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    Earth Surface Processes
  • Earth Surface Processes
    Trend and priority areas in land use research of China
    CHEN Bai-ming, ZHANG Feng-rong
    2011, 30(1): 1-9. https://doi.org/10.11821/yj2011010001
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    Land use research has enhanced the academic status and the academic impact with the close combination of land management practices since the beginning of the 21st century. It has made great progress in the investigation and monitoring, comprehensive property evaluation, planning and design, change and mechanisms, engineering and technology of land use. In the analysis of development trend, the paper proposes some suggestions, namely, strengthening the basic theory, paying attention to the methods system, widening perspectives and deepening the connotation, and strengthening aggregation and integration capabilities in land use research. In accordance with national demands for land use of participation in the economic macro-control, construction of resource-saving and environment-friendly society, as well as guarantee of food safety, the paper describes four priority areas on land use study. The study of land use change and mechanisms should focus on natural, economic and social factors on the coupling, as well as economic, social, technological development on the transformation of land use. The analysis of environmental impact and effects on land use should put emphasis on the interaction between economic and social development impact and the effects from land-use quantity, quality and ecological factors. The investigation and monitoring of land use should be aided with digital survey and monitoring technology and methodology. The development and decision-making of land use information should be combined with the macro-economic decision model.
  • Earth Surface Processes
    The models of traditional culture landscape conservation based on landscape fragmentation analysis: A case study of Zhibuzhen in Zhejiang Province
    WANG Yun-cai
    2011, 30(1): 10-22. https://doi.org/10.11821/yj2011010002
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    In order to monitor and assess the extent of the impacts of development on historic integrity, this research tries to provide a tool for doing this, draws on the experiences of natural ecological space fragmentation and researches the spatial and temporal process and landscape patterns of the traditional culture landscape taking the total human ecosystem as a local habitat of humans. Zhibuzhen, located in the north of Zhuji City in Zhejiang Province, is the focus of this research. The fragmentation level of the traditional cultural landscape is evident with small amounts of decline from 2005 (0.0301) to 2007 (0.029), which was influenced by modern industrial land-use, multi-pond, modern commercial land-use, modern architecture development, modern yard and design changes in traditional open space and modern open space, which are divided into the active, passive and neutral patches with different functions.
    Based on these, the models of traditional culture landscape space conservation are discussed. (1) Establishing the network of traditional culture landscape spaces, remaining traditional architecture spaces with large areas and as the passive factor in each core reservation area and removing the modern architecture spaces which are next to and as the active patches. The active patches were organized to control the scale and style of these patches and connect the two centers with natural or semi-natural corridors to decrease the fragmentation of total landscape. (2) Establishing the integrating models through setting up comprehensive rural settlements, adjusting landscape spaces of traditional village and rebuilding micro corridors and eco-steps at the village level. (3) Optimizing landscape factors through developing the active factors in right way, conserving the passive factors in order to keep its continuity and implanting the neutral factors into and around traditional culture landscape in order to interweave and surround traditional landscapes.
    In this case the landscape should be managed according to different spaces and different attributes at the town level. A buffer system can be established based on natural landscape, farmland, man-made lakes, green belts and city or rural parks. The preserved village as a central knot of the traditional network should be surrounded by enough buffer spaces. So, this research demonstrates that the traditional culture landscape network and modern landscape network can coexist in an interweaving network.
