• 2011 Volume 66 Issue 1
    Published: 25 January 2011

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  • ZHANG Qiang, LI Jianfeng, CHEN Xiaohong, BAI Yungang
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    Daily precipitation of 53 rain stations in Xinjiang during 1957-2009 is analyzed and 8 extreme precipitation indices are defined in this study. We use Kolmogorov-Smimov method to confirm the most fitted probability distributions and evaluate the ten-year return periods values. Based on that, a nonparametric estimation procedure for Copula and Akaike Information Criterion (AIC) method are used to calculate joint distribution of 2 precipitation indices. Then we comprehensively analyze the spatial variability of probability distribution of one precipitation index and joint distribution of two indices after 1980. The results show that: (1) North Xinjiang is wetter than South Xinjiang. The probability of extreme heavy precipitation is great in North Xinjiang, while that of extreme slight precipitation is great in South Xinjiang. In addition, the precipitation in the Tianshan Mountains is more than that in plain areas. (2) The spatial distribution of the probability of the event that extreme heavy precipitation and extreme slight precipitation occur in the same year is very complex. In terms of the days of precipitation, the probability in Tianshan Mountains is greater than that in plain areas. In terms of the total extreme precipitation, it is greater in plain areas. In terms of the precipitation intensity, it is greater on the southern slope of Tianshan Mountains. (3) There are relations between probability distribution of drought-flood and terrain: Tianshan Mountains is the dividing line of the occurrence of drought-flood, and the plain areas are prone to drought-flood disasters than the mountain regions. This study is of significance to get a better understanding of the droughtflood and scientific water resources management in arid and semi arid areas.
  • ZHANG Shifeng, HUA Dong, MENG Xiujing, ZHANG Yongyong
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    Based on the precipitation and temperature data of the 12 meteorological stations in the "Three-River Headwaters" region and the observed runoff data of Zhimenda in the Source Region of the Yangtze River, Tangnag in the source region of the Yellow River and Qamdo in the source of Lancang River during the period of 1965-2004, this paper analyses the trends of precipitation, temperature, runoff depth and carries out significance tests by means of Mann-Kendall-Sneyers sequential trend test. Makkink model was applied to calculate the potential evaporation. The runoff model driven by precipitation and potential evaporation was developed and the influence of climate change on runoff is simulated under different scenarios. Results show that during the period of 1965-2004 the temperature of the "Three-River Headwaters" region was increasing, the runoff of the three hydrological stations was decreasing. Both of them had abrupt changes in 1994, and no significant trend changes happened to the precipitation. The runoff model suggests that the precipitation exerted positive effect on the runoff depth, while the potential evaporation played a negative role. The influence of the potential evaporation on the runoff depth of the Lancang River is found to be the most; for the Yangtze River, it is less, and for the Yellow River, it is the least.
  • LI Qian, WEI Fengying, LI Dongliang
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    Based on the drought/flood grads of 90 meteorological stations over eastern China and summer average sea-level pressure (SLP) during 1850-2008, this paper analyzed the coupling relationship between the drought/flood grads and the East-Asian summer SLP using BPCCA statistical methods. The East-Asian summer monsoon index which is closely related with interdecadal variation of drought/flood distribution over eastern China was defined by using the key areas of SLP. Then, we studied the impact of the interdecadal variation of East-Asian summer monsoon on the drought/flood distribution over eastern China in the last 159 years. The results showed that there were four typical drought and flood spatial patterns in eastern China: the drought/flood distribution in South China was contrary to that of the other areas; the drought/flood distribution along the Huanghe-Huaihe river valleys was contrary to that of the Yangtze River valley and the areas south of it; the drought/flood distribution along the Huaihe River valley was contrary to that of the other areas; and the drought/flood distribution in the eastern areas was contrary to the western areas. The main distribution pattern of the SLP in summer was that the strength of SLP in Asian continent was opposite to that in Western Pacific. The interdecadal variation of drought/flood distribution patterns over eastern China had a close relationship with that of the East-Asian summer monsoon defined in this study, although their correlation was not stable and had a significant difference in interdecadal phase change. When the East-Asian summer monsoon was stronger (weaker), the northern regions of the Yangtze River valley were more susceptible to drought (flood), but the Yangtze River valley and its southern regions were more susceptible to flood (drought) before the 1920s; when the East-Asian summer monsoon was stronger (weaker), the northern regions of the Yangtze River valley were more prone to flood (drought), but the Yangtze River and its southern regions were prone to drought (flood) after the 1920s. It is indicated that by using the data of the longer period more results could be obtained than by using the data of the last 50-60 years. The interdecadal phase differences between the East-Asian summer monsoon and the drought/flood distribution in eastern China may relate to the nonlinear feedback of the East-Asian summer monsoon to the extrinsic forcing (e.g. solar activity).
