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Table of Content

    20 January 2013, Volume 33 Issue 1 Previous Issue    Next Issue
    Orginal Article
    Non-equilibrium Dynamic Simulation of Two-region Scenario of Tourism System in China
    Ling XUE, Jin WENG, Chun-ping WU
    2013, 33 (1):  1-7.  doi: 10.13249/j.cnki.sgs.2013.01.1
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    In recent years, tourism in China have experienced a period of rapid growth. This article builds a mathematic model based on asymmetric monopolistic competition, scale economy, spatial cost, preference for variety, and product/service differentiations between inland and coastal regions in China. To overcome the weakness of traditional deductive model and equilibrium analysis in tourism research, the article puts forward an approach to integrate economic model with agent-based modeling for better understanding the evolutional process of tourism systems in different scenarios. The TourSwarm, a computational environment we developed, contains multiple economic interactions between tourist and firm agents that are crucial in understanding dynamic process and mechanism because the basic force driving the tourism system is inherently microscopic. This parallel processing agent-based approach has shown various advantages over existing economic approaches such as neoclassical model and equilibrium analysis. By using agent-based modeling and out-of-equilibrium simulation, this article gives a detailed discussion on the impact factors such as continuous decline of transport cost to inland region, continuous decline of substitution elasticity between inland and coast region, continuous decline of substitution elasticity of product and service in inland region. TourSwarm shows that 1) tourism tends to congregate in the coastal region with advantages of location, more demands and scale economy, and 2) the continuous reduction of travel cost and regional differentialization and product/service differentialization could change the systematic state between inland and coastal region significantly and accelerate the dynamic process of tourism agglomeration in some region. In conclusion, the main engine of recent rapid changes in tourism system is the major reduction of transport costs for people through transportation development in China. Due to love-of-varieties, the specialization and diversity of tourist products contribute much to the emergence of tourism in inland region by continuous innovation and difference-making competition strategy. The greater the gap of fixed cost between the inland and coastal region is, the more imbalanced tourism distribution would be, and more easy to form the core-periphery structure. Inland region should pay close attention to improve on its own infrastructure such as facilities and transportations. What's more vital is that the domestic demand of tourism is key to change the spatial structure of tourism system between inland and coastal region in China.

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    Quality of Urban Residential Environment Based on Stated Preference Methods
    Qian ZHAO, De WANG, Wei ZHU
    2013, 33 (1):  8-8.  doi: 10.13249/j.cnki.sgs.2013.01.8
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    Quality of Residential Environment (QRE) is becoming an important goal of modern society. With the rapid advancement of urbanization in China, many issues are emerging in fields of the society, space, security and so on. Urban residents have been increasingly concerned about the QRE that reflects their actual living conditions. As a result, urban planners have been studying the evaluation of QRE in terms of residential environment since the 1980s. A variety of evaluation methods have been explored, among which economic models have been increasingly used for QRE evaluation in recent years. The purpose of this study is to build a system for evaluating residential environment of Chinese cities, by exploring the mechanisms of the elements influencing the quality of residential environment. Stated preference method (SP), a mature approach in the areas of environmental impact assessment, is used to estimate the influence based on the data of residents’ choices from the virtual urban environments composed of elements that considered important for defining quality of residential environment. Yangpu District of Shanghai was taken as the example. Firstly, a pilot survey was implemented, which asks the residents to choose the elements influencing the quality of residential environment most. A system of residential environment evaluation is proposed, focusing on 3 indexes including convenience, comfort and security. Each index includes 4 sub-indexes. Secondly, residents’ preference data were obtained through SP surveys. Then the evaluation functions taking into account convenience, comfort and security of living environment were estimated based on discrete choice models. At last the results of the SP survey and modeling were validated with a comparative analysis on separate elements’ impact on QRE. The validation results show that the models of the convenience, comfort and the comprehensive elements were well fitted, while the model of the security fitted relatively poorly. The case study in Yangpu District shows that elements of convenience and comfort have more influences on QRE evaluation than elements of security. To maintain certain QRE, more improvements of other elements are needed for compensating the ambient noise and security elements’ decline. It is also found that people who are low-educated, female, old, with low income are more sensitive to the basic elements that affect their daily lives. When the level of basic elements decline, residents need more compensation from other elements to keep up their QRE level.

