25 December 2017, Volume 39 Issue 6
    

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  • Analysis of sea ice area change in the Arctic and Antarctic based on the satellite climate data during 1989-2015
    ZHANG Lei, XU Bin, SHI Chunxiang, ZHOU Zijiang, REN Guoyu
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1163-1171. https://doi.org/10.7522/j.issn.1000-0240.2017.0129
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    In this research, the trends of sea ice area (SIA) and concentrations in the Arctic and Antarctic from 1989 to 2015 were analyzed by using the climate data of passive microwave satellite sea ice concentrations (SIC). The results showed that the annual SIA had decreased in Arctic and increased in Antarctic. The ratios were -0.569×106 km2·(10a)-1 and 0.327×106 km2·(10a)-1, respectively, being significant at the 0.01 confidence level. The asymmetry of trends in the Arctic and Antarctic had been obvious. The total SIA had decreased, with a trend of -0.242×106 km2·(10a)-1. The trend of annual SIC had universally declined in the Arctic, but had been obviously spatial difference in the Antarctic. The SIC had increased in the north of Weddell Sea and Ross Sea with the rate more than 10%·(10a)-1, but had decreased in Bellingshausen Sea and Amundsen Sea. There was obvious seasonal difference in monthly SIA variation in the Arctic. The SIA had obviously reduced from July to October, significantly in September, reaching -0.955×106 km2·(10a)-1. The sea ice freezing time and melting time had not completely corresponded between the Arctic and Antarctic; in the Arctic melting time and freezing time had been roughly balanced, but in the Antarctic freezing time had been significantly longer than melting time. Within a year, the variation of SIA in the Antarctic had been greater than that in the Arctic, showing significant seasonal characteristics. Changing in the minimum SIA in the Arctic had been most significant, reaching -0.636×106 km2·(10a)-1. The occurrence time of the maximum SIA in the Antarctic had moved backwards obviously, with the ratio of 0.733 pentad per decade; the occurrence time of the minimum SIA in the Antarctic had been very stable without any obvious tendency.
  • Variation characteristics of glaciers and their response to climate change in the Qilian Mountains: take the Suganhu basin as an example
    ZHOU Zuhao, HAN Ning, CAI Jingya, LIU Jiajia
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1172-1179. https://doi.org/10.7522/j.issn.1000-0240.2017.0130
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    Glaciers are important water sources of rivers in the arid regions of Northwest China. In recent decades, the glacierized area in the inland river basins in Northwest China has shrunk evidently owing to climate change, significantly impacting the water resources in these basins. In this paper, the TM/ETM+ (Level 1T) images from 1989 to 2013 were used as the data sources in the Suganhu basin in the Qilian Mountains, and the watershed ratio threshold method combined with GIS technology was taken to extract the glacier boundary data. The change trends of glacierized area and number were analyzed. Furthermore, the response relationships among summer temperature, precipitation in earlier stage (from last September to August) and glacierized area changes in glacier coverage regions, together with meteorological data, were analyzed. The results show that glaciers have retreated continuously since 1989, with a shrinking rate of about -3.01 km2·a-1 and an annual average rate of -0.87%. However, the glacierized area has changed from rapid shrinking to slight shrinking. For example, the glacierized area had retreated sharply before 2000 with a rate of -4.49 km2·a-1, while has gently retreated after 2000 with a rate of -0.09 km2·a-1. Based on the analysis of meteorological data, it is found that the rising of air temperature had been the major controlling factor of the glacier shrinkage in the basin since the 1990s, while the change in glacierized area is not sensitive to the change in precipitation in a short-term. Thus a regression equation may be established between the air temperature averaged over July and August and the glacierized area in the glacier coverage regions.
  • A comparative study of the two weather processes with cold and snowing in southern China in 2008 and 2016
    HU Yuling, ZHAO Zhongjun, KANG Caiyan, KANG Yanzhen, WANG Shigong, SHANG Kezheng
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1180-1191. https://doi.org/10.7522/j.issn.1000-0240.2017.0131
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    In this paper, a comparative study of two weather processes with cold and snowing in southern China occurred over the period from 10th January to 2nd February, 2008 and from 20th January to 25th January, 2016 was performed by using 2.5°×2.5° NCEP/NCAR monthly average data, 1°×1° FNL reanalysis data and January West Pacific subtropical ridge line and western ridge point circulation indexes from 1951 through 2016 from the National Climate Center, from the truth (precipitation, temperature and disasters), circulation conditions, energy, water vapor conditions and dynamic conditions. The following conclusions can be drawn:(1) The first event was featured as having precipitation of large areas, the process lasted long and caused heavy disaster; the second event was characterized as having precipitation of small areas, the process lasted short and caused light disaster. However, the intensity of cold air of the first event was much stronger than that of the second event. (2) The Asia-Europe circulation background of the first event was north ridge and south trough. However, in the second event the circulation pattern in low and middle latitudes was the same phase, featuring as a ridge from Siberia to Iran and a low vortex controlling China and Mongolia. (3) The temperature difference between 20 and 30 N in the middle and lower of troposphere in the second event was stronger than that in the first event. (4) The water vapor transport from south to north extended to 34° N and reached 300 hPa in the first event, but it extended to 28° N and reached 400 hPa in the second event. (5) In the first event, the water vapor at the heights of 5 000 m, 3 000 m and 1 500 m came from the southwesterly path, but in the second event the water vapor at the same heights came from the northwesterly path. (6) The vertical movement of the whole layer was small in the first event but it was extended upward to 200 hPa; in contrast, it was strong in the second event but it was extended upward to 500 hPa.