  • Earth Surface Processes
    Study on the driving force of tourist flows
    YANG Xing-zhu, GU Chao-lin, WANG Qun
    2011, 30(1): 23-36. https://doi.org/10.11821/yj2011010003
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    Tourist flow is the basis of the tourism phenomenon and tourism industry, but also one of the core issues in tourism geography. However, the driving force of tourist flows is still under-explored. How to achieve shift from a brief description of the spatial distribution of tourist flows to mechanism? On the basis of document analysis and system induction method, this paper analyzed the driving force of tourist flows, and built the driving mechanism conceptual model of tourist flows from the multi-disciplinary perspective. The theoretical basis on tourist flow included push-pull theory, demand theory, spatial interaction theory, competitiveness theory etc. Although these theories can explain tourist flows, there are relatively few systematic and comprehensive multi-disciplinary studies. As for the driving mechanism of the tourist flow, the authors found that the formation mechanism of the tourist flow has not yet been systematically studied. Scholars attach importance to spatial distance factor and ignore spatial structures of tourism origin and destination; attach importance to tourism demand factors and ignore tourism product supply. Based on the conclusion and reference of domestic and abroad relevant theory of tourist flow, pull, push, resistance, inertia and spatial structure forces are the main driving factors. Pull, push, inertia and spatial structure forces have positive correlation with tourist flows. Resistance force has negative correlation with tourist flows. Finally, the paper builds conceptual model of tourist flow-driven mechanism. A conceptual model can reflect the formation of tourist flow driven by tourism activities in both internal and external systems, consisting of tourism demand and tourism attraction. At the same time, the formation of tourist flow is affected by resistance and spatial structure. A conceptual model can also reflect a comprehensive, holistic, dynamic development and change. The conceptual model offers a new study viewpoint of tourism geography. It also provides a simple analytical framework for tourism planning, tourism marketing and management. The model can guide spatial development and travel routes organization, and infrastructure and transportation planning and also provide a scientific foundation for the harmonious and sustainable development of tourism destination as well as the implementation of tourism policy.
  • Earth Surface Processes
    Study on tourist loyalty model of ancient village: Based on the tourist perceived value and its dimensions
    LI Wen-bing
    2011, 30(1): 37-48. https://doi.org/10.11821/yj2011010004
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    From the residence into a tourist destination, the ancient village's evolution is inseparable from the perception and evaluation of tourists when experiencing in the ancient villages. The paper builds a conceptual model (M1) on loyalty based on the tourist perceived value and its intrinsic dimensions of ancient village, and takes Zhangguying village as an example. It was found by EFA (Exploratory Factor Analysis) that the conceptual model on tourist loyalty of ancient village consists of eight exogenous latent variables, that is the social value, emotional value, epistemic value, economic cost, non-economic costs, guide services, community services, and the resource ontology of ancient village tourism, as well as three endogenous latent variables, that is tourist perceived value, satisfaction and loyalty. After using SEM (Structural Equation Modeling), it was found that the social value, economic cost and non-economic costs have not notable influence on the loyalty in the conceptual model, and then a revised loyalty model (M2) based on the tourist perceived value and its intrinsic dimension of ancient villages was put forward through cutting out three paths and referring to MI (modified index). In the meantime, the revised model (M2) is better than the conceptual model (M1) in goodness of fit. The revised loyalty model shows that the perceived value of ancient village's tourists as a single-dimension structure indirectly impacts the loyalty formation through satisfaction, but loyalty-driven mechanism of the perceived value's inner dimensions is significantly different. The resource ontology of ancient village tourism is the most important dimension, and the social value and economic cost have not any direct or indirect influence on the tourist loyalty. It is a general tendency that the functional dimension's effect is dominant, and emotional dimension's effect is hidden. Finally, the practical significance of this research is discussed. The paper considers that we should create a good tourism environment of the ancient village, enhance tourist perception on profits, reduce loss of tourist perceived benefits, and raise tourist perceived value. Only in this way can the loyalty of tourist to the ancient village be cultivated.
