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    20 September 2011, Volume 66 Issue 9 Previous Issue    Next Issue
    Variation of Glacier Area in China against the Warming in the Past 50 Years
    ZHANG Mingjun, WANG Shengjie, LI Zhongqin, WANG Feiteng
    2011, 66 (9):  1155-1165.  doi: 10.11821/xb201109001
    Abstract ( 815 )   PDF (898KB) ( 841 )   Save
    According to the remote sensing records on glacier area in the typical regions of China, as well as the meteorological data of air temperature and precipitation at 139 stations and the 0 ℃ isotherm height at 28 stations, the variation of glacier area in China and its climatic background in the past 50 years was discussed. The initial glacier area calculated in this study was 23982 km2 in the 1960s/1970s, but the present area was only 21893 km2 in the 2000s. The area-weighted shrinking rate of glacier was 10.1% , and the temporal-interpolated annual percentage of area changes (APAC) of glacier was 0.3% a-1 since 1960. The high APAC was found at the Ili River Basin and the Junggar Interior Basin around the Tianshan Mountains, the Ertix River (a tributary of the Ob River) Basin around the Altay Mountains, the Hexi Interior Basin around the Qilian Mountains, etc. The retreat of glaciers was affected by climatic background, and the influence on glaciers of the slightly-increased precipitation is counteracted by the significant warming in summer.
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    Responses of Temperature Zone Boundaries in the Arid Region of China to Climatic Warming
    ZHANG Xueqin, SUN Yang, ZHENG Du, MAOWeiyi
    2011, 66 (9):  1166-1178.  doi: 10.11821/xb201109002
    Abstract ( 619 )   PDF (1172KB) ( 727 )   Save
    Under the background of global climatic warming, the growth and distribution of natural vegetations will be influenced by the variation of heat resources and the dynamic changes of temperature zones. And the variation of agro-climatic resources will have great impacts on the distribution of agricultural production, and the adjustment of cropping systems as well. Therefore, the dynamic changes of the temperature zone boundaries in the arid region of China were explored during the past 50 years and under the scenarios in the first half of the 21st century. Here we adopted two kinds of data, i.e., regional downscaling gridding data under the A1B scenarios in the first half of the 21st century simulated by the model of MPI_ECHAM5, and the homogenization temperature data during the period of 1961-2007, respectively. And the isolines for the duration and the accumulated temperatures of the daily mean temperature ≥ 10 ℃ with the guaranteed rate of 80% were selected as the index of the northern boundaries of temperature zones in the arid region of China. The main conclusions are summarized as follows. Firstly, the temperature increased apparently for both summer half-year and winter half-year during the period of 1961-2007, and the increasing amplitude of temperature was larger in the winter half-year than in the winter half-year. The dynamic changes of the isolines for the decadal accumulated temperatures and the duration of the daily mean temperature ≥ 10 ℃ were consistent, which demonstrated an obvious movement northward or upward to higher elevations. Secondly, judged by the changes of index for the northern boundaries of temperature zone, the northern boundaries of the warm and middle warm temperate zones moved northward generally, particularly for the Alxa League (prefecture) with a maximum movement of more than one latitude during 1961-2007. It is speculated that the northern boundaries of warm and middle temperate zones would move northward continually, among which the former would move much more remarkable in the first half of the 21st century. Moreover, the northern boundaries showed a tendency of moving upward to higher elevations not only for the warm temperate zone, but also for the middle temperate zone in the arid region of China in the first half of the 21st century. Thirdly, corresponding with the dynamic changes of temperature zones, several related climatic factors, e.g., the first date of the growing season and the last frost date appeared earlier significantly, and the northern boundaries of natural vegetation and crop planting moved northward and westward, and extended upward in regions with higher elevations.