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    The Coordination About Quality and Scale of Urbanization: Case Study of Jiangsu Province
    Chun-mei ZHANG, Xiao-lin ZHANG, Qi-yan WU, Hong-bo LI
    2013, 33 (1):  16-22.  doi: 10.13249/j.cnki.sgs.2013.01.16
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    With the rapid progress of urbanization in China, a series of problems such as the traffic congestion, resource depletion, environmental pollution, ecological damage, etc., have become increasingly serious. At this time, the central government of China proposes the goal of "promoting the healthy development of urbanization". In this historical background, the problem of the healthy development of China becomes the research focus of domestic and foreign scholars. In this article, from the perspective of the coordination about the quality and scale of urbanization, the health conditions of the process of urbanization in Jiangsu are analyzed in order to provide the basis for the government to develop the macro-control policies and a reference for the other parts of China. Quality and scale is two aspects of the urbanization process, which are dependent and restraint each other. Recognizing their relationships is important for healthy urbanization. On the basis of defining the concept of quality and scale of urbanization, the quality and scale of urbanization about 13 provincial cities in Jiangsu Province are measured by the evaluation index system, then the coordinated development relations between them are analyzed by the improved quadrant method of classification and recognition. The result shows that: First, the coordinated developing relations between quality and scale of urbanization in Jiangsu are gradually turning to the high level from the low level and changing to the coordination type from the larger delay-type of quality urbanization and to the larger ahead-type of quality urbanization from the coordination type. Second, there are apparent spatial heterogeneities of southern and middle and northern Jiangsu in the coordinated developing relations between quality and scale of urbanization. On the basis of them, the phenomenon of scale lagging behind quality of urbanization in Jiangsu is worthy of attention now, at the same time, the varied development policies of urbanization are necessary to guide the building of the urbanization according to local conditions.

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    Progress of Nanjing University’s Cultural Geography
    Min ZHANG, Jie ZHANG, Lei YAO
    2013, 33 (1):  23-28.  doi: 10.13249/j.cnki.sgs.2013.01.23
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    Along with the renaissance of human geography and the rapid development of cultural geography in China in recent years, cultural geography studies at Nanjing University are developing rapidly in the 21st century. Besides the traditional aspects of cultural geography, such as cultural landscape, regional culture, and spread and diffusion of the cultural phenomena, there are many new research fields have been derived, which represents the future direction and characteristics of new cultural geography’s study, such as symbol and representation of space, local and identity, the sense of place, place attachment, the production of space, feminist study, focusing on the urban and crossing study with social and economic study. Based on the interdisciplinary study in urban geography, economic geography and tourism geography, etc., the cultural geography research group at Nanjing University extends the traditional research to varient areas, such as the cultural mechanism of urbanization, urban spatial reconstruction, urban development, the shaping of urban cultural spaces, and many applied areas, especially of tourism research and planning, urban cultural preservation and cultural development, cultural industries’ research and planning. Turning to medium and micro scale, especially the city and sub-city scale, the cultural geography of Nanjing University has done more contribution. Their experience shows that there are more efforts needed to explore the new cultural geography approaches which can be applied to urban development and planning consultation, to push the innovation of theories and methods which should uphold and develop the human geography’s core theory of ‘human and land’ relationship, to avoid the dangerous of being de-geographic and pan-cultural, to pay more attention to the value of Chinese culture, to avoid the dangerous of being de-China. In the context of globalization, the cultural and symbolic landscape of contemporary urban culture with Chinese characteristics has been a markable characteristic of cultural geography study at Nanjing University, which has the potential for international exchange in cultural geography research areas.

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    Review on the Social Geography of Nanjing University
    Li-zhen SHEN, Feng ZHEN, Xian-jin HUANG
    2013, 33 (1):  29-35.  doi: 10.13249/j.cnki.sgs.2013.01.29
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    The geography of Nanjing University is one of the important basis for geography education and research in China. The study on the achievements of the social geography in Nanjing University can outline the basic context of the development of Chinese social geography, and then provide some useful references to the social geography of the development Chinese characteristics. The development of the social geography of Nanjing University follows the research focus of the international social geography, with a strong sense of discipline pioneering and innovative, and it has become a leading part of social geography, in particular its important research efforts to the study of urban social geography. The initial research results is in the fields of the concept and content of the social geography. Recently research interests include population, urban geography, rural geography and the study of related social problems. The study fields include population distribution, demographics and expression, women, geography, urban space, differentiation of social space, urban governance, urban poverty, rural economy, rural urbanization, rural settlements, rural land use and the geography of information society. The social geography of China is gradually maturing, and the social factors are more important than beforein the impact on the economic development, so there is an urgent need to analyze these social phenomena with the features of space of places. In the social transformation, China urgently needs geographical researchers to analyze and summarize the social phenomenon with the features of spatial geography, absorb theories and methods from foreign social geography, combine with Chinese social reality and establish gradually the Chinese social geography, which is the macro background of the development of Chinese social geography.