  • Earth Surface Processes
    The evaluation and spatial-temporal evolvement of the city competitiveness of Zhongyuan Urban Agglomeration
    WANG Fa-zeng, LV Jin-rong
    2011, 30(1): 49-60. https://doi.org/10.11821/yj2011010005
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    The paper established an evaluation index system of the city competitiveness of Zhongyuan Urban Agglomeration, and used principal component analysis to evaluate the city competitiveness in 1988, 1992, 1998 and 2006, respectively. Moreover, the paper studied time evolvement of the city competitiveness. The index system includes basic competitiveness, economic competitiveness, science and technology competitiveness, opening competitiveness, government function, environment competitiveness, and 15 element layer indexes, as well as 40 basic variable layer indexes. In actual problems, it is common that several maximal principal components are selected. The paper used calculated results of the city competitiveness, space expression method and space interpolation method to research space evolvement of the city competitiveness of Zhongyuan Urban Agglomeration. According to comprehensive scores, the cities are divided into four grades, >1.5, 1.5 to -0.5, -0.5 to -2 and <-2. Cities in different grades are expressed in the map of Zhengzhou Urban Agglomeration with different colors, and the evolution situation of spatial differentiation of the city competitiveness is expressed through different time sections. The paper selects brief and exact spatial interpolation method—IDM (Inverse Distance Weighted) to research the evaluation situation of spatial patulous of the city competitiveness. Numerical value of interpolation points that are calculated will be automatically created in the city competitiveness map, and the effect maps are formed about the city competitiveness.According to the analysis result, the basic points of view are obtained as follows: (1) Principal component and comprehensive scores of the city competitiveness of nine cities for four time sections were calculated, and the city competitiveness was evaluated and sorted. (2) According to the evaluation result, the rules and features of general evolution, principal component evaluation, influencing factors in evolution of the city competitiveness of Zhongyuan Urban Agglomeration, were revealed. (3) The evolution laws and features of spatial differentiation and spatial expansion of the city competitiveness of Zhongyuan Urban Agglomeration were revealed through analysis of grade maps and effect maps in different stages.
  • Earth Surface Processes
    Space of fragmentation: A study of the linkages between gated communities and their neighborhoods in Guangzhou, China
    FENG Dan, Werner Breitung, ZHU Hong
    2011, 30(1): 61-70. https://doi.org/10.11821/yj2011010006
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    The rise of gated communities has become a global phenomenon with the appearance both in developed countries such as North American and European countries and in Asia, Latin America, South America, and South Africa. Accordingly, discussion about this type of private communities has been largely inspired by observations in various cities worldwide. Most of the insights towards gated communities are negative, regarding them as urban enclaves and relating this spatial fragmentation to residential segregation and social exclusion. However, due to different social and cultural backgrounds, the implications and consequences of gated communities in different places may not be exhibited in the same way. Local experience seems to be of great significance to the debate on the social effects of gated communities. The emergence of gated communities in China is a relatively nascent urban phenomenon even though enclosed housing compounds have cultural roots in China's history. Against the context of urban sprawl, gated communities invade into rural areas of China, co-standing to mix with traditional villages. Through a case study of a neighborhood named Lijiang Garden in the suburban Panyu District in Guangzhou, this paper explores the relationship between residents of gated communities and outsiders, addressing the material connections of gated community in suburban area of China to the outside world, conceptions and attitudes of residents living in both sides towards each other, exploring social contacts between them, in order to examine the impacts of gated communities on local areas. The empirical study revealed that the physical existence of wall does not mean gated community which can be seen as enclave in China since the functional connections and social contacts can be observed between gated community and its poorer neighborhood. Furthermore, the perceptions and attitudes towards each other are not negative, especially the outsiders of gated communities in China have not, psychologically, been segregated by the new walls, so that little negative impacts of gated communities are perceived in the suburban districts of urban China. Thought sharing certain similarities, the findings in China challenge the prevalent view of gated communities worldwide. It is demonstrated that gated communities should be investigated by considering specific local economic, cultural and political contexts.
  • Earth Surface Processes
    PAF model of study on urban industrial agglomeration dynamic mechanism and patterns
    WU Feng-lin, FANG Chuang-lin, ZHAO Ya-ping
    2011, 30(1): 71-82. https://doi.org/10.11821/yj2011010007
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    Based on the studies at home and abroad, this paper considers that the study methods of dynamics mechanism and patterns are still relatively weak. Especially, the quantitative studies by constructing models are rare. Firstly, the paper analyzes the concept of the dynamics mechanism and patterns in detail. Secondly, from the perspective of system theory, the paper divides urban industrial agglomeration system into inner system and regulative system. Finally, PAF model is constructed by coupling of the Parallelogram Law (P), Analytic Hierarchy Process (AHP) (A) and Fuzzy Membership Function Model (F). PAF model which couples the relation between dynamics mechanism and patterns could be used to analyze the following issues quantitatively. What is really the urban industrial agglomeration dynamics mechanism? Which is the rational development model that should be taken? And how do we regulate the dynamics mechanism to achieve the healthy development of urban economy?
