Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this s...Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this study. An interactive interpretation and a manual modification procedure were carried out to acquire cultivated land information. An overlay method based on classification results and a visual change detection method which was supported by land use maps were employed to detect the cultivated land changes. Based on the changes that were revealed and a spatial analysis between cultivated land use and related natural and socio-economic factors, the driving forces for cultivated land use changes in the study area were determined.The results showed a decrease in cultivated land in Kenli County of 5321.8 ha from 1987 to 1998, i.e.,an average annual decrement of 483.8 ha, which occurred mainly in the central paddy field region and the northeast dry land region. Adverse human activities, soil salinization and water deficiencies were the driving forces that caused these cultivated land use changes.展开更多
A network perspective has increasingly become an organizational paradigm for understanding regional spatial structures. Based on a critical overview of existing empirical models for estimating intercity networks based...A network perspective has increasingly become an organizational paradigm for understanding regional spatial structures. Based on a critical overview of existing empirical models for estimating intercity networks based on firm linkages, this study extends the re- cently proposed regional corporate city model algorithm by proposing a new method for ap- proximating urban networks based on the Iocational strategies of firms. The new method considers both regional and hierarchical network features and avoids the information loss associated with the conversion from two-mode firm-city networks to one-mode city-city networks. In addition, networks estimated by using the method proposed herein are suitable when employing social network analysis. Finally, this method is empirically validated by ex- amining intercity firm networks formed by advanced producer services firms in China＇s two largest metropolitan areas, namely the Yangtze River Delta and Pearl River Delta. The pre- sented empirical analysis suggests two main findings. First, in contrast to conventional methods （e.g., the interlocking city network model）, our new method produces regional and hierarchical urban networks that more closely resemble reality. Second, the new method al- lows us to use social network analysis to assess betweenness and closeness centralities. However, regardless of the model applied, the validity of any method that measures urban networks depends on the soundness of its underlying assumptions about how network actors （firms, in our case） interact.展开更多
On the basis of field investigations, observations andexperimental data combined with environmental monitoring information,the status and the spatial and temporal patterns of surface waterpollution over the past ten y...On the basis of field investigations, observations andexperimental data combined with environmental monitoring information,the status and the spatial and temporal patterns of surface waterpollution over the past ten years in the Yangtze River Delta havebeen assessed. The water quality of large rivers is still very goodbut most of the medium-sized and small rivers have been veryseriously polluted. The appearance of black and odorous conditions inrivers in the urban areas has increased due to serious pollution byorganic matter with consequent high oxygen demand. Annual increasesin N and P concentrations in lakes have accelerated eutrophication.The water quality of river sin small towns is rapidly deteriorating.The main sources of surface water pollution include industrial anddomestic sewage, animal manures, chemical fertilizers in farmland,and polluted sediments in rivers and lakes.展开更多
According to the highway data and some socioeconomic data of 1990, 1994, 2000, 2005 and 2009 of county units in the Pearl River Delta, this paper measured urban integrated power of different counties in different year...According to the highway data and some socioeconomic data of 1990, 1994, 2000, 2005 and 2009 of county units in the Pearl River Delta, this paper measured urban integrated power of different counties in different years by factor analysis, and estimated each county＇s potential in each year by means of expanded potential model. Based on that, the spa- tio-temporal association patterns and evolution of county potential were analyzed using spa- tio-temporal autocorrelation methods, and the validity of spatio-temporal association patterns was verified by comparing with spatial association patterns and cross-correlation function. The main results are shown as follows： （1） The global spatio-temporal association of county po- tential showed a positive effect during the study period. But this positive effect was not strong, and it had been slowly strengthened during 1994-2005 and decayed during 2005-2009. The local spatio-temporal association characteristics of most counties＇ potential kept relatively stable and focused on a positive autocorrelation, however, there were obvious transformations in some counties among four types of local spatio-temporal association （i.e., HH, LL, HL and LH）. （2） The distribution difference and its change of local spatio-temporal association types of county potential were obvious. Spatio-temporal HH type units were located in the central zone and Shenzhen-Dongguan region of the eastern zone, but the central spatio-temporal HH area shrunk to the Guangzhou-Foshan core metropolitan region only after 2000; the spatio-temporal LL area in the western zone kept relatively stable with a surface-shaped continuous distribu- tion pattern, new LL type units emerged in the south-central zone since 2005, the eastern LL area expanded during 1994-2000, but then gradually shrunk and scattered at the eastern edge in 2009; the spatio-temporal HL and LH areas varied significantly. （3） The local spa- tio-temporal association patterns of county potential among the three zones presented signi展开更多
This article situates the Pearl River delta market town of Jiujiang within a system of market towns and cities along the West River and its tributaries in southern China. Exploring the history of this town as an emigr...This article situates the Pearl River delta market town of Jiujiang within a system of market towns and cities along the West River and its tributaries in southern China. Exploring the history of this town as an emigrant community, this article follows the upstream movement of officials, civil service examinees, merchants, and permanent settlers along the West River basin between the sixteenth century and the nineteenth century. The trajectory of migration from this market town was shaped by the geographical factors of the West River system. At the same time, migration, which was related both to strategies that Jiujiang families embraced for socioeconomic advancement and to policies that the Ming and Qing states adopted for controlling the southwestern frontier, played an important role in the historical construction of a unified region linked by economic ties and personal networks.展开更多
基金Project supported by the Department of Science and Technology of Shandong Province (No. 02BS044).
