25 December 2005, Volume 27 Issue 6
    

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  • Study on the Fluctuations of Typical Glaciers and Lakes in the Tibetan Plateau Using Remote Sensing
    LU An-xin, YAO Tan-dong, WANG Li-hong, LIU Shi-yin, GUO Zhi-long
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 783-792. https://doi.org/10.7522/j.issn.1000-0240.2005.0117
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    Glaciers and lakes on the Tibetan Plateau play an important role in the earth’s climatic system.The remote sensing techniques and the Geographic Information System technology is an efficient tool to analyze the status and fluctuations of glaciers and lakes.In this paper,the variations of typical glaciers and lakes throughout the Tibetan Plateau were investigated by analyzing the datasets from aerial photos,satellite images,topographical and the derived digital elevation models during the period of 1960-2000.The results show that variation of lake area depends clearly on local climate change.Over the past 30 years,the most of lakes in the middle Tibetan Plateau,such as the Seling Lake and Nam Lake,expanded and glaciers around the lakes retreated dramatically.It is inferred that the increasing of precipitation,decreasing of potential evaportranspiration and runoff from glacier melting are responsible mainly for the lake expanding.However,the lakes in the head regions of the Yellow River in the northeastern plateau shrunk in the period of 1960-2000 despite of glacier retreating.In the source regions of the Yellow River,the changing trend of precipitation,although positive,is not significant while temperature increased apparently,indicating water loss of the lakes enhanced through increasing of evaportranspiration and thus lakes shrunk in the past 30 years.It is also argued that ecosystem regression resulted from human activity in the regions played an important role in the lake shrinking.
  • Change in Glaciers and Glacier Lakes in Boiqu River Basin, Middle Himalayas during Last 15 Years
    CHEN Xiao-qing, CUI Peng, YANG Zhong, QI Yong-qing
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 793-800. https://doi.org/10.7522/j.issn.1000-0240.2005.0118
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    There are many glaciers and glacier lakes in the Poiqu River basin within Nyalam county of Tibet Region.Data including distribution and area of glaciers and glacier lakes were obtained based on interpreting the remote sensing data of Landsat satellite.Compared with the data of 1987,it is found that many elements such as area of glaciers,number and area of glacier lakes have changed very much.The area of glaciers has decreased by 20%,the number of the glacier lakes,whose area is over 0.020 km2,has increased by 11%,and the area of glacier lakes has increased by 46%.Specially,the Galongco and Gangxico are very distinct,with an area increase of 104% and 118%,respectively.These data have been verified by field research.Owing to the global temperature warming,the area of glaciers will continuously decrease,and the number and area of glacier lakes will continuously increase.After the number of glacier lakes increases a little,many large-scale debris flows will appear because some glacier lakes may outburst.Many countermeasures must be taken as soon as possible in order to mitigate disasters.
  • Monitoring Glaciers and Associated Glacial Lakes on the East Slopes of Mount Xixabangma from Remote Sensing Images
    CHE Tao, LI Xin, P. K. Mool, XU Jian-chu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 801-805. https://doi.org/10.7522/j.issn.1000-0240.2005.0119
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    The remote sensing images from 1977 to 2003 have shown that the glaciers on the East slopes of Mount Xixabangma were retreating, while the associated glacial lakes were increasing rapidly.The Jicong Pu Glacier and Reqiang Glacier decreased about 57099 m2 and 63224 m2 in area,48 m and 71 m in length per year,respectively,while the Glacial Lake Lumu Chimi and Glacial Lake Gangxi increased 79048 m2 and 73425 m2 in area,respectively.The dams of the tow lakes are terminal moraines,which means the lake dams are quite unstable.It is expected that the two glacial lakes have the potentiality of glacial lake outburst flood,and should be investigated in detail.Additionally,several possible mitigation measures for reducing glacial lake outburst flood were discussed and proposed.