  • Earth Surface Processes
    Growths of industrial energy consumption in China's prefecture-level cities: Based on the data in 2001-2006
    HONG Li-xuan, LIANG Jin-she, CAI Jian-ming, ZHUANG Li
    2011, 30(1): 83-93. https://doi.org/10.11821/yj2011010008
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    Since the 1980s, industrial energy has always been dominating the nation's total energy consumption. Statistics show that the trend has been strengthened by further industrialization of cities during the past 30 years. Hence, this paper aims to explore the interrelationships between industrial energy consumption and urban development, and finds an efficient mode for urban development from the perspective of energy consumption. A simple and practical method of energy decomposition analysis is proposed in this paper. The changes of industrial energy consumption are decomposed into industrial structure effect, technological effect and economic scale effect. Based on available data from statistical yearbooks, 99 prefecture-level cities of China are chosen as samples and the period spans from 2001 to 2006. The results show that the growing weight of heavy industry, such as metallurgical, chemical and building material industries, has led to a new round of industrial energy consumption growth during this period. Expanding economic scale of cities is the major factor for the sharp increase of industrial energy consumption. The advancement of technology has effectively suppressed industrial energy demands in cities, while the industrial restructuring has little impact on the changes of industrial energy consumption. It is also indicated that cities with the population size of 20—50 million have the most effective industrial structure effect, technological effect and economic scale effect. As the deviation from the population size of 20—50 million increases, cities have less efficient industrial structure effect and technological effect for energy conservation. But increasing growths of population size and industrial economy will not definitely lead to sharp growths of industrial energy consumption and low efficiency of energy utility, which largely depends on the energy-saving effect of technological potential. Taking Beijing as an example, its high speeds of industrial and population increases in 1999-2007 were sustained by fast technical progresses and thus nearly zero growth of industrial energy consumption. On the other hand, industrial energy consumption per industrial added value is used as a complementary parameter to reflect the difference of energy efficiency among various scales of cities. It is suggested that cities with the population size above 200 million perform much higher energy efficiency than smaller cities. However, one cannot ignore individual differences among cities; they might perform quite differently on the efficiency of industrial energy consumption even in the same population size.
  • Earth Surface Processes
    The evolution of regional differences of Changzhutan Urban Agglomeration since the 1990
    TANG Fang-hua, CHEN Li-li
    2011, 30(1): 94-102. https://doi.org/10.11821/yj2011010009
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    As the national two-type bases, regional differences in Changsha-Zhuzhou-Xiangtan (Changzhutan) urban agglomeration will hinder the development and construction of this region. This paper studies the regional differences and the countermeasures for the construction of Changzhutan. This article examines the dynamic changes and relationship between regional population, economic development, inter-county difference in living standards, by researching dynamic evolution of Changzhutan's population, GDP, industry, agriculture, tertiary industry and consumer focus since 1990. On the basis of the result, it analyses the dynamic evolution of the various elements of the mechanism factor. Finally we can draw some conclusions. (1) The regional population center is moving slowly to the northwest. (2) GDP, the secondary industry and population center offset in the same direction, and tertiary industrial and consumer focus shift to the northeast; (3) Regional differences are expanding in general. (4) Compared with the population center, economy in the north and south is developing unevenly, while the east and west are relatively balanced.