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    The Spatial Evolution and Formation Mechanism of Population Density in Lanzhou City Over the Past 30 Years
    Zhi-bin ZHANG, Jing PAN, Xiao-hu LI
    2013, 33 (1):  36-44.  doi: 10.13249/j.cnki.sgs.2013.01.36
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    Base on the demographic data at a district level, the article analyzed the spatial evolution of population density in Lanzhou in recent 30 years, by a comprehensive application of software ArcGIS and GS+Version7. The result shows that: 1) in the evolution of spatial pattern in population density of Lanzhou, with the growth of spatial distance, the positive correlation of population density was gradually weakening and the negative correlation was gradually strengthening in 1982-2009. The spatial autocorrelation range has been continuously increased. The influence coverage of the high density area on the low density area has been increasing year by year. The random elements that arouse the spatial difference in population density are increasing continuously, and structure differentiation that space correlation causes is more and more outstanding. The regional difference in population density distribution was enlarging as a whole. It can be predicted that, in the near future, the difference remains and in a short term there will no any great changes. This illustrates that population distribution in Lanzhou is always in an imbalanced state. 2) From the changes of population density gravity in different years, it can be seen that, the population distribution is partially on the east. The tendency of space pattern in population distribution shows its regularity, which is high on the east and low on the west as a whole. In two-center space pattern formed by increase peak in Chengguan District and Xigu District, the population density is gradually reducing from center to the surrounding. The general tendency of population density in different years changes little. The high and low population gravities focus on Chengguan District and Qilihe District, which shows the gradual and stable eastward tendency and low population density center is moving at a relatively speed. The moving directions of the gravity of high and medium population density and low population density are opposite, which shows that the difference of population density in districts is enlarging. Meanwhile, as for high population gravity and medium density center, the area of research units of population gravity at the different levels is different. The district area which is high in population density is commonly small, and the district area that is low in population density is generally large. 3) The differences in population density of the districts in main urban areas existed in 30 years ago. And the revolution is under combined influences by nature element, history element, policy element and economy element. Among them, nature element is the direct factor that influences population density; history element is the key factor that influences the difference in population density; policy element plays a controlling and leading role in the revolution of space structure in a city; the difference in social and economic development directly influences mechanical growth of population, and makes population gravity transfer. Therefore, economy element is the decisive factor that influences population density distribution.

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    The Spatial Distribution Characteristics and the Basic Types of Rural Settlement in Loess Hilly Area: Taking Qin'an County of Gansu Province as a Case
    Xiao-dong GUO, Li-bang MA, Qi-yuan ZHANG
    2013, 33 (1):  45-51.  doi: 10.13249/j.cnki.sgs.2013.01.45
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    The rural population distribution depends on the rural settlement that is an important site for the working and living of rural people. It has very important significance to analyze on the spatial distribution characteristics and the law of spatial evolution of the rural settlement for optimizing the rural settlement spatial layout and promoting the construction of a new socialist countryside and the integration of urban and rural development. Taking Qin'an County of Gansu Province as a case, this article analyses the essential characteristic of spatial distribution of rural settlement based on GIS and statistical analysis technique. The results of the research show that: 1) the inside rural settlement of Qin'an County is dense and its spatial distribution is extremely scattered, which is formed after a long spatial diffusion process of the original settlement. With the increasing growth of population, the limited arable land fail to gradually meet the need for the life of settlement population in its effective farming radius, so people have been forced to spread gradually to possible living space; 2) the spatial distribution of rural settlement is closely related to its altitude, slopes, rivers and other natural geographical conditions, and the settlement patches present the normal distribution obviously along with the variations of elevation and slope, and the differences between the space distributions are significant; and 3) the complicated rural settlement types of Qin’an County are not only closely related and correspondence obviously to the spatial distribution characteristics. The rural settlements that large and medium-sized, agglomeration-typed, commodity economy and half-commodity economy are mainly distributed in the valley and flat areas, and while the small, diffuse, traditional agriculture and services output type are mainly distributed in loess hilly areas.