  • Comparison of precipitation observed by T-200b and standard rain gauge and precipitation change during 1980-2015 in the headwaters of Irtysh River, Chinese Altai Mountains
    HE Bin, ZHANG Wei, SHEN Yongping, LUO Guanghua, HE Xiaobo, KANG Shichang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1192-1199. https://doi.org/10.7522/j.issn.1000-0240.2017.0330
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    Assessing the observation accuracy of rainfall gauge is the first step to investigate the regional and global precipitation change. The comparison and analysis between T-200b rainfall gauge and ø20 cm standard rainfall gauge of China was carried out based on precipitation observations from 2011 to 2016 at Kuwei National Hydrological Station and Kuwei Snow Station in the headwaters of the Irtysh River basin, Chinese Altai Mountains. Then, the precipitation dataset during 1980-2015 from Kuwei National Hydrological Station was utilized to analyze the long-term precipitation change in this region. Comparison indicated that:(1) There are good relationships among daily, monthly and annual precipitations observed by the two methods; (2) The relationship for rainfall observed by the two methods is better than that for solid precipitation; (3) The relationship of precipitation observed by the two methods would get better with increasing rainfall intensity. Generally, the precipitation observed by T-200b is more than that by ø20 cm standard rainfall gauge. The annual precipitation in the headwaters of the Irtysh River had increased from 1980 to 2005, and then had slightly declined. Precipitation in cold season from November to March had significantly increased during 1980-2015, and the proportion of precipitation in cold season to annual precipitation had increased gradually.
  • Characteristics of heavy metal elements deposited on glaciers in the southeastern Tibetan Plateau
    LIU Yajun, ZHANG Yulan, KANG Shichang, LI Xiaofei, CHEN Pengfei, GUO Junming
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1200-1211. https://doi.org/10.7522/j.issn.1000-0240.2017.0133
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    Atmospheric heavy metal elements can be preserved in snow and ice. Based on the snowpit and surface snow/ice samples collected from glaciers in the southeastern Tibetan Plateau during June 2015, elements concentrations were analyzed and discussed. The results indicate that the concentrations of heavy metal elements, such as Pb and Cd, are a little lower than that recorded in snow/ice in other regions of the Tibetan Plateau, and much lower than that in Tianshan Mountains and European Alps; they are comparable to that in Greenland and Canadian Arctic, while much higher than that in Antarctica. These results suggest that element concentrations in snow/ice in the southeastern Tibetan Plateau can represent atmospheric conditions in the background of the remote area. The enrichment factors show that elements such as Pb, Cr, Cd, Cu, Zn, Mo and Sn had strongly enriched with EFs>10, while crustal elements such as Fe, Ti, Mn and Th had enriched weakly. Principal component analysis suggests that there were different sources of pollution among different heavy metal elements. Using backward trajectories analysis, it is revealed that the anthropogenic emissions from South Asia had paid a significant role on the heavy metal element enrichment recorded on the glacier snow/ice. Nowadays, glaciers on the plateau are retreating rapidly, causing abundant heavy metal elements releasing from glacier meltwater flowing into the rivers, which may profoundly affect the human life, industrial activities and ecosystem in the downstream regions.
  • Analysis of surface flow velocity on the Baishui Glacier No.1 during ablation period in the Yulong Mountain
    YAN Xingguo, HE Yuanqing, ZHANG Songlin, NIU Hewen, ZHU Guofeng, WANG Shijin, PU Tao, SHI Xiaoyi, SHI Xiaofei, QI Cuishan
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1212-1220. https://doi.org/10.7522/j.issn.1000-0240.2017.0326
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    On July 15, 2016, 16 stakes were set up on the surface of the Baishui Glacier No.1 in Yulong Mountain, in order to establish a network for survey glacial movement velocity Handheld difference GPS, TrimbleGeoXT, was used to survey the positions of these stakes. The displacement data of these stakes, from July to October in 2016, were collected and analyzed. The results show that:(1) in a transverse profile the velocity of glacier flow was larger in the mainstream line than that in both sides; in a longitudinal profile, the velocity of glacier flow gradually decreased from the terminus to the firn basin, which was different with general mountain glaciers; in the direction of glacier movement, the velocity vector is mostly moving down along the mainstream line or slightly off the mainstream line; (2) the flow velocity of the glacier was not synchronized with the change of the ablation speed of the glacier, having a lag; (3) the strongly developed ice crevasses divided the ice bodies, affecting the overall flow of the glacier and making the flow of the glacier more special; (4) the retreat speed of the glacier terminal will continue to accelerate and the retreat trend will continue.
