25 June 2002, Volume 24 Issue 3
    

  • Select all
    |
  • SHI Ya-feng, SHEN Yong-ping, HU Ru-ji
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 219-226. https://doi.org/10.7522/j.issn.1000-0240.2002.0044
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    A rapid, high amplitude global climatic warming would speed global water cycle and strengthen rainfall and evaporation. Climatic warming and drying course were dominated in past about 100 years since the end of Little Ice Age in Northwest China. The strong signals of climatic shift to warm humid pattern have been appearing in the western part of Chinese Tianshan Mountains and neighborhood regions including Northern Xinjiang since 1987. Precipitation, meltwater of glacier and runoff of rivers increase continuously, and results in lake level rising, flood damaged magnification and intensified, vegetation coverage extending and dust storm weaken in western parts of Northwest China. In the other areas of Xinjiang, and the middle and western section of Qilian Mountains, the precipitations and runoff of rivers have also an increasing tendency. How is the foreground of climatic shift to warn humid conditions, it is just restricted to decadal fluctuation, or possibility to century scale shift trend, and is just limited to western Tianshan or could extend and/or wholly Northwest China down to North China? Using the results of regional climatic model simulation from IPCC and China Assessment Report published, predicting river runoff regime and similar paleoclimate scenarios for the Northwest China are analysed and discussed, and the trend of shifting warm humid climate can be fixed in recent future. However, uncertain of projected results remain, and rating and magnitude of climatic shift extending in temporal and spatial scales can not at present be projected in detail and in being exactitude.
  • LIU Shi-yin, SHEN Yong-ping, SUN Wen-xin, LI Gang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 227-233. https://doi.org/10.7522/j.issn.1000-0240.2002.0045
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Variations of global land ice are of particular interest to global change scientists and governmental authorities, which concern the effects of glacier change on worldwide sea level change, glacial related disasters in mountainous regions and water resources in arid areas. For mountainous areas like high mountains and plateaus in Central Asian, glacier melt water plays an important role in the water supply for irrigation, industrial and common life, especially, in the drought years. In this paper, a comparative analysis is performed for glacier area variation since the maximum of the Little Ice Age (LIA) in the western Qilian Mountains, Northwest China. Glacier extents in the LIA maximum and in 1956 were derived from air photos and relevant photogrammetric maps. The extent in 1990 was extracted from Landsat TM image acquired in Sept. 1990, which was geometrically corrected by coregistering to the above-mentioned maps. It is found that total glacier area in four large river basins was in average 16.9% more than that in 1956 (Table 1). The satellite image of 1990 in the north part (Daxueshan Mountains) of the western Qilian Mountains demonstrated a glacier area decrease of 4.8% compared with that in 1956. An analysis has been performed for the data of glacier inventory of the western Qilian Mountains. The analysis shows that glacier area has close relationship to ice volume, as well as to glacier length. Thus, Glacier volume and length changes between the LIA and 1956 and between 1956 and 1990 can be calculated. Calculation shows that glacier volume and length changes were about 14.1% and 11.5% (relative to the situation in 1956) from the LIA to 1956. The calculation for the Daxueshan Mountains from 1956 to 1990 was extended to the western part of the Qilian Mountains by using the derived relations. It is revealed that glacier area and volume decreased by 10.3% and 9.3% during this period, which means that there was a much stronger recession of glaciers from 1956 to 1990, and correspondingly the rivers in this region have received an extra glacial runoff of about 50?108 m3.
  • WANG Ning-lian, DING Liang-fu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 234-244. https://doi.org/10.7522/j.issn.1000-0240.2002.0046
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Through analyses of the new data of the glacier variation in Bujiagangri Section of the East Tanggula Range since the Little Ice Age (LIA), it was found that the area and volume of the glaciers during the maximum of the LIA, the 15th Century, were 24146 km2 and 19 6282 km3 respectively in the section,which indicates that the glacier area and volume have decreased by 23.7% and 15.1% respectively since then. 184 glaciers with a length of about 0.6 km have been molten away since the LIA. The absolute variation in area and volume of each glacier since the LIA increased and the relative variation decreased with size. The mean area shrinkage, the mean retreat and the mean terminus height rise of the glaciers on the south slopes were larger than that on the north slopes, which implies that the glaciers on the south slopes were more sensitive to climate change than that on the north slopes. Since the LIA, the snow line in this section has risen about 90 m, equivalent to a temperature rise of about 0.6℃.
