25 April 2003, Volume 25 Issue 2

    

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  A Summary of 40-Year Observed Variation Facts of Climate and Glacier No.1 at Headwater of Ürümqi River,Tianshan,China

  LI Zhong-qin, HAN Tian-ding, JIN Zhe-fan, YANG Hui-an, JIAO Ke-qin

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 117-123. https://doi.org/10.7522/j.issn.1000-0240.2003.0021

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  Comprehensive, Glacier No.1 centered o bservations are conducted at headwater of Ürümqi River by Tianshan Glaciological Station since 1959.This paper presents analyses of mass balance, terminus, area and surface velocity histories of Glacier No.1, and as well as spatial distributed streamflow and climate factor (air temperature and precipitation) records from nearby area. Our study demonstrates that the continuous local annual temperature rising, resulting in reduction of cooling energy in the glacier, might be responsible for recent acceleration of glacier melting. The headwater region of Ürümqi River is experiencing a warm and humid period ever sine the mid-90s. From 1958 to 2000, with an average annual balance -188.6 mm (about -34.6×10⁴m³ in volume), the cumulative balance of Glacier No.1 is reach u p to -7925 mm(1452×10⁴m³), in other words, the thickness of the glacier stream decreased by more than 8m over the past 42 year span. With an accelerated shrinking tendency, the glacier area decreased by 11% from 1962 to 2001. The terminus of the glacier is in the state of retreat since it has been observed from 1960s. From 1962 to 2001 East Branch retreated 168.95 m, whilst West Branch retreated 185.23 m. In agreement with ice mass losing, surface velocity of the glacier is appreciably slowing down. By using water balance model, annual meltwater runoff of the glacier has been computed sine 1958. It shows an elevated trend, especially after 1985. The mean meltwater runoff depth from 1986-2001 is 936.6 mm, comparing to 508.4 mm from 1958 to 1985, it increased by 84.2%.
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  Glacier Mass Balance Change in Tailanhe River Watersheds on the South Slope of the Tianshan Mountains and Its Impact on Water Resources

  SHEN Yong-ping, LIU Shi-yin, DING Yong-jian, WANG Shun-de

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 124-129. https://doi.org/10.7522/j.issn.1000-0240.2003.0022

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  The Tarim Basin is the biggest arid inland basin in China, it is located in Asia European Continent and far away from the sea. Tailanhe Watershed is located on the southern slope of the highest peak, Tumer, 7435.3 m asl, of the Tianshan Mountains, source from the Jong Tailan Glacier, inflow to the Tarim Basin, southern Xinjiang. The area of the watershed controlled by the Tailan Hydrological Station is 1 324 km², the existing glaciers cover 431 km² in area and 32.6% of the total watershed area. Precipitation increases with altitude, mean annual rainfall is about 683 mm, the maximum rainfall appears on glacial cover area with 1 329 mm depth. Mean annual streamflow of 1957-2000 is 7.5×10⁸m³ in the watershed, with 566 mm in average water depth. The climate is controlled by the westerly stream and air mass from Northern Atlantic Ocean and Artic Ocean pass through centre Asia and Europe, the warm season is the main glacier replenishment period. Major climatic features are a spring-summer precipitation maximum occurring simultaneously with ice and snow melt. Over the past decades years, the Tianshanin have started melting down with the increase in temperature leading to increasing glacier fed streamflow. The glacial runoff is 65% of average annual runoff in the Tailanhe watershed, mean annual glacier mass balance in 1957-2000 is -287 mm per year and total 44 years ice mass loss 12.6 m in thickness. 1982 is a key year, a dominating weaker positive mass balance character shift to strong negative phase, and mean annual mass balance changed from -168 mm per year in 1957-1981 to -445 mm per year in 1982-2000. A sensitivity test shows that 1 ℃ annual air temperature change will cause 300mm glacier mass balance fluctuation, and 16% amplitude of average annual runoff. As global warming, the glacier melts strengthening and meltwater increasing rapidly, more water resources supply to arid Tarim Basin. In the Xinjiang area, the climate is affected mostly by the westerly current coming from the Atlantic Ocean and the Arctic Ocean. The Northern Atlantic Oscillation and the Arctic Oscillation indices affect the precipitation, temperature and glacier mass balance variations of the Tianshan Mountains. The climate shift in northwest China is linkage to NAO/AO strength change, a reason of the causes.
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  Characteristic of Present Warming Change Recorded in Malan Ice Core,Central Tibetan Plateau

