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  • 2013 Volume 68 Issue 11
    Published: 20 November 2013
      
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  • Spatio-temporal changes of agrometrorological disasters for wheat production across China since 1990
    ZHANG Zhao, WANG Pin, CHEN Yi, ZHANG Shuai, TAO Fulu, LIU Xiaofei
    2013, 68(11): 1453-1460. https://doi.org/10.11821/dlxb201311001
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    Agro-meteorological disasters (AMDs) are increasingly of concerns due to their critical stresses on crop production. In this study, firstly the temporal and spatial changes in the occurrence frequency of major AMDs on wheat production were investigated using the observed records at national agro-meteorological stations of China from 1990 to 2009. Then the impacts of climate change on AMDs were investigated by comparing the spatiotemporal pattern of AMDs in the warmer decade (2000-2009) with that in the other decade (1991-2000). We found that drought was the most frequent disaster during the last two decades, accounting for 79% of total disasters. The frequency of wheat disasters increased significantly in the warmer decade. The major disasters occurred more frequently during reproductive growth period than during vegetative growth period. The spatial changes in the frequency of main disasters were region-specific. For example, the wheat cultivation areas in the Loess Plateau and the middle-lower reaches of Yellow River suffered mainly from drought. These changes in AMDs during the last two decades were closely related to changes in climate extremes. Effective adaptation options should be developed timely to reduce crop loss based on the new characteristic of AMDs under global warming.
  • The impacting mechanism and laws of function of urban heat islands effect：A case study of Shanghai
    PENG Baofa, SHI Yishao, WANG Hefeng, WANG Yali
    2013, 68(11): 1461-1471. https://doi.org/10.11821/dlxb201311002
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    Urban heat island is the interactive result between human factors and the local weather conditions. In terms of human factors, land use and land cover change, anthropogenic heat and atmospheric emissions of pollutants caused by the interaction between industrialization and urbanization are particularly important. This article reveals the impacting mechanism of urban heat islands effect from the three aspects including scale and intensity, types and layout, and patterns of land use changes exemplified by Shanghai. Empirical evidences show that: (1) Land urbanization is the most important factor affecting urban heat island intensity in Shanghai. In terms of the influence of built-up area expansion on heat island intensity, accumulative effect is greater than incremental effect; (2) Industrialization, real estate development, and population growth are the second more important factors impacting urban heat island intensity in Shanghai. As far as the influence of economic development and energy consumption on heat island intensity is concerned, density effect is often greater than size effect; in terms of the influence of floor space of completed buildings and buildings with over 20 storeys on heat island intensity, accumulative effect is less than incremental effect; as for the influence of population growth on heat island intensity, density effect and size effect are approximately equivalent; (3) Dissimilar urban land properties or types and urban development modes lead to spatial disparity in urban heat island intensity.
  • Spatial and temporal distribution and its impact factors of the last frost over Shanxi Province from 1961 to 2010
    LI Fen, ZHANG Jianxin, WU Yongli, ZHOU Jinhong, CHENG Yanfang
    2013, 68(11): 1472-1480. https://doi.org/10.11821/dlxb201311003
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    Based on each day's minimum ground temperature data of 62 meteorological stations in Shanxi from 1961 to 2010, the spatial and temporal distribution characteristics of the province's last frost dates are analyzed. The results show: (1) Shanxi's average last frost date is April 12, the last frost date of the southern part is generally earlier than that of the north, but for a particular site, "early" or "late" of the last frost date also depends on its topography and location. The average last frost date has obvious positive correlations with altitude and latitude, and the correlation with altitude is closer than that with latitude. (2) M-K mutation test shows that the last frost date of most meteorological stations had obvious mutations from 1975 to 1996, and that the mutation year has negative correlations with altitude and latitude, and that the correlation with latitude is closer than that with altitude. (3) The changing trend of last frost dates has apparent regional difference, the large advancing scope region is located in the central-western and southern parts, while the large delaying scope region is observed in the northwestern and central-eastern parts. The changing trend has negative correlations with altitude and latitude, and the correlation with altitude is closer than that with latitude. (4) Probability of the normal last frost in this province is 54%-74%, and the maximum probability appears in the southeastern and northern-central parts. Probability of the later last frost in Shanxi is 2%-22%, and the maximum probability appears in the northern and southeastern parts of the province. Probability of the latest last frost in Shanxi is 14%-36%, and the larger probability area is located in the northern-central and central-western parts. (5) Altitude has negative correlation with later last frost probability, and latitude has positive correlation with the latest last frost probability, and there is little correlation between altitude (or latitude) and normal last frost probability. Latitude has greater impacts on all degrees' last frost probability than altitude.