  • ZHANG Xin-ping, YAO Tan-dong, Masayoshi NAKAWO, HAN Jian-kang, XIE Zi-chu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 245-253. https://doi.org/10.7522/j.issn.1000-0240.2002.0047
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The temporal and spatial variations of stable isotopic compositions in precipitation and their relationship with temperature, precipitation and vapor sources are analyzed in a meridianal section of the Tibetan Plateau and its adjacent regions. There is no temperature effect in the southern Tibetan Plateau and South Asia. Amount effect has been observed at New Delhi, Katmandu, Kyangjin and Lhasa that account for about a half of the statistical stations. However, the seasonal variations of stable isotopic compositions in precipitation at those stations are inconsistent with that of precipitation intensity: the maximum δ18O in precipitation usually appears in spring before the rainy season, and the minimum δ18O in precipitation is in fall during the late rainy season or after the rainy season. This distribution shows that the variations of stable isotopic compositions in precipitation are not mainly controlled by precipitation intensity in the southern Tibetan Plateau and South Asia. There is notable temperature effect in the middle northern Tibetan Plateau and its adjacent Northwest China. It has been observed that the seasonal variations of δ18O in precipitation are almost consistent with those of air temperature in these regions, which shows that temperature is a main factor controlling the stable isotopic variations in precipitation. The relationship between the weighted mean δ18O and the mean temperature on the Tibetan Plateau and its adjacent regions is not distinctly different from the global scale pattern. Comparatively speaking, during the cold season, there is a closer correlation between the weighted mean δ18O and the mean temperature on the Tibetan Plateau and its adjacent regions, with a nonlinear correlation coefficient reaching 0.9414. This probably arises because all of Asia is under the control of the strong cold high pressure over Mongolia during the winter season. The situation during the warm season is different. Although the general trend of the weighted mean δ18O with the mean temperature has not been changed, the spatial variation clearly displays that the weighted mean δ18O for the stations from Kyangjin on the southern slope of the Himalayas to the Tanggula Mountains in the middle Tibetan Plateau are all lower than the typical ones of the globe for the same temperature. As for the other stations on the middle and northern Tibetan Plateau in the north of the Tanggula Mountains and Northwest China, their weighted mean δ18O, all greater than -10.0‰, are distributed around the global regression line. Because vapor is directly originated from low latitude oceans, the relative heavy δ18O with small variation characterizes the rainfall in South Asia. A sharp depletion of stable isotopic compositions in precipitation takes place from Kyangjin on the southern slop of the Himalayas to the Tanggula Mountains in the middle Plateau. δ18O reaches its minimum due to very strong rainout of the vapor from oceans as the vapor rises over the Himalayas. From the Tanggula Mountains to the northern Tibetan Plateau, δ18O in precipitation increases with increasing latitude. Isotopes in the northern Plateau transfer into the Northwest China with little disruption.
  • CHEN Gui-chen, HUANG Zhi-wei, LU Xue-feng, PENG Min
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 254-259. https://doi.org/10.7522/j.issn.1000-0240.2002.0048
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Qinghai Province, 72.12×104 km2 in area, located in the northeast of the Tibetan Plateau, is the source regions of the Yangtze River, Yellow River and Lancang River. It ranges about 31°39’~39°19’ N, 89°35’~103°04’ E. Wetlands in the Qinghai Plateau include natural and artificial ones. The total area of the wetlands is about 55662.7 km2, 7.7% of the total area of Qinghai Province. The distribution patterns of the wetlands in the Qinghai Plateau are as follows: circle belt distribution surrounding lakes or ponds; strip belt distribution along rivers or streams; patch mosaic distribution in riverhead regions. Species of the wetland in the plateau are rich. According to statistics, there are 428 species of spermatophytes and 151 species of animals, including 73 species of birds, 55 species of fishes, 14 species of mammals and 9 species of amphibians in the wetlands. The wetland vegetation types are as follows: aquatic vegetation, swamp vegetation and swamp meadow. In recent tens years, wetlands in the plateau have a visible change, such as lake water level lowering, lake shrinking, dry of rivers or streams, degradation of swamp wetland, and so on. It is important to strengthen the conservation of the wetlands in the plateau according to its function.