  WANG You-qing, PU Jian-chen, ZHANG Yong-liang, SUN Wei-zhen

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 130-134. https://doi.org/10.7522/j.issn.1000-0240.2003.0023

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  Climate change since the 1920s was rec onstructed based on annual δ¹⁸O from a 102.07 m ice core recovered from the Malan Ice Cap in Hoh Xil region in the central Tibetan Plateau in May 1999. The Malan ice core shows that warming trend during the 20th in central Tibetan Plateau is similar to the warming of the Northern Hemisphere. The warmest period recorded by the core was during the 1950s to the early 1980s. There are also several colder stable periods punctuated through the warming, especially, the climate during the late 1980s to 1990s was colder, maybe caused by the strong summer monsoon. The record also suggests that there were some short terms with cooling fluctuation, which might appear in some regions during the rapid global warming in the latest 20th century.
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  The Present Facts and the Future Tendency of the Climate Change in Northwest China

  LI Dong-liang, WEI Li, CAI Ying, ZHANG Chun-jie, FENG Jian-ying, YANG Qing, YUAN Yu-jiang, DONG An-xiang

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 135-142. https://doi.org/10.7522/j.issn.1000-0240.2003.0024

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  Based on the data observed from the meteorological stations in Northwest China for the periods from the year of beginning observation to the year of 2000 and NCEP/NCAR reanalysis monthly mean data, the characteristics of the present climate change in Northwest China have been comprehensively analyzed. The study reveals the observed evidence of the climate transition from the warm dry pattern to the warm wet pattern. And the tendency of the climate change for the future multi-decades have also been estimated in this paper.
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  Changing Features of Precipitation over Nothwest China During the 20th Century

  SONG Lian-chun, ZHANG Cun-jie

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 143-148. https://doi.org/10.7522/j.issn.1000-0240.2003.0025

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  The precipitation dataset for global land from 1900 to 1998 presented by Dr. Mike Hulme (Climate Research Unit, East Angles University, UK) is the longest global precipitation dataset available now. The evolutional trends of precipitation were studied by using the long historical data in the 20 th century in Northwest China. It is found that the mean precipitation appeared a downward trend from the beginning of the 20 th Century, but a slight upward trend appeared in the end of the 20 th Century. The interannual trends of precipitation between the East and the West showed a contrary variation. In the end of the 20 th century, the mean precipitation appeared an obviously upward trend in the central and western portions of Northwest China, but in the east the mean precipitation continuously decreased, many drought events have happened.
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  Spatial and Temporal Distribution of Water Vapor and Its Variation Trend in Atmosphere over Northwest China

  YU Ya-xun, WANG Jin-song, LI Qing-yan

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 149-156. https://doi.org/10.7522/j.issn.1000-0240.2003.0026

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  The interannual and intermonthly variation of the water vapor and its mean transfer in the atmosphere over Northwest China are calculated and analyzed by using the NCEP/NCAR global reanalysis grid data(2.5°×2.5°Lat/Lon) for 43 years (1958-2000). The results show that: (1) The climatic averaged water vapor in whole air column over Northwest China is concentrated in the east and west areas, respectively, with the maximum in summer and the minimum in winter. In the east areas water vapor is most abundant and stable, while in the west areas, such as the Tarim Basin and north part of the Tianshan Mountains, water vapor prominently varies with course, which changes seasonally. The climatic moisture over the middle of Northwest China is the least, especially over the west and north parts of Qinghai Province. (2) The water vapor over Northwest China mainly comes from the southwest warm and wet air flow over South China Sea, Arabian Sea and Bay of Bengal, subjected to the influence of the Tibetan Plateau’s lifting force, forming three vapor transfer centers over eastern, middle and western parts of the plateau, respectively, with the strongest one located in eastern part of the plateau along the gorge of Yarlung Zangbo River. Another one comes from southeast warm and wet airflow over the Qinling Mountains in eastern Sichuan Province and southern Shaanxi Province, and the third one is the northwest moisture from Siberia and Mongolia during spring and summer. (3) On the average, the water vapor over Northwest China decreases obviously during the late 1950s to the middle 1980s, but it has being increasing since the late 1980s. The vapor increasing areas are mainly located in Tarim Basin, Northern Xinjiang Region and eastward along Hexi Corridor to the middle Qilian Mountains, while the vapor decreasing areas are located in the middle and eastern parts of Northwest China. (4) For the decadal scale of climate change, the water vapor in most parts of Northwest China decreased during the 1960s to 1970s, but increased obviously during 1980s to 1990s, especially in western parts of Northwest China, where the increasing rate of vapor reached 0.8～1.6 mm·10 a^-1. (5) Finally, the climatic dynamical factors influencing vapor distribution and transfer over Northwest China are discussed. Subjecting to the impact of increasing Mongolia anticyclone located in north side of Northwest China, the westerly at 500 hPa decreases and the southerly increases obviously over western parts of Northwest China, but the northerly at 500 hPa increases and the southerly decreases obviously over eastern parts of Northwest China. This may be one of the causes resulting in interannual variation and transfer of water vapor in atmosphere over Northwest China.
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  Impact of Global Warming on Autumn Precipitation in Northwest China

