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    20 October 2010, Volume 29 Issue 10 Previous Issue    Next Issue
    Urban and Rural Studies
    The residential differentiation of tour-based spatio-temporal decision-making of travel behavior in Beijing City
    CHAI Yan-wei, MA Jing, ZHANG Wen-jia
    2010, 29 (10):  1725-1734.  doi: 10.11821/yj2010100001
    Abstract ( )   PDF (2065KB) ( )   Save

    The relationship between built environment and travel behavior has long been studied in geography, transportation and city planning. There has been a large body of such researches in western countries from macro and micro perspectives, using different methods such as simulation, description and modeling. Relatively, in China most such researches have centered on trip-based analysis, no matter from aggregation level or individual level, paying little attention to tour-based analysis. In addition, the travel decision-making process of residents has rarely been considered either. This paper attempts to construct the concept model of tour-based spatio-temporal decision-making of travel behavior and explore its residential differentiation on workdays in Beijing city, by using nested logit model with the data of travel diary obtained in 2007. Moreover, it attempts to discuss the relationship between activity and mobility.The results first of all show that residential neighborhood has an effect on the tour type decision-making, but the effect varies with the change of travel purpose. For example, if it is a work tour, its residential differentiation will be significant; but if it is a non-work tour, it will be indistinct. This may be closely related with Chinese unique suburbanization. Secondly, the start time decision-making is mainly affected by the activity type, which implies that there is a strong tie between activity and mobility. But, anyhow, the residential differentiation of start time decision-making is not significant. Thirdly, the travel distance and mode choice is distinct in different neighborhoods, that is to say the residential differentiation of spatial decision-making is significant. On the whole, the travel distance of Danwei residents is comparatively short, and the mode choice is mainly non-motor vehicle. In contrast, the travel distance of residents in commercial housing community and policy-oriented housing community is much longer, and the mode choice is mainly motor vehicle, with car in the former and public transport in the latter. Therefore, the travel behavior of Danwei residents is to some extent low carbon while the travel of policy-oriented housing community residents is long and dependent on public transport. We should pay more attention to these unique neighborhoods in China.

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    The jobs-housing relocation and spatial matching of residents in alleviatory housing neighborhoods in Guangzhou
    ZHOU Su-hong, CHEN Lu-ping, WU Zhi-dong
    2010, 29 (10):  1735-1745.  doi: 10.11821/yj2010100002
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    Alleviatory housing is one kind of houses provided by the government for low-income families. It has become one of the important parts in the social security system of China. By doing a case study in the alleviatory housing neighborhoods named Tangxia and Tongde developed during the 1990s in Guangzhou, the jobs-housing relocation and spatial mismatch are tested. The types of residents in both of the neighborhoods have changed a lot from 1996 to 2007. A large number of sub-rent and re-sold houses came up due to the changing of location, relatively low price and inefficient management about immigration and emigration of this indemnificatory housing community. Accordingly, the main structure of housing consists of alleviatory housing, commercial housing, re-rent (sub-rent) housing and Danwei housing. The residents in alleviatory housing and commercial housing meet with great changes of jobs-housing relocation and jobs-housing mismatch with different mechanism factors. As to alleviatory housing residents, the jobs-housing distance became longer after they moved into the houses allocated by the government. The passive jobs-housing mismatch is mainly driven by policies and the barriers from the residents themselves. In the latter case, commercial housing residents who have an average income or above are attracted by the low price of houses due to the political welfare, and they can afford to take taxi or private cars to meet with the long distance commuting. The jobs-housing mismatch is mainly driven by market and the initiate choice of the residents. Different from the residents in both alleviatory housing and commercial housing, residents in re-rent (sub-rent) housing and Danwei housing do not meet with jobs-housing mismatch problems. The former is the residents who work near the neighborhoods and are mostly attracted by the low price of houses, and the latter is the Danwei employees who get houses from their Danweis. Both residents in re-rent (sub-rent) housing and the Danweis on behalf of their employees would take account into the short distance when they select the jobs-housing places. The sub-renting and re-selling of alleviatory housing have carried some inequity and the spatial mismatch for residents in both alleviatory housing and commercial housing has generated some adverse impact on their quality of lives. It is necessary to conduct more researches on the optimization of the alleviatory housing policies and the implementations, as well as the optimization of urban structure.