  • HE Ping, CHENG Guo-dong, YANG Cheng-song, ZHAO Su-ping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 260-263. https://doi.org/10.7522/j.issn.1000-0240.2002.0049
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The strength of frozen soil depends on the join strength of soil particles and ice. Ice content or initial water content and dry density are the factors that control the strength of unsaturated frozen soil. The greater the dry density is, the greater the load bearing area of soil particles is, and the greater the strength of frozen soil will be. For a given dry density, the more the ice content is, the greater the strength of frozen soil is under unsaturated conditions. A new concept of the degree of ice saturation is suggested in the paper to explain the strength mechanism of unsaturated frozen soil. A strength prediction formula is put forward in this paper and verified by test data. The strength of unsaturated frozen soil is related with degree of ice saturated as shown in Eq. (10), which also can be expressed as a function of dry density and initial water content as shown in Eq. (11).
  • NIU Fu-jun, ZHANG Jian-ming, ZHANG Zhao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 264-269. https://doi.org/10.7522/j.issn.1000-0240.2002.0050
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The Qinghai-Tibetan Railway is the highest and longest railway on plateau in the world. The railway will cross 550 km of permafrost. Under global warming and permafrost degradation, many engineering difficulties will occur to the construction of the railway. In order to efficiently solve the problems caused by permafrost, it is necessary to deeply prospect and evaluate the engineering geological characteristics of permafrost, over which the railway will cross. In this paper the permafrost in the Beiluhe Test Field of the Qinghai-Tibetan Railway is analyzed from geological aspect. In fieldwork, as the present classification system of frozen soil has application difficulty, a practicable classification is put forward based on visible ice content in soils. Through practice and comparing with classical system, it is proved the practicable classification is reliable. Surveying shows that the soil is dominated by granule soil, and ground water is rich in the field. There are both high temperature permafrost and low temperature permafrost with rich ground ice layers, and the permafrost table is 2~3 m in depth. Such geological conditions are susceptive to engineering construction. From the above characteristics, the Test Field is classified into bad and very bad engineering geological sections. In these sections, special engineering treatment depending on geological conditions must be applied to the railway construction, otherwise potential failure might appear.
  • ZHAO Shu-ping, HE Ping, ZHU Yuan-lin, CHANG Xiao-xiao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 270-274. https://doi.org/10.7522/j.issn.1000-0240.2002.0051
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Determining creep indices and developing creep model are two main tasks of the research on creep behavior of frozen soil, one important part of frozen soil mechanics. Many researchers have engaged in this field. As a result, some creep models, such as attenuation creep model, steady creep model, gradual flowing creep model and tertiary creep model, were developed. The influence of confining pressure, maximum axial stress and loading frequency on creep properties was evaluated. The creep yield criteria were presented. However, most of these works involve the creep behavior of frozen soil under static loading condition, and involve the frozen silt under dynamic loading condition. Fewer documents involve the creep characteristics of frozen sand under dynamic loading, which will be discussed in this paper. A series of creep experiments under various conditions, namely different temperature, various frequency and different maximum axial stress, were conducted on MTS, then creep curves were drawn and creep modal was put forward. The primary creep model ε=mtλ (Vyalov) was used to analyze the first and second stages of creep. Then, referring to the creep models under static loading condition and considering the features of dynamic loading, equation ε/σn=B1+B2t1/3+B3t was used to predict the whole creep process. Comparing the two analysis methods, it can be noticed that the coefficients of two regression methods are similar. However, the latter method has the advantage of predicting whole creep process. The influence of loading, temperature and loading frequency on creep failure factors (failure strain, time to failure and minimum creep rate) was evaluated. The test results indicate: (1) Failure strain increases, time to failure shortens and the minimum creep ratio quickens with increasing axial stress. The variation rate of creep factors is different between stress less than 2 MPa and stress more than 2 MPa. (2) The lower the temperature is, the less the failure strain, the longer the time to failure and the less the minimum creep ratio will be. The variation rate of creep factors is different between temperatures lower than -10℃ and higher than -10℃. (3) No obvious frequency dependent change of the minimum creep rate was found, which seems varying within a range. But there is a trend that the minimum creep rate slightly decreases with increasing frequency. Time to failure shortens and failure strain lessens with increasing frequency. When it is less than 7 Hz, the frequency greatly influences the failure strain and time to failure. But the failure strain and time to failure slightly decrease with increasing frequency when frequency is greater than 7 Hz.