  ZHANG Cun-jie, GAO Xue-jie, ZHAO Hong-yan

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 157-164. https://doi.org/10.7522/j.issn.1000-0240.2003.0027

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  On the background of global warming, the spatial and temporal variation characteristics of autumn precipitation were analyzed in Northwest China; major influencing factors were also studied. It was found that the catastrophe of autumn precipitation is more obvious than that in other seasons. The interannual variation of precipitation presents a contrary trend between the East and the West. In the autumn of El Nino years, Xinjiang ridge is intensified, India-Burma trough is weakened, and the east of Northwest China is dry. The case of La Nina years is opposite. Numerical simulation experiment has been carried out with doubling CO₂ using the regional climatic model. The results show that in west of Northwest China, precipitation will increase in summer, but it is not obvious in autumn; in east of Northwest China, the case is opposite, autumn precipitation will increase obviously.
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  Climate Change Due to Greenhouse Effects in Northwest China as Simulated by a Regional Climate Model

  GAO Xue-jie, ZHAO Zong-ci, DING Yi-hui

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 165-169. https://doi.org/10.7522/j.issn.1000-0240.2003.0028

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  Climate change due to greenhouse effects (2×CO₂) over China, with focus on Northwest China, is simulated by RegCM2 regional climate model (RCM). The model has a horizontal grid point spacing of 60 km and 16 vertical layers, and is nested to a global coupled ocean-atmosphere model (CSIRO R21L9 AOGCM). Driven by lateral boundary conditions from the GCM, both control (1×CO₂) and sensitive (2×CO₂) experiments of the RCM have been run for 5 years respectively. Model outputs are interpolated in 34 stations in the region for convenience of analysis. Results of control run of the RCM indicated that it has a better capability in reproducing present climate in both the whole China and Northwest China than that of the GCM. It reproduced the fine scale structure of air surface temperature (T_s) caused by small topography fluctuations, and lowered down the over-estimated precipitation (P_r) by the GCM. The annually averaged spatial correlation coefficient of the monthly mean T_s and P_r between the RCM simulation and observation are 0.80 and 0.85, respectively. Results of sensitive experiment by the RCM with 2×CO₂ showed a remarkably warming over Northwest China due to greenhouse effect. In Northwest China, mean T_s will increase 2.7 ℃, higher than that in the whole China (2.5 ℃). The warming is higher in winter and spring, about increasing 3.0 ℃. Rising of T_s can be noticed in all the 12 months of a year. The summer daily maximum temperature also increases in Northwest China, with an average increasing of 3.1 ℃, higher than the average over the whole country, 2.0 ℃. While the winter daily minimum temperature raises 1.6 ℃, near the average over the whole country, 1.7 ℃. More rainfall may also be expected over the region under the greenhouse effect. Increasing rate of annual P_r is usually greater than 20% in most of Northwest China, and 30% or more in some places. The mean P_r increase is 25 % in Northwest China, much higher than that averaged over the whole China (12 %). Increasing rates of P_r follow the order of winter, spring, autumn and summer. The P_r increase is found in all months, except for September, when a slightly decrease appears. T_s and P_r change by month is also given in this paper for some representative stations in different parts of Northwest China. The simulated change of T_s and P_r under 2×CO₂ showed some similarities with observation in the recent years.
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  The Evidences and the Causes for the Shift of Climate Pattern in Northwest China During This Century

  TANG Mao-cang, GAO Xiao-qing, ZHU De-qin

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 170-173. https://doi.org/10.7522/j.issn.1000-0240.2003.0029

