Table of Content

    20 January 2014, Volume 69 Issue 1 Previous Issue    Next Issue
    Spatiotemporal characteristics, patterns and causes of land use changes in China since the late 1980s
    LIU Jiyuan, KUANG Wenhui, ZHANG Zengxiang, XU Xinliang, QIN Yuanwei, NING Jia, ZHOU Wancun, ZHANG Shuwen, LI Rendong, YAN Changzhen, WU Shixin, SHI Xuezheng, JIANG Nan, YU Dongsheng, PAN Xianzhang, CHI Wenfeng
    2014, 69 (1):  3-14.  doi: 10.11821/dlxb201401001
    Abstract ( )   PDF (3813KB) ( )   Save
    Land-Use/land Cover Changes (LUCC) are a direct consequence of human and nature interactions. China's Land Use/cover Datasets (CLUD) were updated regularly at five-year intervals from the late 1980s to the year of 2010 with standard procedures based on Landsat TM/ETM + images. A dynamic zoning method was proposed to analyze major land-use conversions. The spatiotemporal characteristics, differences, and causes of land-use changes at a national scale were then examined. The main findings are summarized as follows: Land-Use Changes (LUC) across China indicated a significant variation in spatial and temporal characteristics in the past 20 years between the 20th and 21st centuries. The amount of cropland change decreased in the south and increased in the north, but the total area remained almost unchanged. The reclaimed cropland was shifted from northeast to northwest. The built-up lands were expanded rapidly, which were mainly distributed in the east and gradually spread out to the midwest. Woodland decreased first and then increased, but desert area was inverted. Grassland continued decreasing. Different spatial patterns of LUC in China were found between the late 20th century and the early 21st century. The original 13 LUC zones were replaced by 15 units with changes of boundaries in some zones. The main spatial characteristics of these changes included (1) an accelerated expansion of built-up land in the Huang-Huai-Hai region, the coastal areas of southeastern China, the midstream area of the Yangtze River, and the Sichuan Basin; (2) the shifted land reclamation in the north from Northeast China and eastern Inner Mongolia to the oasis agricultural areas in Northwest China; (3) the continuous transform from rain-fed farmlands in Northeast China to paddy fields; and (4) the effectiveness of the “Grain-for-Green” project in the southern agricultural-pastoral ecotones of Inner Mongolia, the Loess Plateau, and mountainous areas of southwestern China. In recent two decades, although climate change in the north impacted the change in cropland, policy regulation and economic driving forces were still the primary causes of LUC across China. During the first decade of the 21st century, the anthropogenic factors that drove variations in land-use patterns have shifted the emphasis from one-way land development to both development and conservation. The "dynamic zoning method" was used to analyze changes in the spatial patterns of zoning boundaries, the internal characteristics of zones, and the growth and decrease of units. The results revealed "the pattern of the change process," namely the process of LUC and regional differences in characteristics at different stages. The growth and decrease of zones during this dynamic LUC zoning, variations in unit boundaries, and the characteristics of change intensities between the former and latter decades were examined. The patterns of alternative transformation between the "pattern" and "process" of land use and the reasons for changes in different types and different regions of land use were explored.