  • Earth Surface Processes
    Effects of tourism activities on soil macrofauna community in Mount Jiuhua scenic area
    JIN Xiu-long, LU Lin, GONG Jie, WANG Li-long
    2011, 30(1): 103-114. https://doi.org/10.11821/yj2011010010
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    Soil animal is one of the most sensitive environmental factors in the scenic area ecosystem influenced by tourism activities, and also the focus of the ecological environment research. Six main trails were chosen and eight investigation belt transects have been set up in Mount Jiuhua scenic area. Each belt transect is mutually perpendicular with the location of trails. In each sampling belt, four sampling quadrats with different distances away from the trail were investigated. Under the layer of withered defoliation, each sampling quadrat was divided into four layers at an interval of 5cm along the vertical section. The macrofaunas in soil and the layer of withered defoliation were collected by means of hand sorting and boult. A total of 2076 individuals were found to belong to 27 orders, 8 classes, and 3 phyla. In comparison to Shannon-Wiener index (H') and gathering degree, the clusters and amounts of soil macrofaunas in different sampling layers of each sampling quadrat situated in different sampling belts were analyzed. The results are obtained as follows. (1) Soil macrofaunas of Mount Jiuhua scenic area were affected obviously by tourism activity, that is, the more the tourism activity is, the less the number of soil animals is. (2) The categories and amount of soil macrofaunas rose gradually with the increase of distance away from the trails. (3) Soil macrofaunas gathered obviously in surface layer of soil in the vertical section. Affected by tourism activity, the gathering degree of soil macrofaunas in surface layer increased in farther sampling quadrats away from the trail. (4) Different correlations were observed. The number of tourists showed a negative correlation with the quantities of soil macrofaunas of 01 and 02 sampling quadrats, and a positive correlation with the quantities of soil macrofaunas of 03 and 04 sampling quadrats. At the same time, this paper used a comparison method to discuss the macrofauna captured in Zheshan hill park and Mount Jiuhua scenic area at a similar latitude. Due to the impact of tourism activities, the distribution of macrofauna has the same law on the one hand and differences on the other hand due to different natural environments in these two places. It is found that, in both places along the trail to the inside, the macrofauna increase horizontally and become more concentrated vertically, and both of these phenomena are closely related to the intensity of tourism activity. Likewise, at the quadrats far away from trail, the distribution of macrofauna was slightly affected by tourism activity but strongly affected by natural environment factors.
  • Earth Surface Processes
    Characteristics of nitrogen and phosphorus losses in surface runoff from farmland in a typical irrigation district in southern China
    HONG Lin, LI Rui-hong
    2011, 30(1): 115-124. https://doi.org/10.11821/yj2011010011
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    In order to reveal the mechanisms of agricultural non-point source pollution, the Zhanghe Irrigation District in Hubei Province, a typical irrigation district in hilly areas in central China, is selected to conduct field experiments on the influencing factors and characteristics of nitrogen and phosphorus losses in surface runoff from farmland. On the basis of field observation in Tuanlin Experiment Station in the irrigation district in May-September, 2007, the influencing factors and laws of nitrogen and phosphorus losses in surface runoff from paddy rice and corn fields are analyzed. In the experiment station, observations on 10 plots of three kinds of typical terrain are conducted for field-scale experiment. Observations include surface runoff and water leakage monitoring under different land-use types and different irrigation activities. Water sample analysis indicators in surface runoff from the fields include total nitrogen, nitrate-nitrogen, ammonium-nitrogen, total phosphorus and phosphate-phosphorus, and the chemical analyses are conducted according to the national standards. The results show that land-use types have a significant effect on the concentration of the nitrogen, and the total nitrogen losses in surface runoff are in the order of corn > paddy rice. Land-use types have greater impact on the losses of total phosphorus but not at a significant level. With the increase of rainfall intensity from 6.0 mm·d-1 to 52 mm·d-1, ammonium-nitrogen and nitrate-nitrogen concentration decreased remarkably, organic nitrogen increased from 3.2% to 69.7%, inorganic nitrogen decreased from 96.8% to 30.3%, which means that the proportion of organic nitrogen lost in the surface runoff increased; while the total phosphorus and phosphate-phosphorus concentrations increased gradually. Through using the water-saving irrigation technique, rainfall use efficiency was increased by about 14%~23%, irrigation water was saved up to 25%, and surface drainage was decreased by about 20~25 mm, thus, water pollution caused by the losses of nitrogen, phosphorus and other nutrients in surface runoff can be reduced effectively. Crop growing stages and topography and landscape also have impacts on rainfall-runoff characteristics and farmland nutrient losses.