  • Impact of Climate Warming on Summer-Autumn Crop Planting Structure in Gansu Province
    LIU De-xiang, ZHAO Hong-yan, DONG An-xiang, YANG Su-hua,
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 806-812. https://doi.org/10.7522/j.issn.1000-0240.2005.0120
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    By analyzing the data of accumulative temperatures of above and below 0℃ and above 10℃ and planting areas of winter and spring wheat and corn,it is found that,in the dry farmland of middle Gansu province,the correlation between the accumulative temperature below 0℃ and planting area of winter wheat is significantly positive,but that between the accumulative temperature below 0℃ and planting area of spring wheat is significantly negative.The relation exhibits a significantly negative correlation between the accumulative temperature above 0℃ and the areas of irrigated spring wheat in Hexi and non-irrigated winter wheat in Southeast Gansu province.However,the relation exhibits a significantly positive correlation between accumulative temperature above 10℃ and the areas of maize in Hexi and Hedong.The area of winter wheat has expanded with climate warming,but the area of spring wheat has decreased in the middle Gansu province.The areas of winter wheat in the southeast Gansu province and spring wheat have reduced.Planting areas of corns have expanded rapidly in Gansu.Pronounced change of crops planting structure in summer-autumn can be seen.
  • Climate Warming at Headwater of Ürümqi River,Xinjiang in Past 44 Years and Its Impact on Glacier Shrinking
    WANG Guo-ya, SHEN Yong-ping, MAO Wei-yi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 813-819. https://doi.org/10.7522/j.issn.1000-0240.2005.0121
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    Based on the daily data observed of Daxigou Meteorological Station from 1961 to 2004,the characteristics of climate warming at Headwater of Ürümqi River have been analyzed from the aspects of maximum temperature,minimum temperature,daily temperature range and the climate accumulated temperature.It is found that maximum temperature,minimum temperature,mean annual temperature,and extreme minimum temperature in winter are rising.The asymmetry of minimum temperature increase more than maximum is detectable.The decrease of daily temperature range is obvious.The decrease of sunlight hours is related to increase of water vapor and cloud.That indicated water vapor greenhouse effect could play an important role in climate warming.At headwater of Ürümqi River,most cloud come forth in afternoon and evening.Water vapor greenhouse effect results from cloud increases making minimum temperature rise obviously,and impact on glacier melting and increasing the temperature of glacier.The climate accumulated temperature of T ≥0℃ is calculated.Its correlation with glacier mass balance is the best.The relationship of climate accumulated temperature change trend and Glacier No.1 mass balance is discussed in theend.
  • Annual Change and Abrupt Change of the Seasonal Frozen Soil in Xinjiang,China during 1961-2002
    WANG Qiu-xiang, LI Hong-jun, WEI Rong-qing, WANG Xiao-mei
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 820-826. https://doi.org/10.7522/j.issn.1000-0240.2005.0122
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    In this paper,the average and maximum depths of seasonal frozen soil and the frozen duration of soil at 10 cm deep in Xinjiang during the 40-year period of 1961-2002 are analyzed.The results show that the average and maximum depths of seasonal frozen soil decrease and the frozen duration of soil becomes short under climate warming in Xinjiang.Such changes become more significant after climate warming-wetting since 1986.A significant mutation of the maximum depth of frozen soil occurred in both south Xinjiang and north Xinjiang in the mid-1980s.
  • Regional Sensitivities of the Response to the Global Warming across China in the 20th Century
    LU Ai-gang, HE Yuan-qing, ZHANG Zhong-lin, PANG Hong-xi, GU Juan
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 827-832. https://doi.org/10.7522/j.issn.1000-0240.2005.0123
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    A Mann-Kendall trend test is carried out on the basis of the high resolution grid data (0.5°×0.5°) of time-series temperature,which are available at the Climatic Research Unit and the Tyndall Center.By comparing the mutation times of temperature across China responding to the global warming,a regular pattern of regional temperature structure can be outlined: 35°N is an approximate boundary of the two warming-up phases in the 20th century in the longitude direction.From 35°N,in the first warming-up phase the temperature mutation time occurred earlier with latitude decreasing,and in the second warming-up phase the temperature mutation time occurred earlier with latitude increasing.Along the latitude direction,the points of temperature mutation in eastern region of China are approximately accordant,but the temperature mutation times are widely different in western region of China as a result of the great influence of the Tibetan Plateau.The response time of the plateau to the global warming is much earlier in its west and northwest than that in its southwest.A detailed analysis in this paper suggests that regional responding sensitivity of temperature change is comprehensively influenced by the latitude and landform.Latitudinal is a major factor that influences the temperature sensitivity in different parts of China during the 20th century.