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    Spatial-temporal dynamics of grassland coverage and its response to climate change in China during 1982-2010
    ZHOU Wei, GANG Chengcheng, LI Jianlong, ZHANG Chaobin, MU Shaojie, SUN Zhenguo
    2014, 69 (1):  15-30.  doi: 10.11821/dlxb201401002
    Abstract ( )   PDF (72691KB) ( )   Save
    Global climate warming has led to significant vegetation changes in the past half century. Grassland in China, most of which is sensitive to climatic change and ecologically fragile region, undergoes a process of prominent warming and drying. It is necessary to investigate the response of grassland to the climatic variations (temperature and precipitation) for a better understanding of the accumulated consequence of climate change. Vegetation coverage, as an important indicator for evaluating grassland ecosystem condition, is used to monitor grassland change. GIMMS NDVI from 1982 to 2006 and MODIS NDVI from 2001 to 2010 were adopted and integrated in this study to extract the time series of grassland coverage, and to analyze its spatial pattern and changes. The response of grassland coverage to climatic variations at annual and monthly time scales was analyzed using temperature and precipitation time series at Chinese meteorological stations from 1982 to 2010. During the 29 years, the national annual surface air temperature increased with an annual rate of 0.04℃, while national precipitation decreased with an annual rate of -0.39 mm with the exception of Northwest China. Grassland coverage distribution increased from northwest to southeast across China. During 1982-2010, the mean national grassland coverage was 34% but exhibited apparent spatial heterogeneity being highest (61.4%) in slope grasslands and lowest (17.1%) in desert areas. There was a slight increase of the grassland coverage over the study period with an annual rate of 0.17%. Regionally, the largest increase in the grassland area was observed in Northwest China and Tibetan Plateau. The increase in slope grassland areas was as high as 0.27% per year, while in the plain grassland and meadow, the grassland coverage increase was the lowest (being 0.11% per year and 0.1% per year, respectively). Across China, the grass coverage with extremely significant (P<0.01) and significant (P<0.05) area increases accounted for 46.03% and 11% of the total grassland area, respectively, while those with extremely significant and significant decrease were only 4.1% and 3.24% , respectively. At the annual time scale, there were no significant correlations between grassland coverage and annual temperature and precipitation for the total grassland area. However, the grass coverage was mainly affected by temperature in alpine and sub-alpine grassland, alpine and sub-alpine meadow, slope grassland and meadow, while grass coverage in desert grassland and plain grassland was mainly affected by precipitation. At the monthly time-scale, there are significant correlations between grass coverage with both temperature and precipitation, indicating that the grass coverage is mainly affected by seasonal fluctuations of the hydrothermal factors. Additionally, there is obvious time lag-effect between grass growth and climate factors for each grassland type: the highest correlations are observed between the grass coverage and temperature and precipitation of the preceding month.
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    Impacts of land use on vegetation coverage in the rich and coarse sediment area of Yellow River Basin
    YANG Shengtian, ZHOU Xu, LIU Xiaoyan, LIU Changming, LUO Ya, WU Linna, ZHAO Haigen
    2014, 69 (1):  31-41.  doi: 10.11821/dlxb201401003
    Abstract ( )   PDF (6361KB) ( )   Save
    As a main component of terrestrial ecosystem, vegetation has profound effects on the sharp decrease of water and sediment in the Yellow River Basin. In order to research the effects of land use on vegetation coverage in the typical rich and coarse sediment area (Weihe River), this paper chose MSS, TM and HJ-CCD as data sources, applied adjacent images progressive regression analysis method to eliminate the radiometric difference and retrieved vegetation coverage based on NDVI, and used man-computer interactive method to interpret land use. Some conclusions can be drawn as follows. (1) Vegetation coverage in this area has been significantly restored from 1978 to 2010, but changes in vegetation have strong volatility and heterogeneity. (2) Significant changes can be found in land use, and present unique spatial and temporal characteristics. (3) Both of land use transition and land use gradient are conducive to vegetation restoration, but comparatively speaking, land use transition performs better than land use gradient. (4) Effects of land use on vegetation coverage are complex and diverse, and vegetation restoration in this region urgently needs targeted land use transition and land ecological optimization strategies.