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    Administrative boundary re-organization in Nanjing metropolitan region
    LUO Xiao-long, YIN Jie, TIAN Dong
    2010, 29 (10):  1746-1756.  doi: 10.11821/yj2010100003
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    In today's globalizing age, cities and regions have experienced intensive restructuring in the world, giving rise to deterritorialization and reterritorialization. From the perspective of reterritorialization, this study investigates administrative boundary re-organization in Nanjing metropolitan region, using the case of Jiangning's abolishing county and designating district.According to the theory of territorial restructuring, this study focuses on two territorial organizations-city and state, investigating the process of administrative boundary re-organization, impacts of reterritorialization on urban development and power struggle in administrative boundary adjustment in Nanjing and Jiangning. We argue that territory restructuring is a gradual process in Nanjing metropolitan region, involving abolishing county and designating district and annexation of towns and townships into street offices. Through these administrative boundary adjustments, Jiangning is transforming from a county economy to a city economy. Its economy grows dramatically and the built-up area is extending rapidly after the administrative boundary adjustment. This is due to the independent economic and political status of Jiangning after reterritorialization to a large degree. However, with the restructuring of city space, there is little change in another territorial organization-state. Jiangning district still possesses the former county's administrative system and power. In the new city space, the new administrative system (two-layer governments-city and district) and the old administrative system (three-layer governments-city-county-town/township) co-exist. Therefore, Jiangning's reterritorialization is an incomplete process of reterritorialization due to the lack of state restructuring. Such incomplete reterritorialization causes intensive interest conflicts between city government and district government, especially in urban planning, public transportation and land use, etc. The findings of this study will shed light on other metropolitan administrative boundary re-organizations, and have important policy implementations for improving metropolitan governance.

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    Quantitative evaluation on effect of farmers' interaction in rural community:Evidence from Mengzhai Village, Henan Province
    LUO Qing, LI Xiao-jian
    2010, 29 (10):  1757-1766.  doi: 10.11821/yj2010100004
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    Agriculture information flows will produce interactive learning effect, and the existence of interactive learning effect plays very important roles in the spread of agricultural technology. Based on the surveys in Mengzhai Village, Henan Province, we collect the data concerning the social and economic conditions on garlic production of neighbors, relatives and nearby-plot farmers, examine interactive learning effect, and analyze the interaction consequences in different types of groups. Results show that: (1) endogenous interaction effects exist only in the kinship group; (2) contextual interaction effect exists in nearby-plot groups and neighborhood group, but interactive learning effects have remarkable differences between the groups; (3) correlated effect exists in all the groups. Compared with the kinship group, the other groups have more correlated effect. Correlated effect is much weaker than endogenous interaction effect in the kinship group, and it is also smaller than contextual interaction effect in nearby-plot group and neighborhood group; (4) direction can be identified in farmers' interactive learning. This suggests that a few farmers learn new methods by communicating with external actors or accumulating the new knowledge by planting the garlic, and their interaction with other farmers might result in knowledge externalities. The size of externalities depends on the degree of intimacy between farmers. The above conclusions have some important policy implications for the diffusion of new technology in Mengzhai Village. For example, in the extension of new technology, we can select a few farmers with stronger absorptive ability in different kinship groups, encourage them to adopt new technology, and thus affect other farmers to accept new technology by the interactive effect. These results revise the findings of foreign scholars. This academic research has important meanings for policy-making.