  • Impact of Global Warming on the Groundwater Temperature of Shallow Aquifer in the Plain Area of Central Jilin Province
    FANG Yan-na, LIN Xue-yu, LIAO Zi-sheng,
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 833-837. https://doi.org/10.7522/j.issn.1000-0240.2005.0124
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    The physical and chemical characteristics of water and the speed of water reaction can change with the changing water temperature.Taking the plain area of central Jilin Province as an example,the change of air temperature is a governing factor to the temperature variation in shallow groundwater,the function of which is cut down by the precipitation decrease and groundwater table decline.The perennial change of groundwater temperature of two hundred shallow groundwater observation wells in the plain area of central Jilin is analyzed systemically.The results show that under the circumstance of 1.5℃ increase of global temperature in the recent twenty years,the temperature of shallow groundwater in the plain area will increase 1.3℃,from 7℃ in 1978 to 8.3℃ in 2001.
  • Interdecadal Variations of Annual Precipitation in Northeast China and Its Neighborhood during Past 50 Years
    HOU Yi-ling, LI Dong-liang, SHI Ya-feng, SHEN Yong-ping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 838-845. https://doi.org/10.7522/j.issn.1000-0240.2005.0125
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    The climatic inter-decadal variations in Northeast China are analyzed and studied by using the observational data from 195 stations in Northeast China and 6 stations in Mongolia with EOF and REOF analyses and the means of separated time interval linear fitting.It is found that: (1) In the recent 50 years the annual precipitation performed the course of more-less-more in Northeast China and more-less in North China,showing that Northeast China has been changing from dry to humid while Northern China has been changing from humid to dry since the 1980s. (2) There are three precipitation patterns in the studied region: the consistent pattern in all of the sub-regions,the opposite pattern in the north and the south and the pattern with consistency in the north and south but opposite in the middle. (3) The precipitation is gradually decreasing,resulting in a worse drought of the south,but it is slightly increasing in the northeast part in the last 30 years. (4) The precipitation in most sub-regions experienced an abrupt change in the middle of the 1970s and early in the 1980s,but the changing direction,scope and time were different.
  • Dating of a Shallow Ice Core from Chongce Ice Cap Using Micro-particle Content
    HAN Jian-kang, Nakawo Masayoshi, Goto-Azuma Kumiko, ZHANG Wan-chang, Izumi Kaoru, ZHU Feng-nian
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 846-852. https://doi.org/10.7522/j.issn.1000-0240.2005.0126
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    An accurate time scale is necessary for interpretation of an ice core record.The establishment of chronology is especially difficult for sites where the conventional annual-layer counting using stable isotopes fails due to much less snow deposition.In this work,dating from the analysis of insoluble micro-particles ranging from 0.66 to 1.33 μm in diameter,in combination with the soluble Ca2+ concentration,was applied to an ice core from a middle-sized Chongce Ice Cap,West Kunlun Mountains of China.The ice core was retrieved from the summit,6530 m a.s.l.,of the ice cap.The dated core of 18.7 m in length represents about 2/5 of the total ice thickness at the drilling site.The assisting dating parameters include the measured net accumulation in the last 5 years prior to the drilling and the stratigraphic marker of atmospheric nuclear weapon test.Based on the combined techniques,a time scale covering the period of 1903-1992 was derived.The cumulative dating uncertainty by the bottom is estimated less than 2 years. This work suggests that the insoluble micro-particle takes an advantage in the dating of ice cores from Asian mountainous glaciers.The concentration in a certain size range (< 2 μm),rather than the total concentration,is more preferable.It is significant to exclude the possible "noise" of weathered mineral dust of local sources.