  • Temporal and spatial distribution characteristics and changing trend of meteorologic disaster in Tibet Autonomous Region from 1983 through 2013
    XIONG Junnan, LIU Zhiqi, FAN Chunkun, ZHANG Hao, PENG Chao, SUN Ming
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1221-1231. https://doi.org/10.7522/j.issn.1000-0240.2017.0323
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    Tibet autonomous region is located on the Tibetan Plateau, where frequently occurs meteorological disasters, significantly impacting the local agriculture, animal husbandry, ecological environment. The frequent occurrence of meteorological disasters is especially harmful to the sensitive areas, such as agriculture and animal husbandry, and ecological environment. Therefore, based on the historical meteorological disaster events, it is of great significance to carry out a study of the temporal and spatial distribution characteristics and changing trend of meteorological disasters in Tibet Autonomous Region, which can be used for meteorological disaster prediction and disaster prevention and mitigation. In this paper, the annual, monthly and spatial distribution characteristics of drought, snow, frost, hail and flood disasters are analyzed through collecting information of agricultural meteorological disasters and losses in the region from 1983 through 2013. The results are as follows. In terms of temporal distribution, the frequency of the agrometeorological disaster had presented an increasing trend from 1983 to 1995. After 1995, it has changed to stationary. Drought had occurred mostly from March to June. The snowstorm had occurred throughout the year. Frost mostly had occurred in spring and early autumn. Hail and rain flood disasters had characterized of strong seasonality. They almost all had occurred from June to September in summer. In terms of spatial distribution, southern Tibet had been a high incidence area of agricultural meteorological disasters. Drought disasters had occurred mostly in the mid-eastern Xigaze Prefecture and the northern Lhoka Prefecture. The snowstorms had easy appeared widely in Nagqu Prefecture, Ali Prefecture and the southern edge of the Tibet Autonomous Region. The influence scope of frost disaster had been the least, which had occurred only in some eastern and southern areas. Hail disasters had showed zonal distribution, which had occurred mostly in the Yarlung Zangbo River basin. Storm flood disasters had been prone to occur in the mid-eastern valley areas. This research has great significance to the regional agricultural disaster prevention and mitigation.
  • Convective weather in China: quality control of the observation data and its annual and seasonal characteristics
    ZHAO Yufei, LIU Na
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1232-1240. https://doi.org/10.7522/j.issn.1000-0240.2017.0136
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    Based on the convective weather data (including thunderstorms, lightning, hail and gale) from 2 474 national meteorological stations from 1954 through 2015, the temporal and spatial variations of the convective weather in China and their climate trends were studied by using climatological statistics. The average probability of thunderstorms, lightning, hail and gale were 11.0%, 6.8%, 0.33% and 3.8%, respectively, with distinct seasonal variation. Spatially, the thunderstorms and lightning days have been gradually increasing from north to south. In the Inner Mongolia Region, the Tibetan Plateau and the coastal regions, where the average wind speed are relatively high, there are correspondingly more days of gale weather. The number of days of convective weather is decreasing. There are significant climatic decrease trends in annual variations of thunderstorms, lightning, hail and gale with 68.3% (thunderstorms), 67.5% (lightning), 0.8% (hail) and 41.6% (gale) of station number, respectively.
  • Analysis of land use/cover change and its driving force in Tomur National Nature Reserve
    Mansur Sabit, MA Guofei, ZHANG Xueqi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1241-1248. https://doi.org/10.7522/j.issn.1000-0240.2017.0137
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    In the paper, the land use/cover change and its driving force in Tomur National Nature Reserve were analyzed using GIS technology and the regional eco-environmental quality index, based on the remote sensing data of three phases. The analysis showed that in recent 27 years, glacier and grassland areas had increased with the increasing rates of 12.37% and 99.36%; water and desert areas have decreased, with the rates of 23.07% and 12.15%, respectively; forest area has decreased by 16.77% in the early phase and then increased by 57.91% in the later phase; Regional land use/cover dynamic degree has been 0.39% in the early phase and 0.36% in the later phase, with the conversion rate of 21.95% in the early phase and 18.91% in the later phase; the conversion rates of water, grassland and forest land have been higher, while those of glacier and deserted land have been lower; in spite of the internal structure changes of land use/cover type have been more complicated and frequent, the active degree of mutual transformation among different land uses/cover types has gradually gentled down. The ecological environment quality in the study area has increased, for example, the regional eco-environmental quality index was 0.479, 0.486 and 0.518 in 1989, 2003 and 2016 respectively. The average annual growth rate has been 0.31%. The main driving forces for the improvement of the ecological environment quality in the study area are the changes of climate and land use policy. Nearly 27 years, with the increase of precipitation in the middle and high mountain zones in the nature reserve, the area covered by glacier and snow in the nature reserve has been enlarged; the land use policy after the promotion of the National Nature Reserve effectively curb the impact of human activities on land use/cover, thus, the deserted land with low ecological contribution rate has transformed into the forest and grassland with high ecological contribution rate, which has greatly improved the quality of the regional ecological environment.