  • Earth Surface Processes
    Spatial distribution and pollution assessment of Zn in urban soils of Yibin, Sichuan Province
    GUO Guang-hui, ZHANG Hang-cheng
    2011, 30(1): 125-133. https://doi.org/10.11821/yj2011010012
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    Urban soils are regarded as recipient of large amounts of heavy metals from various sources. Information on the environmental effects of different functional zones is lacking, especially in Yibin, a city with a rapidly increasing rate of development. Such information will assist in developing strategies to protect urban environment against long-term hazardous accumulation. In order to identify the concentration and spatial distribution of Zn in urban soils, 63 topsoil samples of Yibin, Sichuan Province, were collected and analyzed with geo-statistics extent based on GIS. The results showed the concentration of Zn in the soils of Yibin ranged from 36.16 to 362.15 mg/kg, with the average value of 138.88 mg/kg, which is apparently higher than the background value of Sichuan Province (p=0.000). Moreover, compared with the soil baseline value of Sichuan Province, 28.57% of the samples exceeded this reference. The concentrations of Zn in industrial areas, traffic areas and commercial areas were significantly higher than the background value, respectively. Using the soil-baseline concentration as a criteria, 71.42%,41.67% and 33.3% of the samples in industrial areas, commercial areas and traffic areas exceeded the limit, respectively. The geo-statistical analysis showed that the spatial correlations of Zn belonged to the medium degree, indicating that the concentration of Zn in the soils was influenced by the random factor and structural factor. Spatial distribution of Zn pollution accumulative index produced by kriging showed that Zn exhibited serious pollution risk in Shangjiangbei and Xiajiangbei districts, and that soils in Cuiping and Nan'an districts were contaminated by Zn to some degree, particularly in industrial areas, commercial areas and traffic areas.
  • Earth Surface Processes
    Effects of the Three Gorges Project on the typical wetland vegetations of Poyang Lake
    YU Li, HE Long-hua, ZHANG Qi, CHEN Yu-wei, WANG Xiao-long
    2011, 30(1): 134-144. https://doi.org/10.11821/yj2011010013
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    In the paper, the evolution law of the typical wetlands (the wetland near the confluence of Raohe River estuary and main branch estuary of the Ganjiang River, and Ganjiang southern-branch delta wetland) in the Poyang Lake wetland was studied by the classification of the Landsat-TM images during the period from 1991 to 2008. Results showed that the wetlands expanded the main water body of the Poyang Lake obviously. Furthermore the wetland was in a positive succession from 1989 to 2001 before the operation of the Three Gorges Project. With the running of the Three Gorges Project, the effects on the succession of the wetlands were very different depending on the distance from Hukou. The succession of the Raohe River wetland near the Hukou Station was changed, which was obviously affected by the running of the Three Gorges Project. Some of the Carex beach changed into Bulrush beach, and the range of the Carex beach has greatly extended because the time when the wetland was exposed has been moved up. While the Ganjiang middle-branch delta wetland that is far from the Yangtze River had less changed after the operation of the Three Gorges Project and it was in a steady positive succession.