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  Whether the climate in Northwest China is shifting or has been shifting are not only a scientific issue, but also an important factor to regional, even national, social-economical development and ecologic construction. Standing on the viewpoint of earth system, the issue on climatic shift has been discussed in this paper. After analyzing the periodicities of climate change in Northwest China by using data of Length of Solar Cycle, pollen and ice cores, it is found that the climate in Northwest China has completed the transferring from cold to warm, a new millenarian wet period will begin since 22^nd century, and the climate in the east part of Northwest China will turn to wet after 2020.
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  Changes in Air Temperature and Evaporation in Xinjiang during Recent 50 Years

  SU Hong-chao, WEI Wen-shou, HAN Ping

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 174-178. https://doi.org/10.7522/j.issn.1000-0240.2003.0030

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  After lot of researches, it is found that the climate in northwest China is changing from the warm-dry type to the warm-wetting type since 1987. In this paper, the two important climatic factors, i.e., the air temperature and the evaporation in the different regions of Xinjiang in recent 50 years are analyzed, and the scientific facts affecting the climate change from the warm dry type to the warm-wetting type are discussed. Based on the observation data collected by 77 hydrologic and meteorological stations in Xinjiang, the analyzed results show that the air temperature in Xinjiang has increased in recent 50 years, and the average increase amplitude is 0.27 ℃.10·a^-1. The average annual temperature has obviously increased since 1987 than that before 1986, especially the increase amplitudes are as high as 0.6～1.6 ℃ in the western and northern parts of north Xinjiang and in east Xinjiang. The change amplitude of air temperature is highest in winter and lowest in summer, however, the air temperature increases generally in all the seasons. The change of the annual evaporation and the aridity index in Xinjiang is in a decrease trend, which reveals that the signals of climate wetting have occurred.
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  Precipitation Signal of the Climatic Shift in Xinjiang Region

  HAN Ping, XUE Yan, SU Hong-chao

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 179-182. https://doi.org/10.7522/j.issn.1000-0240.2003.0031

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  In accordance with the advanced scientific issue of climatic variation, it is systematically discussed the precipitation variation regulars of Xinjiang in this article. According to the hydrometric data provided by the 61 national hydrometric stations, within 5 years, through the way of the moving average, residual mass curve, linear variability and so forth, to analyze and calculate the precipitation variation of Xinjiang in recent 50 years. Results shows that among the 61 national hydrometric stations, the variation precipitation of 46 is trend to increase, making up 75% of the total stations, the average increment is 0.3 2.8 mm·a^-1. Of which ,the upper parts of the exit mountain pass of south Tianshan mountain,Yili Prefecture in west areas of north mountain and east mountain areas are increased greatly, the average increment is reached to 1.0 2.8 mm·a^-1. thus it can be seen that the precipitation in the most area of Xinjiang is mainly trend to increased, especially in the mountain areas, looks from the yearly variation, the precipitation of Xinjiang in the sixties, seventies is in decrease stage, in the eighties, it began to increase, and enter the transition period, and in the nineties, it is trend to increase year after year, of which, the yearly maximum mean precipitation of each station is appeared in the eighties or nineties, and most of them in mountain areas, the increasing range in mountain areas is higher than plain, west areas higher than east areas. Through analysis the residual mass curve of annual precipitation of each station, we know that the precipitation of Xinjiang is began to increase mainly in the end of the seventies to the middle of the eighties, of which, the precipitation of most station is increased during 1986 1987, making up 75% of total researched station. Therefore, the transition years of precipitation from decrease to increase is round about 1987.on the basis of this, bounded from 1987, we have compared and analyzed the average value of annual precipitation of Xinjiang before 1986 and after 1987 of each station of Xinjiang, and reached that the precipitation of Xinjiang is varied greatly in round about 1987, all are increased in a great extend. Thereby, it is shows that the forceful signal of climatic variation of becoming warm is not only reflected in the west mountain areas of Xinjiang, but also reflected in whole regions in a different extend, the growth rate of south Xinjiang is higher than north Xinjiang, west areas higher than east areas, and it is just the precipitation variation regulars of Xinjiang.
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  The Signal of Climatic Shift in Northwest China Deduced from River Runoff Change in Xinjiang Region

  ZHANG Gou-wei, WU Su-fen, WANG Zhi-jie

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 183-187. https://doi.org/10.7522/j.issn.1000-0240.2003.0032