  • Study on the absorption characteristics of winter aerosol in Lanzhou: the distinction between black carbon and brown carbon and a characteristic analysis
    XIE Conghui, XU Jianzhong
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1249-1257. https://doi.org/10.7522/j.issn.1000-0240.2017.0138
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    The optical absorption properties and composition of non-refractory submicron aerosol were measured by the combination of aethalomerter and HR-ToF-AMS in Lanzhou, China, from 10th January through 4th February 2014. Black carbon and brown carbon from combustion were segregated by optical method. The average mass concentrations of black carbon and organics in PM1 were 3.7 μg·m-3 and 29.3 μg·m-3, respectively. Visibility decreased exponentially with the increase of BC concentration. BrC absorption coefficient increased faster than those of BC when haze became heavier. During the campaign, the absorption coefficient at 550 nm was (51.0±28.1) Mm-1 for BC and (9.9±5.9) Mm-1 for BrC, respectively. The absorption Angstrom exponent of BrC was approximately 4.4. Source apportionment of organic aerosol detected by HR-TOF-AMS was performed by positive matrix factorization (PMF) and six species of OA were identified, including hydrocarbon-like OA (HOA), cooking-emission related OA (COA), biomass burning OA (BBOA), coal combustion OA (CCOA), semi-volatile oxygenated OA (SV-OOA) and low-volatility oxygenated OA (LV-OOA). A multiple linear regression was used to calculate the relative absorption contribution of each species in OA. Thereinto, BBOA and CCOA accounted for 41.5% of the total absorption of BrC, followed by SV-OOA (32.8%), LV-OOA (14.2%), HOA(7.8%) and COA (3.8%), suggesting that POA and SOA might have contributed comparably to BrC absorption coefficient in Lanzhou.
  • Study of the anti-frost effect of heat insulation-water proof embankment in seasonally frozen ground regions
    ZHANG Wenqing, LI Chengcheng, LIU Deren, YANG Cheng, NIU Yaqiang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1258-1264. https://doi.org/10.7522/j.issn.1000-0240.2017.0312
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    Based on the numerical simulation of frozen soil embankment temperature field and combined with laboratory model test, the coupled thermal and stress calculation of heat insulation-water proof embankment was carry out, then experimental results were used to verify the calculation model. The aim was to investigate the variation characteristics of the temperature field and displacement field of the ordinary and heat insulation-water proof embankments in case of external temperature changing. Compared to the ordinary embankment, the results showed that the freezing time of the heat insulation-water proof embankment delayed about 22%, the frost heave rate reduced by 60% and the frost heave amount reduced by 35%~60%. The vertical deformation of the new embankment was smaller and smooth, the transverse deformation was significantly reduced as well. Therefore, the damage due to deformation will be diminished. So it is a better anti-frost embankment.
  • Field test study on railway subgrade against frost damage in seasonally frozen ground areas by using salt injection method
    WANG Yanhu, WANG Xu, YANG Nan, WANG Yuewu, ZHANG Yanjie
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1265-1272. https://doi.org/10.7522/j.issn.1000-0240.2017.0322
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    Based on the frost damage of Qinghai Lake section of the Qinghai-Tibet Railway, in this paper, the causes of frost damage of the subgrade are analyzed from three aspects, namely, water, temperature and soil by selecting a typical frost damage section in the seasonally frozen ground areas. According to the grouting and salt injection method, which has been applied maturely to treat subgrade disease, a new method has been put forward to treat the subgrade disease by drilling and injecting salt. Furthermore, the effectiveness of this method can be monitored by observing frost heave in-situ. The results show that the damage to the subgrade in the lake section is mainly due to a layer of silty clay, characterized with low-liquid limit and low-permeability, in the subgrade, of which the clay content and water content are high, resulting in the maximum frozen depth reaching 1.5 m; the silty clay freezing causes frost heaving to the subgrade. Based on the in-situ test, reasonable construction suggestion is put forward, including the amount of salt and its composition, construction technology and parameters. In-situ frost heave monitoring shows that the amount of frost heave in the road section which has been drilled and injected salt is significantly reduced. Thus, the method can be used to deal with the frost damage of subgrade in the seasonally frozen ground areas.
  • Study on frost resistance of EPS particles modified soil as subgrade filler in cold regions
    ZHANG Xiangdong, REN Kun, LI Jun
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1273-1280. https://doi.org/10.7522/j.issn.1000-0240.2017.0141
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    In order to study the frost resistance of EPS particles modified soil as subgrade filler in cold regions, the frost heave ratio and secant modulus were used as indicators to evaluate the frost resistance of modified soil. The relationship between frost heave ratio and the freeze-thaw cycles under different EPS particles contents was obtained by frost heave test. The attenuation law of secant modulus was obtained through the triaxial test under different confining pressures and under various freeze-thaw cycles. The dimensionless unit residual secant modulus ratio was defined to establish the relationship with frost heave ratio. The results show that the incorporation of EPS particles has a significant improvement in the frost resistance of modified soils, which effectively reduces the frost heave ratio of the modified soil. With the increase of EPS dosage, the frost heave ratio decreases gradually, and between the two there are a roughly exponential relationship. The frost heave ratio develops rapidly in the initial stage of freeze-thaw cycles, and tends to be gentle in later stage. The attenuation of the secant modulus after the improvement is greatly reduced. The secant modulus decreases gradually with the increase of freeze-thaw cycles, and the residual secant modulus ratio is approximately a parabola with frost heave ratio. The attenuation of secant modulus with the freeze-thaw cycles can be predicted by using grey theory. The model prediction results are accurate, which would be useful for frost damage prevention of subgrade engineering.