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    Climate Characteristics of the Extreme Drought Events in Southwest China during Recent 50 Years
    HE Jinyun, ZHANG Mingjun, WANG Peng, WANG Shengjie, WANG Xingmei
    2011, 66 (9):  1179-1190.  doi: 10.11821/xb201109003
    Abstract ( 1013 )   PDF (1131KB) ( 1329 )   Save
    Based on the daily data of temperature and precipitation of 108 meteorological stations in Southwest China from 1960 to 2009, we calculated the surface humid indexes of months and years, as well as the extreme drought frequency. According to the data, the temporal and spatial characteristics of the extreme drought frequency in inter-annual, inter-decadal, summer monsoon and winter monsoon has been analyzed. The results are indicated as follows: (1) In general, the southwest of Sichuan Basin, the southern part of Hengduan Mountains, southern coast of Guangxi and north of Guizhou are the areas in which the extreme drought frequency has significantly increased in the past 50 years. For the decadal change, from the 1960s to the 1980s the extreme drought frequency has presented a decreasing trend, and the high frequency area appeared alternately in the southeast - northwest - east of Southwest China; the 1990s is the most wettest decade and it is wet over the whole area. In the 2000s, the extreme drought frequency rises quickly, but the regional differences reduce. (2) In summer monsoon, the extreme drought frequency is growing, which generally happens in the high mountains around the Sichuan Basin, most parts of Guangxi and "the broom-shaped mountains". It is obvious that the altitude has impacts on the extreme drought frequency of summer monsoon; in winter monsoon, the area is relatively wet and the extreme drought frequency is decreasing. (3) In summer monsoon, the abrupt change happened in 2003, while the abrupt change of winter monsoon happened in 1989, and the joint abrupt changes in different periods lead to the extreme drought frequency variation. The departure sequence vibration of annual extreme drought frequency is quasi 5 years and quasi 12 years.
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    Variation of 0 ℃ Isotherm Height and Ground Temperature in Summer in Northwest China during the Past 50 Years
    HUANG Xiaoyan, ZHANG Mingjun, WANG Shengjie, LI Yaju, PAN Shukun
    2011, 66 (9):  1191-1199.  doi: 10.11821/xb201109004
    Abstract ( 698 )   PDF (848KB) ( 474 )   Save
    Based on the data of 112 meteorological stations and 21 aerological stations in Northwest China from 1960 to 2009, the variation of 0 ℃ isotherm height and mean temperature in summer was analyzed. The result indicated that the mean height of 0 ℃ isotherm in summer was 4675.7 m during 1960-2009, with an annual decrease of 5.6 m before 1987 and an annual increase of 2.6 m after 1987. The ground temperature showed a similar annual trend at the 0 ℃ isotherm height, which was converse around the climatic mutation in Northwest China, with a considerable increase rate of 0.53 ℃ per decade after 1987. During 1960-2009, in most parts of Northwest China, the 0 ℃ isotherm height at Beijing Time 8:00 in summer increased significantly, and the height at Beijing Time 20:00 decreased. However, during 1987-2009, the 0 ℃ isotherm height in most parts of Northwest China increased at Beijing Time 8:00 and 20:00. A marked increasing trend of mean temperature in summer was observed in most parts of Northwest China, but the trend was opposite in Urumqi and Qinling-Daba Mountains. For the different climatic zones, the main trend and correlation between 0 ℃ isotherm height and mean temperature in summer varied spatially. The correlation was significant in the Cold Region on the Qinghai-Tibet Plateau, less significant in the Arid Region in Northwest China, and not significant in Monsoon Region in eastern China.
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    The Trend Analysis and Statistical Distribution of Extreme Rainfall Events in the Huaihe River Basin in the Past 50 Years
    SHE Dunxian, XIA Jun, ZHANG Yongyong, DU Hong
    2011, 66 (9):  1200-1210.  doi: 10.11821/xb201109005
    Abstract ( 666 )   PDF (1039KB) ( 766 )   Save
    Based on the daily precipitation data from 27 meteorological stations in the Huaihe river basin during 1960-2009, we analyzed the trend and statistical distribution of extreme precipitation events in this area. The annual maximum series (AM) and peak over threshold series (POT) are selected to describe the extreme distribution. The results show that positive trend of annual maximum precipitation is detected in most of the stations, only a small number of stations are found to be negative during the past five decades, and neither of the positive or negative trend is significant. The daily maximum precipitation events during a year almost occurred in the flood seasons of the 1960s-1970s. By the L-moments method, the parameters of three extreme distributions, which are GEV, GP and Gamma, are estimated. From the results of goodness of fit test and K-S test, we found that AM series can be better fitted by GEV model and POT series can be better fitted by GP model. In comparison with the precipitation amounts at different return levels, we found that the values obtained from POT series is slightly larger than the values fromAM series, and they can better fit the observed values in the Huaihe River Basin.
