25 May 1989, Volume 11 Issue 2
    

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  • A Pollen Profile from the Permafrost Region in Southwest Yukon Territory and Its Paleoenvironmental Significance
    Wang Xiacheng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1989, 11(2): 99-112. https://doi.org/10.7522/j.issn.1000-0240.1989.0015
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    Pollen records from peat deposits in the Middle Mackintosh Creek, southwest Yukon Territory, Canada indicate that change of pollen spectra from peat deposits can be caused by the evolution of local environmental condition related to geomorphological process. A significant decrease of Picea pollen percentages in about 20% at the upper part of the pollen diagram has been interpreted as the result of a substitution of shrub birch community for the sedges, because the change of microtopography resulted from the development of a palsa field in the bottom of valley improved the drainage condition, therefore favoured the expansion of shrub birch community which is a heavy pollen producer. Consistent values of Picea pollen concentration support this interpreation. The regional spruce forest-tundra vegetation of the creek has had little change since the eruption of White River ash at 1230 yr B. P. Accordingly, it is important to distinguish the local and regional pollen spectra in terms of the reconstruction of environmental history.
  • A Preliminary Study on Existing Snowline Tember Line and Their Relations in Southeastern Part of the Qinghai-Xizang Plateau
    Wu Xihao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1989, 11(2): 113-124. https://doi.org/10.7522/j.issn.1000-0240.1989.0016
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    The southeastern part of Qinghai-Xizang plateau is a typical region in which there are glaciers and dark coniferous forests. Some conclusions were obtained based on the study of altitudes of regional snowline, regional timber line, temperature, precipitation and their relationships: 1. Because of the decrease of precipitation from the margin to the inland of Tibet and of the temperature-rising effect of Tibet in summer, snowline and timber line rise from southeast margin of the plateau to the inland, which has interrupted the normal latitude distribution law. 2. Temperature, precipitation annual distribution of precipitation and the perantage of snow in annual precipitation are all the factors cotrolling the spatial distribution of snowline when the lo.west requirement for temperature and precipitation to form snowline were met. 3. When the lowest growth requirement for precipitation was met, the annual amplitude of temperature and its annual distribution controll spatial distribution of tember line. 4. The altitude difference between snowline and timberline, which depends on snowline controlled by precipitation, is different in different climate zones. 5. It is certain that all the glaciers in the region where there is no periglacial zone are the most typical temperate glacier, as seen in the southeast Xizang.
  • The Characterisitcs of the Present Glaciers on the Northern Slope of Mt. Qiaogeli
    Qin Dahe, R. J. Thwaites, Xie Zichu, Liu Yongping
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1989, 11(2): 125-136,194. https://doi.org/10.7522/j.issn.1000-0240.1989.0017
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    The studing region on the Northern Slope of Mt. Qiaogeli is one of the centres of existing glaciers in the mountains of the mid-latitude, where 69 glaciers existing and the total glacial area is 815.91 km2,in which 709.06 km2 area is occupied by the four largest glaciers (sikanyang Glacier, Qiaogeli Glacier, Musitage Glacier and Yinsugaiti Glacier).The investigations and measurements show that the high elevation of the region supllies the condition of low temperature to glacier is mostly precipitation caused by the Southwest Monsoon from India Ocean. Combining with the landscape factor of the topography highest mountain area, the avalanche also is a important source of the accumulation. According to hte measurements of snow pits in Qiaogeli Glacier and the comparison with the previous studes,the estimated accumulation rate in the higher mountain area is much more than 1000 mm/a, and the estimated ablation rate of ablation area is about 1-2 m or to several metres in" amount. The distribution of the formation zones from upper to the end of Qiaogeli Glacier is sequential the small cold-infiltration zone the infiltration zone,the large infiltration-congelation zone (superimposed ice zone) and ablation zone. The equilibrium line in 1986 was between 5700-5900 m.The Qiaogeli Glacier is a complex-valley type glacier. It consists of the five west firn basins and ice falls in west side, the main firn basin, the west firn basin and a long tongue. There are pyramids on the surface of the upper and the middle parts of the tongue, and the lower part of the tongue is covered by superglacial moraine. The lands cape of the surface on the four largest glaciers is as similar as Qiaogeli Glacier.The measured flow velocity of Qiaogeli Glacier shows that the highest part of the flow velocity is in the middle of the tongue, about 40 m/a, the flow velocity starts to reduce upward and down from this part, and the flow velocity is just 6 m/a near the endof the tongue. The temperature measurements in the 10 m deep ice are-6℃ at 5300 m and 0℃ at 4400 m Respectively. Based on the mentioned characteristics, the glaciers in our studing region belong to sub-continent type glacier replenished in warm season only, their features are similar to glaciers on the Northern Slope of Mt. Zhumulangma.