  • The flow state of South Inylchek Glacier in the Tianshan Mountains in 2016: extraction and analysis based on Landsat-8 OLI image
    LI Yi, YAN Shiyong, LI Zhiguo, ZHOU Hongyue, ZHENG Yitong, LIU Xixi
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1281-1288. https://doi.org/10.7522/j.issn.1000-0240.2017.0315
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    In this paper, the three-stage optical Landsat-8 OLI remote sensing imagery from March to September in 2016 were acquired, which covered the Tomur-Khan Tengri area in the western Tianshan Mountains. The flow velocity distribution on the South Inylchek Glacier, extracted by the spectral normalized cross-correlation algorithm, was analyzed for its temporal/spatial variation characteristics during the ablation period. The result showed that the maximum flow velocity up to~55 cm d-1 could be observed in the upper part of the glacier during the ablation period of 2016. Due to the impact of both less ice mass supply and increasing debris cover on the glacier surface, the velocity was smallest at the terminus. During the whole ablation period, the flow velocity of glacier trunk was in between 20 cm d-1 and 50 cm d-1, with an average of about 35 cm d-1. Moreover, on the contrary to the decreasing velocity in the lower part of the glacier, the velocity in the upper part of the glacier had been increasing from 9 March to 17 Sept. 2016. In conclude, compared with the earlier studies, the glacier flow velocity has slowed down and the terminus has retreated obviously.
  • Issues on criteria and methods for discriminating Quaternary glacial relics: also on the origin of the boulder-piled levees in Mount Mengshan
    WANG Nai'ang, DAI Shuang, ZHANG Lülü, YU Yingxiao, YU Xinran, TIAN Lu, YIN Liying
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1289-1297. https://doi.org/10.7522/j.issn.1000-0240.2017.0143
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    The authenticity of glacial relics in the middle-low mountainous areas, eastern China, could only be discriminated through scientific practice and academic contention. Field measured data proves no Quaternary glacial relic exists in Mount Mengshan. Furthermore, the middle-low mountainous areas in Shandong Province where Mount Mengshan locates has found no last glacial geomorphic assemblage so far, which should contain three elements of glacial erosional landform, glacial depositional landform, and glaciofluvial depositional landform. The form ratio of Lanxi Valley in Mount Mengshan, from 0.07 to 0.24, do not match the real U-shaped valleys' around the world. The scratches on the Lanxi Valley wall and the Lanmaqiang boulder-piled levee, which are considered as evidence of glacier presence, are not of uniqueness and exclusiveness. They are the result of gravel rolling, dragging, rubbing and striking along the valley. The Lanmaqiang boulder-piled levee, distributed intermittently and asymmetrically in the downstream concave bank extending downflow or linearly arranged, has landscapes of flattops paralleled to the mainstream as well as steep gravel piles and standing stones. The roundness, sorting, and fabric of gravels in the levee all point to its origin that is the boulder levee of debris-flow or the boulder-strewn bed of catastrophic flooding. The boulder-piled levee probably is the relic of group disaster caused by the Tancheng Great Earthquake on July 25, 1668.
  • Adfreezing strength at the interface between frozen soil and structure: research status and prospect
    SHI Quanbin, YANG Ping, ZHANG Yingming
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1298-1306. https://doi.org/10.7522/j.issn.1000-0240.2017.0144
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    In order to comprehensively study the progress of adfreezing strength at the interface between frozen soil and structure, firstly, the latest research results about the adfreezing strength were systematically summarized from multiple angles, such as definition of adfreezing strength, the research and development of shear instruments used to test the adfreezing strength, the adfreezing strength test under static and dynamic loads, and the numerical simulation of adfreezing strength. Secondly, the shortcomings of the existing shear test instruments were pointed out by comparing different shear test devices. The reasons of the failure of in-depth revealing the causes and damage mechanisms of adfreezing strength were put forward. The existing questions with respect to the element model of interface between frozen soil and structure, the prediction method of adfreezing strength and so on, were discussed. Finally, it was proposed to research and develop the shear test instruments for better simulating the actual working conditions. It was pointed out that the research methods in the microstructure of frozen soil should be used to reveal the cause and shear failure mechanisms of adfreezing strength. It was suggested to construct a more reasonable element model of interface between frozen soil and structure by combining experimental and theoretical deduction and to explore a more perfect prediction method of adfreezing strength based on the multi-influence factor test. Through the analysis of domestic and international research status, existing problems and their development trends related to adfreezing strength, this study will be useful for experimental studies on adfreezing strength, designs and constructions of underground engineering in permafrost regions and artificial freezing reinforcements when tunneling.
