China has been entered the new period of urbanization. In order to investigate the role of skill complementarity in this process, firstly, the coupling coordination degree of high-low skilled labor force in 285 prefecture level cities in 2003-2012 was measured, selecting ‘information transmission, software and information technology service’‘financial service’‘wholesale and retail trade industry’ and ‘accommodation and catering industry’ as main representative industries. Then, the effect of expanding the scale of low-skilled labor force on worker’s income analyzed, both on national level and regional level. Finally, the effects of several kinds of public services are also been discussed. The three main findings were as followed. Firstly, the coupling coordination degree of high-low skilled labor force at prefecture level was generally increased in the past decade, while varied across regions greatly. In descending order of improvement degree, the 7 main national regions can be sorted as followed: northwestern (0.427), southwestern (0.353), eastern (0.346), middle (0.253), southern (0.192), northern (0.190), northeastern (0.143) China. This may be related to the intra-regional difference in industrial structure. For example, in the period been investigated, the eastern China experienced increasing labor force cost, which leaded to a back-flow of labor force from the eastern to the western areas. Secondly, the standard error of coupling coordination degree of cities within 7 main national regions was increased, which implied an accelerated flow of labor force in these regions. Especially, the value in the eastern China increased from 0.367 to 0.410, which may be related to economic development periods, while the value in southwestern China decreased from 0.410 to 0.377, in the northeastern China the value increased from 0.365 up to 0.453, which may also be reflection of its economic situation.Thirdly, percentage of low-skilled labor force, urban income level and urban size were positively related, which showed that the larger the city was, the greater positive effect would be expanding low-skilled labor force scale on urban income. This finding may suggest that, in current period of urbanization in China, expanding the population of low-skilled labor force in middle and large cities can be beneficial for increasing of urban wage level.
Constructing environmental adaptability index system of human-sea economic system based on adaptability factors of sensitivity, stability and response. The entropy method was used to measure the environmental adaptability of human-sea economic system from 2001 to 2016. Combined with ARIMA-BP combined forecasting model, this article forecasts the environmental adaptability of the Chinese human-sea economic system from 2017 to 2020 and makes a detailed analysis of the light display mechanism. The results show that: 1) The environmental adaptability of the Chinese human-sea economic system continued to increase from 2001 to 2016, the warning degree rose from serious alert to slight alert and the indicator lamp turned from orange lamp to blue lamp, and 70% of the years in the medium alert. The environmental adaptability evolutionary process of human-sea economic system is a trade-off between human-sea economic system and the human-sea environment system, which experienced a comparative advantage phase of human-sea environment system→coupling and coordination stage→the comparative advantage phase of human-sea economic system. It is estimated that it will re-enter the highly coordinated phase of slight alert state from 2017 to 2020. 2) From 2001 to 2016, there was a short rise period and a long decline in the environmental adaptability of the Chinese human-sea economic system. It is estimated that the rate of environmental adaptability fluctuation of the Chinese human-sea economic system will not be optimistic in the context of economic downturn and ecological constraints from 2017 to 2020. 3) The ARIMA-BP combination forecasting model has a good simulation effect, and it is feasible to apply it to the environmental adaptability pre-warning study of the human-sea economic system. 4) The environmental adaptability evolutionary process of human-sea economic system is unique and dynamic, thus, it is the main policing strategy for the future to weigh the relationship between the human-sea economic system and the human-sea environment system in pursuit of maximizing the overall efficiency and extending the expansion period of adaptive cyclical fluctuations, and to develop a differentiated and flexible adaptation action policy.
By way of the multi-factor comprehensive evaluation method, the suitability of establishing bulk commodity trading markets in 35 ports above the designated size is evaluated from 4 aspects such as levels of logistics, finance, information and e-commerce, and port city opening-up, the results of which are used to select 20 ports proper for establishing bulk commodity trading markets. Then the gravity p-median model is used to calculate the appropriate size and type for ports to set up the bulk commodity trading market. The results show that: 1) Coastal ports have more advantages in developing the port bulk commodity trading market. 2) The spatial distribution of the port bulk commodity trading markets is characterized by "regional aggregation", mainly concentrated in the areas of Bohai Rim, the Yangtze River Delta, and the Pearl River Delta. 3) The distribution of every type of port bulk commodity trading market presents a decentralized state, which is more favorable for a trading market to provide services required by nationwide supplying and demanding sides of bulk commodities.