  • The spatial-temporal variation of sunshine duration in Xinjiang during 1961-2010
    ZHANG Shanqing, PU Zongchao, LI Jinglin
    2013, 68(11): 1481-1492. https://doi.org/10.11821/dlxb201311004
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    Based on the monthly sunshine duration, total cloud cover and low cloud cover data during 1961-2010 from 101 meteorological stations in Xinjiang, the spatial-temporal change characteristics of seasonal and annual sunshine duration, and the connection between annual sunshine duration with total cloud cover and low cloud cover were analyzed by using the methods of linear regression, Mann-Kendall test, three-dimensional quadratic trend surface simulation and Kriging residual error revision based on GIS. The main results are obtained as follows. (1) There was an obvious regional difference in climatic distribution of seasonal and annual sunshine duration, generally, the sunshine duration of spring increased from the southwest to northeast. In summer, the sunshine duration was longer in the northern and eastern parts than in the southern and western parts, and it was longer in plain and valley than in mountainous areas. Autumn sunshine duration increased southeast to northwest, and in winter it increased from west to east in Xinjiang. Affected by their joint effect, the annual sunshine duration increased from west to east, mountainous areas to plain and valley in Xinjiang. (2) The changing trend of spring sunshine duration was not significant, but that of the summer, autumn, winter and annual sunshine duration showed a significant decreasing trend with the rate of -4.27 h·(10a)-1, -4.30 h·(10a)-1, -14.36 h·(10a)-1 and -19.42 h·(10a)-1 respectively in recent 50 years, and summer, autumn, winter and annual values had mutations in 1988, 1986, 1987 and 1982, respectively, but there were regional differences before and after mutations. For example, the annual sunshine duration increased in Turpan-Hami Basin and southern Tarim Basin, while it showed a decreasing trend in most parts of Xinjiang, especially in Junggar Basin, areas along the Tianshan Mountains, central and eastern parts of Tarim Basin. (3) The cloud cover was the main factor influencing sunshine duration in Xinjiang. On the whole, the areas with less total and low cloud cover have relatively much sunshine duration, and vice versa. In recent 50 years, the total amount of cloud did not change significantly, but low cloud cover increased significantly, which was the main cause for the decrease of sunshine duration in Xinjiang.
  • Spatial and temporal variations of winter snow over east of Qinghai-Tibet Plateau in the last 50 years
    HU Haoran, LIANG Ling
    2013, 68(11): 1493-1503. https://doi.org/10.11821/dlxb201311005
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    By using the snow cover days data at 64 weather stations in the east of Qinghai-Tibet Plateau for the period 1961-2010 and the methods of REOF, polynomial fitting, running t-test, linear regression analysis, we analyzed spatial distributions and interdecadal variations of the snow cover days in winter. The results indicate the spatial distribution of the snow cover days in winter is far from uniformity. These regions, located in the Bayan Har Range, Tanggula Range and Nyainqentanggula Range, have rich snowfall and large interannual variability. These regions located in the valley of southern Tibetan Plateau, the dry-hot valley of western Sichuan Plateau and the Qaidam Basin have little snow and small interannual variability. The spatial distributions of the snow cover days in winter in the east of Qinghai-Tibet Plateau are jointly caused by the surrounding atmospheric circulation system and the local complicated terrain. By using polynomial fitting and running t-test methods, we found two abrupt interdecadal changes of winter snow in the east of Qinghai-Tibet Plateau. The first shift that changed from the stage of little snow to the stage of rich snow was observed at the end of the 1980s. The second shift that changed from the stage of rich snow to the stage of little snow occurred more significantly at the end of 20th century. By using linear regression method, we found that snowfall and air temperature in winter had a great effect on winter snow in the east of the plateau, especially the snowfall. The shift of winter snowfall that changed from the little stage to the rich stage at the end of the 1980s is the main cause for the corresponding change of winter snow. The common function about the shift of winter snowfall that changed from the rich stage to the little stage and winter air temperature that changed from the low stage to the high stage at the end of 20th century is the cause for the second shift of winter snow that occurred more significantly.