  • WANG Shengjie, ZHANG Mingjun, LI Zhongqin, WANG Feiteng, LI Huilin, LI Yaju, HUANG Xiaoyan
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    Based on the statistics of glacier area variation measured in Chinese Tianshan Mountains since 1960, the response of glacier area variation to climate change is discussed systematically. Results show that the total area of the glaciers has reduced by 11.5% in the past 50 years, which is a weighted percentage according to the glacier areas of 10 drainage areas divided by Glacier Inventory of China. The annual percentage of area changes (APAC) of glaciers in the Tianshan Mountains is 0.31% , after the standardization of the study period. According to the 14 meteorological stations in the Tianshan Mountains, both the temperature and precipitation display a marked increasing tendency from 1960 to 2009 with a rate of 0.34 ℃· (10 a)-1 and 11 mm·(10 a)-1, respectively. The temperature in dry seasons (from November to March) increases rapidly with a rate of 0.46 ℃·(10 a)-1, but the precipitation grows slowly at 2.3 mm·(10 a)-1; while the temperature in wet seasons (from April to October) grows with a rate of 0.25 ℃·(10 a)-1, but the precipitation increases at 8.7 mm·(10 a)-1.
  • ZHANG Geli, XU Xingliang, ZHOU Caiping, ZHANG Hongbin, OUYANG Hua
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    Global warming, a global concern, has led to significant vegetation changes especially in the past 30 years. The Hulun Buir Grassland in Inner Mongolia, one of the world's three prairies, is undergoing a process of prominent warming and drying. It is necessary to investigate the effects of climatic variations (temperature and precipitation) on vegetation changes for a better understanding of acclimation to climatic change. NDVI (Normalized Difference Vegetation Index), which can reflect characteristics of plant growth, vegetation coverage, biomass, and so on, is used as an indicator in monitoring vegetation changes. GIMMS NDVI from 1981 to 2006 and MODIS NDVI from 2000 to 2009 were adopted and integrated in this study to extract the time series characteristics of vegetation change conditions in Hulun Buir. The responses of vegetation coverage changes to climatic variations from the yearly, seasonal and monthly time scales were analyzed combined with temperature and precipitation data of seven meteorological sites. In the past 30 years, vegetation coverage change was closely correlated with climatic factors, and the correlations were different on different time scales. Annual average of vegetation change was better correlated with precipitation, suggesting that rainfall was the main factor for driving vegetation change. Correlations between seasonal average of vegetation coverage and climatic factors showed that the sensitivity of vegetation growth to hydrothermal condition change was different in different seasons. The sensitivity of vegetation growth to temperature in summer was higher than in the other seasons, while that of vegetation growth to rainfall in both summer and autumn was higher, especially in summer. Correlations between monthly average of vegetation coverage and climatic factors during growing seasons showed that the response of vegetation change to temperature in April and May was stronger, indicating that the temperature effect occurred in the early stage of vegetation growth. Correlations between NDVI of the current month and precipitation of the month before the current month were better from May to August, showing a hysteresis response of vegetation growth to rainfall. Grasses turned green and began to grow in April, and the impacts of temperature on grass growth was obvious, therefore, the increase of NDVI in April might be due to an advanced growing season caused by climatic warming. In summary, relationships between annual variation of monthly vegetation and climatic factors represent temporal rhythm controls of temperature and precipitation on grass growth.