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    The impact of rural households' concurrent businessbehaviors response on the housing land-use patternin poor mountain area:Based on a survey of 568 households in Yunyang County,Chongqing
    ZHOU Jing, YANG Qing-yuan, XIN Gui-xin, FENG Ying-bin, DAI Pei-qi
    2010, 29 (10):  1767-1779.  doi: 10.11821/yj2010100005
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    The rural households have been increasingly taking part in diverse production activities apart from farming in poor mountain areas, which has a great impact on their land-use activities. Taking Yunyang County of Chongqing as a case study, we employed a Participatory Rural Appraisal method to investigate randomly selected 568 households and analyzed the spatial distribution of their rural housing land by using a landscape pattern analysis. The results show that the concurrent business level of rural households was high in Yunyang County. First, according to the ratio of off-farm income to the total income and the proportion of off-farm workforce inputs, we classified rural households into five groups: full-farm, farm-dominated, half-farm, non-farm-dominated and non-farm households. We find that the lower proportion of the elderly or women the households have and the higher education they get, the higher concurrent business level they will be. However, households with multiple divisions of work and a big family size tend to be at the middle stage of concurrent business. Of full-farm and farm-dominated households, the housing land area per family is relatively high, about 180 m2, which indicates extensive landuse utilization. Compared with the farm-dominated households, full-farm households themselves used a large proportion of land for rearing livestock and storing groceries except for housing. The residential land of half-farm households increases by approximately 190 m2 per family, indicating a relatively intensive and less diverse residential land use. For half-farm households, they reduce the land of storing and increase the land of living to enlarge their housing land. As for non-farm-dominated and non-farm households who almost drop all their farming activities, the residential land area per family tends to be lessened, about 160 to 130 m2, which means a more intensive but a less diverse land use pattern. The causes are that the land used for agricultural production decreases, and the decreased land of producing is less than the expanded land of living. As a consequence, the study suggests that the adjustment or arrangement of housing land should be fit to the concurrent business needs of households.

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    Economy and Regional Development
    The mechanism of the spatial dissimilarity of regional economy: A theoretical model and its application in the Yellow River Valley
    QIN Cheng-lin, LI Min-na
    2010, 29 (10):  1780-1792.  doi: 10.11821/yj2010100006
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    The mechanism of the spatial dissimilarity of regional economy is an important problem for regional economic research. At present, on this problem, there are 5 research visual angles, namely factor endowments, main body of economic activity, object of economic space, division of labor and the system. The research result of each visual angle only explains the mechanism of spatial dissimilarity of regional economy from a certain aspect, the unified theoretical frame of explaining the mechanism of spatial dissimilarity of regional economy has not yet taken shape. The factors influencing the spatial dissimilarity of regional economy are multidimensional and multi-level. It is essential to consider the research results of each visual angle as a whole so that we can get a better understanding of the mechanism of spatial dissimilarity of regional economy. In view of this, this paper embarks on the connotation of the mechanism of spatial dissimilarity of regional economy, takes the relevant theories of economic growth factors and the theory about the division of labor as the rationale and constructs a theoretical analytical model for explaining the mechanism of the spatial dissimilarity of regional economy. The theoretical analytical model reveals that comprehensive factor endowments determine division of labor, and the division of labor produces the result of agglomeration. Thus, comprehensive factor endowments, division of labor and agglomeration are coupling and interacting. Under the control of this relation, in the aspect of spatial dissimilarity of regional economy, there are 3 mechanisms which are both distinguishing mutually and inseparable, namely factor endowments decision function mechanism, the conductive function mechanism of division of labor and the circulation accumulation causality mechanism. Moreover, this paper uses the theoretical analytical model to conduct the empirical analysis for the mechanism of economic spatial dissimilarity in the Yellow River Valley. The results show that there are obvious coupling interaction relations among factor endowments, division of labor and agglomeration in the Yellow River Valley, and the economic spatial dissimilarity in the Yellow River Valley is greatly affected by factor endowments decision function mechanism, the conductive function mechanism of division of labor and the circulation accumulation causality mechanism.