  • Spatio-temporal pattern changes of ambient air PM10 pollution in China from 2002 to 2012
    LI Mingsheng, ZHANG Jianhui, ZHANG Yinjun, ZHOU Lei, LI Qian, CHEN Yuanhang
    2013, 68(11): 1504-1512. https://doi.org/10.11821/dlxb201311006
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    Based on the annual average daily concentration of PM10 by city was collected from 2002 to 2012, the statistical and GIS methods were used to study the spatio-temporal changes of concentration of PM10 in ambient air of China. The results showed that during the study period, (1) annual daily average concentration of PM10 in cities at or above prefecture level decreased from 0.130 mg·m-3 to 0.076 mg·m-3, and the proportion of cities meeting the Grade Ⅱ national air quality standard increased from 37.6% to 92%. (2) PM10 had a highest monthly average concentration in December, followed by January and November; and showed a lowest monthly average concentration in August, followed by July and September. (3) Seriously PM10 polluted areas decreased significantly, and the distribution type changed from centralized distribution to scattered punctuate distribution. But the spatial pattern of PM10 pollution did not change obviously. Northern China, especially northwest China, north China, Shandong, Jiangsu and Hubei were still the relatively serious PM10 polluted areas. (4) PM10 pollution was more serious in northern China than in southern China, and this difference was mainly observed in heating season (from November to next April). (5) Mitigation of PM10 pollution was mainly reflected on the decrease of seriously polluted cities, which accounted for 1/10 of all the cities, and could reduce about 1/3 of the national average concentration of PM10. Different from heavily PM10 polluted cities, the situation of PM10 pollution in relatively clean cities showed an aggravating trend. (6) The PM10 pollution in major environmental protection cities was slightly polluted, accounting for 80.4% of the total number of pollution days. The proportion of serious pollution day was higher in March and April due to the dust-sand weather. The results can provide reference for a better understanding of the situation and changing trend of atmospheric particulate matter pollution in China, and of significance to help the governments at all levels or policy makers to make targeted prevention and control on particulate matters pollution.
  • The characteristics and mechanisms of carbon emissions from energy consumption in China using DMSP/OLS night light imageries
    SU Yongxian, CHEN Xiuzhi, YE Yuyao, WU Qitao, ZHANG Hong'ou, HUANG Ningsheng, KUANG Yaoqiu
    2013, 68(11): 1513-1526. https://doi.org/10.11821/dlxb201311007
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    It is critical for China to make the emission reduction targets and development of the scientific emission reduction planning in the future. On the basis of the DMSP/OLS night light imageries, this research estimates the China's city-level carbon emissions from 1992 to 2010. This makes up the vacancies of statistical carbon emission data and overcomes the inconsistence of statistical carbon emission methods. Analysis results from three scales (the whole mainland of China, 4 economic regions and 6 urban agglomerations) show that the national CO2 emissions grew continually, but varied from place to place. What is more, the spatial agglomeration of China's CO2 emissions has become more and more obvious, which have led to the current CO2 emission pattern—"high-high concentration in eastern coastal cities and low-low concentration in western undeveloped cities". The carbon emission intensity of per capita basically maintains as the "Eastern > Northeastern > Western > Central" pattern. The carbon emission intensity of per GDP shows the "Higher in Northeastern and Western China" and "Lower in Eastern and Central China" pattern. Growth rate of GDP is the major factor affecting the increasing speed of carbon emissions. Energy structures, energy efficiencies, industrial structures are the three main factors influencing the carbon intensities. As for the Western and Northeastern regions, whose industries are mainly energy-related and heavy ones, their best mitigation policies should be optimizing the energy structure and increasing energy use efficiently.
