu River and Nu River in summer, Lhari, Nyingchi, and Bomê in the fall, and the Nyalam in winter. Different from summer and autumn, floods will occur frequently in spring and winter in 2018 and 2019. There will be a relatively normal situation of flood in Tibet in 2018, most counties in an unblemished or normal state with slight flood in a few counties and middle or serious flood in a few counties. The flood in 2019 will be more than that in 2018. Additionally, there will be a great possibility for waterlogging disasters in Lhazê County in 2018 and Lhasa in 2019; the local government should pay special attention to the flood prevention during the flood season. These consequences are of profound significance for the flood prevention in Tibet in the next two years.
  • Evaluation on the performance of five precipitation datasets of monthly precipitation in the upper reaches, middle and lower reaches of Shule River basin
    WU Qianxin, MA Siyu, ZHANG Zhihua, GUO Jiakai, ZHANG Shiqiang
    Journal of Glaciology and Geocryology. 2019, 41(2): 470-482. https://doi.org/10.7522/j.issn.1000-0240.2019.0022
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    Multiple global precipitation datasets provide a new perspective for understanding the temporal and spatial distribution of precipitation. However, their applicability varies widely in different regions. At present, the study on the performance of different datasets in mountainous areas of upper reaches and plains in the middle and lower reaches is still very limited. The observed precipitation data from 9 national meteorological stations from 2001 to 2013 and 4 self-built meteorological stations from 2008 to 2013 were used in this study, and Pearson Correlation Coefficient (R), Root Mean Squared Error (RMSE), Mean Absolute Deviation (MAE) and Relative Deviation (BIAS), were used to evaluate the performance of five precipitation dataset monthly precipitation including CMFD, ERA-Interim, GPCC, GPCP V2.3 and JRA-55 in the upper reaches, middle and lower reaches of Shule River basin, respectively. The results suggested that the five precipitation datasets could better reproduce the spatial pattern of yearly average annual precipitation in the Shule River basin. The performance of precipitation dataset in the upper reaches are higher than that in the middle and lower reaches. The relative performance of five precipitation datasets are same in the upper reaches, middle and lower reaches, both are CMFD > GPCC > ERA-Interim > GPCP V2.3 > JRA-55. The best performance of CMFD may be related to a variety of factors. The evaluation on the performance of different precipitation dataset in the Shule River basin provides an important clue for hydrological process simulation.
  • Analysis of factors affecting groundwater use by farmers in inland river basins of Hexi Corridor
    TAN Yanmei, QU Wei, Eefje AARNOUDSE
    Journal of Glaciology and Geocryology. 2019, 41(2): 483-493. https://doi.org/10.7522/j.issn.1000-0240.2019.0062
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    In the arid inland areas where exist agriculture and ecosystem water use contradictions, over-exploitation of groundwater has led to a sharp deterioration of ecological environment. In the past, the management of groundwater was mainly based on the direct control of groundwater use by local government, but the effect was not very ideal or the management cost was very high. Therefore, it is a better choice to seek indirect measures to regulate the use of groundwater. Taking the Shiyang River, Heihe River and Shule River basins in the Hexi Corridor as examples, the key factors affecting the use of groundwater by farmers based on the survey data of farmers has been explored in this paper, in order to seek more targeted policies to affect farmers' conservation and efficient use of groundwater, ultimately reaching the water saving effect. It is found that farmers’ using groundwater at different stages have different characteristics, but are strongly dependent on surfacewater supply; surfacewater supply increases a round for a unit of hectares of arable land, surfacewater consumption increases 237.3 m3, corresponding will reduce 795.2 m3 of groundwater, as a whole, 504.1 m3 of total water use will be reduced, the proportion of groundwater to total irrigation water will decrease by 3.7%. In addition, the use of groundwater is closely related to the following factors such as family business scale, business model, groundwater supply conditions and farmer’s preferences. Therefore, according to the comprehensive conditions and characteristics of surfacewater and groundwater resources in the basin, the government should formulate a development and governance system and a program that effectively combine government-led management policies with farmers' self-regulation capabilities, realizing the dual goals of regional water resources conservation and efficient utilization.
  • Analyzing the driving factors of water footprint in typical crop production in Xinjiang by using Cobb-Douglas production function
    HAI Yang, LONG Aihua, ZHANG Pei, DENG Xiaoya, LI Yang
    Journal of Glaciology and Geocryology. 2019, 41(2): 494-503. https://doi.org/10.7522/j.issn.1000-0240.2019.0016
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    The shortage of water resources is a main bottleneck restricting the agricultural development in the arid regions of Northwest China. Correct assessment of regional agricultural water use efficiency and its impact mechanisms can provide a theoretical basis for improving agricultural water use efficiency. In this study, Xinjiang Uygur Autonomous Region is taken as the study area; using the water footprint of crop production (WF) as an indicator of water consumption, the water footprints of typical crops (wheat and cotton) are calculated in North Xinjiang, South Xinjiang and East Xinjiang from 1988 through 2015. On this basis, the influencing factors were evaluated of changes in WF during the 28-year from the perspectives of change in climate (temperature, precipitation, sunshine hours, wind speed and relative humidity) and technical factors (agricultural machinery power, fertilizer consumption and the rate of effective irrigation) by the method of Cobb-Douglas production function. The results show that from 1988 through 2015, the water footprint of wheat and cotton in East Xinjiang had been significantly higher than that in North and South Xinjiang. Under the combined influence of climate change and technological progress, the water footprint of typical crop production in each region has been significantly reduced. Furthermore, the influence of technological progress on the water footprint of typical crop production in Xinjiang had been significantly higher than that of climatic factors, and become the main controlling factor driving the change of water footprint of typical crop production in various regions of Xinjiang. On the regional scale, climate change and agricultural technology development show significant regional differences. Overall, the climatic condition in North Xinjiang had been the most suitable for crop growth, while the climate in East Xinjiang had been the worst. The climate change over the 28 years in North and East Xinjiang had reduced the water demand of crops, while the situation in South Xinjiang had been reversed. The rate of agriculture technological development in North Xinjiang and South Xinjiang had been generally higher than that in East Xinjiang. However, to adjust the planting structure to give play to regional climate advantages and to improve agricultural water use efficiency in East Xinjiang are worth learning for other regions.
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