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    The Spatial Fractal Characteristics and Complexity of Rural Residential Areas in Beijing
    Zhi-jun SONG, Xiao-ke GUAN, Zhan-qiang ZHU
    2013, 33 (1):  52-60.  doi: 10.13249/j.cnki.sgs.2013.01.52
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    Under the background of multifunctional integration, this article analyzes the spatial characteristics of the residential areas in the overall suburb zone, plain zone, the outskirts plain zone of Beijing based on the spatial evolution of residential shape properties. The spectrum analysis shows that, the rural residential areas of the three zones are in crisscross distribution with Qianmen as the center, on the basis of three basic circles of mid-outskirts, outer suburbs, mountainous zone in Beijing. Based on this analysis, the article calculates the spatial dimension and Hurst index of three zones’ rural residential patches, and argues that the spatial structure of rural residential patches in overall suburb zone (20-122 km) is complex but not have fractal characteristics; but those in the plain zone (7-76 km) and the outskirt plain zone (7-49 km) are relatively simple but have fractal characteristics. The spatial evolutions of the latter two zones’ rural residential patches are different from their agricultural development processes. On the whole, the spatial evolution of the three zones’ rural residential areas is driven by urbanization, industrialization and non-agriculturalization of rural areas, and it is current at a critical stage of spatial expansion of the metroposis and coordinated development of agriculture, rural areas and farmers.

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    The Process and Pattern of Urban Construction Land Expansion in Xuzhou
    Ai-xue QU, Fang-dao QIU
    2013, 33 (1):  61-68.  doi: 10.13249/j.cnki.sgs.2013.01.61
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    The expansion of urban construction land, which reflects the urbanization, the spatial process and the characteristics of city development directly, is the most remarkable characteristics of a city in space. Based on maps of urban land use status in 1979, 1994, 2003, 2008 of Xuzhou, the urban construction land information including residential land, industrial land, and commercial and public service land is extracted. Using the method of grid analysis, the spatial and temporal pattern of the urban construction land expansion is analyzed in Xuzhou during the period of transformational development in 1979-2008. The results are showed as follows: 1) The structure of the urban construction land is constantly optimized. During each period of the sustainable expansion of urban construction land, the residential land achieves the sustainable and rapid development, whose growth area and intensity are the highest, in contrast, the industrial land growth is stead, for being controlled, its growth area and intensity is lower. The commercial and public service land growth is inferior, whose growth area and intensity is the lowest. 2) The inverse expansion of industrial and residential land is distinctive. As to the structure of expansion types, the inverse expansion of industrial land is the most outstanding, whose inverse expansion is promoted from center to edge of the urban. With the rapid extension of the residential land, its inverse expansion is developed gradually from urban center to middle zone of the urban. All of these also induce that the spatial distribution of urban construction land is optimized. 3) Expansion processes of the three types of urban construction land are very quickly and their expansion forms are different. The industrial land constantly expands in form of sheet shape in city’s periphery region, then of radial shape alone traffic axis zone and of progressive sheet shape in city periphery region, which shows that the characteristic of aggregating in economic development zone of city periphery region is especially distinctive. The residential land expands rapidly along traffic axis zone, filling in the empty blocks, expanding along axis zone progressively, whose spatial expansion is relative dispersed. The commercial and public service land has been developed more rapidly since 1994, and discrete expansion has been dominating and service industry cluster district has not been formed. And 4) the transition industrial and mining cities are in the period of industrial structure quick adjustment and service function of regional central city rapid enhancement, economy transition and adjustment of industrial structure are the leading forces of the urban construction land expansion, and the transportation is a strong traction force, and city planning is an important regulation force.

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    Spatial Prediction of Soil Properties by RBF Neural Network
    Fei-xiang CHEN, Jia-chang CHENG, Yue-ming HU, Yong-zhang ZHOU, Yuan ZHAO, Jia-chun YI
    2013, 33 (1):  69-74.  doi: 10.13249/j.cnki.sgs.2013.01.69
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    The key problem in precision agriculture research is how to use fewer samples to reflect the distribution regular pattern of farmland information and to use scientific interpolation method to interpolate and estimate farmland. Based on the soil chromium (Cr) content areas with large differences in Zengcheng City as an experimental base, 200 soil samples were collected by random sampling method. According to GB/T17137-1997 in China, the flame atomic absorption spectrometric method was used for the determination of a variety of chromium in soil. By Create subsets function in ArcGIS 9.3, four kinds of layout program were set,which were 200 sample points, 150 samples points , 100 samples points and 50 samples points . In accordance with the ratio of 4:1, the four of sample sets were divided into training dataset and test dataset, which were used to train the neural network, testing the accuracy of the interpolation results. Then RBF neural network method were used in soil Cr content interpolatin in the previous three date sets, and their error were analyzed and forecasted using the variance of the RMS (root mean square) error. In order to highlight the contrast, the previous corresponding Kriging interpolation maps and Kriging interpolation results of RMS error were gotten when Kriging interpolation method for data of the corresponding treatment was used. The results show that, in the case of fewer sample points, the interpolation result of RBF neural network was smaller than the root mean square error of traditional Kriging interpolation method, which are 0.003, 0.009 and 0.008, respectively. It was found that RBF neural network method was more accurate. However, when it was applied to the date set which were only 50 samples, whether the RBF neural network or Kriging interpolation method, numerical root mean square error of the prediction results was great, which were 0.179 and 0.128, respectively. Hence, it is hard to obtain the right result. Compared to the traditional method of statistical interpolation, RBF neural network method could overcome the smoothing effect with good self-learning features and strong non-linear computing power. Especially in the case of fewer sample points, the effect of spatial prediction was relatively good. Then, it can be concluded that RBF neural network method is applied more broadly and it is enough when it is used for the interpolation of the data sampling points.