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  Under the global warming, mainly in the middle and west regions of northwest China, the climate is characterized basically with the development of warm-dry since the ending of the Little Ice Age about during 1860s to 1880s until 1980s. While a climatic shift to warm-wet happened in 1987. Since 1980s, air temperature has been increasing more rapidly. The average air temperature during 1987 to 2000 had risen by 0.7 ℃ as compared with that during 1961 to 1986. During 1990s, it is the warmest period in recent 1000 years, its temperature is 0.8 ℃、0.7 ℃ and 0.5 ℃ higher than that of 1960s, 1970s and 1980s respectively. Nevertheless, going with the rapid rising of air temperature, precipitation and glacial melt water increase also rapidly widespread. As compared with the period from 1961 to 1986, the average yearly precipitation during 1987 to 2000 increases by 22% in the north Xinjiang, 33% in the south Xinjiang, 12% in the Tianshan Mountains. Along with the increase of precipitation, the hydrological conditions and ecological environment are also correspondently changed. Most rivers in Xinjiang, have experienced the trend of yearly runoff increase since 1987, and the increase range is averaged at more than 5%, and is above 20% in most regions and the maximum increase range arrives at 40% from the years of 1956 to 1986 and to the years of 1987 to 2000. The increasing trend is quite clear in the Tianshan Mountains, and is clear, more or less, in the other areas. However, the changing trend is slightly decreasing in the Kunlun Mountains. Based on analysis of annual runoff variation, a signal of climate shift from warm-dry to warm-humid can be seen in the Tianshan Mountains, but in the other areas it seems still in the process of climatic shifting. Further work is required to improve the ability to detect, attribute, and understand climate change, to reduce uncertainties, and to project future climate changes. Adapting the change of the climatic pattern, we have to promote that which is profitable and abolish that which is harmful, have to enhance the high efficient utilization of water resources and ecological construction, have to emphasize the construction of mountain reservoirs to regulate runoff and to reduce the flood disasters and to improve the utilization ratio of water power.
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  Responding of River Streamflow to the Climate Shift in the Hexi Inland Region

  LAN Yong-chao, DING Yong-jian, SHEN Yong-ping, KANG Er-si, ZHANG Ji-shi

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 188-192. https://doi.org/10.7522/j.issn.1000-0240.2003.0033

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  In Northwest China, climate warming and drying dominated the past 100 a. In the middle Tianshan Mountains and the eastern Qilian Mountains, temperatures rose 1.3 ℃ and 1.0 ℃ and precipitation decreased 50～65 mm and 70～85 mm, respectively, until the 1980s. The result of tree-ring study shows that the negative precipitation departure in the north Uygur Autonomous Region of Xinjiang reaches -11.8% during the period from 1920 to 1978. In the last 50 a, the measured hydrological and meteorological data indicate that air temperature in West China rises with a mean rate of 0.2 ℃ per ten years. In northern Xinjiang, air temperature rising even reaches 1.4 ℃ in the last 50 a, which exceeds greatly the mean rise range of 0.4～0.8 ℃ of global air temperature rising in near upon 100 a. The while, precipitation in the west part of Northwest China and North China decreased and many rivers in northwest arid areas of China all appeared a fluctuant downtrend during the period from 1951 to 1989. Water level of the Qinghai Lake has descended from 3250 m a.s.l. in 1908 to 3 193.78 m a.s.l. in 1986, definitely showing a warm dry trend of climate change in the west of China. But the observed data of some meteorological and hydrological stations have showed that climate of Xinjiang, located in the west of Northwest China, send out a signal of climate shift from warm dry to warm humid. Hexi inland arid region is adjacent to Xinjiang. Especially, the Shulehe River basin, located in the west of the region, similar to Xinjiang, located in the middle latitude westerly belt, where precipitation is under the influence of Atlantic vapor carried by westerly; Again the Heihe River basin in the middle of the Hexi inland arid region is located in the transition area between westerly belt and east Asia monsoon zone, where precipitation is also under the influence of Atlantic vapor. So climate change in the Hexi inland region should have a quite consistency with Xinjiang, having a climate shift from warm-dry to warm humid. Water cycles will be exquisite with global warming, bringing on further precipitation. Global temperature has risen since the 20 Century, because of increase of CO₂ and other house gases in atmosphere, which accelerates global warming. Concretely,there appears a fluctuant, warming and drying trend in northwest arid regions of China. But analyzing the change process and trend of the mountainous runoff in the Hexi inland region revealed that the climate-environment of the region relates a clear signal of climatic environment shift from warm dry to warm humid beginning from the 1980s. The signal concretely shows an increase in mountain runoff with air temperature rising and precipitation increasing in mountainous area. Prediction and calculation from some regional climatic models and hydrologic statistic models also approve the shift. Besides, Shiyanghe River in the east of the region and under the influence of east monsoon still not occurs such a shift signal, where the mountain runoff has continuously decreased since the 1950s, indicating the climate environment still developing towards warm dry.
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  Hydrological Elements Change of Qinghai Province in Past 50 Years