  • Study on Time Scale of Snow-Ice Transformation through Snow Layer Tracing Method——Take the Glacier No.1 at the Headwaters of Ürümqi River as an Example
    YOU Xiao-ni, LI Zhong-qin, WANG Fei-teng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 853-860. https://doi.org/10.7522/j.issn.1000-0240.2005.0127
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    Fresh snow transfers to glacier ice through a cold or a warm ice formation process.In China,the transformation of most glaciers takes place following a warm ice formation process.However,the time scale of the transformation from snow to ice is poorly documented in literatures.The main reason for it is of lack of long-term field observation data.In this paper,an explicit transformation period from snow to ice on the accumulation zone (4130 m) of the Glacier No.1 is given out based on a 24-month continuous observation of snow pits profiles by employing snow layer-tracing method.The study demonstrates that,in summer,the time for snow developing to fine firn is about 7 days,and the time for fine firn turning to coarse firn is about 20 days~3 months.The same transformation processes take about 2.5 months and 2~4.5 months in winters.Thus,the total snow to ice transformation age at this site is about 41~47 months.In this paper,the seasonal variability of snow layer’s movement,the relationship between movement velocity changing with snow depth and density,and the magnitude of ice formation in summer are also discussed.It is concluded that the late summer (August-September) is a main period for ice formation,and melting water greatly affects the snow to ice transformation process.
  • Geochemical Features of a Profile in Salawusu River Valley and Their Response to Global Climate Changes since 220 ka BP
    JIN He-ling, LI Ming-qi, SU Zhi-zhu, DONG Guang-rong, ZHAO Hui
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 861-868. https://doi.org/10.7522/j.issn.1000-0240.2005.0128
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    The Salawusu River Basin is situated on the transition zone between desert and loess in North China and characterized a vulnerable ecotone,which sensitively responses to the global climate change.So,the basin is an ideal zone for studying climate changes in China.Commonly,the geochemical elemental oxides and their ratio can well reflect environmental change,which have been widely applied in the researches of Quaternary environmental and climatic changes.An ideal profile-Dishaogouwan Profile in Salawusu River basin was selected to study the climate changes in North China.The vertical sequence of geochemical elements and their ratios in the profile all indicated that the climate in North China has been very unstable since the Penultimate Interglacial Period,with frequent climate changes in different time periods.The climate of whether in the Ice Age or in the Interglacial Period was unstable.The climatic indexes in the Dishaogouwan Profile showed that there were three climatic fluctuations in the Penultimate Interglaciation,seven climatic cycles in the Penultimate Glaciation,seven cycles in the Last Interglaciation,and nine cycles in the Last Glaciation.These climate changes are well accordant with the global climate changes recorded in the deep-sea oxygen isotope and the polar ice cores,showing a consistency in time of climate changes between the study area and the globe.
  • Impacts of Land Coverage on Runoff Production and Sediment Yield in the Headwaters of the Yangtze River, China
    LI Yuan-shou, WANG Gen-xu, SHEN Yong-ping, WANG Jun-de, WANG Yi-bo
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 869-875. https://doi.org/10.7522/j.issn.1000-0240.2005.0129
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    The small Zuomaoxikongqu River in the headwaters of the Yangtze River,where vegetation is simple and dominated by cold alpine meadows and alpine steppe meadows,are selected as typical catchments to study contrastively the impacts of alpine land coverage change on rainfall-runoff processes and soil erosion.The study indicates that in the field of alpine meadow with 30? slope,the runoff production in the meadow of 30% land-coverage is apparently more than that in the meadows of 92% and 68% land-coverage under the same condition of precipitation.So is sediment yield.The average sediment amount for a precipitation event in the meadow of 30% land-coverage is twice to four times that in the meadows of 92% and 68% land-coverage.Therefore,the erosion amount in the surface in the former is 3~10 times that of the latter two.Under the same precipitation,the runoff production in the meadows of 92% land-coverage is higher than that in the meadows of 68% land-coverage,and the sediment yield is just opposite.The precipitation form has a pronounced effect on the sediment yield.Solid precipitation results in more runoff production and less sediment yield.The study supports the concept of vegetation being a major control factor for runoff production and sediment yield.The simulative results of this study indicate that,for a middle-grade degraded alpine meadow land with coverage less than 68%,it will be apparent runoff production and sediment yield,when the a precipitation event reaches 3.5 mm.Runoff of 2885 mL,2450 mL and 1030 mL have been measured in the field of 25 m2,when precipitation reaches 7.2 mm and lasts 30 minutes.The sediment content in the serious degraded alpine meadow with coverage below 30% is apparently higher,on average,twice to seven times that with high coverage.