文摘Taking Kenli County in the Yellow River Delta, China, as the study area and using digital satellite remote sensing techniques, cultivated land use changes and their corresponding driving forces were explored in this study. An interactive interpretation and a manual modification procedure were carried out to acquire cultivated land information. An overlay method based on classification results and a visual change detection method which was supported by land use maps were employed to detect the cultivated land changes. Based on the changes that were revealed and a spatial analysis between cultivated land use and related natural and socio-economic factors, the driving forces for cultivated land use changes in the study area were determined.The results showed a decrease in cultivated land in Kenli County of 5321.8 ha from 1987 to 1998, i.e.,an average annual decrement of 483.8 ha, which occurred mainly in the central paddy field region and the northeast dry land region. Adverse human activities, soil salinization and water deficiencies were the driving forces that caused these cultivated land use changes.
基金National Natural Science Foundation of China, No.51478189 No.41401178+2 种基金 National Social Science Fund, 1 l＆ZD154 State Key Laboratory of Subtropical Building Science, No.2013KB20 Fundamental Research Funds for the Central Universities, No.2013ZZ0022
文摘A network perspective has increasingly become an organizational paradigm for understanding regional spatial structures. Based on a critical overview of existing empirical models for estimating intercity networks based on firm linkages, this study extends the re- cently proposed regional corporate city model algorithm by proposing a new method for ap- proximating urban networks based on the Iocational strategies of firms. The new method considers both regional and hierarchical network features and avoids the information loss associated with the conversion from two-mode firm-city networks to one-mode city-city networks. In addition, networks estimated by using the method proposed herein are suitable when employing social network analysis. Finally, this method is empirically validated by ex- amining intercity firm networks formed by advanced producer services firms in China＇s two largest metropolitan areas, namely the Yangtze River Delta and Pearl River Delta. The pre- sented empirical analysis suggests two main findings. First, in contrast to conventional methods （e.g., the interlocking city network model）, our new method produces regional and hierarchical urban networks that more closely resemble reality. Second, the new method al- lows us to use social network analysis to assess betweenness and closeness centralities. However, regardless of the model applied, the validity of any method that measures urban networks depends on the soundness of its underlying assumptions about how network actors （firms, in our case） interact.
基金National Natural Science Foundation of China (No.49831070) ShanghaiMunicipal Education Commission.
文摘On the basis of field investigations, observations andexperimental data combined with environmental monitoring information,the status and the spatial and temporal patterns of surface waterpollution over the past ten years in the Yangtze River Delta havebeen assessed. The water quality of large rivers is still very goodbut most of the medium-sized and small rivers have been veryseriously polluted. The appearance of black and odorous conditions inrivers in the urban areas has increased due to serious pollution byorganic matter with consequent high oxygen demand. Annual increasesin N and P concentrations in lakes have accelerated eutrophication.The water quality of river sin small towns is rapidly deteriorating.The main sources of surface water pollution include industrial anddomestic sewage, animal manures, chemical fertilizers in farmland,and polluted sediments in rivers and lakes.
基金National Natural Science Foundation of China, No.41001078 No.41271060
文摘According to the highway data and some socioeconomic data of 1990, 1994, 2000, 2005 and 2009 of county units in the Pearl River Delta, this paper measured urban integrated power of different counties in different years by factor analysis, and estimated each county＇s potential in each year by means of expanded potential model. Based on that, the spa- tio-temporal association patterns and evolution of county potential were analyzed using spa- tio-temporal autocorrelation methods, and the validity of spatio-temporal association patterns was verified by comparing with spatial association patterns and cross-correlation function. The main results are shown as follows： （1） The global spatio-temporal association of county po- tential showed a positive effect during the study period. But this positive effect was not strong, and it had been slowly strengthened during 1994-2005 and decayed during 2005-2009. The local spatio-temporal association characteristics of most counties＇ potential kept relatively stable and focused on a positive autocorrelation, however, there were obvious transformations in some counties among four types of local spatio-temporal association （i.e., HH, LL, HL and LH）. （2） The distribution difference and its change of local spatio-temporal association types of county potential were obvious. Spatio-temporal HH type units were located in the central zone and Shenzhen-Dongguan region of the eastern zone, but the central spatio-temporal HH area shrunk to the Guangzhou-Foshan core metropolitan region only after 2000; the spatio-temporal LL area in the western zone kept relatively stable with a surface-shaped continuous distribu- tion pattern, new LL type units emerged in the south-central zone since 2005, the eastern LL area expanded during 1994-2000, but then gradually shrunk and scattered at the eastern edge in 2009; the spatio-temporal HL and LH areas varied significantly. （3） The local spa- tio-temporal association patterns of county potential among the three zones presented signi
文摘This article situates the Pearl River delta market town of Jiujiang within a system of market towns and cities along the West River and its tributaries in southern China. Exploring the history of this town as an emigrant community, this article follows the upstream movement of officials, civil service examinees, merchants, and permanent settlers along the West River basin between the sixteenth century and the nineteenth century. The trajectory of migration from this market town was shaped by the geographical factors of the West River system. At the same time, migration, which was related both to strategies that Jiujiang families embraced for socioeconomic advancement and to policies that the Ming and Qing states adopted for controlling the southwestern frontier, played an important role in the historical construction of a unified region linked by economic ties and personal networks.