  YAN Hua-yun, JIA Shao-feng

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 193-198. https://doi.org/10.7522/j.issn.1000-0240.2003.0034

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  By use of gauged data series of representative stations, the evolution characteristics of precipitation, runoff and evaporation of Qinghai Province in past 50 years are analyzed and following conclusions are reached: 1) Precipitation in the area to the north of Kunlun Mountain, Bayan Har Mountain and Daban Mountain obtained presents an increased trend, precipitation on the west of A’Nyêmaqên Mountains and Riyue Mountain with Qiadam Basin have the greatest increase, and the result show the changes of precipitation have not the clear trend in other regions except Huanghe Basin which experienced a minute trend of decrease in precipitation; 2) Runoff in the south of Qiadam Basin present a trend of increase, runoff in Qinghai Lake Basin and Huanghe Basin except one of its branch Datong River present a trend of decrease, and no clear trend in other area; 3) Water surface evaporation, besides one station (Qiaotou Station) in Huanghe Basin, almost all increased everywhere in past 50 years; 4) Because of the lack of gauge stations in mountain areas and the violent spatial variance of water balance factors, we should set more gauge stations in mountain areas to get more detail information and make the change characteristic of water balance factors more clear.
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  Preliminary Approach on the Floods and Their Calamity Changing Tendency in Xinjiang Region

  WU Su-fen, ZHANG Guo-wei

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 199-203. https://doi.org/10.7522/j.issn.1000-0240.2003.0035

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  Floods and their calamity in Xinjiang Region may apparently reflect the climatic shift from warm dry to warm humid in Northwest China. Therefore, frequencies of exceed standard flood and floods with possibility of 5% and 2% are worked out from statistics of annual maximum floods of 29 rivers in Xinjiang Regions. The changing tendency and regional distribution of the floods was analyzed. It is found that the flood amount and frequency have been increasing since 1987. By analyzing the frequency of calamity flood and comparing their calamity losses, it is believed that calamity floods, especially rainstorm floods and catastrophic floods, have been increasing since the 1990s. The loss due to calamity foods in 1987-2000 increased 30 times as compared with that in 1950-1986, causing serious damage to the national economic construction, as well as to the life and properties in Xinjiang Region.
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  Flash Flood Event of July,2002 in Weigan River Watershed,Xinjiang,China

  HUANG Jian, MAO Wei-yi, LI Yan, WANG Shun-de

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 204-210. https://doi.org/10.7522/j.issn.1000-0240.2003.0036

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  As the global warming, water cycle accelerating, frequent and intensity of flood occurred tend to increasing and more damage in Xinjiang region. Floods are among the most frequent and costly natural disasters in terms of human hardship and economic loss. A flash flood is typically defined as flooding that occurs within short time of a heavy rain event. In Weigan River watershed on the southern slope of the Tianshan Mountains, Xinjiang, a heavy rain and snow weather process were spawned by an influx of moisture from the westerly in July 2002. During the more 30 hours period from 08 am July 22nd to 08 pm July 24th, 20～30 mm of rain were measured in the official recording rain gauge at lower and middle mountains and plain region of Weigan River, and more 50mm in high mountains of Tianshan. Heavy rain fell leaded to causing rapid rises of water in a short amount of time, 5 branch streams and main stream of the Weigan River caused the largest peak discharge of the historical recording data, and 2～3.5 times over the alerting and risking discharges. The storm weather process bring water to flooding in the Weigan River watershed, and the largest peak discharge source from the storm rain fell in the lower and middle mountains. The continues melting snow combined with storm precipitation rates in high mountains lead to large inflow to the reservoir, and a showery weather can tap continuous in prophase, low-level moisture inflow and outflow increasing from the ground were combined to contribute the flood. The storm peak flood simultaneous with melting snow peak flood, and simultaneous peak floods from four branch streams over Tokxun of the Muzart River, and simultaneous inflow flood from the two rivers to the reservoir are main the cause of the large flooding occurred in the watershed. The largest inflow peak discharge was up 3 660m³·s^-1 in the Kezir Reservoir, and outflow peak discharge was only 1 000m³·s^-1, and reducing 72.7 % of peak discharge.
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  Climate Change Indicated by the Recent Change of Inland Lakes in Northwest China