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    Regional LUCC and Its Ecological Effect Based on Elevation Constraint: A Case Study of Fuzhou City
    Ming-yong LI, Lu-ming YAN, Li-li WANG, Zhi-lei LIN
    2013, 33 (1):  75-82.  doi: 10.13249/j.cnki.sgs.2013.01.75
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    Land use and land cover change (LUCC) has become a critical field of land change science (LCS) in the study of global environmental change. Based on the remotely sensed data of land use change with a spatial resolution of 30 m × 30 m in the five sub-regions and seven counties of Fuzhou City in the years of 1994, 2001 and 2006, a improved models for evaluating ecosystem services value and ecological effect of LUCC was designed by introducing the value coefficient of food yield for regional farmland per unit area and the payment coefficient of regional ecosystem services in order to analyze the characteristics of LUCC and its ecological effect under the constraint of elevations during 1994-2006, which were divided into five levels (-0.4-50 m, 50-100 m, 100-200 m, 200-500 m and 500-+∞ m) ascending respectively. The results show that: 1) The distribution of different land use and cover types was quite distinct along elevation. Forest and garden land mainly distributed on the fourth and fifth level; cultivated, built-up and unused land on the first level; grassland on the third, fourth and fifth level; and water body on the first and second level. 2) The areas of all land use and cover types showed rapid variation which appeared different characteristics under the altitude constraint in the period 1994-2006. Arable, unused and built-up area had changed sharply on the first level. The first two types decreased whereas the last one increased. The area of garden land increased significantly on the fourth and fifth level. Water body and grassland variation mainly distributed on the third and second level. The woodland change concentrated on the first, third and fourth level. 3) The ecosystem services value had increased at all elevations in 1994-2006, which appeared some inconsistency in different periods. The increasing amount of ecosystem services value from large to small along elevation levels were the fifth, fourth, first ,third and second levels respectively in the period 1994-2001 while those were the fifth, fourth, third, first and second levels in 2001-2006. The indexes of ecological effects had decreased with the rise of elevation levels in 1994-2006, Compared with 1994-2001, the indexes of ecological effects had significantly reduced in the period of 2001-2006. The modulus of ecological effects had also reduced with the go-up of elevation levels, which had increased at the first, second and third levels but decreased at the fourth, fifth levels in the latter phase compared with the previous period.

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    Spatial Variability of Soil Organic Matter and Factor Analysis in the South of Middle Jiangsu Plain
    Ming-song ZHAO, Gan-lin ZHANG, De-cheng LI, Yu-guo ZHAO, De-cai WANG
    2013, 33 (1):  83-89.  doi: 10.13249/j.cnki.sgs.2013.01.83
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    In this research, a square area (32°20′17″-32°44′50″ N,119°53′37″-120°14′4″E), about 1 350 km2, was chosen as a case in the south of the middle Jiangsu plain. A total of 178 soil samples were collected according to nested scenario’s, for the analysis of SOM content and soil mechanical composition. And furthermore, spatial variability of SOM in the surface layer was analyzed using the Geostatistical and GIS method, and its dominating factors, too, by means of correlation analysis and analysis of variance. The result suggested that the SOM content varied in the range of 28.51±7.80 g/kg with a coefficient of variation being 27.31%, a moderate level. Geostatistical analysis suggests that the study area was very strong in spatial autocorrelation and the semi-variogram was best fitted by spherical model, which was significant in anisotropy and the anisotropy ratio was 1.30. The variation at 39° and 219° in direction was the most severe,and the spatial heterogeneity range at the direction was 33.26 km. The variation at 129° and 309° in direction was the slightest,and the spatial heterogeneity range at the direction was 43.08 km. The structural factors played a dominating role in spatial variability of SOM. SOM in the area was distributed in a band, of which high content was in the northeast ,in which the area of more than 30 g/kg accounting for 42% of the total area. But low content was in the southwest part. Correlation coefficients between SOM and soil mechanical composition were -0.548 for sand, 0.534 for silt and 0.259 for clay, respectively, indicating the degree of correlation between SOM and sand was the strongest, followed by silt and clay. Analysis of variance showed that parent material and soil type effected spatial variability of SOM significantly. Soil generated in the lake sediment had higher SOM content than that in the alluvial deposit. Soil type with high in clay and silt content had higher SOM content than that with sand content. Soil mechanical composition played a key role in spatial variability of the study area.