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    Variation of Air Temperature and Thermal Resources in the Northern and Southern Regions of the Qinling Mountains from 1951 to 2009
    ZHOU Qi, BIAN Juanjuan, ZHENG Jingyun
    2011, 66 (9):  1211-1218.  doi: 10.11821/xb201109006
    Abstract ( 563 )   PDF (652KB) ( 941 )   Save
    On the basis of daily air temperature data from 47 meteorological stations in the northern and southern regions of the Qinling Mountains (QLM) from 1951 to 2009, the variations of several criteria for temperature zones were analyzed including the mean annual temperature, the number of days with steady temperature above 10 ℃ and its accumulated temperature, the minimum temperature, mean temperatures during the coldest and hottest seasons. Our results show that climate warming in both northern and southern QLM was mainly observed after the 1990s, and the trends of mean annual temperature were consistent with the number of days with steady temperature above 10 ℃ and the accumulated temperature. Although these three indices showed a slight decline from 1951 to 1993 and a rapid increase since 1993, some seasonal and regional differences do exist. The average temperature of cold seasons of January exhibited the same changing trends with the minimum temperature, since they both slightly increased from 1951 to 1985 and declined since 1985. Meanwhile, the average temperature of hot seasons of July showed no significant trends. In addition, the increment of some indices showed differences among the northern areas to the QLM, southern slope of QLM, Hanshui River Basin and valleys in Daba and Wushan mountains. Compared with the period before 1993, the number of days with accumulated temperature steadily above 10 ℃ increased by 10, 10, 8 and 5 in the above four regions after 1993, accompanied by increments of related accumulated temperature by 278 ℃, 251 ℃, 235 ℃ and 207 ℃ respectively. Although the increment of thermal resources in the northern region of QLM had larger extent than that in the southern region, their variation trends were consistent and more marked in the cold season. Thus, the Qinling Mountains are still a boundary between the warm temperate zone and sub-tropical zone in China under the background of climate warming since the 1990s.
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    Spatial-temporal Characteristics of Lake Level Changes in Central Asia during 2003-2009
    LI Junli, CHEN Xi, BAO Anming
    2011, 66 (9):  1219-1229.  doi: 10.11821/xb201109007
    Abstract ( 747 )   PDF (815KB) ( 1323 )   Save
    ICESat/GLAS satellite altimetry data is employed to extract lake level information of 24 lakes in central Asia during 2003-2009, and the spatial and temporal characteristics of these level changes are also analyzed with other land features such as drainage basins, glaciers and dam information, so as to discuss the responses of level changes of different types of lakes to climate change and human activities. It is shown that the ICESat/GLAS lake level changes in october correlate with changes of precipitation inside the drainage basins. Glaciers also have great impact on alpine closed lakes, and their level changes act in two modes according to glacier distribution inside the lake drainage basins. Lakes in the Kunlun Mountains, the Pamir Plateau and the middle Tianshan Mountain have glaciers in their drainage basins, whose level changes have positive relations with the lake supply coefficients, while lakes in the Altay Mountains and the Tianshan mountains have no glacier-melting water to feed, whose water levels are negatively related with their supply coefficients. Level changes of open lakes and plain closed lakes aree significantly correlated with the distribution of dams. Lakes with dams decrease dramatically in water levels, while the open lakes without dams remain are stable, indicating that the overexploitation of water resources in central Asia has resulted in lake level decline.
