The typical regions of the Taihu Lake Basin,China,were selected to analyze the variation characteristics of river-lake networks under intensive human activities.The characteristics of the fractal dimension of river ne...The typical regions of the Taihu Lake Basin,China,were selected to analyze the variation characteristics of river-lake networks under intensive human activities.The characteristics of the fractal dimension of river networks and lakes for different periods were investigated and the influences of river system evolution on water level changes were further explored through the comparison of their fractal characters.The results are as follows:1) River network development of the study area is becoming more monotonous and more simple;the number of lakes is reducing significantly,and the water surface ratio has dropped significantly since the 1980s.2) The box dimension of the river networks in all the cities of the study area decreased slowly from the 1960s to the 1980s,while the decrease was significant from the 1980s to the 2000s.The variations of lake correlation dimension are similar to those of the river network box dimensions.This is unfavorable for the storage capacity of the river networks and lakes.3) The Hurst exponents of water levels were all between 0.5 and 1.0 from the 1960s to the 1980s,while decreased in the 2000s,indicating the decline in persistence and increase in the complexity of water level series.The paper draws a conclusion that the relationship between the fractal dimension of river-lake networks and the Hurst exponents of the water level series can reveal the impacts of river system changes on flood disasters to some extent:the disappearance of river networks and lakes will increase the possibility of flood occurrence.展开更多
Based on seismic data from the regional network for the last 34 years, we analyzed the present fault behavior of major fault zones around the Mabian area, southern Sichuan, and identified the risky fault-segments for ...Based on seismic data from the regional network for the last 34 years, we analyzed the present fault behavior of major fault zones around the Mabian area, southern Sichuan, and identified the risky fault-segments for potential future. The method of analysis is a combination of activity background of historical strong earthquakes mainly show ~ （ 1 ） The spatial distribution of b-values strong and large earthquakes in the spatial distribution of b-values with and current seismicity. Our results indicates significant heterogeneity in the studied area, which reflects the spatial difference of cumulative stress levels along various fault zones and segments. （2） Three anomalously low b-value areas with different dimensions were identified along the Mabian-Yanjin fault zone. These anomalies can be asperities under relatively high cumulated stress levels. Two asperities are located in the north of Mabian county, in Lidian town in western Muchuan county, and near Yanjin at the south end of the fault zone. These two areas represent potential large earthquake seismogenic sites around the Mabian area in the near future. Besides them, the third relatively smaller asperity is identified at southern Suijiang, as another potential strong- earthquake source. （3） An asperity along the southwestern segment of the Longquanshan fault zone indicates the site of potential moderate-to-strong earthquakes. （4） The asperity along the segment between Huangmu town in Hanyuan county and Longchi town in Emeishan city on Jinkouhe-Meigu fault has potential for a moderate-strong earthquake.展开更多
A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are un...A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are under construction. It is the second network in China that is operated by enterprises with the purpose to observe and study earthquake precursors in reservoir areas. This paper presents the layout and technical constitution of the network, features of its observational wells and aquifers and the preliminary result of its experimental operation. Its capability to monitor seismic precursor is evaluated based on an analysis of the well-aquifer system as well as the multiple-monthly, monthly, daily and hourly variations of water levels and water temperatures observed by this network.展开更多
China＇s new urbanization process requires coordinated development between cities and rural areas. Territorial functions of rural areas are defined as advantageous effects on nature and human society that, in particul...China＇s new urbanization process requires coordinated development between cities and rural areas. Territorial functions of rural areas are defined as advantageous effects on nature and human society that, in particular, rural systems perform via their property and interactions with other systems at certain social development stages. This paper establishes an index System for evaluating rural territorial functions including agricultural function, social function, economic function and ecological function. By establishing a model based on a General Regression Neural Network （GRNN） with the county-level as the basic unit, we comprehensively evaluate the rural territorial functions of 109 counties and/or cities in Henan province, China in 2000, 2005 and 2010. Results show that compared with that in 2000, each function in 2010 improved, with the spatial heterogeneity of economic func- tion the most evident, social service function comparatively balanced and spatial distribution of agricultural produc- tion function changing little. Cluster analysis was adopted to study the major functions of rural regions. Henan was divided into six major function zones to enhance administrative management and developmental policy. The six major function zones are Type I （core economic development zone）, Type II （agricultural production safeguarding zone）, Type III （function improving zone for rural areas）, Type IV （model zone of livelihood and social services）, Type V （economic restructuring and development zone）, and Type Vl （nature conservation areas）. Different development goals and development strategies should be considered according to different major function areas to achieve the coordinated development of urban and rural areas in China.展开更多