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    Informal job-seeking agencies and their role in the 'World Factory&rsquo|of the Pearl River Delta: A case study in Tangxia Township, Dongguan City, Guangdong Province
    XUE De-sheng, LIN Ting, KRAAS Frauke, KILLIAN Pamela
    2010, 29 (10):  1793-1801.  doi: 10.11821/yj2010100007
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    Previous research findings have often suggested that rural migrant workers rely on social networks as a job-seeking strategy. But in Dongguan city, a typical area of the Pearl River Delta 'world factory', our study has revealed the existence of many informal and semi-legal small-scale private job agencies. The case study was conducted in Tangxia, a township in Dongguan city. The informal job agencies were examined through thorough research, focusing on their spatial distribution, organisational structure and operational processes. Furthermore, the aim was to understand the conditions of the agencies' appearance and utilities for the involved actors. The methodology employed includes explorative field investigation, participant observation, mapping of 45 informal agencies, a survey of 585 migrant workers in the manufacturing sector, interviews and casual talks with 22 migrants and agents. Their location along a street in the 138 Industrial Zone is suitable for collecting job demand information from the firms in the vicinity. The entire process of the agencies' operations is characterised by informality. Five main reasons for the existence of the informal job agencies were identified. The informal job agencies' advantages are that they are non-binding and offer comparably low cost services and flexibility. The attitude of the local government to these informal job agencies is one of tolerations, "opening one eye, and closing the other eye". Moreover, it has become obvious that the informal job-seeking agencies are playing an increasingly important role in the migrant workers' second and further job seeking after they have become familiar with the environment of the 'world factory'. Finally, it became apparent that (1) the informal job agencies' services cover not only the township of Tangxia, but also several places across Dongguan and Shenzhen. This facilitates intraregional information flow and labour mobility within the Pearl River Delta. (2) Most of the involved stakeholders are previous factory workers who gathered personal contacts to staffing departments of factories. (3) Most informal job agencies have been established in a niche, serving both consumers and suppliers of labour, but the lack of control and sanctions to prevent fraud gives them a bad reputation.

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    Culture and Tourism
    Evaluation on tourism community participation level based on AHP method with entropy weight
    HOU Guo-lin, HUANG Zhen-fang
    2010, 29 (10):  1802-1813.  doi: 10.11821/yj2010100008
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    The paper attempts to set up a community participation level evaluation model based on AHP method and entropy weight theory. By taking examples of traditional village and town resorts including Zhouzhuang, Tongli, Xidi and Hongcun, community participation levels and the main influencing factors are analyzed. 1) The importance of the factors that affect community participation levels in traditional village and town resorts is, in proper order, the community participation level in tourism planning and decision-making, the community participation level in tourism income apportionment, the community participation level in tourism resources and environmental protection, publicity and education, and the community participation level in tourism operation and management. Among those factors, the community participation level in tourism planning and decision-making is the key factor. 2) The community participation level of Xidi is in a high state; while that of the rest three, i.e., Zhouzhuang, Tongli and Hongcun, are moderate. Their community participation level order from large to small is Xidi > Zhouzhuang > Tongli > Hongcun. 3) The low degree of tourism planning and decision making in community are the main reason that influences the general community participation level in China's traditional village and town resorts. 4) The principle factors that lead to community participation level difference in China's traditional village and town resorts are the operation and management modes of those resorts, the socio-economic development stage of those tourism destinations, the community tourism systems and policies and the community patterns and tourism resource properties. 5) The key measures to promote community participation level in tourism development in traditional village and town resorts are transforming management system of tourism destinations, implementing the "people-oriented" scientific development concept, and protecting the political rights of tourism development participation of the residents.

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    Study on tourists' ecotourism perception and attitude towards environmental management: The case of Jinggangshan Scenic Area
    ZHONG Lin-sheng, SONG Zeng-wen
    2010, 29 (10):  1814-1821.  doi: 10.11821/yj2010100009
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    The objective of this study was to explore the ecotourism perception an attitude towards environmental management of tourists visiting Jianggangshan Scenic Area in Jiangxi Province, China. A survey was conducted between December of 2005 and December of 2007, using structured questionnaires. A convenient sample of 363 tourists was interviewed during their visit to the scenic area, using the expectations questionnaire. It was found that there is much more perception of "nature base ", "tourism resources protection" and "environmental education" towards ecotourism, but less perception of "communities' interests". And different types of tourists including gender, age, education, occupation, income and traveling ways have distinct perceptions. It was also found that, the attitude towards the five types of environmental management measures, such as "responsibility to environment", "environment and resources protection", "attention to environment impact", "importance to environment education", "respecting local culture" is positive, while the attitude towards "enhancing tourists management" is negative. And several sectors of tourists' characters have significant impact on ecotourism environmental management. For example, the male tourists' attitude towards the environmental management measures consisting of "responsibility to environment", "attention to environment impact", "importance to environment education", and "enhancing tourists management" is more positive than that of female tourists. Furthermore, ecotourism perception is related to some attitude towards ecotourism environmental management according to statistical analysis. The tourists who have perception of "nature base", "tourism resources protection" and "communities' interests" hold a more positive attitude to "importance to environment education". Finally, some countermeasures on enhancing environmental management were discussed in this paper.