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    Land use change in the reach from Hekouzhen to Tongguan of the Yellow River during 1998-2010
    LUO Ya, YANG Shengtian, LIU Xiaoyan, LIU Changming, SONG Wenlong, DONG Guotao, ZHAO Haigen, LOU Hezhen
    2014, 69 (1):  42-53.  doi: 10.11821/dlxb201401004
    Abstract ( )   PDF (4527KB) ( )   Save
    In order to evaluate the effect of Grain for Green Policy in the reach from Hekouzhen to Tongguan of the Yellow River, based on dryness/wetness, geomorphic type, slope gradient and aspect, from macroscopic to microcosmic, three indicators, including (a) a land use change significance index, (b) a land use change proportion (c) a vegetation change index, are used to characterize the primary transformation types, the intensity of land use changes, and the degree of vegetation restoration in the period 1998-2010. The results show that: (1) The area of land use change accounted for 19.19% of the study area. High coverage grassland, forest, and other woodland increased significantly, while low coverage grassland, farmland decreased markedly. (2) Spatially, land use change was found primarily west of the Yellow River, between 35 and 38 degrees north latitude, including Malian River basin, Beiluo River basin, Yanhe River basin. (3) The transformation types, including low coverage grassland to moderate coverage grassland, moderate coverage grassland to high coverage grassland, farmland to other woodland, shrub to forest were the primary types resulting from land use change. (4) The effect of dryness/wetness, geomorphic type and slope gradient on land use change was significant, but that of aspect on land use change was not so clear.
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    Response analysis of land use change to the degree of human activities in Beiluo River basin since 1976
    WU Linna, YANG Shengtian, LIU Xiaoyan, LUO Ya, ZHOU Xu, ZHAO Haigen
    2014, 69 (1):  54-63.  doi: 10.11821/dlxb201401005
    Abstract ( )   PDF (2583KB) ( )   Save
    Land use change as an important factor reflects the degree of human activities. Analysis of spatial-temporal change of land use is an effective way to reveal the degree of land use change. Based on the remote sensing and GIS, the authors used man computer interactive image processing methods to acquire the land use data in 1976, 1998 and 2010, and analyzed the spatial-temporal variation of land use in Beiluo River basin from the rate of land use change, the direction of land use transformation, and the degree of land use. The results can be obtained as follows. (1) The integrated dynamic degree of land use increased from 0.61 during 1976-1998 to 6.66 during 1998-2010, the area of arable land and grassland decreased gradually, the rate was increased from 2.00% and 2.69% to 26.20% and 23.33% respectively, while the area of forest land and residential land increased gradually, the rate of the former increased from 5.93% during 1976-1998 to 59.68% during 1998-2010, and that of the latter decreased from 6.59% during 1976-1998 to 3.52% during 1998-2010. (2) The direction of land use change showed similar characteristics during the two periods. Forest land was converted from arable land and grassland, and a small part of residential land was converted from arable land. (3) The integrated degree of land use change ranged from -2-1 during 1976-1998 to -27-4 during 1998-2010. The authors proved that the impact of human activities on the natural environmental showed increasing trends, that arable land, grassland, forestland and residential land were mainly converted, that affected areas were mainly distributed in the upper basin, i.e., Wuqi county, Fuxian county, Ganquan county, Huangling county and Luochuan county, while the increasing area of forest land was much larger than the decreasing area of both arable land and grassland area, and the increasing area of residential land.
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    Characteristics of soil and water conservation measures change in the watershed slope of the middle Yellow River Basin
    ZHOU Xu, YANG Shengtian, LIU Xiaoyan, LIU Changming, ZHOU Qiuwen, ZHAO Haigen, LUO Ya, MA Hongbing
    2014, 69 (1):  64-72.  doi: 10.11821/dlxb201401006
    Abstract ( )   PDF (2177KB) ( )   Save
    This study chose multi-source remote sensing images to extract spatial information, and designed three parameters. It applied integrated cluster analysis and factors contribution model to research the variation of watershed slope in the rich and coarse sediment area of the middle Yellow River Basin. Conclusions can be drawn as follows. (1) The watershed slope characteristics of the study area have changed from 1998 to 2010, including a great increment of forest, grassland and terrace area, and vegetation coverage has restored obviously. (2) There are 7 types of watershed slope variation, which are the result of changes of soil and water conservation measures. According to contribution rates, they are named as type-1 dominated by vegetation coverage change, type-2 by vegetation coverage and land use change, type-3 by land use and vegetation coverage change, type-4 by vegetation coverage and terrace area change, type-5 by terrace area and vegetation coverage change, type-6 by terrace area change and type-7 by multi-source factors. (3) The spatial distribution of each type has its unique geomorphic background, and the future work should take the watershed slope characteristics and geomorphic patterns into account, and should assess the sensitivity of different hydrological and sediment yield models rationally.