  • The research status and analysis of frozen soil interior materials based on CT nondestructive scanning technology
    ZHAO Yue, HAN Qiaoling, ZHAO Yandong, LIU Jinhao
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1307-1315. https://doi.org/10.7522/j.issn.1000-0240.2017.0145
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    Computed tomography (CT) is a wide-used technology of nondestructive dynamic scanning in medical science, which can scan the samples without disturbing the internal structures, and has been successfully applied in soil science as an effective mean for quantifying the internal structures and change of frozen soil. In this article, the achievements about frozen soil research are summarized and four key links involved in frozen soil research are introduced based on computed tomography scanning technology. They were preparation of frozen soil specimen, computed tomography image acquisition, computed tomography image processing and comprehensive analysis of frozen soil computed tomography image. In the first key kink, it is illustrated how to obtain the frozen soil specimen and has listed all the equipment used for freezing soil involved in the experiment. The aim of this link is to offer the scan specimen for the subsequent computed tomography image acquisition. The second key link is to state the principle of the computed tomography images and the development of the computed tomography machine, especially accounting for the advantages about the new generation of the computed tomography machine. In the third key link, three procedures of computed tomography image processing are mainly stated, which are computed tomography image preprocessing, computed tomography image enhancement and computed tomography image segmentation, respectively. The step of computed tomography image preprocessing offers available and manageable image for the experiment. Then, the step of computed tomography image enhancement improves image quality and supplies abundant information. At last, the purpose of computed tomography image segmentation is to divide the image into several unique area and extract the target of interest. In a word, the technology of computed tomography image processing aims at providing ideal image for the next technology, and the effect of it has a great influence on the experimental results. The last key link is the analysis about the computed tomography image of frozen soil, which offers effective internal information. Finally, on the basis of the above summary, three problems are found in the computed tomography technology in current research condition of frozen soils. The first one is the limit of computed tomography machine. There are five disadvantages about the computed tomography machine, they are cost, calibration, hardware and machine performances about gray resolution and density resolution. The development of computed tomography would be a great challenge, so it is necessary especially to illustrate the technical problems in the computed tomography image processing and combine with frozen soil science. The possible methods are put forward in order to solve the key issues above, which require the integration of advanced image processing technology and efficient image analysis into the frozen soil research. Images are presented through the method of image enhancement and image segmentation to prove the feasibility of this method. Theoretical and technical guidance are provided for the recognition and quantification of frozen soil and a foundation has been laid for wide application of computed tomography technology in the further research of frozen soil.
  • A study on the changes of soil water infiltration in alpine meadow of permafrost regions in the Tibetan Plateau
    ZHU Meizhuang, WANG Genxu, XIAO Yao, HU Zhaoyong, SONG Chunlin, HUANG Kewei
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1316-1325. https://doi.org/10.7522/j.issn.1000-0240.2017.0324
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    A typical slope of the permafrost regions was divided into three slope positions:the low (L), middle (M) and high (H) parts. The vegetation coverage of 92%, 60% and 30% for each slope position were selected as study objects to determine the soil water infiltration process by double ring infiltration apparatus. The environmental factors,which impact the process of soil infiltration, were analyzed and model simulation had done based on soil physical properties and soil water. The results showed that the soil water infiltration of different vegetation coverage in the study area had obvious difference during the freezing and thawing process of the active layer, and the initial soil water content had a good negative correlation with the initial infiltration rate. The stable infiltration rate was:vegetation coverage of 92% (0.61 mm·min-1) > vegetation coverage of 60% (0.50 mm·min-1) > vegetation coverage of 30% (0.29 mm·min-1) during the period of active layer thawing, and vegetation coverage of 60% (0.56 mm·min -1) > vegetation coverage of 30% (0.39 mm·min-1) > vegetation coverage of 92% (0.26 mm·min-1) during the beginning period of active layer freezing. The soil water infiltration rate had a significant difference among slope positions and was closely related to the freezing-thaw cycle, mainly reflected in that the infiltration rate decreased with the slope position downwards; the infiltration rate during the beginning period of freezing was less than that during the thawing period on the same slope position. During the whole infiltration stage, the cumulative infiltration at the slope top was the maximum, showing a better infiltration performance. The environmental factors influencing the infiltration of alpine meadow soil were bulk density, organic matter content and particle size. It was concluded that in the source regions of the Yangtze River the general empirical model f(t)=a+bt-n is more suitable for the period of active layer thawing to study soil water infiltration in alpine meadow in the study area, while the Horton model f(t)=ic+(i0-ic)e-kt is more suitable for the beginning period of active layer freezing.