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    Water Chemistry Variations of Lake and Inflowing Rivers Between Pre- and Post-monsoon Season in Nam Co,Tibet
    Jun-bo WANG, Jian-ting JU, Li-ping ZHU
    2013, 33 (1):  90-96.  doi: 10.13249/j.cnki.sgs.2013.01.90
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    In mid-May (pre-monsoon season) and late October (post-monsoon season), water samples were taken from 2 sites in Nam Co Lake and 16 rivers around the lake for dynamic changes study of water chemical composition in different seasons. Water chemistry analysis and comparative studies have been conducted to illustrate the dynamic changes of ions concentrations between the two seasons. The results indicated that all ions showed higher concentrations in post-monsoon than that in pre-monsoon season for lake water.Among them, Mg2+ increased by 46.84% and 46.95% on average in two sites, while Ca2+ increased by 67.02% and 75.11% on average, respectively.Na+ and K+ showed relatively less increase in concentration. As for anions, HCO3- showed the largest increase of 27.61% and 25.02% in two sites, respectively. Meanwhile, most ions in river water also showed the similar trends, Mg2+ and Ca2+ increased by 40.55% and 33.20% on average in all rivers. HCO3- and SO42- increased 36.81% and 28.48%. However, F-, Cl- and NO3- showed opposite patterns, i.e., the concentrations were lower in post-monsoon season. Cl- was the most remarkable decreasing ion, averagely decreased 28.43% in all rivers. It is indicated that the ion concentrations dynamic changes of Nam Co Lake and river water were mainly influenced by weathering in the drainage area. Weathering production such as Mg2+, Ca2+ and HCO3- were the main source of increased ions, resulting from the weathering of carbonate in the catchment. On the other hand, lake evaporation has also slightly contributed to ion concentrations increase of lake water. The river Cl- decrease in post-monsoon season was mainly influenced by individual river flux, more changes in river flux between two seasons led more decrease of Cl- concentration and the ultimate controlling factors should be water supply from precipitation and glacier melting water within the catchment.

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    Comparative Study of Evapotranspiration in an Alpine Meadow in the Upper Reach of Shulehe River Basin
    Jin-kui WU, Jun-wu CHEN, Hao WU, Shi-qiang ZHANG, Ming-jie GAO, Yu QIN
    2013, 33 (1):  97-103.  doi: 10.13249/j.cnki.sgs.2013.01.97
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    The evapotranspiration (ET) of alpine meadow ecosystem in the upper reach of the Shulehe River Basin, Northeastern Qinghai-Tibetan Plateau during the main growing season in 2011 was measured using the micro-lysimeter(ML) method, the eddy covariance (EC) technique, and the Bowen Ratio Energy Balance (BREB) method. Results showed that the turbulent fluxes measured by EC and available fluxes measured by BREB system were imbalanced. The energy balance ratio (EBR) was 0.84. The reasons were as follows: non-synchronization of fluxes, low closure degree in nighttime and the effect of precipitation. The evapotranspiration values that estimated by BREB, ML and EC were 270.6 mm, 238.9 mm and 236.1 mm, respectively. Significant correlation existed between the evapotranspiration measured by the three methods. The determination of evapotranspiration by EC system was lower than the BREB system as many similar findings indicated. The presence of vertical diffusion and convection resulted in the underestimation of latent heat flux in EC systems was the main reason. Though the evapotranspiration results estimated by EC method and ML method were very close, the diurnal variations were not entirely consistent. According to the local natural conditions of soil and hydrology, water for evapotranspiration originated from the precipitation in the observation station. During the observation period, there was nearly no soil water storage and surface runoff. In addition, the vegetation growth was in good condition. Deduced by those facts, the value of evapotranspiration should be equal to that of precipitation, i.e. about 250 mm. From this point, the evapotranspiration values estimated by the three methods were within a reliable range. The results suggested that the evapotranspiration may be underestimated by EC while overestimated by BREB. Although EC method might underestimate evapotranspiration due to the underestimation of latent heat flux, the evapotranspiration could be obtained directly and the continuous long-term site observation could be realized either. Also, the obtained results of evapotranspiration could represent the average moisture exchange rate between the land surface and the atmosphere in a certain area. Furthermore, the EC system could also be used for the determination of CO2 flux in the prairie region. Considering the estimation precision and data continuity, the eddy covariance method had advantages over the other two methods and had more application perspective in an alpine meadow area as the upper reach of the Shulehe River Basin.