  • Field Observations of Water Intake Flow in Unsaturated Freezing Soils With Different Groundwater Tables
    Gao Weiyue, Xu Xiaozu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1989, 11(2): 137-147. https://doi.org/10.7522/j.issn.1000-0240.1989.0018
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    Sandy silt and silty clay with the dry density of 1.38-1.40 g/cm3 were packed in the steel cylinders. The cylinders were open at the top and sealed at the bottom and buried into ground. The soil columns in the cylinders had a water supply with constant groundwater tables and were freezing under the natural conditions. The field observations lasted 5 years. It was found that the total amount of water intake flow during freezing was lowest and highest in the sandy silt when the depth of groundwater table was 1.0 and 2.0 m, respectively, and was highest in the silty clay when the depth of groundwater table was 1.5 m. The curve of the water intake flux vs. the elapsed time of freezing had a peak value. With the increase in depth of groundwater table, the time when the peak value occured was delayed. The relationships between the water intake flux during freezing and the elapsed time and between the water intake flux during freezing and the freezing rate could be expressed in the exponential form.
  • Ice-Snow-Melt Water Debris Flows in the Dongru Longba (Gully) Bomi County, Xizang (Tibet)
    Lu Ruren, Li Deji
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1989, 11(2): 148-160. https://doi.org/10.7522/j.issn.1000-0240.1989.0019
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    The Dongru Longba, with a drainage area of 23.74 km2, and 80 km from Bomi County, Tibet, is located along the Chengdu-Lasa Highway. There are 2.06 km2 of modern glacier and snow basin. Debris flows induced by ice-snow melt water occurred repeatedly in the 1960s-1970s. The Yupu Zangbu River section of Palong Zangbu River was blocked up and changed to a lake, which destroyed the roadbed of the Chengdu-Lasa Highway.Topography in the Dongru Longba is rugged, mountain slope is precipitous, gully bed gradient is greater. The maximum amplitude from peak to valley in basin is 2500 m, average gradient of mountain slojje is above 33°, average gradient of the gullybed is 214.0%. The loose meterials storage in the basin is about 179.6 million m3. The annual average temperature in the basin is about 7℃, the annual precipitation is about 750 mm. Because of the influence of ice-snow melt water, the daily amplitude of discharge in summer is up to 3.A ice-snow-melt water debris flow occurred in the Dongru Longba on June 12, 1975, velocity below the outlet is 8.1 m/s, discharge is 562.1 m3/s, total quantity of the debris flow deposit is 12.2 thousand nv, 290 m of the Chengdu-Lasa Highway was dashed and buried, 1.5 km of the highway roadbed was destroyed by dam burst flood, it had been restored after a half month.After having analyzed debris flows in different scales in history, authors recongnize that the debris flow development tendency in the Dongru Longba is weakening, so it is suitable that bridge opining scheme of the Chengdu-Lasa Highway through the gully can deal with middel scale debris flows.The middle and long range forecast of ice-snow-melt water debris flow in the southeast Tibet, is a extremely complex problem, it has been proved from analyzing that in a period of ice-snow-melt water debris flows, relative wet-warm, wet-cold and dry-warm years are decreasingly favourable to apperance of this phenomenon, but indry-cold years, it nardly occurs. The detail explanation is that if precipition in earlier pe riod (a year or years ago, winter and spring etc.) is plentiful, the atmospheric temperature in later stage rises suddenly (0.6-1.2℃ from year to year) or temperature in spring and summer leaps up, it will first cause ice-snow-melt water debris flow taking snowmelt water as main water source, after this, lead to appearance of glacier debris flows taking ice-snow-melt water as major water source; suppose long or short rain process appears, it will quickly accelerate evolution of this nature process. This is only weather criterion for middle and long range forcast of ice-snow-melt water debris flows by authors. It will be tested in the coming practice.