  GUO Ni, ZHANG Jie, LIANG Yun

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 211-214. https://doi.org/10.7522/j.issn.1000-0240.2003.0037

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  Inland lakes are sensitive indicators of climate change. High mountain lakes, due to less influence from human activity, can reflect the climate state accurately. On the other hand, the lake at the end of an inland river may change under the effect of both the human activity and the natural variation. In this article, area changes of some inland lakes in Northwest China in recent years were analyzed using data from NOAA/AVHRR and EOS/MODIS. The results show that the Har Lake in higher west part of the Qilian Mountains is expanding; the Big Sugan Lake and the Small Sugan Lake in lower west part of the Qilian Mountains are stable. There is more precipitation in the Heihe valley in 2002. The area of inland and higher mountain lakes in Xinjiang increases notably in 2002. This suggests an increase in precipitation and meltwater of snow and ice in these regions. Attention should be given to these changes.
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  Study on Hydrological Features of the Kaidu River and the Bosten Lake in the Second Half of 20th Century

  LI Yu-an, TAN Yuan, JIANG Feng-qing, WANG Ya-jun, HU Ru-ji

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 215-218. https://doi.org/10.7522/j.issn.1000-0240.2003.0038

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  Kaidu River is the largest river in the Bayinguolen Prefecture, Xinjiang, supplied by snow ice melting water and rainfall, with the total length of 560 km. There are 722 glaciers with total area of 445 km² and total water amount of 22.4 km³ in this watershed. By analysis, the glacier melted water and the ground water still share a larger amount of the total water discharge of Kaidu River even in the abnormal plentiful runoff year of 2000. The seasonal distribution of the rivers water discharge, however, is the same as those in other years. Kaidu River is the main recharge source of Bosten Lake, which plays an important role in the eco-environment of the lake. According to the surveying data, the total salts amount of Bosten Lake has increased from 75×10⁴t in 1958 to 210×10⁴t at present, owing to the increase of the agricultural waste-water channeling into the lake. It is the mean reason of that the lake is always in the high level of the mineralized degree. Since the late of 1990s, the lake water level has returned to that in 1950s, and even to the highest one in the history due to enhancement of the environmental protection and increasing of the water discharges of Kaidu River.
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  Influence of the Warm-wet Climate on Sailimu Lake

  MA Dao-dian, ZHANG Li-ping, WANG Qian-jin, ZENG Qing-jiang, JIANG Feng-qing, WANG Ya-jun, HU Ru-ji

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 219-223. https://doi.org/10.7522/j.issn.1000-0240.2003.0039

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  Located at the west of the Tianshan Mountains, the southwest of the Junger Basin, Sailimu Lake is the largest alpine lake in Xinjiang with a catchment area of 1 408 km², lake area of 457 km². Its maximum depth reaches to 86 meters, and total water capacity is 210×10⁸m³. The altitude of the lake is 2 073 m. Surrounded by high mountains, it is an occluded lake. Since 1980s, there is a warm-wet trend of the climate in Sailimu Lake and its neighboring areas, indicated by increasing of the precipitation and rising of the air temperature. According to the meteorological records, the mean decadal temperature in 1980s is 0.4～0.6 ℃ higher than the mean temperature in former 20 years.The mean decadal temperature in 1990s is 0.3～0.4 ℃ higher than that in 1980s, 0.7～1.0 ℃higher than the mean temperature in former 20 years, and 0.6～0.8 ℃ higher than he mean temperature in former 30 years. In 1990, the precipitation amounts at Qiedeke station and Piliqing station are 5.4% and 7.0% more than the multi-year mean values respectively. At Wenquan station, precipitation in 1990s increases about 20.3% compared with the annual mean value. The correlation coefficient for the precipitation between the Sailimu Lake Meteorological station and the Wenquan Station is 0.948, which means that increasing of the precipitation and runoff in neighboring area will be a indication of increasing of those inSalimu lake. Therefore, the water level of Sailimu Lake will certainly rise because of the influence of the warm-wet climate.
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  Analysis on Causes of the Water Level Variation of Ebinur Lake in Recent 50 Years

  WANG Qian-jin, Bayinchahan, MA Dao-dian, ZENG Qing-jiang, JIANG Feng-qing, WANG Ya-jun, HU Ru-ji

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 224-228. https://doi.org/10.7522/j.issn.1000-0240.2003.0040