  • Spatial and temporal distribution of prehistoric human sites and its driving factors in Henan province
    LI Zhongxuan, ZHU Cheng, WU Guoxi, ZHENG Chaogui, SHAO Shixun, FENG Feifan, WANG Ning
    2013, 68(11): 1527-1537. https://doi.org/10.11821/dlxb201311008
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    Based on the ArcGis10.0 platform, this article analyzed the geographic indexes of prehistoric human sites in the Yangshao Cultural Period (approx. 6.9-6.0 ka BP) and in the Longshan Cultural Period (approx. 4.6-4.0 ka BP) in Henan, i.e. spatial distribution, river-orientation, spatial agglomeration etc. Results showed that 18.8% of the sites in Yangshao period are distributed within 1 km river-buffer area, while there were 16.5% in Longshan period, indicating that human activity in Longshan period became weaker at river-orientation. In contrast to the Yangshao period, spatial agglomeration indexes of the western part of Henan, Nanyang Basin and Yinghe-and-Huaihe river basin respectively increased by 0.006, 0.016 and 0.021, which suggested that human activity in Longshan-period was restricted by natural environment. At 4.0 ka BP, Henan was subjected to the cooling events, accompanied by natural disasters such as drought, flood and low temperature, which accelerated the spread of human activities. At that time, the exotic cultures such as Shijiahe and Dawenkou expanded into Henan and complicated the spatial-temporal patterns of human activities.
  • Identifying plant priority conservation areas based on the NPWP distribution in Yunnan, China
    YANG Feiling, HU Jinming, WU Ruidong
    2013, 68(11): 1538-1548. https://doi.org/10.11821/dlxb201311009
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    The function upgrading and spatial structure optimization of nature reserve networks are currently the core task of biodiversity conservation in Yunnan. The identification of priority conservation areas and the assessment of their protection status are the premises for fulfilling this task. This study used the National Protected Wild Plants (NPWP) as indicator species, and then based on the county (city or district) level NPWP distribution data, we applied Dobson algorithm to identify the plant priority conservation areas in terms of the 75% and 100% NPWP conservation levels. Then we used the information of existing nature reserves to assess the protection status of the plant priority conservation areas and sub-ecoregions in Yunnan. Results show that: in terms of the 75% and 100% NPWP conservation levels, seven and twenty-four counties (cities, districts) were identified as priority conservation areas, respectively. The former seven priority areas are critical for plant conservation. The coverage percentages of nature reserves of four and eight identified priority conservation areas were less than 5% in terms of the 75% and 100% NPWP conservation levels. It is urgent to strengthen the upgrading of existing nature reserves or even construct new nature reserves in these identified priority areas with low conservation level. The percentages of nature reserves of two ecoregions and seven sub-ecoregions do not meet the conservation target in 2010 (10% ) set by Global Strategy for Plant Conservation. Three sub-ecoregions should be included in the nature reserve network systems in Yunnan.
  • Historical evolution of tidal flat reclamation in the Jiangsu coastal areas
    ZHANG Xiaoxiang, YAN Changqing, XU Pan, DAI Yuxuan, YAN Wangbo, DING Xianrong, ZHU Chenxi, MEI Dandan
    2013, 68(11): 1549-1558. https://doi.org/10.11821/dlxb201311010
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    The large-scale tidal flats have been reclaimed in the Jiangsu coastal areas during the last century. The purpose of this study is to evaluate and analyze the historical evolution of Jiangsu coastal reclamation. A variety of historical maps, local chronicles and remote sensing data are collected and collated since the late Qing Dynasty, and statistical analysis and spatial analysis are used to examine the temporal changes over the past century. The results are shown as follows. (1) The 1910s and 1950s are two relatively high-density periods before 1949 and after 1949. (2) The reclamation lands are mostly distributed in Yancheng, accounting for 70% of the total in Jiangsu coastal areas, and they are relatively small in Nantong and Lianyungang. In terms of the reclamation areas, the top five counties are Dafeng, Sheyang, Lianyungang, Xiangshui, and Rudong. (3) Buffer zone analysis shows that the pattern of Jiangsu coastal reclamation is like a mosaic fish-scale shape, and the reclamation lands are mainly used for agriculture, aquaculture, and salt industry, while less are used for industrial purpose and port construction.