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    Failure criteria of the warping dams on sediment interception in the Middle Yellow River in northern Shaanxi
    GAO Yunfei, GUO Yutao, LIU Xiaoyan, HE Xingzhao
    2014, 69 (1):  73-79.  doi: 10.11821/dlxb201401007
    Abstract ( )   PDF (936KB) ( )   Save
    In this paper, we tried to set up a new criterion. First of all, the average deposition ratio of the key dams was calculated year by year from 1950 to 2011 using 4157 key dams data in Water Census. The results showed that the average deposition ratio was around 0.77 as of the year 1980 and then decreased; the average deposition ratio of the small and medium-sized dams was calculated year by year from 1956 to 1989 using survey data for 1640 warping dams in northern Shaanxi. The results showed that the average deposition ratio was around 0.88 before 1980 and decreased gradually afterwards. Therefore, 0.77 and 0.88 were considered as the block sediments criterion for key and mid-small sized warping dams respectively. And then, the survey data for warping dams in northern Shaanxi were used for validation for the criterion of key dams and the results are consistent, which confirmed the applicability of the new criterion. With Wuding and Yanhe river basins as an example, the variation trend of the sediment transportation at hydrological stations is highly correlated with that of the warping dams. This paper also explains the formation of the criterion for the engineering structure of the warping dams, indicating that the spatial movement of water and sand drain point is the main reason.
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    Simulation and analysis of vegetation interception at a large scale in the middle reaches of Yellow River
    SONG Wenlong, YANG Shengtian, LU Jingxuan, LIU Changming, WANG Shudong
    2014, 69 (1):  80-89.  doi: 10.11821/dlxb201401008
    Abstract ( )   PDF (2892KB) ( )   Save
    Quantitative simulation and analysis of vegetation canopy interception in a large scale is of great significance to reveal water-sediment changing mechanism under combined influences of climate change and human activities. Hekouzhen-Tongguan region in the middle reaches of the Yellow River was taken as the study area. Quantity of vegetation canopy interception in 1984, 1995 and 2010 were simulated by using models coupled with spatial data such as remote sensing data. The main data used in the study include precipitation data from weather stations and GLASS- LAI remote sensing data. Results show that vegetation coverage has increased since the 1980s, especially since the end of 1990s due to ecological restoration policy. And vegetation canopy interception has varied since the 1980s. The average yearly precipitation intercepted by canopy in 1984, 1995 and 2010 were 19.57 mm, 13.66 mm and 22.68 mm respectively, with the interception rate of 3.24%, 3.32% and 4.92% accordingly. It is found that vegetation canopy interception has been influenced by precipitation characteristics and vegetation synthetically in the study area, where precipitation plays a determinant factor. And LAI is the main factor affecting yearly vegetation interception variation since the 1980s.