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  Three stages, rapid shrunk from 1950 to 1977, remained stable in 1980’s and escalated in 1990’s, have been experienced in the process of evolution of Ebinur Lake in recent 50 years. During the period of 1950-1977,the lake area shrunk rapidly from 1 070 km² to 522 km² due to large amount of the river water were drawn into the cropland. In 1980s, the lake area remained stable at about 500 km² . Main causes for this can be attributed to the broken off of Kuitun River, a tributary of the lake, and the stable water discharges from Boertala River and Jinghe River. In the valleys of the two rivers, the river waters drawn into the cropland are strictly restricted by the unique hydrological features of the rivers. Since 1990’s, the area of the lake enlarged yearly. According to the analysis of the hydrological records, the rivers in the lake watershed are just in a plentiful water period. Meanwhile, the precipitation in Boertala River valley increased obviously. Abundant precipitation helped to release the agricultural drought and decrease the waters drawn from the rivers. Hence, water discharges drained into the lake in 1990’s increased much more than that in 1980’s. It should be pointed out that abundant river waters are not the result of the melting of the glaciers in catchment of the lake but the result of climatic wetting. The rapid enlargement of the lake’s area is a natural phenomenon of climatic variation of dry and wet, and can not be related with the agricultural water saving.
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  Environment Change over the Aydingkol Lake Region in Turpan Basin,Xinjiang

  WANG Ya-jun, WU Su-fen

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 229-231. https://doi.org/10.7522/j.issn.1000-0240.2003.0041

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  Aydingkol Lake, -154 m a. s. l., is the lowest lake in China. It is located in an extremely area of Central Asia, the evaporation is 110-500 times higher than the precipitation and the natural environment is severe in the lake region. In the history recording, the environment in the lake region has been seriously changed, the water area reduced, and the lake was dried up for a time in the whole balance process of the system of population, resources environment and development. The water area of Aydingkol Lake, however, has been enlarged with increase of the inflow from the rainstorm floods and the stream flow due to climate wetting in recent more 10 years.
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  Study on the Dynamically Monitoring and Simulating the Vegetation Cover in Northwest China in the Past 21 Years

  MA Ming-guo, DONG Li-xin, WANG Xue-mei

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 232-236. https://doi.org/10.7522/j.issn.1000-0240.2003.0042

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  The study area of this paper is Northwest China. The data is 8 km AVHRR from 1981 to 2001. The average value method, difference value method were used to analyze the annual and interannual changes. The linear regression of one variable was used to simulate the change trend of the maximal NDVI values and calculate the change quantity. As a result, the vegetation cover reaches the best condition between July and August in each year. During the last 21 years, the vegetation degradation is popular in most of Northwest China. However, there are some regions where vegetation cover is increasing. But the increasing range is smaller than the decreasing range on the whole. The simulating results indicate that the improved regions of vegetation cover mainly appear in west and north parts of Uygur Autonomous Region of Xinjiang.
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  Vegetation Change during the Last 10 Years Derived from Satellite Image in the North Slopes of the Tianshan Mountains

  LUO Ge-ping, CHEN Xi, HU Ru-ji

  JOURNAL OF GLACIOLOGY AND GEOCRYOLOGY. 2003, 25(2): 237-242. https://doi.org/10.7522/j.issn.1000-0240.2003.0043

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  A method for studying vegetation change in the arid areas and preliminary quality evaluation of ecological environment has been put forward based on the technology of remote sensing and GIS, and a satisfactory consequence has been obtained by applying the method to the north slopes of the Tianshan Mountains and a specific area —— Sangong River basin, based on satellite remote sensing data and meteorological data. It is found that: (1) Vegetation coverage and biomass in north slopes of the Tianshan Mountains were increasing during 1992-1998, which responded to a climatic shift from warm-dry to warm-humid; the increasing extent in the plain areas was more than that in the mountainous areas, and the increasing extent during 1995-1998 was more than that during 1992-1995. (2) The vegetation coverage and biomass in 1987-1998 increased from foothill belts to northern deserts in the Sangong River basin, especially in northern deserts and transition zones outside of oasis; the increasing extent in plain areas was more than that in mountains areas, and that in the anaphase was more than that in the prophase. (3) No evident change of vegetation index with monthly, seasonal and annual changes in temperature and precipitation were found. However, there were obviously positive correlations with temperature and precipitation averaged over 6～7 years, and evident negative correlation with potential evaporation averaged over 6～7 years, remarkably showing a climate change in the time-scale of 6～7 years.