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    Land Resource and Use
    Expansion of urban space and land use control in the process of urbanization
    DAI Jun-liang, GAO Xiao-lu, DU Shou-shuai
    2010, 29 (10):  1822-1832.  doi: 10.11821/yj2010100010
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    Urban expansion brought by the rapid progress of urbanization has caused many problems in China. It is a significant issue to evaluate the extent of urban expansion and to make appropriate controls over the sprawl of urban areas. With a comprehensive review and analysis of relative planning and economic theories as well as international experiences, this paper argued that Chinese cities have no better choice but compact urban forms. A policy package integrating planning and taxation measures should be adopted to achieve the goal of compact development. To achieve this goal, intensive use of public transportation and high proportion of collective houses should be encouraged. It is necessary to determine the best density of cities based on solid research, where the variation of cities should be considered. Based on comparative analysis, for instance, 80~105 m2 per capita is recommended as the reasonable range of urban density in large and middle-scale Chinese cities with about 80% of housing stocks being collective houses.

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    Spatial expansion pattern and its dynamic mechanism of typical rural settlements in Huang-Huai-Hai Plain
    WANG Jie-yong, LIU Yan-sui, CHEN Yu-fu
    2010, 29 (10):  1833-1840.  doi: 10.11821/yj2010100011
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    The study on rural residential land in China is important and complicated. There are 7.5 billion local farmers settled in 3 million villages across the country. In this paper, Zhaozhuang Village is chosen as a study area, which is located in the central region of Huang-Huai-Hai Plain. Through the analysis of high resolution airborne images data and hut-to-hut survey data, the changes of rural settlement land are examined between 1967 and 2008 by detailed land use classification. The result shows that the area of rural residential land increases by 126% from 1967 to 2008, and the main increment is from rural residential land and grain-sunning ground; the number of rural houses increases faster during the period 1985~1990 than that in other periods; rural settlements extend mainly towards the south and west, which is 182 m to south and 285 m to west. In general, the rural settlement land extension has three periods featured by gradual sprawl, leapfrogging expansion and filling space. The increase of farmers' residential demand and the enlargement of production scale are interior driving forces of rural settlement extension, and the striking contrast between inner and external condition is external environmental force. Growth of farmer income provides the economic support, however, the absence of rural land-use plan and inefficient management of rural land use makes rural extension out of control, and these interactive factors drive rural settlements to extend quickly. It is suggested that the system of rural land management should be modified and the local governments should pay more attention to the change of grain-sunning ground, waterhole and woods in the future. Finally, the authors indicate that it is important to make a long-term planning of strategic and integrated consolidation for the sustainable development of rural residential lands.

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    Environment and Ecology
    The numerical simulation on green water cycle of typical vegetation types in karst area
    WEN Zhi-qun, YANG Sheng-tian, SONG Wen-long, BAI Xiao-hui, GAO Fang, LIU Wei
    2010, 29 (10):  1841-1852.  doi: 10.11821/yj2010100012
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    Green water is vital to vegetation recovery in karst area. Considering the processes in green water cycle, this paper coupled the canopy interception process, soil moisture movement process and evaportranspiration process, and built a green water cycle processes model to simulate and analyze green water cycle of typical vegetation types in karst area. Under the rainfall simulation experiment calibration and soil moisture monitor calibration, the model was extended to regional scale, and was used to simulate the green water cycle in a karst area, Guizhou Province, China, during October 2005 to March 2006. The results show that: First, most of the rainfall during this period turns into green water through canopy interception and infiltration into soil, which totally occupies 87.4% of rainfall and is supplied for vegetation ecosystem water use. Second, there are many differences in green water cycle processes of different vegetation types in the study area. The percentages of green water of different vegetation types are 93.3%, 93.2%, 91.5%, 81.9% for shrubs, coniferous woodland, mix woodland, grassland respectively. It can be concluded that with the vegetation recovery from grassland to shrubs and woodland in the study area, there will be more and more rainfall turning into green water which is used by the vegetation ecosystem and benefits the vegetation recovery. Third, the changes of green water cycle between months in different vegetation types share the same characteristics. The green water storage is increasing in October, January, and March in all vegetation types, and is decreasing in November, December, and February. In this period, the amount of green water is much greater than that of blue water, and the green water storage is increasing overall. Drought is unlikely to occur during October to March and the green water storage is supplemented in this period before the "spring drought" and "summer drought" in this karst area.