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    Remote Sensing and the SEBAL Model for Estimating Evapotranspiration in the Tarim River
    LI Baofu, CHEN Yaning, LIWeihong, CAO Zhichao
    2011, 66 (9):  1230-1238.  doi: 10.11821/xb201109008
    Abstract ( 1053 )   PDF (748KB) ( 1053 )   Save
    The paper estimates evapotranspiration of the mainstream by using remote sensing data in 1985, 2000, and 2010 respectively and SEBAL model in the mainstream of Tarim River. The results show that evapotranspiration in the area ranges from 0 to 5.11 mm /d; the evapotranspiration of the area close to the river was significantly higher than the area away from the river; the land use types asSociated with evapotranspiration are listed in the order of water bodies > farmland > woodland > grassland > unused land > home-work sites, which is mainly related to its vegetation coverage and water supply; the total daily evapotranspiration islisted in the order of grassland > unused land > farmland > forestland > water bodies > home-work sites, which are closely related to the land use types. During 1985-2010, the total daily evapotranspiration in the Tarim River basin decreased firstly and then increased; the average total daily evapotranspiration in the upstream is 1.27 times that of the middle-stream and is 1.42 times that of the lower-stream. The total evapotranspiration in the Tarim River basin in 2000 decreased by 6.80×104 m3 compared with in 1985, because the total daily evapotranspiration in the middle and lower reaches decreased while the upper reaches increased by 3.02×105 m3. The total daily evapotranspiration in the mainstream of the river in 2010 is 6.78×105 m3 higher than that in 2000, with the upper and middle reaches up by 1.19×106 m3 and the lower reach down by 5.16 × 105 m3, which is mainly due to the fact that rapid expansion of cultivated land and excessive exploitation of water resources in the middle and upper reaches resulted from water decrease in the downstream.
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    Reservoir-induced Downstream Changes of Water, Sediment and Channel Morphology: A Literature Review
    FU Kaidao, HUANG Heqing, ZHONG Ronghua, WANG Xingyong, Su Bin
    2011, 66 (9):  1239-1250.  doi: 10.11821/xb201109009
    Abstract ( 589 )   PDF (532KB) ( 717 )   Save
    Reservoir building to meet human's growing need for water resources utilization is still an important mission in the water conservancy construction for the present world, especially for the developing countries. However, damming changes the condition of stream flow boundary as well as water and sediment transport, which trigger the corresponding adjustment of channel morphology. Large-scale dams have been built since the 1930s, asSociated with more and more researches focusing on the their impacts of dams building on downstream discharge regime, sediment decline and geomorphologic change. This paper devotes to emphasize rearrangement and summary on the global research progress of the above issues. A brief literature review on the historical and present situation for the reservoir-induced downstream changes of water, sediment and channel morphology is reported in this paper, aiming to conclude and sum up abundant research results in this field.
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    Responses of Water Regimes in Dongting Lake Area under Different Dispatching Modes during the Running Period of the Three Gorges Reservoir
    LI Jingbao, ZHANG Zhaoqing, OU Chaomin, LI Xichun, YU Guo, LIAO Xiaohong
    2011, 66 (9):  1251-1260.  doi: 10.11821/xb201109010
    Abstract ( 637 )   PDF (781KB) ( 569 )   Save
    Based on the field-survey hydrological data in typical years, the effect of different dispatching modes during the running periods of the Three Gorges Reservoir on water regimes in Dongting Lake area is comparatively analyzed. The results are shown as follows. 1) The influence periods are from 25th May to 10th June, from 1st July to 31st August, from 15th September to 31st october and from December to the next April, among which the influence of the water-supplement dispatch in the dry season is not very sensitive. 2) During the period under the pre-discharge dispatch, the runoff slightly increases as well as both the average and highest water levels rise in the usual year, while in the wet and dry years, the average increase in the runoff is 40.25 × 108 m3 and the average rises of the average and highest water levels are both 1.06 m. 3) As for the flood-storage dispatch, the flood volume increases slightly in the usual years. In the dry and wet years, the flood volume, the average and highest flood water levels averagely reduce by 444.02 × 108 m3, 2.64 m and 1.42 m respectively. 4) Under the water-storage dispatch, the runoff slightly increases and the water level rises in a sort in the usual year. And in the dry and wet years, the average decreases in the runoff, the average water level and the highest water levels are respectively 185.27 × 108 m3, 3.13 m and 2.14 m. 5) During the period under the water-supplement dispatch, the runoff, the average water level and the highest water levels averagely decline by 337.7 × 108 m3, 1.89 m and 2.39 m respectively in the usual and wet yeas. However, in the dry year, the runoff increases, and the average and highest water levels slightly go up.