  • Correlation between Deuterium Excess in Monsoon Precipitation of New Delhi and the Origin of Precipitation
    PANG Hong-xi, HE Yuan-qing, ZHANG Zhong-lin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 876-880. https://doi.org/10.7522/j.issn.1000-0240.2005.0130
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    The isotopic data (δ18O and δD) in precipitation at New Delhi,the IAEA/WMO station in southwest monsoon region,were collected and analyzed.A few absent δD records were predicated based on the monsoonal water meteoric line,and finally the 36-year deuterium excess series was constructed by the isotopic data.The NCEP/NCAR Reanalysis Data,the relative humidity and zonal wind speed at 1000 hPa level over the western Arabian Sea,as well as the monsoon rainfall data in the northwest of India,have been used in order to explore the origin of monsoon precipitation by deuterium excess.It is indicated that the variation of deuterium excess is accordant with that of the relative humidity over the western Arabian Sea,which suggests that the vapor for monsoon precipitation in New Delhi originates mainly from the western Arabian Sea.
  • Water Resources of Inland Rivers in the Hexi Region and Their Dynamic Changes
    LAN Yong-chao, DING Yong-jian, MA Xie-yao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 881-889. https://doi.org/10.7522/j.issn.1000-0240.2005.0131
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    The Qilian Mountains is the cradle of allinland rivers in the Hexi arid region.The mountain glaciers are an important water resources for this region.Changes ofthe mountain runoffs resulted fromglobal climatewarming will have important impacts onthe development of human society and economy in the region.In this paper,the river runoffs from the Qilian Mountains and theirdynamic changes are analyzed on the basis of the instrumental data of precipitation,air temperature,and discharge from theweather and hydrologicalstations in the studyarea.The results show that the annual change in the mountain runoffs isaffected mainly by precipitation in the east of the region,but also by temeprature in the west of the region.There are some obvious regional differences in the influence of climatic change onsurface runoffsin the Hexi region.River runoffsin the western part of the Hexi region have beenincreasing,whereas thosein the easternpart have beendecreasing.River runoffs in the central part such as the Heihe River,present a slow increasingtrend,although it isnotquite visible.
  • Analysis of the Characteristics of Soil and Groundwater Salinity in the Lower Reaches of Heihe River
    LIU Wei, WANG Tao, SU Yong-hong, FENG Qi, SI Jian-hua, ZHANG Yan-wu, CHANG Zong-qiang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 890-898. https://doi.org/10.7522/j.issn.1000-0240.2005.0132
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    Using field investigations and chemical analyses (including 405 soil samples and 101 water samples),the evolution of soil salt with groundwater quality and the location change in the lower reaches of Heihe River were made clear.The soil is coarse,and the salt content is high with high surface concentration in Ejin delta.In the study area,land desertification and land salinization is serious,land resources decrease rapidly,and ecosystem environment deteriorates seriously.Soil salinity has a funnel distribution in the vertical section and it became complicated with topography changing;however,its changing trend is similar to the groundwater quality.The salinity of groundwater is usually high,varying from 800 mg·L-1 to 3000 mg·L-1.The main water chemical types are HCO3·SO4-Na,Cl·SO4-Na(Ca),HCO3·Cl-Na(Ca)SO4·Cl-Na and SO4·Cl-Na(Ca-Mg).Analyses of the samples from two longitudinal profiles(a-a’ and b-b’) show that the salinity of groundwater is close related with the distance to the river course.The far to the river course is,the high the salinity is,and the vice versa.