  • Variation characteristics of precipitation events of different levels in Hotan Prefecture of Xinjiang during 1961-2015
    Bupatiman Aibaidoula, Maimaitiabudoula Yimier, Ayixiamuguli Maimaiti, Yusufu Abula
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1326-1335. https://doi.org/10.7522/j.issn.1000-0240.2017.0147
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    For studying the characteristics and changing tendency of precipitation under the effect of global change in Hotan Prefecture, daily precipitation data from seven meteorological stations, including annual precipitation (Pm), annual precipitation days (Ds), and precipitation intensity (Pi), from 1961 through 2015 were analyzed. The result revealed that the annual mean Pm, Ds and Pi had been increasing, with the rates of 3.7 mm·(10a)-1, 1.15 d·(10a)-1 and 0.046 mm·d-1· (10a)-1, respectively; Pm and Ds had a big change in 1986. 1986 was the year of climatic transition for the annual average precipitation and precipitation days in the prefecture, and so did the spring and summer precipitations, except for winter. In the prefecture, annual mean Pm was 44.0 mm, with 42.4% at the light precipitation level and 78.4% in spring and summer. Annual mean Ds was 49.8 days, with 95.3% at mini and light precipitation levels, and the summer precipitation days took 48.0% of the year-round. The result also showed that there was an increasing tendency for Pm and Ds at all levels, of which the most distinct increasing reason for Pm and Ds was the increase at light and moderate precipitation levels. Besides, the seasonal precipitation and precipitation days also had increased, especially in summer; Pi also had increased except for spring. From above analyses the following conclusion can be drawn:precipitation in spring and summer determines the annual precipitation; light level Pm and Ds are the chief forms of Pm and Ds, and Ds is the key factor to determine the Pm; precipitation and precipitation days have obvious climate change, is now at the stage of increase after the turning point; the increase of precipitation and precipitation days at light and moderate precipitation levels are the main characteristics of the present annual variation of precipitation.
  • Research and establishment of a comprehensive evaluation model of rainstorm process in Sichuan Province
    GAN Weiwei, FAN Jianglin, XIAO Tiangui, JING Fengrong, ZHAN Zhaoyu, WANG Li
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1336-1344. https://doi.org/10.7522/j.issn.1000-0240.2017.0148
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    According to a selection criteria of rainstorm process, there were 851 precipitation processes counted as rainstorm events by using the national meteorological observation from 156 stations in Sichuan Province during 1961-2013. Four indications, which were suitable for weather climate characteristics of the province, were selected to describe the torrential rain events. According to the historical return period and using the method of the Euclidean distance function, the rainstorm event evaluation model in Sichuan Province was established. A comprehensive evaluation model of the rainstorm process with clear physical significance was built to fully reflect the intensity of rainstorm process. The model has objectively considered the weight of the four indicators and their own changing rate, able to describe the process of rainstorm more scientifically. Through the evaluation and analysis of the historical rainstorm events, it is found that the evaluation result is consistent with the records of historical disasters in time and intensity. The evaluation effect is satisfactory, which can meet the demand of quantitative evaluation of rainstorm weather process in the province.
  • The spatial and temporal variation of vegetation cover in Mongolian Plateau and its response to surface hydrothermal factors from 2000 through 2014
    Wendurina, BAO Yuhai, YIN Shan, WANG Yongfang
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1345-1356. https://doi.org/10.7522/j.issn.1000-0240.2017.0149
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    In this paper, annual and seasonal variations of vegetation coverage and its response to land surface hydrothermal conditions in Mongolian Plateau during 2000-2014 were analyzed by using MODIS NDVI dataset and corresponding hydrothermal data, including land surface water index and land surface temperature. The results indicated that the annual and seasonal vegetation coverages had increased during 2000-2014 in Mongolian Plateau, especially in the Inner Mongolia Region, showing the effectiveness of the ecological restoration project. The vegetation coverage in the study area has close relationship with LSWI (land surface water index). It is demonstrated that the vegetation coverage is increasing due to a combination action of natural and human factors. The normalized difference vegetation index (NDVI) of various vegetation types is increasing too, especially in desert, but NDVI of forest increasing gently. In addition, there are seasonal differences in the influence of hydrothermal factors on NDVI of different types of vegetation.
  • Analysis of factors affecting watershed ecological compensation innovative mechanism of ecological workers: a case study in the Shiyang River basin
    SHANG Haiyang, DING Yang, SONG Nini
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1357-1364. https://doi.org/10.7522/j.issn.1000-0240.2017.0306
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    On the one hand, the introduction of ecological workers mechanism is useful for improving the practice performance of the environmental protection and maintenance project. On the other hand, it also provides economic compensation to employees who are directly involved in ecological conservation and maintenance. Especially for the residents living in ecological vulnerability areas and having a decline in income and livelihood caused by environmental protection projects (such as implementing eco-compensation of returning farmland to/animal husbandry to forestry/grass), it not only raises awareness and participates in the protection, but also enhances the initiative and participation. Though listing ten ecology professional positions related to ecological watershed protection and ecological management, and taking the Shiyang River drainage as an example to conduct a survey about basin residents recognize situation of the ecological workers, and analyze the impact factors of influencing farmers becoming ecological workers. From the survey, it was found that reasons for supporting ecological workers mechanisms include:the main source of income; works near home; doing odd jobs in slack season to supplement the family income; not to earn money, just to protect the ecological environment; and make the benefit to future generations. In the reasons of rejecting receive the ecological workers mechanisms, the reason that "having more things at home and it's too busy to participate" is the most, and the reason that "salaries cannot be guaranteed", "ecological wage is low", "although trended, it's still too technical to do" centralized distribution, the reason of "I do not care whether the ecological environment is good or bad" is less, but the direct resistant answer "there is no reason, just do not want to participate" is in a large proportion.