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    The Statistical Relationship Between Summer Cloud Cover and Daily Temperature in Eastern China
    Yuan-xi GUO, Dao-yi GONG, Wen-shan WANG, Rui MAO, Miao HU
    2013, 33 (1):  104-109.  doi: 10.13249/j.cnki.sgs.2013.01.104
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    Based on the data of daily temperature from 130 meteorological stations of Eastern China in 1980-2009, statistical relationship between cloud cover and temperature on no rain conditions were quantitatively analyzed, and the reason was explained from the perspective of radiation. It was showed that daily maximum temperature and daily mean temperature in Eastern China decreased significantly with the increasing of cloud cover, which is mainly because solar radiation and surface net radiation decreased significantly due to increase of cloud cover. This is in consistent with the relationship between daily maximum temperature, daily mean temperature and cloud cover in the whole China, in the Northern Hemisphere and even in the Globe. Specifically, the daily maximum temperature and daily mean temperature would decrease by 0.219℃ and 0.109℃ respectively as the total cloud cover increased by each 10 percent. And also, when low and middle cloud increased, the daily maximum temperature and daily mean temperature would decreased by 0.367℃ and 0.247℃ respectively, and when high cloud increased, the daily maximum temperature and daily mean temperature would decreased by 0.087℃ and 0.006℃ respectively. This significant negative correlation between daily maximum temperature, daily mean temperature and cloud cover may be mainly caused by the reduction of surface solar radiation and surface net radiation. In the northern part of the study region, daily minimum temperature increased significantly with the increase of total cloud, low and middle cloud, or high cloud, and in the south, it decreased significantly with the increase of total cloud or low and middle cloud. But it shows no obvious relationship with the amount of high cloud. This phenomenon can hardly be explained simply from the aspect of radiation effect, because there is a significant negative correlation between cloud cover and surface effective radiation. It was found that diurnal temperature range in Eastern China was significantly decreased with the increase of cloud cover, and the rate of reduction in the north is faster than that in the south.

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    Flood Simulation Study of Typhoon Storm Surge Based on Scenarios in Shanghai
    Jie YIN, Zhan-e YIN, Da-peng YU, Shi-yuan XU
    2013, 33 (1):  110-115.  doi: 10.13249/j.cnki.sgs.2013.01.110
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    Storm surges from tropical cyclones, as one of the most devastating natural hazards in Shanghai, have caused considerable personal injury and property damage in the history. A scenario-based study that investigated the storm induced flood potentials in Shanghai coastal area was conducted. Based on the probability analysis for several gauge stations, the findings show that due to the high standard seawall, it is less likely to occur overtopping inundation in the short term. Therefore, two vulnerable sections of seawall and six kinds of storm surge barrier bursts scenarios were built. Comparing the local land elevation with the flood levels of different return periods, flood scenarios with return periods of 20, 50, 100, 200, 500 and 1000 years were designed to cover the probable situations. The shape of the flow hydrographs at the boundary gauging stations for various return periods was derived based on 9711 typhoon induced flood event where hourly flow boundary conditions were available. To reduce the computational costs of the simulation, the design flood scenarios were represented with 20 hours tidal hydrographs, which include two rising phases and two falling limbs. The topographic contours (0.5 m intervals) of Shanghai were interpolated to generate a DEM with a grid cell resolution of 50 m. These provided the flow and topographic boundary conditions for the model simulations. A well-established 2D flood numerical model (FloodMap) was used to predict the flood dynamics and inundation process. Subsequent analysis using Geographical Information Systems (GIS) was employed to illustrate the spatial and temporal distribution of flood-prone areas under different scenarios. The results indicated that, 1) maximum inundation depths were reached in all simulations at approximately the second to third hour, decreasing afterwards as the stage recedes. 2) Inundation area for each scenario increased throughout the simulation, even during the receding limb of the hydrograph. 3) The maximum inundation extents and depths increased with the increasing return periods. 4) Flooding from levee breach only caused local inundation. It can be concluded that the impact of storm flooding was not particularly high in Shanghai at present situation with the protection of high standard dike systems. However, extreme events caused by global climate change should be considered in future studies.