  • The Spatio-Temporal Variations of Land Use and Their Driving Mechanisms in Ningxia,China
    QI Yuan, WANG Yi-mou, WANG Jian-hua, YAN Chang-zhen
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 899-906. https://doi.org/10.7522/j.issn.1000-0240.2005.0133
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    Study on regional land use/land cover change with the remote sensing and GIS method is one of the important parts of the researches of global change.Ningxia Hui Autonomous Region has a special geography location,where the physical conditions characterized by much more variety,complexity and transition.The object of this paper is to analyze the spatio-temporal change of land use in Ningxia and the driving mechanisms of the change. Using remote sensing the accurate land use data is obtained.With TM image in 1990 and 2000 in Ningxia,the actuality maps of the 1990s and the 2000s are drawn by using GIS.According to the data of the 2000s,the area percentages were 46% for grassland,35.8% for farmland,10.8% for unused land,4.7% for forest,2.0% for residential area and 0.9% for water area,respectively.The land use has changed by nearly 7.8% in Ningxia from 1990 to 2000.The primary change was grassland and other land converting into farmland.Farmland area increased about 2247 km2 and grassland decreased about 2375.1 km2.Farmland had the rapidest land-use change with an annual variation rate of 0.99%;the following was residential area (0.94%).During the fourteen years,agriculture,especially farmland,and city had developed greatly;much more grassland had been dug up as farmland. Special research of land-use change was done on several regions with similar physical and social-economic condition.The change in Ningxia has a remarkable regional difference.Different land types in different regions had different transformation.In Region Ⅰ3,farmland had the largest change,1160 km2;Grassland in Region Ⅰ3 changed 1257.8 km2;forest in Region Ⅱ1 changed 85.15 km2;residential area in Region Ⅰ1 changed 85.09 km2;water area in Region Ⅰ1 changed 47.01 km2;unused land in Region Ⅰ1 changed 221.27 km2.Different land uses in different regions would bring about different physical,social and economical results.The reason causing the difference is the special physical environment and social basic. The driving Mechanisms of land-use change were analyzed by using Logistic regression.Human activity is the most important driving force.The increasing farmland is dependent on the distribution of population and the social-economic base.Altitude and slope are the second important factors rather than precipitation and temperature.The people,who live in the bad physical environment,where the irrigation and topographical conditions have not advantage to the planting,develop most new farmland. Land-use change in Ningxia causes resource and environmental problems.The first is unreasonable farmland structure.The largest farmland increase takes place in Region Ⅰ3,where precipitation is poor and terrain is cracked,but the grain yield of 80% of the total in Ningxia is in Region Ⅰ1.The second is degradation of grassland owing to estrepement,heavy feeding and denudation,and much grassland converts to low-level farmland,sand land and unused land.The last one is desertification when plant has been damaged,because of the arid physical condition,heavy evaporation and strong wind.
  • Glacial Landforms and Glaciations at the Headwaters of the Manas River in the Tianshan Mountains
    JU Yuan-jiang, LIU Geng-nian
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 907-912. https://doi.org/10.7522/j.issn.1000-0240.2005.0134
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    There are 18 cirques in the studied area (40 km2) of the Lujiaowan Glacier at the headwaters of the Manas River in the Tianshan Mountains.All these cirques can be recognized as three levels,showing that there were three times of glacier advancing of different scale.Most cirques face to north,showing that the heat-water conditions were disadvantageous for glacier developing.Cirques No.18 and No.2 face to south,which means there were good conditions for glacier developing for a long time at the periods of glacier advancing they took place. There are 10 well-conserved moraines can be recognized in the main valley,which can be divided into 5 stratum: upper moraine knap stratum,moraine knap stratum,lower moraine knap stratum,watershed stratum and forest level stratum.The upper moraine knap stratum is considered as a sediment in the Little Ice Age, and the forest level stratum is considered as a sediment in the oldest glacier advanced in the region.Judging from the morphology characteristics,the forest level stratum is considered as the deposit of the Reciprocal Third Glaciation or the Penultimate Glaciation. There were five times of glacier advancing at least in the region.The latest one was the Little Ice Age,including three phases of glacier advancing and shrinking.The two older phases were in about (1720±60) a BP and (250±60) a BP. The Neoglaciation included three times of ice advancing and shrinking,of which the first and the last one respectly occurred in (4.2±0.4) ka BP and (2.9±0.3) ka BP.The Last Glaciation included two times of ice advancing and shrinking,of which the last one occurred during 11~12 ka BP.The watershed suit and the forest level suit mean two times different glacier advancing.The watershed stratum may be deposited in the forepart of the Last Glaciation or in the Penultimate Glaciation.The forest level stratum may be deposited in the Penultimate Glaciation or the Reciprocal Third Glaciation.