From the development of modern transportation to the current era of high-speed transportation networks, the Beijing-Tianjin-Hebei(BTH) region has always played a national leading role in land transportation developmen...From the development of modern transportation to the current era of high-speed transportation networks, the Beijing-Tianjin-Hebei(BTH) region has always played a national leading role in land transportation development of China. In order to explore the long-term evolutionary characteristics of land transportation in the BTH region, this paper utilized a temporal scale of 100 years to systematically interpret the development process of the land transportation network. Taking 13 cities within the BTH region as research anchor cities, we took into account "leaping" mode of transportation in order to investigate the evolution of accessibility. Our research shows the following results:(1) The land transportation network in the BTH region has undergone five stages of development: the initial period of modernization(1881–1937); the period of stagnation of transportation development(1937–1949); the network expansion period(1949–1980); the period of trunk construction(1980–1995), and the period of high-speed transportation network development(1995–present). The network structure centered around Beijing has existed from the outset of modern transportation development.(2) The accessibility spatial pattern of land transportation in BTH region has evolved from expansion along traffic corridors to the formation of concentric circles. The stratified circular structure of transportation in anchor cities has gradually developed into a contiguous development pattern.(3) There are clear hierarchical differences in the transportation structures of anchor cities. Beijing has always been at the top of this hierarchy, while the hierarchical position of Zhangjiakou has fallen noticeably since 1949. The Beijing-Tianjin region was the first region to form a short-duration transportation circle structure, while the transportation advantages of the central part of Hebei Province, which is located in the center of the BTH transportation region, have yet to be realized.展开更多
基金Under the auspices of Special Fund for Scientific Research in the Public Interestgranted by Ministry of Water Resources(No.2012010072,200701024)+3 种基金Key Program of National Natural Science Foundation of China(No.40730635)Open Foundation of State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering(No.2011491111)Research Foundation of Nanjing University of Information Science and Technology(No.20100406)a Project Funded by the Priority Academic Program Development of Jiangsu Higher Education Institutions(PAPD)
文摘The typical regions of the Taihu Lake Basin,China,were selected to analyze the variation characteristics of river-lake networks under intensive human activities.The characteristics of the fractal dimension of river networks and lakes for different periods were investigated and the influences of river system evolution on water level changes were further explored through the comparison of their fractal characters.The results are as follows:1) River network development of the study area is becoming more monotonous and more simple;the number of lakes is reducing significantly,and the water surface ratio has dropped significantly since the 1980s.2) The box dimension of the river networks in all the cities of the study area decreased slowly from the 1960s to the 1980s,while the decrease was significant from the 1980s to the 2000s.The variations of lake correlation dimension are similar to those of the river network box dimensions.This is unfavorable for the storage capacity of the river networks and lakes.3) The Hurst exponents of water levels were all between 0.5 and 1.0 from the 1960s to the 1980s,while decreased in the 2000s,indicating the decline in persistence and increase in the complexity of water level series.The paper draws a conclusion that the relationship between the fractal dimension of river-lake networks and the Hurst exponents of the water level series can reveal the impacts of river system changes on flood disasters to some extent:the disappearance of river networks and lakes will increase the possibility of flood occurrence.
基金This research is supported by the National Key Basic Research 973 Project(Grant No.:2008CB425701)the Special Project M7.0~8.0 of China Earthquake Administration
文摘Based on seismic data from the regional network for the last 34 years, we analyzed the present fault behavior of major fault zones around the Mabian area, southern Sichuan, and identified the risky fault-segments for potential future. The method of analysis is a combination of activity background of historical strong earthquakes mainly show ~ （ 1 ） The spatial distribution of b-values strong and large earthquakes in the spatial distribution of b-values with and current seismicity. Our results indicates significant heterogeneity in the studied area, which reflects the spatial difference of cumulative stress levels along various fault zones and segments. （2） Three anomalously low b-value areas with different dimensions were identified along the Mabian-Yanjin fault zone. These anomalies can be asperities under relatively high cumulated stress levels. Two asperities are located in the north of Mabian county, in Lidian town in western Muchuan county, and near Yanjin at the south end of the fault zone. These two areas represent potential large earthquake seismogenic sites around the Mabian area in the near future. Besides them, the third relatively smaller asperity is identified at southern Suijiang, as another potential strong- earthquake source. （3） An asperity along the southwestern segment of the Longquanshan fault zone indicates the site of potential moderate-to-strong earthquakes. （4） The asperity along the segment between Huangmu town in Hanyuan county and Longchi town in Emeishan city on Jinkouhe-Meigu fault has potential for a moderate-strong earthquake.