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    Environmental influence evaluation of land development and arrangement based on scenarios analysis: A study on Lianshui County, Jiangsu Province
    FANG Bin, YANG Ye, LEI Guang-hai
    2010, 29 (10):  1853-1862.  doi: 10.11821/yj2010100013
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    Land development and consolidation plan is bound to affect ecological environmental conditions within the planned area. However, the specific evaluation method, index system and modeling algorithm should be standardized. By taking Lianshui County of Jiangsu Province as an example, Land Development and Arrangement Plan of Lianshui County (2000~2010) was analyzed, and the affection was compared by a evaluation model of scenarios. The result shows that the influence in 1997 was lower than in 2000 in Lianshui County. This can be explained as: during the three years, not only the occupation of cultivated land has been strictly controlled, but more cultivated lands have been transferred also. Environmental quality declined in 2010 because of without planning. The possible reason is that the construction of land fragmented farmland and unutilized land, which increases density of plaques. In comparison of future scenarios without planning and with planning in 2010, it is indicated that eco-environmental conditions could obviously increase by 0.6736 percentage point. This shows that proper land development and consolidation plan plays an important role in promoting a healthy eco-environment within the planned area.

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    Ecological water effect of returning orchard to cultivated land in apple base of gully region of the Loess Plateau
    HE Fu-hong, JIANG Wei-guo, HUANG Ming-bin
    2010, 29 (10):  1863-1869.  doi: 10.11821/yj2010100014
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    Recently, a lot of orchards in the gully region of the Loess Plateau have been degenerated, which should be returned to cultivated land. But the ecological water effect of returning orchard to cultivated land is still unclear. Taking the Wangdonggou watershed as a case study, this paper chose three land use types such as peak period orchard, waste orchard and cultivated land converted from orchard, the ecological water effects of returning orchard to cultivated land have been studied based on the soil moisture data of 1986, 2002 and 2009. The results show that: (1) The mean soil moisture content and water storage of wasted orchard and cultivated land converted from orchard are significantly bigger than those of the peak period orchard in 2009. With the orchard disuse or return to cultivated land, the soil moisture content will increase significantly. (2) When the land use changes from peak period orchard in 2002 to cultivated land in 2009, the mean soil moisture content of 200-600 cm profile of cultivated land converted from orchard is 10.62%, which is significantly bigger than that of the peak period orchard (8.53%). (3) Dried soil layer affected by biota use is a common soil water phenomenon in the peak period orchard, wasted orchard, and cultivated land converted from orchard, which is an urgent ecological problem that need to be resolved.