  • YAO Xiaoying, PU Jinyong, YAO Ruxin, JIA Haiyuan, MAJie
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    The precipitation suitability degree and given year had no good linearity and temperature and light suitability degree had increased with year and synthesized climate suitability had improved in jointing to tasseling period. Duing the tasseling to milky mature period, the temperature suitability degree and given year had no good linearity and light suitability degree had went down and precipitation suitability degree had increased and synthesized climate suitability improved with year. The correlative relationship between unit yield and light suitability degree in emergence to jointing, jointing to tasseling, and tasseling to milky mature are notability. The correlative relationship between unit yield and temperature suitability degree in sowing to emergence tasseling to milky mature are notability. The correlative relationship between unit yield and precipitation suitability degree in jointing to tasseling and tasseling to milky mature are notability. The climate changes are favorable for maize production, because of temperature suitability degree increasing in the future.
  • XU Duanyang, LI Chunlei, ZHUANG Dafang, PAN Jianjun
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    Desertification is becoming one of the most serious global social-economicenvironmental issues of our time, which threatens human survival and development. Climate change and human activities are the two kinds of driving forces in desertification, and assessing their relative role in desertification has important significance for deeply understanding the driving mechanism of desertification and preventing desertification expansion. This paper systematically reviewed the methods of assessing the relative role of climate change and human activities in desertification from qualitative, semi-quantitative and quantitative aspects. The authors found that there were some disadvantages in the previous researches. For example, the subjectivity in assessment was obvious, the assessment cannot be easily repeated, and the assessment and its results were always based on administrative regions and less taken and expressed in continuous space. According to the progress of previous researches and the works conducted by the authors recently, we thought that the key point of assessing the relative role of climate change and human activities in desertification was breaking through the bottleneck that restricted the expression of the relative role of two drivers in continuous space. Meanwhile, the authors put forward a quantitative approach to assess the relative role of climate change and human activities in desertification basing on selecting NPP as a common indicator to measure the relative role of climate change and human activities in desertification and identifying the ecological process of "driving force affecting-desertification land dynamically responded" into several scenarios. Besides, validation and scale of assessment should be taken into account when quantitatively assessing the relative role of climate change and human activities in desertification.
  • GONG Zhaoning, ZHANG Yiran, GONG Huili, ZHAOWenji
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    Supported by remote sensing and GIS technology, using multi-temporal TM images from 1984 to 2008 in Beijing, this paper analyzed the dynamic characteristics of wetland landscape pattern through selected indices including patch area, patch average area, fractal dimension index, diversity, dominance and contagion indices. Furthermore, the spatial centroids of each wetland type were calculated. Finally, the paper explored the evolution mode and driving factors of wetland landscape pattern. The results were obtained as follows: the total wetland area increased during the period 1984-1996, while it obviously declined from 1996 to 2004. The wetland area in 1994 accounted for only 47.37% of that in 2004. The proportion of artificial wetland area was larger than that of natural wetland. The proportion of reservoir wetland was 33.50%-53.73% and had the maximum average area. Pond and paddy field wetland type with the least average area accounted for 16.46%-45.09% of the total wetland area. The driving force of natural river wetland is mainly natural elements, so its fractal dimension index is greater than the others. The Shannon diversity index of wetland landscape increased from 1.11 in 1992 to 1.34 in 2004, indicating that the difference between proportions of each wetland type decreased and its area was evenly distributed. The contagion index went down from 65.59 to 58.41, indicating that the connectivity decreased. Miyun reservoir had the largest area and its area change had a great impact on the location of the centroid. Wetland resources degenerated gradually for the joint effects of natural and artificial factors. During the period 2006-2008, the precipitation increased and the droughty condition was relieved. The government implemented a series of proactive policies to save water resources, and the wetland area increased.
  • CHEN Zhongsheng, CHEN Yaning, LIWeihong, CHEN Yapeng
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    Based on the monitoring data of annual runoff in the mainstream of Tarim River from 1957 to 2008, runoff consumption is calculated in the mainstream, and then the time series variation tendency of runoff consumption in the mainstream is analyzed by using linear regression method. The results can be drawn as follows. (1) In recent more than 50 years, runoff consumption shows a decreasing tendency on the whole, but the upper, middle and lower reaches are different. The upper reaches increases significantly with the highest rate, being approximately 2.09 × 108 m3/10a, but the middle and lower reaches display a remarkably decreasing tendency, with a rate of 1.61×108 m3/10a and 2.30×108 m3/10a, respectively. (2) The input water volume and runoff consumption have a good positive correlation with R2 = 0.9996 in the mainstream, suggesting that the water volume reduction is immediate cause of runoff consumption decrease. (3) Human activities intensity indexes and artificial runoff consumption also show significantly positive correlation, R2 = 0.9822 between them, which indicates that since the mid-1970s, with gradual increase of human activities intensity, human activities interference on runoff consumption has been expanding and aggravating.