基金sponsored by the Jinsha River Development Corporation Ltd. Program of China Three Gorges Cooperation (JSJ(06)007)
文摘A groundwater observational network for monitoring seismic precursors has been established at the reservoirs on the lower reaches of the Jinsha River in southwestern China, where a series of hydropower stations are under construction. It is the second network in China that is operated by enterprises with the purpose to observe and study earthquake precursors in reservoir areas. This paper presents the layout and technical constitution of the network, features of its observational wells and aquifers and the preliminary result of its experimental operation. Its capability to monitor seismic precursor is evaluated based on an analysis of the well-aquifer system as well as the multiple-monthly, monthly, daily and hourly variations of water levels and water temperatures observed by this network.
基金National Natural Science Foundation of China(41571096)
文摘China＇s new urbanization process requires coordinated development between cities and rural areas. Territorial functions of rural areas are defined as advantageous effects on nature and human society that, in particular, rural systems perform via their property and interactions with other systems at certain social development stages. This paper establishes an index System for evaluating rural territorial functions including agricultural function, social function, economic function and ecological function. By establishing a model based on a General Regression Neural Network （GRNN） with the county-level as the basic unit, we comprehensively evaluate the rural territorial functions of 109 counties and/or cities in Henan province, China in 2000, 2005 and 2010. Results show that compared with that in 2000, each function in 2010 improved, with the spatial heterogeneity of economic func- tion the most evident, social service function comparatively balanced and spatial distribution of agricultural produc- tion function changing little. Cluster analysis was adopted to study the major functions of rural regions. Henan was divided into six major function zones to enhance administrative management and developmental policy. The six major function zones are Type I （core economic development zone）, Type II （agricultural production safeguarding zone）, Type III （function improving zone for rural areas）, Type IV （model zone of livelihood and social services）, Type V （economic restructuring and development zone）, and Type Vl （nature conservation areas）. Different development goals and development strategies should be considered according to different major function areas to achieve the coordinated development of urban and rural areas in China.
基金National Natural Science Foundation of China,No.41701122,No.41430635China Postdoctoral Science Foundation,No.2017M611854,No.2016M600356
文摘From the development of modern transportation to the current era of high-speed transportation networks, the Beijing-Tianjin-Hebei(BTH) region has always played a national leading role in land transportation development of China. In order to explore the long-term evolutionary characteristics of land transportation in the BTH region, this paper utilized a temporal scale of 100 years to systematically interpret the development process of the land transportation network. Taking 13 cities within the BTH region as research anchor cities, we took into account "leaping" mode of transportation in order to investigate the evolution of accessibility. Our research shows the following results:(1) The land transportation network in the BTH region has undergone five stages of development: the initial period of modernization(1881–1937); the period of stagnation of transportation development(1937–1949); the network expansion period(1949–1980); the period of trunk construction(1980–1995), and the period of high-speed transportation network development(1995–present). The network structure centered around Beijing has existed from the outset of modern transportation development.(2) The accessibility spatial pattern of land transportation in BTH region has evolved from expansion along traffic corridors to the formation of concentric circles. The stratified circular structure of transportation in anchor cities has gradually developed into a contiguous development pattern.(3) There are clear hierarchical differences in the transportation structures of anchor cities. Beijing has always been at the top of this hierarchy, while the hierarchical position of Zhangjiakou has fallen noticeably since 1949. The Beijing-Tianjin region was the first region to form a short-duration transportation circle structure, while the transportation advantages of the central part of Hebei Province, which is located in the center of the BTH transportation region, have yet to be realized.