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    Earth Surface Processes
    Experimental study on the effect of slope vegetation distribution variation on runoff and sediment yield in slope-gully system
    DING Wen-feng, LI Mian
    2010, 29 (10):  1870-1878.  doi: 10.11821/yj2010100015
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    The runoff erosion formation and the sediment yield intensity present a vertical distribution because of the complicated topography and the special climate condition in the Loess Plateau of China. The variation of vegetation distribution has great effects on sediment yield in slope-gully system because of the erosion spatial variability. The authors, taking the slope-gully system as a research object, which is composed of the 4-meter-long slope and the 3-meter long gully slope, made a series of simulated scouring experiments under different flow discharges (3.2 L/min, 5.2 L/min). This paper studies the effects of different flow discharges, different vegetation distribution along the slope (up-slope, middle-slope and down-slope) and different vegetation coverages (0, 30%, 50%, 70%, and 90%) to the sediment yielding of slope-gully system. The results show that, the total runoff volume and the process of runoff yield have no obvious difference among the three types of different transplanted grass on slope under the same grass coverages and the same flow discharges, but the sediment yield has distinct variation among the three types. That is, different types of grass decrease the sediment yield not by reducing the runoff volume. The total runoff discharge is only related to the grass coverage on slope and the flow discharge under the experimental condition. The amount of sediment yield on gully section increases with the increase of the flow discharges under the same grass coverage, as well as the same transplanted grass on slope. The amount of sediment yield on gully section did not show a decreasing tendency when the flow discharge is raised, but showed an increasing tendency instead. According to this result, if we only take the measure of harnessing the slope without harnessing the gully, the amount of sediment of gully section will increase with the rise of flow discharges. So we should give attention to slope and gully when we harness the soil and water loss in watersheds of the Loess Plateau.

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    Spatial and temporal variations of suspended sediment capacity by erosion or deposition in the Ningmeng Reach of the Yellow River and its influencing factors
    WANG Sui-ji, FAN Xiao-li, ZHAO Xiao-kun
    2010, 29 (10):  1879-1888.  doi: 10.11821/yj2010100016
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    The channel variation of the Ningmeng Reach has been very remarkable in the upper Yellow River and has increased flood risk. To reveal the channel variation trend and its influencing factors the sediment budget method was adopted in this study. The Ningmeng channel was divided into 5 sub-reaches, simultaneously, the total time period was divided into the 5 time periods. The mean annual erosional or depositional suspended sediment capacity (SSC) at the 5 different sub-reaches during the different time periods was calculated and analyzed. The results show that, sedimentation strongly occurred during 1952~1959 when there was no big reservoir and during 1994~2003 when the three big reservoirs of Qingtongxia, Liujiaxia and Longyangxia had been built and the downstream channel had been adequately adjusted. The mean annual SSC is 9.588×107 t/a and 9.503×107 t/a for the two periods, respectively. Intense erosion (-6.127×107 t/a), slight deposition (0.161×107 t/a) and stronger deposition (7.475×107 t/a) respectively occurred in the periods of 1960~1968, 1969~1985 and 1986~1993. The mean annual deposited SSC is 3.45×107t/a in the Ningmeng Reach, including 0.76×107 t/a in the Ningxia reach and 2.69×107 t/a in the Neimenggu reach. The annual mean SSC deposited in the 5 downstream channel reaches in the Ningmeng Reach of the Yellow River is 0.73×107 t/a, 0.029×107 t/a, 0.084×107 t/a, 1.131×107 t/a and 1.47×107 t/a, respectively. The temporal variation of the SSC in the Ningmeng Reach of the Yellow River was mostly influenced by the decrease of suspended sediment load from the tributaries and reservoir construction, whereas, the spatial variation was mostly influenced by the interception of suspended sediment load in the Qingtongxia reservoir and adjustment of flood discharge in the Liujiaxia and Longyangxia reservoirs. The Ningmeng Reach is located in a subsidized area and the sedimentation in this river reach is the general trend. Human activities may induce channel erosion in certain periods or sub-reaches, but cannot change the general trend.