  • Analysis of location advantage value in Gansu Province using GIS technology
    WU Cuifang, ZHAO Qi, YI Haiying, ZHANG Linling, ZHAN Yuhui
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1365-1373. https://doi.org/10.7522/j.issn.1000-0240.2017.0151
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    The location advantage value (LAV) is an important index reflecting regional economic and social development. This paper developed a model of the LAV on the basis of the scored grid to quantitatively analyze it across the Gansu Province using GIS technology. The LAV as a function of the traffic network density, distance of traffic trunk routes and influence of main cities and towns in Gansu was determined to investigate the Gansu's total location advantage. The result shows that the LAVs in the lower level are in the most of Gansu territory accounting for 86.88%. The LAVs in the higher level are in the minority of Gansu territory accounting for 0.5%. The LAVs in the medium level are in the rest of Gansu territory accounting for 12.62%. The LAV difference in Gansu is obvious. Namely, the highest LAV of 0.86 is in Lanzhou and the lowest LAV value almost approaching to zero is in the Kazak Autonomous County of Aksay. The LAVs in the higher level are near the areas along the traffic trunk routes such as the traffic corridor from Lianyungang in Jiangsu Province to Lanzhou in Gansu Province, then to Vrümqi in Xinjiang Uygur Autonomous Region. The LAVs in the central and eastern Gansu are significantly higher than those in western Gansu. They decrease gradually from Lanzhou towards west such as Wuwei, Jinchang, Zhangye and other cities, towards east such as Dingxi and Tianshui, towards northeast such as Baiyin. The LAVs in western Gansu decrease gradually from Jiuquan and Jiayuguan towards west such as Guazhou, towards east such as Zhangye and Wuwei, towards south such as Dunhuang.
  • Study on monitoring and evaluating the cultivated land quality grade in Gansu Province based on 3S technology
    MI Chenglin, BU Chunyan, WANG Yanbin
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1374-1380. https://doi.org/10.7522/j.issn.1000-0240.2017.0402
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    In order to fully grasp the change of cultivated land quality and its driving factors in Gansu Province, in this article, a "province-prefecture-county-gradient type district-plot" monitoring system was established from the macroscopic view. Then the grade of cultivated land is divided and the driving factors are determined. Based on the monitoring in various monitoring counties, the driving factors of the cultivated land quality variation in the monitoring units were revealed and the trend evaluation of cultivated land quality was obtained. Finally, based on the change of cultivated land quality in the monitoring counties, the Kriging space interpolation method was used to estimate the quality of cultivated land in the province, and the spatial distribution of cultivated land quality was analyzed. The results show that:(1) Compared with the results of the evaluation of cultivated land quality in 2015, the average utilization rate in the monitoring counties has increased by 0.14 grade. The central region of the Hexi corridor and the southern part of the Longnan mountainous region has increased more. In the Jinling hilly and valleys, east of the Longdong loess highland and in the central Gannan plateau, the cultivated land quality has been greatly reducing, and the changes in the south has been higher than that in the north. (2) In Gansu Province, the content of organic matter in cultivated land is quite different, and low as a whole; the province's land is of dryland type, farmland irrigation guarantee rate is generally satisfied or no-satisfied; in recent years, the province has built large-scale water supply projects to make the province's cultivated land irrigation guarantee rate improved; cultivated land quality distribution regional characteristics are obvious.
  • An assessment model of farmer livelihood risk based on BP neural network
    SU Fang, LI Jingkun, XU Shaohua
    JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2017, 39(6): 1381-1390. https://doi.org/10.7522/j.issn.1000-0240.2017.0305
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    Farmers in the Shiyang River basin are faced with serious livelihood risk, which has aggravated the farmers' livelihood vulnerability. It is extremely urgent now to distinguish the key livelihood risk which the farmers are facing, explore the potential factors which has hindered the farmers to resist the main types of livelihood risk in order to seek effective measures which can improve the abilities of farmers to cope with livelihood risk. In the light of the complexity and nonlinear characteristic of livelihood risk for farmers in the basin, as well as the strong adaptability of BP neural network to nonlinear dynamic system, an assessment model with livelihood risk based on BP neural network was put forward. Meanwhile, the variances among different types of livelihood risk are calculated by entropy method based on data from practical survey. According to the above, combining the characteristics of livelihood risk of farmers in the Shiyang River basin, a evaluation system is put forward which can help to count, evaluate and determine the network structure of BP and characterization of evaluation results. Finally, the feasibility of the model was verified by an example calculation.
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