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    Response to Climate Change and Prediction of Runoff in the Source Region of Yellow River
    LI Lin, SHEN Hongyan, DAI Sheng, XIAO Jianshe, SHI Xinghe
    2011, 66 (9):  1261-1269.  doi: 10.11821/xb201109011
    Abstract ( 590 )   PDF (969KB) ( 731 )   Save
    The hydrological and meteorological data of the source region of Yellow River from 1956 to 2010 and future climate scenarios from regional climate model (PRECIS) during 2010-2020 are used to analyze the flow variations and revealing the climate causes, and to predict the variation trend for future flows. Some conclusions can be drawn as follows. 1) Annual mean flow shows a decreasing trend in recent 50 years in the source region of Yellow River, and there are periods of 5a, 8a, 15a, 22a and 42a. 2) The precipitation decrease due to the weakened South China Sea summer monsoon as well as the increasing evaporation and the degenerating frozen soil in global warming are the climate origin of decreasing flow. 3) Based on the regional climate model PRECIS prediction, the flows in the source region of Yellow River are likely to decrease in the next 20 years.
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    An Efficient Quantitative Sensitivity Analysis Approach for Hydrological Model Parameters Using RSMSobol Method
    KONG Fanzhe, SONG Xiaomeng, ZHAN Chesheng, YE Aizhong
    2011, 66 (9):  1270-1280.  doi: 10.11821/xb201109012
    Abstract ( 625 )   PDF (848KB) ( 1179 )   Save
    Sensitivity analysis of hydrological models is a key step for model uncertainty quantification. It can identify the dominant parameters, reduce the model calibration uncertainty, and enhance the model optimization efficiency. However, how to effectively validate a model and identify the dominant parameters for a large-scale complex distributed hydrological model is a bottle-neck to achieve the parameters optimization. There are some shortcomings for classical approaches, e.g. time-consuming and high computation cost, to quantitatively assess the sensitivity of the multi-parameters complex hydrological model. For this reason, a new approach was applied in this paper, in which the support vector machine was used to construct the response surface (a surrogate model) at first. Then it integrated the SVM-based response surface with the Sobol method, i.e. the RSMSobol method, to achieve the quantification assessment of sensitivity for complex models. Taking the distributed time-variant gain model in the Huaihe River Basin as a case study, we selected three objective functions (i.e. water balance coefficient WB, Nash-Sutcliffe efficiency coefficient NS, and correlation coefficient RC) to assess the model as the output responses for sensitivity analysis. The results show that the RSMSobol method can not only achieve the quantification of the sensitivity, and also reduce the computational cost, with good accuracy compared to the classical approaches.
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    The Spatial Distribution of Heavy Metals in the Urban Topsoil Collected from the Interior Area of the Second Ring Road, Xi'an
    CHEN Xiuduan, LU Xinwei, ZHAO Caifeng, LUO Dacheng
    2011, 66 (9):  1281-1288.  doi: 10.11821/xb201109013
    Abstract ( 750 )   PDF (810KB) ( 582 )   Save
    The concentrations of Co, Cr, Cu, Mn, Ni, Pb, Zn and V in 78 urban topsoil samples collected from inside the Second Ring Road in Xi'an were measured by X-ray fluorescence spectroscopy. The spatial variability of eight heavy metals was identified by geostatistical analysis with the aid of GIS tools. And correlation coefficient analysis, factor analysis and cluster analysis were used to analyze the data and to identify the possible sources of these heavy metals. The multivariate analytical results show that the spatial variability of Co, Cr, Cu, Pb and Zn was obvious. The higher concentrations of five heavy metals were found in some high-value bands and high-value areas, while Mn, Ni and V were evenly distributed in space. The source analytical results show that the accumulations of Co, Cr, Cu, Pb and Zn were mainly related with transport activities, industrial activities and consumption residues, while Mn, Ni and V originated mainly from soil parent material.
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