  • Earth Surface Processes
    Spatial-temporal distribution and wind-erosion features of farmland around Beijing
    WANG Ren-de, ZOU Xue-yong, ZHAO Jing-yan
    2011, 30(1): 145-152. https://doi.org/10.11821/yj2011010014
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    As the capital of China and a world famous metropolis, Beijing has the wind-sand problem, which attracts the attention across the country. The researches on the wind-sand problem of Beijing has been done by many related scholars and placed emphasis on the influence of local sand source. As the largest kind of bare land in Beijing suburbs, farmland is the most important local sand source in this region. This paper studied specially the spatial-temporal distribution and wind-erosion features of farmland around Beijing,which were analyzed with the aid of satellite images, field investigation and fixed-point observation. The results shows that stub keeping and ploughed land are the main wind-erosion farmland around Beijing. Stub keeping land is mainly distributed in Beijing suburbs and ploughed land is mainly in the Yanqing basin. In recent years, the farmland of Beijing reduced largely, but the stub keeping and ploughed land has increased. The strong wind-erosion happens in March and April due to stub keeping land, which lasts six months for ploughed and harrowed land, and only happens in April due to ploughed instead of harrowed land. This research can help us get a better understanding of the types, area, distribution and wind-erosion features of the farmland in Beijing suburbs, and establishes basis for the future research on the wind-erosion feature of farmland, wind-erosion quantity, dust emission quantity and its influence on the air environment. It is important for the research of wind-sand movement in Beijing.
  • Earth Surface Processes
    Influence of climate change on climate suitability of wheat in Gansu
    PU Jin-yong, YAO Xiao-ying, WANG Wei-tai
    2011, 30(1): 153-160. https://doi.org/10.11821/yj2011010015
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    Based on the data of winter wheat experimental field and meteorological data in Xifeng and Tianshui agrometeorological experiment stations and Pingliang and Chenxian agrometeorological observation stations from 1981 to 2008, the models of climate suitability had been established. The dynamic variation of climate suitability in the whole growth period from 1971 to 2008 was evaluated. The results showed that the suitability degrees of temperature, light, precipitation and synthesized climate were 0.77, 0.66, 0.50 and 0.60 respectively during the whole growth period of winter wheat. It is indicated that the temperature and light suitability degree increased by 0.001 and 0.0014 every year respectively and precipitation suitability degree decreased by 0.0013 every year from 1971 to 2008. The accumulated departure of temperature and precipitation suitability degree increased by 0.006 every year and accumulated departure of light suitability decreased by 0.0923 every year from sowing to stopping growing period in recent years. The accumulated departure of temperature decreased by 0.0254 every year and light suitability increased by 0.0139 every year during the overwinter period in recent years. The accumulated departure of temperature and light suitability decreased by 0.0497 and 0.0186 every year respectively from reviving to heading period in recent years. But the accumulated departure of precipitation increased by 0.0262 every year since 1971 and the meteorological condition was becoming better in this growth period. The accumulated departure of temperature and precipitation suitability degree decreased by 0.0031 and 0.016 every year and the accumulated departure of light suitability degree increased by 0.0637 every year during heading to mature period in recent years. The synthesized results of all climatic factors trended grim in this period. Precipitation was main limiting factors during the later growth period of winter wheat. We suggested that countermeasures for climate change should be modified in accordance with climate suitability in order to utilize climate resource effectively.
  • Earth Surface Processes
    Modern sedimentation rates and dry-humid change inferred from grain size records in Dianchi Lake, Yunnan Province
    WANG Xiao-lei, YANG Hao, ZHAO Qi-guo, CHEN Ye, CHEN Jing-song, WANG Lin-xian
    2011, 30(1): 161-171. https://doi.org/10.11821/yj2011010016
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    Based on radionuclide dating (210Pb and 137Cs) in the sediment core of the Dianchi Lake, Yunnan Province of China, we calculated the sedimentation rates in the past 159 years. The vertical profile of 137Cs has three obvious 137Cs peaks in the core corresponding to 1963, 1975 and 1986, since the onset of 137Cs fallout in 1954. Using the dating of the 137Cs peaks, the four time-averaged accumulation rates of the Dianchi Lake were 0.062, 0.051, 0.049 and 0.043 g/cm2·a-1, respectively. Four stages with different accumulation rates in core DC1 indicated a slower process since the onset of atmospheric nuclear weapons testing in the 1954. According to the result of 210Pb (CRS) dating in DC1, the sedimentation rate is 0.052 g/cm2·a-1, which is unstable in the past 129 years, which might be related to human activities during different historical periods of the past 100-150 years. As for dissimilar physical and chemical associations, diffusion characteristics for the two radionuclides (Pb and Cs), we interpreted the rationality of deviation by the two dating methods. The further precise result can be obtained by combining two or more dating methods, respectively. Compared with the local rainfall in the past 50 years with sediment grain size in the region of Dianchi Lake, it is found that there was an obvious variation trend in the sediment grain size with the fluctuations of rainfall. All these findings indicate that there is a positive correlation between grain size and the fluctuations of rainfall. This shows that sediment grain size could reflect the rainfall changes trend at a short time-scale and high resolution investigations, i.e. larger sediment grain size reflected more rainfall and wetter climate while smaller sediment grain size reflected less rainfall and drier climate.