  • ZHOU Shi-qiao, NAKAWO M, HASHIMOTO S, SAKAI A, NARITA H, ISHIKAWA N
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 275-281. https://doi.org/10.7522/j.issn.1000-0240.2002.0052
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Extensive studies have been reported on the densification of dry snow, but few have been done in the densification of natural wet snow. This paper deals with the densification and grain coarsening of melting snow. A fieldwork was conducted at Moshiri, in the northern part of Hokkaido, Japan, from March to April in 1998. The work included intensively and successively snow sampling, taking snow grain photos, recording snow and air temperature, as well as measuring water content. Based on the stratigraphical records, the snow pack can be divided into 5 layers. For the surface layer, there was a daily melting freezing process in the melting season. For the bottom layer, its thickness varied with location of pit by several centimeters because of landform fluctuations and a slight bottom melting due to heat flux from the earth. Therefore only the three intermediate layers, which were 16 5 cm (LB), 38 cm (LC) and 24 cm (LD) in thickness respectively at the beginning of the fieldwork, were chosen. These three layers kept a constant temperature of 0℃ and certain water content in the study period. By regarding the snow as a viscous fluid, the following model is used: 1/ρdρ/dt=σ/ηc, where ρ is density, t is time, σ is the load and ηc is the compactive viscosity. By using the observed data and regression, the function ηc (ρ) is obtained. It is found that, the snow compactive viscosity decreases with density increase, which is opposite to the trend of dry snow. Compared with Kojimas data[25], it can be seen that the difference arises from the higher water content and grain coarsening. Based on the measurement of snow grain size, it is also found that, similar to the water saturated snow, the frequency of particle size at different times almost all have the same distribution. This reveals that the water unsaturated melting snow holds the same particle coarsening behavior as the water saturated snow does. It is shown that the water unsaturated melting snow coarsens much more slowly than the water saturated snow. The C value, which is the viscosity when the snow density is zero, is related to the mean particle size. It shows that the C value decreases with particle size increasing. It is also found that the decreasing rate of C value increases with grain coarsening rate decrease.
  • PU Jian-chen, YAO Tan-dong, WANG Ning-lian, DUAN Ke-qin, ZHU Guo-cai, YANG Mei-xue
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 282-286. https://doi.org/10.7522/j.issn.1000-0240.2002.0053
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Ice temperature observation in an ice core hole, 80 m deep, was made in Puruogangri Ice Field (6000 m a.s.l.) in October 2000 by using a thermal resistor thermometers. The observation shows that ice temperature variability in the top 2 m was dramatic under the influence of cold wave, and exhibited an abrupt change in temperature at the depth of 12 m, where the lowest temperature, around -9.9℃, appeared. The observation suggests a positive temperature gradient in the upper 12 m and a negative gradient in the lower 68 m. Ice temperature increases linearly from 12 m to 80 m deep, with a temperature gradient smaller than that in the upper 12 m deep. Ice temperature decreased in the upper 4 m during the observation, with amplitude decreasing with depth. Temperature decreased daily 0.62℃ at 0.5 m deep, 0.35℃ at 1 m deep and 0.2℃ at 2 m deep, suggesting winter cold wave being to diffuse downward, especially in the upper 2 m. However, ice temperature in the deep is mainly influenced and disturbed by geothermal heat and upward thermal diffusion. Puruogangri Ice Field is classified as an extra continent glacier due to its ice temperature. It is found that the lowest ice temperature center appears in the hinterland of the Tibetan Plateau. Ice temperature increases gradually outwards from the center.
  • YU Wen-bing, ZHU Yuan-lin, ZHANG Jian-ming, LI Hai-peng, LAI Yuan-ming, ZHANG Xue-fu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 287-291. https://doi.org/10.7522/j.issn.1000-0240.2002.0054
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In situ borehole pressuremeter tests were conducted to investigate the mechanical behaviors of permafrost along the Qinghai Tibet Highway, and the test data were analyzed. The test results show that the short-term strength parameters of several types of frozen soils are linearly related to water content and soil temperature.