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    Comparison of LCM hydrological models with lumped, semi-distributed and distributed building structures in typical watershed of Yellow River Basin
    ZHANG Yichi, LIU Changming, YANG Shengtian, LIU Xiaoyan, CAI Mingyong, DONG Guotao, LUO Ya
    2014, 69 (1):  90-99.  doi: 10.11821/dlxb201401009
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    The distribution of rainstorm center is critical factor influencing the simulation accuracy of rainstorm runoff process. There are significant differences among the varying discretization responding to rainfall heterogeneities, thus it is important to improve simulation efficiency and accuracy by selecting appropriate discretization methods for reducing the influence of rainfall heterogeneity. For this, the LCM model which deduced from the unsaturated infiltration theory in Loess Plateau by Liu Changming was modeled in three ways: lumped, semi-distributed and distributed. The simulation results indicate that: the NSE with distributed method arrives at 0.81 and correlation coefficient attains 0.82 which shows the best fitness to gauge data. Comparatively, NSE of semi-distributed method arrives at 0.78, while the fitness to main peak of outlet stream-flow reaches 76.1% and 65.8%. Generally, distributed method shows the highest simulation accuracy, lumped method owns the highest calculation efficiency, and semi-distributed method indicates high simulation accuracy, and high calculation efficiency at the same time. So, spatial discretization of modeling is helpful to reduce the influence of rainfall heterogeneity and to improve simulation accuracy of LCM model, but it will consume more time. Thus, it is appropriate to select suitable spatial discretization methods according to the application requirements.
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    Discussion about scale adaptability in virtual geographic environments
    ZHANG Chunxiao, LIN Hui, CHEN Min
    2014, 69 (1):  100-109.  doi: 10.11821/dlxb201401010
    Abstract ( )   PDF (1329KB) ( )   Save
    Along with the focuses of geography changing from static geographic pattern to dynamic geographic process, geographic language is also evolving from maps to GISystem (Geographic Information System) to VGEs (Virtual Geographic Environments). Due to the multiscale characteristic and scale dependence of both geographic processes and study methods, scale adaptability turns out to be an inventible component for the theory and method of VGEs, which aims to solve dynamic geographic problems. This paper discussed the definition of geographic scale by using three parameters, namely dimension, kind and component, and then illustrated the evolution of scale concept along with the evolution of geographic language. In such evolution, from maps to VGEs, the scale concept is becoming much more comprehensive, which makes the study into scale adaptability issues more important and difficult. In regard to the framework of VGEs, four groups of scale adaptability issues are identified and analyzed according to the parameters of scale definition (dimension, kind and component). These four groups reflect different operational levels, which are illustrated in detail to support the implementation of scale adaptability. Meanwhile, the interrelationship among multiple scale adaptability is also illustrated when the VGEs are constructed and applied. Taking a meteorological simulation in Hong Kong as a case study, scale adaptability considering multiscale DEM data and a meteorological model (WRF: Weather Research & Forecasting Model) was investigated, which is on the component level within the spatial dimension and observational kind of scale (namely spatial resolution). This case study not only explained the significance and implementation of scale adaptability in geographic process research, but also showed the contribution to the cognition and decomposition of complex scale adaptability issues from the discussion in this paper. In summary, the attention and research into scale adaptability will enrich the theory and methodology of VGEs and improve practical applications of VGEs.
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    Effects of arable land change on regional carbon balance in Xinjiang
    WANG Yuangang, LUO Geping, ZHAO Shubin, HAN Qifei, LI Chaofan, FAN Binbin, CHEN Yaoliang
    2014, 69 (1):  110-120.  doi: 10.11821/dlxb201401011
    Abstract ( )   PDF (1434KB) ( )   Save
    The potential effect of land use change on global climate change is attracting more and more attention, but in terms of estimation of terrestrial carbon budget, there have been relatively few studies on the effects of land use change on carbon balance in arid region. The large-scale change of arable land has occurred in Xinjiang, and its influences on the regional carbon balance needs to be discussed. First, we analyzed the annual arable land area change of Xinjiang based on the remote-sensing land use/cover data and the statistical arable land area data. Then, we obtained a set of local parameters for Bookkeeping model by exploring published scientific literature, soil census data and field investigation data. Finally, we analyzed the impacts of arable land change on region carbon balance of Xinjiang from 1975 to 2005 by combining mathematical statistics method and Bookkeeping model. The research shows that: land reclamation and arable land transfer were the major forms of arable land change during 1975-2005. The carbon storage of Xinjiang increased by 20.6 Tg C due to these two change forms, while land reclamation and arable land transfer led to the increments of 51.8 Tg C and -31.2 Tg C, respectively. In the period 1975-1985, owing to the large-scale arable land transfer, the changing trend of carbon storage was mainly impacted by the arable land transfer. With the increase of land reclamation scale, the changing trend of carbon storage was mainly impacted by the land reclamation after 1985. Over the past 30 years, the increase of carbon storage in Xinjiang was mainly caused by the grassland reclamation, while the transfer of arable land to grassland was the main reason for the reduction of carbon storage. Generally speaking, proceeding reasonable land and water development is beneficial to the regional carbon sequestration, and long-term management of farming activities will further enhance the carbon sink function of arable land.