  • The vertical differentiation of the mountain settlement niche in the upper reaches of Minjiang River
    WANG Qing, SHI Minqiu, GUO Yalin, ZHANG Yu
    2013, 68(11): 1559-1567. https://doi.org/10.11821/dlxb201311011
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    Based on remote sensing data and the geographic information system, the spatial information of the human settlements in the upper reaches of Minjiang River was extracted. Then, using the method of niche, the geo-information spectra of human settlement niches were established, including their spatial influence scopes, population densities and nationality types. The results show that: the radius in geography of settlement niche increases as altitude increases, spanning from 300-600 m; on the contrary, the population density decreases as altitude increases, ranging from 200-630 people/km2. The vertical differentiation characteristics, namely the radius in physical geography and the population density of settlement niche, reflect the adaptation of local residents to the mountain environment in the periods of historical evolution, which is closely related with the characteristics of the nationalities and their livelihoods. In basin scale, the spatial pattern of settlement niche of national types in the upper reaches of Minjiang River, as one of the national corridors in Southwest China, has some typical characteristics, (1) the settlement niches of Tibetan and Hui nationalities are located in the upper reaches of the main stream and tributaries, (2) the settlement niche of Qiang nationality lies in the arid valley and the gentle slope of the upper V-shaped valley, (3) the settlement niche of Han nationality is located in the valley of the entrance of the upper reaches of Minjiang River. The paper presents important models for clarifying the range of human activities in mountain areas, and useful ways for macro-regulation of the local governments.
  • Hydrological reconstructions of the pre-historical great floods in the Wufeng Reach of Yunxian County in the upper Hanjiang River
    LIU Tao, HUANG Chunchang, PANG Jiangli, ZHA Xiaochun, ZHOU Yali, ZHANG Yuzhu, LIU Ke
    2013, 68(11): 1568-1577. https://doi.org/10.11821/dlxb201311012
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    Palaeoflood hydrological studies were carried out in the upper reaches of the Hanjiang River. Typical palaeoflood slackwater deposits of the Holocene period were identified at several sites along the banks of the Wufeng reach in Yunxian County. They have recorded four episodes of extraordinary palaeoflood events (12,600-12,400 a BP, 4200-4000 a BP, 3200-2800 a BP and 1900-1700 a BP). The palaeoflood peak stages were estimated with the elevations and the deposition depths of the SWD. The palaeoflood peak discharges were estimated by using the HEC-RAS one dimensional model running within an ArcGIS environment. The results indicated that these palaeoflood discharges were between 42,220 and 63,400 m3/s. A sensitivity test performed on the model indicated that for a 25% variation in roughness values, an error between -10.6% and 6.3% was introduced into the results of peak discharge. The error is much smaller than that obtained by using the slope-area methods. Based on the flood stage indicators, the peak discharges of modern floods were also reconstructed in the same reach using the HEC-RAS model and the same hydraulic parameters. The error between the reconstructed and gauged peak flood discharges is between -3.9% and 1.0%. These showed that the palaeoflood peak discharges reconstructed by using the HEC-RAS model are reliable. The reconstructed peak discharges of the palaeoflood are much larger than those of the gauged largest floods in the upper reaches of the Hanjiang River. The flood data series of the river are therefore extended to a 10,000-year time-scale. This result provides reference in hydrological engineering, water resource management and flood mitigation on the river. And it is also very helpful in understanding the relationships between extreme flood events and global climate change.