  • LI Jianfeng, ZHANG Qiang, CHEN Xiaohong, JIANG Tao
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    Climate changes and human activities can lead to hydrological change. Distributions of the samples before and after hydrological change are significantly different. It means the local hydrological condition has changed, which breaks the ecological balance. We use moving rank sum test (Mann-Whitney U Test) to analyse hydrological changes and their causes. Then, L-moment is used to evaluate the parameters of generalized extreme value (GEV) distribution of the monthly flow series before hydrological change, and to calculate the maximum probability density flow, as the ecological instream flow. We use this method to calculate ecological instream flows of 7 hydrometric stations in the Yellow River Basin. The result shows that ecological calculating method which considers the hydrological change is practicable.
  • LUOWen, YUAN Linwang, YI Lin, YU Zhaoyuan, XIE Zhiren
    2011, 66(1): 111-122.
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    Due to the impacts of the inconsistent data timespan, the heterogeneous spatial distribution, and the complexity and uncertainty of sea level change etc., it is difficult to conduct regional sea-level change researches.. Based on the 22 tidal gauge station records in Northwest Pacific ocean marginal sea, the regularized EM algorithm (RegEM) and the Multi-Taper spectral Method (MTM) are adopted to discuss their multi-scale fluctuation processes and their spatial-temporal variations. Integrating orderly cluster and the space adjacent relation of gauge stations, the whole research area is generally divided into five sub-regions, there are Bohai Sea-the coast of the northern Yellow Sea, Yellow-East China Sea near the coast of China, the East China Sea near the coast of Japan, the southern East China Sea and the northwestern South China Sea. Then Mean Generation Function (MGF) is used to predict the medium and long-term trends of each tide station, and Principal Component Analysis (PCA) is employed to obtain regional-scale sea level change trends. The result shows that the sea-level rise rates of five sub-regions from 2001 to 2030 are 1.23-1.27 mm/a, 3.30-3.34 mm/a, 2.72-2.76 mm/a, 1.43-1.47 mm/a and 1.13-1.15 mm/a respectively, and the whole region sea-level rise rate is changed between 2.01 mm/a and 2.11 mm/a. By introducing spatial-temporal variation and multi-scale pedigree characteristic analysis, our work is an attempt of the integrated research on sea-level change characteristic and its prediction.
  • MING Qingzhong, SU Huai, SHI Zhengtao, DONG Ming, ZHANGWenxiang
    2011, 66(1): 123-130.
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    Xiaozhongdian Basin is located in the southeastern margin of the Qinghai-Tibet Plateau which is completely controlled by southwest monsoonal circulation. A thick continental lacustrine sedimentary sequence is preserved due to late Cenozoic fault depression and offers a unique opportunity to study the variability of the southwest monsoonal circulation in detail. Based on the analytical results of grain size, spore-pollen and geochemical elements and 14C datings from a 15.3-m-long lacustrine stratum, five lake dry and shrink events during the last 40 ka, which might be correlated to Heinrich events H0-H4 discovered in North Atlantic region, have been found in Xiaozhongdian Basin, suggesting that Heinrich events for the last 40 ka are strongly imprinted not only in moisture source area of southwest monsoonal circulation, but also in inland area controlled by this circulation. The Heinrich events footprint became drier in inland area, differently from that in moisture source area. However, the signals of the D/O (Dansgaard-Oescher) warm events, which are also clearly recorded in Greenland ice cores and Arabian Sea sediment cores, are ambiguous in Xiaozhongdian Basin. According to the general circulation patterns, we believe that the effect attenuation of the Qinghai-Tibet Plateau on “Pumping Action”of southwest monsoonal circulation system during the glacial periods should be responsible for this phenomenon.