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    Water resource utilization efficiency and its spatial spillover effects measure in China
    ZHAO Liangshi, SUN Caizhi, ZHENG Defeng
    2014, 69 (1):  121-133.  doi: 10.11821/dlxb201401012
    Abstract ( )   PDF (948KB) ( )   Save
    Based on provincial panel data of water footprint and grey water footprint, and with the help of data envelopment analysis model considering and without considering the undesirable output, this paper estimates the water resources utilization efficiency in China from 1997 to 2011. The spatial weighting matrix based on economy-space distance function is established to discuss spatial autocorrelation of water resources utilization efficiency. With the help of absolute β convergence model, this paper concludes that there exists β convergence in the water resources utilization efficiency. Under the condition of considering and without considering the undesirable output, it takes about 52.6 and 5.6 years respectively to achieve the extent of half of convergence. By mean of the space Durbin econometric model, this paper studies spatial spillover effects of the provincial water resources utilization efficiency in China. The results show that, 1) With considering and without considering the undesirable output, there is significant spatial correlation in provincial water resource efficiency in China. 2) Under the two cases, the spatial autoregressive coefficients (ρ) are 0.278 and 0.507 respectively, at 1% significance level. There exist the spatial spillover effects of provincial water resources utilization efficiency. 3) With considering the undesirable output, these factors of the education funds, the transportation infrastructure, and the proportion of industrial and agricultural water have positive impacts. These factors of foreign direct investment, the industrial added value water consumption in ten thousand yuan, per capita water consumption, and the total precipitation have negative impacts. 4) Without considering the unexpected output, the factor of GDP per labor has a greater positive significant influence on the water resources utilization efficiency. However the facts of industrial added value water consumption in ten thousand yuan and the transportation infrastructure have no significant influence. 5) Regardless of undesirable output of water resources utilization efficiency, the assessment of the present real water resources utilization in China will be distorted and policy-making will be misled. The water efficiency measure considering environmental factors (such as gray water footprint) is more reasonable.
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    Spatial and temporal characteristics of large volcanic eruptions in 1750-2010
    WANG Huan, HAO Zhixin, ZHENG Jingyun
    2014, 69 (1):  134-140.  doi: 10.11821/dlxb201401013
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    Based on the dataset provided by Smithsonian Institution Global Volcanic Programme, we extracted the large volcanic eruptions (Volcanic Explosivity Index ≥ 4) events from 1750 to 2010, and then analyzed the main characteristics of large volcanic eruptions since 1750 by their geographic latitudes, elevations, years and months. The results showed that the most of large volcanic eruptions occurred around the margins of Pacific Ocean, and the islands of Sumatra and Java from 1750 to 2010, especially in the equatorial regions (10°N-10°S). Large volcanic eruptions were mainly observed at elevations of 1000-2000 m, and in January and April. The number of the occurrences in the summer half-year (from April to September) was larger than that of the winter half-year (from October to next March). Large volcanic eruptions had interdecadal fluctuations including 15-25 years and 35-50 years, which were detected by Morlet wavelet analysis, and more frequent cyclic fluctuation of volcanic eruption was found after 1870. There were more large volcanic eruptions events during the periods of 1750-1760, 1776-1795, 1811-1830, 1871-1890, 1911-1920, and 1981-1995.
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