  • CHEN Ren-sheng, KANG Er-si, YANG Jian-ping, ZHANG Ji-shi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 292-298. https://doi.org/10.7522/j.issn.1000-0240.2002.0055
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Using several methods of nonlinear dynamics theory, the nonlinear features of the runoff from mountainous watersheds of the main Heihe River have been described, and several hydrologic models of main Heihe River have also been developed. The variation of monthly mean runoff and the variation of annual runoff in the Heihe River agree with Weibull Distribution. Using inserting space methods, it is found that the correlation dimensionality of annual runoff is 4.32, and the least insertion dimensionality is 8. Wavelet transformation method can be used to analyze the periodic feature of annual runoff. Gray system model can be used to analyze the linear tendency of relative long series, such as the runoff in the Heihe River. The analyses show that annual runoff and monthly runoff are all increasing, especially from May to August. Recently the artificial neural network has been used for runoff forecasting extensively, of which the generalized regression neural network (GRNN) has perfect result. In this paper, some new points of this method are introduced. The input and output series may be the primordial measured one, or the one transformed to standard forms, or the one decomposed to wavelet approximation coefficient and detail coefficient one. For using GRNN model to predict runoff, several climate scenarios are supposed according to the global warming theory, or the measured series in i k time is used as input datum. These methods have been used in the runoff model of the Heihe River in this paper and their results are perfect. Time series decomposition model has also been talked of in this paper. Firstly the tendency series is separated from the ordinal runoff series by using Gray System method, and then the periodic parts of the residual series is obtained according to wavelet transformation method, and at last the stochastic part is fitted. The sum of the elongation series of each separated series should be the forecasting results of runoff. The runoff forecasting results are also perfect. The monthly mean runoff at the pass and the monthly precipitation in the Heihe River mountainous watershed has perfectly linear relationship, and the relationship between the monthly mean runoff and the monthly mean air temperature is exponential. From the relationship between the monthly mean runoff and the monthly mean air temperature, base flow can be separated, and then the effect of meltwater of glacier and snow and the liquid precipitation in the runoff formation can be worked out. Using nonlinear dynamics method, a model including monthly mean runoff, monthly precipitation and monthly air temperature of the Heihe River mountainous watershed is put forward. Using the model, the monthly runoff also can be predicted.
  • FENG En-min, WANG Jin-zhi, Li Hong-sheng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 299-303. https://doi.org/10.7522/j.issn.1000-0240.2002.0056
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    In this paper, the necessity and essentiality of parameter identification of frozen soil temperature field are explained first, based on the practical background, physical property and numerical computation need. Taking a deep ditch in winter as an example, a mathematical model of coupled temperature field is presented, then the distributed control model is given for some parameters in the temperature field equation. Since these parameters are continuous and change slowly, the identificaiton problem in infinete dimension space can be decomposed into several identification sub problems in finete dimension space. We also discuss the relationship of identification parameters and system solution of sub problems. At last the existence of optimal identification is proved.
  • LI Yu-min, SHEN Yong-ping, XUE Ji-qun, CAI Chen, SHI Bing, LI Xun, ZHOU Wen-che, LIU Wei-min
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 304-307. https://doi.org/10.7522/j.issn.1000-0240.2002.0057
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The gastric cancer has been higher in malignant tumor for many years. Factors of gastric cancer have lots of aspects, environment and diet customs are important on progressing of gastric cancer. Hexi area is an area of high disease incidence; the study on trace elements in environment is paid close attention to for exploring diseases cause of gastric cancer. Gastric cancer occurred by more factors together, the changing of some trace elements in environment is relative with gastric cancer. we took the samples in 13 countries of the Hexi region as gastric group, including 70 water samples and 70 soil samples, and took Tianshui city samples as comparison group, then determined 13 kinds trace elements by ICP AES. The result indicate that Fe and Al of water and soil samples are higher in gastric group (P<0.05), the lower are Zn、Ga、Se of soil samples(P<0.05), Ca、Zn、Ga、Sr、Se of water samples(P<0.05). The element changes of water and soil in Hexi area have relationship with gastric cancer(Fe、Al、Zn、Se).Zn and Fe may be the precacerous factor; Cu may be the result after gastric cancer. The values of Cu、Cu/Zn、Fe in serum could offer the foundation for early diagnosis of gastric cancer.