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    Landslide hazard spatial prediction in Zigui County ofthe Three Gorges Reservoir Area based on GIS
    PENG Ling, NIU Rui-qing, CHEN Li-xia
    2010, 29 (10):  1889-1898.  doi: 10.11821/yj2010100017
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    Landslide prediction is very important in disaster prevention and reduction procedures, and it is one of practical research fields to evaluate and predict landslide hazards using statistic analysis model and spatial analysis of GIS. The aim of this study is to analyze landslide susceptibility using Logistic regression model in Zigui County of the Three Gorges Reservoir Area. In this paper, seven evaluation factors are selected, i.e. topographic slope, topographic aspect, bed rock-slope relationship, lithology, land use and distance from road and drainage. In susceptibility mapping, the use of logistic regression is to find the best fitting function to describe the relationship between the presence or absence of landslides (dependent variable) and a set of evaluation factors such as topographic slope and lithology. Here, an inventory map concerning 37 landslides was used to produce a variable, which takes a value of 1 for the presence and 0 for the absence of slope failures. In order to improve the accuracy and credibility of the model prediction, methods to reduce spatial autocorrelation in a logistic regression framework are also discussed. An optimal sampling scheme that can eliminate spatial autocorrelation whilst maintaining enough samples to achieve the accuracy based on the model is developed. The model was tested by the overall model statistics, and the results indicate that the model fits the dataset. The effect of each parameter on landslide occurrence was assessed from the corresponding coefficient that appears in the logistic regression function. The interpretation of the coefficients showed that land use plays a major role in determining landslide occurrence and distribution, although field observations showed that engineering construction exerts great influence on slope stability. With the help of a predicted probability map, the study area was classified into four categories of landslide susceptibility: high, moderate, low and none. The moderate and high susceptibility zones make up 38.9% of the total study area. In comparison to the occurrence of historical landslide hazards, the precision using logistic regression model can be up to 77.57%.

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    Geo-information Science
    Analysis of the spatio-temporal distribution of the surface albedo in Sangong River Basin on the northern slope of Tianshan Mountains using TM image
    WANG Ji-yan, LUO Ge-ping, LU Lei
    2010, 29 (10):  1899-1908.  doi: 10.11821/yj2010100018
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    The difference in land surface features and land cover conditions have a great impact on anisotropy surface albedo distribution. Remote sensing is an effective means to study the land surface features by obtaining spatial and temporal characteristics of surface albedo. The northern slope of the Tianshan Mountains is well-known with its typical mountain-basin geomorphology pattern system and mountains-oasis-desert landscape. The unique and complicated background forms the special vertical distribution of the surface albedo. This paper examines the spatial distribution of surface albedo on the northern slope of the Tianshan Mountains using Landsat TM images. Topographic correction was implemented on the images using topographic normalization model based on DEM and atmospheric correction was completed using 6S (Second Simulation of Satellite Signal in the Solar Spectrum) model. The results indicate: (1) The methodology for surface albedo inversed from the moderate spatial resolution remotely sensed data is reliable to be used for estimation of the surface albedo over the northern slope of the Tianshan Mountains with significant heterogeneity in elevation. (2) The distribution of the surface albedo on the northern slope of the Tianshan Mountains is affected by the land surface features, land cover conditions and surface soil moisture. Therefore, the spatial distribution of the surface albedo on the northern slope of the Tianshan Mountains presents a distinctly vertical zonal feature. As to the mountainous forest and the dry grassland in low mountain area, the surface albedo presents regular fluctuation under the effects of the undulating terrain and elevation changes. (3) Influenced by the cover types, the crop structure and the crop phenology of the cropland, the variation of the surface albedo of the oasis in the Sangong River Basin shows instability. In the oasis area, the surface albedo varies obviously with growth seasons of the crops as well.

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    An improvement on CA model of logistic regression: A case study of Guangzhou
    NIE Ting, XIAO Rong-bo, WANG Guo-en, LIU Yun-ya
    2010, 29 (10):  1909-1919.  doi: 10.11821/yj2010100019
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    Due to its simple structure and less input data, CA model of logistic regression is widely applied in urban simulation. However, data dependency has some impact on the accuracy. Therefore, an in-depth research should be conducted to modify the traditional model. This paper established an improved CA model of logistic regression in two major aspects. First, the urbanization factors were divided into forbidden constraint and general constraint. The input data were sampled only in general constraint, while the urbanization probability in forbidden constraint was set to be 0. Second, we reduced the data dependency of general constraint using principal component analysis in SPSS. In the case study of Guangzhou, the improved CA model was applied to simulate the urban growth from 2000 to 2008. Compared to the traditional CA model, the improved CA model made a 4% improvement both on model fitness and simulation accuracy, in which constraints division contributed a 3% improvement on overall simulation accuracy and a 6% improvement on non-urban simulation accuracy, while data dependency reduction gave a more reasonable explanation for urbanization mechanism. The study aimed to establish an improved CA model, which can mine a more reasonable urbanization mechanism, and provide more scientific support for urban planning and land management.

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