  • Earth Surface Processes
    Spatial pattern of forest ages in China retrieved from national-level inventory and remote sensing imageries
    DAI Ming, ZHOU Tao, YANG Ling-ling, JIA Gen-suo
    2011, 30(1): 172-184. https://doi.org/10.11821/yj2011010017
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    The structure and spatial distribution of forest age are important parameters for assessing carbon sequestration potential of forest ecosystems at regional scale.In this study, we tried to estimate those parameters based on survey data of the average forest age and area of dominant tree species retrieved from detailed investigation of the fifth national forest at provincial level, along with the growing season NDVI data derived from NOAA AVHRR sensors in the same period. We then analyzed the spatial patterns of forest ages in China with remote sensing downscaling techniques. The results indicate that the spatial distribution of forest ages showed significant heterogeneity. The forest age of southeast China was lower than that of rest of the country, with average values ranging from 20 to 30 years. The forests aged over 120 years are mainly distributed in central Sichuan and northwestern Xinjiang. And the forest ages of the southeastern Tibet, northwestern Heilongjiang, northeastern Inner Mongolia and southern Yunnan are mostly between 70-120 years. From the national-level perspective, the main forest age is ranged from 10 to 80 years, with their area accounting for 85.4% of the total forest area. The area of forest aged 20-40 years accounted for 35.3% of the total forest area. The average forest age was 40.6 years in China, whose standard deviation is 26.6 years. As for the probability, Chinese forest ages showed a single peak of abnormal distribution.
  • Earth Surface Processes
    Study of karst basin SCS runoff model based on GIS and RS
    ZHENG Chang-tong, LIANG Hong, SHU Dong-cai, JIAO Shu-ling, XIE Xiao-yun, WANG Mao-qiang
    2011, 30(1): 185-194. https://doi.org/10.11821/yj2011010018
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    Parameter λ is an important index of the SCS runoff model. Model researchers take the standard value λ= 0.2 as the model parameter. However, the model has not considered the impact of landform types on runoff. There are a lot of differences between soil thickness, surface slope, lithology and the degree of development of rock fracture of different landform types in karst basin. All these factors have a direct impact on runoff mechanism of watershed. The landform types have a great influence on the runoff of karst basin. The SCS model is modified by calibrating the values of λ of different landform types. GIS and RS are important means to obtain the spatial information of a watershed. By using GIS and RS, we extract the information data of landform types, soil classification, land use, and obtain the CN values of different landform types. There are no karst basins with a single landform type. So it is difficult for measured data alone to calibrate the value of the various landform types of λ. This paper attempts to calibrate the parameter λ of different landform types by analyzing the relationship between landscape structure and the parameter λ. The parameter λ values of the karst basin are calculated in combination with measured data and landform characteristics, and the karst basin SCS runoff model is established at last. The model is applied to the Pinghu basin, compared with the SCS runoff model. The results demonstrate that the precision of the karst basin SCS runoff model is much higher than that of the SCS runoff model. It has been shown that the karst basin SCS runoff model can be used to simulate the runoff of a typical basin of karst. The result of this study showed that this method can be used to complete the model parameterization, calibration and verification, which is feasible under the conditions of lack of information. It can refer to other factors which affect runoff also. At the same time, hydrological models are supported by GIS and RS technology, which not only enriches the means of access to spatial information, but also improves the efficiency of the model calculation.