  • An Analysis on the Palaeogeographic Environment and Periglacial Geomorphy During the Quaternary of Mount Huangshan
    Zhou Binggen, Zou Xueyong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1989, 11(2): 161-166. https://doi.org/10.7522/j.issn.1000-0240.1989.0020
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    Mount Huangshan is Located in the southern part of Anhui Province. Different scholars hold different arguments about the glaciation in Mount Huangshan during the Quarternary. After many times of investigation in Mount Huangshan, some types of periglacial landforms, which are rock deposition of cold period, frozen weathering substances, rock rivers, planation terrace, terrace of flow, cradle-valley, unsymmetrical valley and etc., were discovered. After analysis of the palaeogeographic environment, the authors concluded that the topography were formed by congelifraction and rivers under the monsoon-type periglacial environment during Quarternary glaciation in Mount Huangshan.
  • Application of Raised and Unventilated pile Foundation in Permafrost Regions
    Li Yingwu, Ma Weifang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1989, 11(2): 167-171. https://doi.org/10.7522/j.issn.1000-0240.1989.0021
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    The building investigated is located in permafrost area of Yitulihe on northwest slope of Da Hinggan Ling, and is the one with raised and unventilated pile foundation. After 4 years’ operation permafrost under the building degradated. Permafrost table descended 1.7 m in 3 years.To ensure the stability of the building, it is suggested that the raised and unventilated foundation must be changed to ventilated one, or the insulation layer must be thickened in order to prevent permafrost degradation.
  • The Characteristics and Forming Process of Glacial Peripheral Moraines at Gongba Glaciers in Mt. Gongga
    Kang Jiancheng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1989, 11(2): 172-176,193. https://doi.org/10.7522/j.issn.1000-0240.1989.0022
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    Based on the field observations to the glacial peripheral moraines at Gongba Glaciers in Mt. Gongga, there are differences in shapes between the younger moraines and the older ones, there are also differences at different spost. The inner-slope of lateral moraine is much steeper than the out-slope, and is pressed and abrased by the glacier.The debris becomes from less sharp to less round, in the cross sections of the lateral moraine, the debris is parallel to the out-slope surface. The grain-size analysing data show that in the inner-slope of the lateral moraine the grain-size is smaller than the out-slope, but the degree of sorting of the inner-slope is poorer than the out-slope.At the margin of glacier, the force of glacier to lateral moraine can be separated into three components, they related to the components of the velocity at the ablation area. The forces can be combined into an acting force parallel-to the lateral moraine and an acting force vertical to the moraine. The fore has a "pruning acting" to the moraine, the later forms shear plan between glacier and lateral moraine. The debris can be brought to the superglacial surface from sub-or in-glacial places, and then slips or falls on the out-slope of the moraine under the gravity. In this way, the lateral moraine is made up. In this area, there are similar characteristics and forming process between end moraine and lateral moraine.
  • General Aspect of Correction of Errors in Precipitation Measurementa Abroad
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1989, 11(2): 177-183. https://doi.org/10.7522/j.issn.1000-0240.1989.0023
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  • The Father of Permafrost Research in Canada——John Ross Mackay
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 1989, 11(2): 184-192. https://doi.org/10.7522/j.issn.1000-0240.1989.0024
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