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    The Spatial-temporal Pattern and Changes of Rainfall Erosivity in Chongqing
    Yan-zai WANG, Shi-wei GOU
    2013, 33 (1):  116-122.  doi: 10.13249/j.cnki.sgs.2013.01.116
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    Soil erosion has become a global ecological and environmental problem. Soil erosion has not only led to the destruction of land resources and reduced crop yields, but at the same time can cause water pollution and reservoir sedimentation, and increase flood risks. Therefore, the evaluation of regional soil erosion risk by analyzing the spatial and temporal variation of rainfall erosivity is of both scientific and practical significances. In the Three Gorges Reservoir Area, the quality of the ecological environment has been directly impacted by water soil erosion, it is necessary to make a study on the temporal and spatial distribution of rainfall erosivity in Three Gorges Reservoir Area and its surrounding regions. This study chose Chongqing as the study area, and used EOF technique and non-parametric Mann-Kendall statistical test to investigate spatial-temporal changes of rainfall erosivity of the study area from 1960 to 2010. Major findings are as follows: 1) There are a spatial distribution pattern of annual rainfall erosivity that it is greater in the eastern area and less in the western area in the study area, while the largest is in Chengkou, Kaixian, Wanzhou, Yunyang and Zhongxian , indicating a higher level of potential hazards in these areas. Seasonal rainfall erosivity has a similar spatial distribution pattern, the rainfall erosivty of spring and winter in the southeast of Chongqing are the largest, followed by the northeastern and the western region, where it is the least; but the rainfall erosivity of summer and autumn in the northeast region are the largest, followed by the southeastern and western region. There is great gradient of annual, summer and autumn rainfall erosivity changes in the area of Fengdu, Zhongxian and Shizhu area, and small gradient of annual, all seasonal rainfall erosivity changes in the western area of the study area. 2) Consistent anomaly distribution is the main spatial pattern of annual and seasonal rainfall erosivity in the study area, which means the trend of changes of annual and seasonal rainfall erosivity at all stations are consistent in the study area, and the pattern was caused by large-scale climate impact factors. The annual and seasonal rainfall erosivity generally tended to increase after the year 2000. 3) Reverse changes in the spatial distribution pattern of annual, autumn and winter rainfall erositivy existe between northeastern region and other regions in the study area due to the mountainous terrain. Whenever the annual and seasonal rainfall erosivity in the northeastern of the study area increases or decreases, correspondently, the annual and seasonal rainfall erosivity in other regions of the study area would show opposite changes trend. The reverse changes pattern of autumn rainfall erosivity was typical in the 1960-1980s, and the pattern of winter rainfall erosivity was typical after the year 2004. The results above will be helpful to the research on the soil and water conservation in Chongqing.

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    Environmental Factors Contributing to the Spread of Hemorrhagic Fever with Renal Syndrome and Potential Risk Areas Prediction in Midstream and Downstream of the Xiangjiang River
    Hong XIAO, Xiao-ling LIN, Li-dong GAO, Xiang-yu DAI, Xin-guang HE, Bi-yun CHEN, Xi-xing ZHANG, Jian ZHAO, Huai-yu TIAN
    2013, 33 (1):  123-128.  doi: 10.13249/j.cnki.sgs.2013.01.123
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    HFRS (human hemorrhagic fever with renal syndrome) occurs at very high frequency in the midstream and downstream of the Xiangjiang River. It is of great significance for understanding the regulation of the transmission of HFRS in this area due to its major impact on local economy development and public health. The risk factors and potential risk of HFRS in the midstream and downstream of theXiangjiang River were explored by combining the ecologic niche modeling, geographic information systems (GIS) and remote sensing technique in this article. The average area under the Receiver Operating Characteristic curve was 0.785. The 64 cases in 2010 were predicted correctly except for one case in a low risk area. These showed that the model possess good prediction performance. The modeling results indicated that the north of Wangcheng County and Changsha County, the border of Hengdong County , Zhuzhou County and Xiangtan Countiy, and the south of Hengdong County were predicted as the potential risk area. The following factors were found to be closely relative to the highest risk of HFRS transmission: mean annual temperature of 18℃, annual precipitation of about 1 500 mm, at urban and constructive land, and normalized difference vegetation index between 0.3 and 0.4 in May and July and with low elevation. The transmission of HFRS in the midstream and downstream of the Xiangjiang River was analyzed by using the ecologic niche model combining the geographical environment, climatic condition and human activity data. Our results are more accurate than those from other models and these findings in the study. Therefore, they are applicable for targeting control and prevention efforts.

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