  • SHEN Yong-ping, WANG Gen-xu, WU Qing-bai, LIU Shi-yin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 308-314. https://doi.org/10.7522/j.issn.1000-0240.2002.0058
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Mountain environments are essential to the survival of the global ecosystem. Mountains provide a large variety of both ecological and physical indicators, whose combined use might serve as a unique chance to observe and detect signals of global environmental change. The Changjiang-Yellow Rivers source region is an important ecological function area for the Qinghai-Tibetan Plateau, and also serious vulnerary for environment. Climate change during 20th century has significantly affected the cryosphere. Under climate scenarios, temperature of the Tibetan Plateau may rise by 2.5~3.6℃ by 2100 or so as compared to that at the end of the 20th century. Permafrost zone will greatly change after climate warming. Their area is expected to decrease and permafrost zone will be moving upward and degrading. The area of extreme stable zone will shrink from 5.59% at present to 0.65% in 2099, stable zone from 16.32% in present to 3.28% in 2099, and substable zone from 25.5% in present to 17.43% in 2099. Area will increase with air temperature rising for transition zone and unstable zone. Area of transition zone will change from 22.85% at present to 31.01% in 2099 and that of unstable zone from 10.8% at present to 27.46% in 2099. Extreme stable zone will transform into stable zone, stable zone into substable zone, substable zone into transition zone, transition zone into unstable zone and unstable zone will be in the stage of degradation. Air temperature rising results in changing of distribution of seasonal snow cover and regime of snowmelt runoff, snowfall increasing due to air temperature rising reaches 7%~10%,the snowmelt period stretches with the shifted advance 10 days. While the discharge increases, the peak of runoff also advances to May. For a warming rate of 0.03 K ·a-1, without increase in precipitation, almost all less 4 km of glacier length would disappeared and 40% of all glaciers area here would survive until 2100. On the other hand, if the warming rate were to be limited to 0.03 K·a-1 with an increase in precipitation of 10% per degree warming, the effect of a precipitation change of this magnitude is significant, but by no means enough to compensate for the enhanced melting due to the temperature rise, we predict that overall loss would be restricted to 40% of the 1990 area; the total area of glaciers would decreased from 1168.18 km2 at present day to 700 km2 until 2001 in the source region of Changjiang River. The area and volume of the glacier will greatly decrease, which will have great impact on the ecological environment of the source region of the Changjiang River. Climate change will affect the water balance, and particularly the amount of runoff and recharge, which in turn determines the water resources available for human and ecosystem uses.
  • LI Xin, CHENG Guo-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 315-321. https://doi.org/10.7522/j.issn.1000-0240.2002.0059
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    Modeling the interaction between frozen soil and climatic system is a major focus in the field of geocryology. It is also a concern of scientists to understand the responses of frozen soil to global warming. First, different kinds of frozen soil models developed in the last decade are reviewed in this paper. The physical models based on heat transfer are suitable for engineering calculation. However, when they are applied to environmental modeling, obstruction may occur for the difficult in initialization and parameterization, because they have very fine resolution and need many parameters. GIS aided models are usually empirically based; they need few parameters. Therefore, they are easy to be used for frozen soil mapping. Then, methods of frozen soil parameterization for land surface schemes were reviewed. There is insufficient attention paid to this parameterization until recent years. Most of the literatures appeared in the later 1990’s. These parameterization are different one another. To sum up, the parameterization can be assorted into three categories. The first category only accounts for the hydraulic and thermal properties of frozen soil. The second category calculates ice production rate based on the consumed/released heat and the potential consumed/released heat in a unit volume of soil. The third kind of frozen soil parameterization uses soil matric potential to define maximum liquid water content when soil temperature is below the freezing point. In the third category, liquid water content is a function of soil matrix potential and any additional water is ice.
  • LI Zhen, YAO Tan-dong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2002, 24(3): 322-330. https://doi.org/10.7522/j.issn.1000-0240.2002.0060
    Abstract ( ) Download PDF ( )   Knowledge map   Save
    The heavy metals are good indicators of the human activity impact on atmospheric environment. The investigation of the historic records of heavy metals in the polar and alpine snow and ice is essential in reconstructing the past atmospheric cycles of these metals, and is important in determining the extent and timing of the anthropogenic heavy metal emissions. This paper reviews the progress in the studies of heavy metals in snow and ice. The available data show that human activity had led to the increases in lead and copper concentrations at Greenland two millennia ago, and these increases had become much heavier from the industrial revolution. As to zinc, cadmium and mercury, they also increase in Greenland in recent centuries. However, these trends were followed by a decrease from the 1970s. For the Antarctica, the backgrounds of Pb, Cd, Zn, Cu and Hg in ancient ice were highly dependent upon climatic conditions, the highest values occurred during the coldest periods of the ice ages, especially during the Last Glacial Maximum. Human activity led to increase in Pb and Cu concentrations during the 20th century, and a decrease in Pb has happened since the 1980s. No unambiguous evidence for human activity impact on other heavy metals can be obtained in Antarctica. On the other hand, no much work were carried on deciphering the history of atmospheric heavy metals pollution in the regions with high-altitude cold alpine glaciers in the mid-low latitudes, and the available data show that human activity impact on these regions was heavier than in Greenland and Antarctica. Although such investigations give access to an outline of human perturbation of the distribution of certain heavy metals, much effort is urgently needed to devote in future.