  • Advances of the Geoarcheology in the Holocene
    CUI Jian-xin, ZHOU Shang-zhe, CHANG Hong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 913-919. https://doi.org/10.7522/j.issn.1000-0240.2005.0135
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    The study of the Holocene geoarcheology is one of the most important projects that have received more attention in the last few decades.A large mount of works has been conducted by the researches all over the world,which focused on the following aspects: How the Neolithic cultures impacted by the abrupt climate events,human adjustment and response to the changing environment,human interference on the nature and the relationship between the prehistoric agricultures and the environmental conditions.Many different kinds of records indicated that the extreme climate event did have made a great impact on the agricultures and the Neolithic culture systems,but human have developed some adaptive strategies under the changing conditions.With the lapse of time,the relationship between human and nature changed greatly and the human altered its passive role and turned to the strong impact and interference on the nature.Up to date,the discussions about these two issues have advanced from qualitative analysis to more accurate understand.The geoarcheology studies based on the multi-proxy data,such as the pollen,the magnetic susceptibility and the organic matter,would be more promising and animate.As an import aspect of Holocene geoarcheology,the studies on the prehistoric agricultures are so complex,which include the problems of the origin,spread and development of the agriculture.Simultaneously,the scientists have been always trying to explore the potential connections among agriculture,environment conditions and human activities.However,it has been a matter of dispute for decades.
  • An Experimental Study of the Effect of Specimen Shape on Compressive Strength of Frozen Silt
    LI Hai-peng, YANG Wei-hao, HUANG Jia-hui, SONG Lei, ZHU Yuan-lin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 920-925. https://doi.org/10.7522/j.issn.1000-0240.2005.0136
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    To explore specimen shape effects on the compressive strength of frozen silt,a series of uniaxial compressive strength tests was respectively performed on frozen silt in cylindrical and cubic shapes at the same experimental conditions.The obtained data included the relationships of stress-strain,compressive strength and failure strain.It is found that the mechanical behaviors are different between cylindrical and cubic samples under uniaxial compression.For the cubic sample,an elastic yield occurs distinctly in the initial section of the stress-strain curve,and the sample behaves linearly strain hardening after initial yield.For the cylindrical sample,the whole stress-strain curves show approximately a parabola shape and have no distinct elastic yield in the initial section.The degree of strain softening for cylinder specimens is higher than that of cubic specimens at the same temperature and strain rate.The compressive strength and failure strain of cubic specimen are higher than that of cylindrical specimen at the same testing conditions.The difference of compressive strength and failure strain between cubic and cylindrical specimens is independent of temperature and strain rates.In the ranges of tested temperature and strain rate for frozen silt,the compressive strength of cubic specimen is 0.8 times higher than that of cylindrical specimen.The failure strain of cubic specimen is 1.4 times higher than that of cylindrical specimen.This study provides an important basis for designing frozen wall in artificial freezing shaft.
  • Analysis of the Air Temperature Change Indexes Associated with the Reliability of Engineering Measurements in Permafrost Regions along the Qinghai-Tibet Railway
    ZHAO Shi-yun, ZHANG Lu-xin, WU Zhi-jian
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 926-931. https://doi.org/10.7522/j.issn.1000-0240.2005.0137
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    Permafrost is a special geological phenomenon controlled by climatic conditions.The changes of air temperature and precipitation will greatly influence on the permafrost along the Qinghai-Tibet Railway.The effects of climate changes on the reliability of engineering construction and permafrost thermal regime are analyzed and discussed based on climate changes in the global and in the Tibetan Plateau.By analysis of engineering design principles,engineering structures and reliability of engineering measurements,how to understand the reliability of frozen soil engineering is discussed.
  • Numerical Analyses of the Temperature and Stress Fields of Channel in Frozen Soil Regions
    LIU Xiong, NING Jian-guo, MA Wei
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2005, 27(6): 932-938. https://doi.org/10.7522/j.issn.1000-0240.2005.0138
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    In this paper,an elasticity constitutive model of damaged frozen soil is established.A calculation is made for frozen sand soil under different ice content and temperature conditions,using damage constitutive model,which agrees with the curves of measured stress-strain.Numerical computations are done by using the procedure developed in this study,and the computation results of moisture,temperature and stress fields of the channel are analyzed.It is found that the results are more exact and agree with actual temperature field,stress field,moisture field and strain field,and is consistent with the results of predecessors and the test results.The procedure developed in this study could calculate the related physical properties of frozen soil.In addition,it could describe the relation between the related physical quantities well,and provide a necessary reference for engineering design and construction.
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