Based on big data of flights of 37 aviation enterprises in China (data of Hongkang,Macau and Taiwan are exluded), using external linkage degree, assortativity /disassortativity index, hierarchical analysis and dominant niche analysis, the spatial organization mode and competition mechanism of China air passenger transport network were studied in this paper. Findings are as follows: 1) China’s domestic aviation network has developed to a relatively mature level where obvious hierarchy and core-periphery structure are formed, all aviation enterprises could be divided into 6 hierarchies based on the number of nodes, routes and the number of flights. 2) From the aviation enterprise perspective, network scale, hierarchy and assortativity/disassortativity as indexes, organization mode (stage of development) of aviation enterprise in China could be divided into 4 stages including core cultivation stage, core competition stage, transition stage and steady growth stage. 3) Most of aviation enterprises’ aviation network are core-periphery and assortative/disassortative whose competition focuses on ‘core competition’. 4) Referring to the judgement method of aviation network’s organization mode, there are two convergence laws in China aviation network namely hierarchical convergence andassortative/disassortative convergence. 5) Aviation enterprise with strong strength and large scale has high niche and a uniform distribution proportion in navigable cities. In contrast, aviation enterprise with weak strength and small scale has a low niche which leads to regional and uneven distribution in navigable cities. In order to optimize the structure of aviation network and avoid the malignant competition, aviation enterprises need to take actions. On the one hand, aviation enterprises have to optimize the organization mode according to distinctive features of different stages of development and explore the dominant niche which is adapted to the grade of enterprises. On the other hand, aviation enterprises need enhance the cooperation with each other for avoiding saturation of airlines and improving the whole aviation network’s resilience and efficiency.
China Ocean Shipping Group and China Shipping Group, as the leading shipping enterprises in China’s shipping industry have started reorganization in 2015. Using the historical shipping data published on the official websites of the two enterprises, this study quantitatively characterized the spatial pattern of the enterprises’ shipping network by complex network method using Gephi and ArcGIS; an evaluated the impact of integrated China Ocean Shipping (Group) Company (COSCO) Shipping’s shipping network in 2016, based on two dimensions of the network economic and hub economic. The results showed that: 1) The total number of service node and anchored ports of COSCO Shipping increased significantly as compared to 2015. In addition, the covered ports were expanded and new links were introduced. 2) In 2016 , COSCO Shipping strengthen the hub capacity in different navigation areas, such as the traditional markets of Southeast Asia, the Mediterranean, East North-American , emerging markets of West Africa, East South-America hub strengthened significantly. Ports with good location conditions have stronger transit capacity, while the resources of some highly homogeneous hub ports have been integrated and optimized. 3) The change of shipping network integration port can be affected by many factors, including local conditions of ports, strategy of market expansion, strategy for port selection (terminal operation), and homogenization degree of original shipping network.
The gradual improvement of the feeder network makes the rapid transportation network of northeast basically form. This article uses GIS spatial analysis method to measure the influence of high-speed rail on accessibility of urban tourism traffic in Northeast China. Then, it analyzes the new characteristics and changes of the city tourism market under the high-speed rail network in Northeast China. Results found that: 1) High speed rail has greatly improved the accessibility of tourist traffic in cities of Northeast China, and the accessibility of space has obvious "high speed corridor effect". In the process of network formation, the change of accessibility spatial pattern has changed from the polarization characteristic of main road operation period to the balanced characteristics of the perfect line of the branch line, and the development pattern of the northeast "all dimensional tourism" has begun to take shape; 2) The main road formation period, high iron to siphon effect is dominant, exacerbating the imbalance in the development of the tourism market of Northeast cities, Harbin Tourism Economic Belt gradually formed; in the improvement of the branch period, high-speed rail have the diffusion effects become dominant, balanced development situation began to highlight; 3) High speed rail has promoted the development of urbanization in Northeast China, the pattern of city tour and surrounding tour will be changed, and the mode of inter provincial tour and inter regional tour will gradually be popular. At the same time, the high-speed rail has greatly promoted the development of the “fast-food” tourism market, the mode of short-term tourism development model will become the new darling of the high-speed rail era.
Community structure, as an emerging research field of network science, is very critical for us to cognize the spatial structure of city clusters more deeply. So far, however, previous work has failed to examine the spatial structure of the urban system in terms of its community structure systematically. To rectify this situation and provide new research approach, this article uses community detection algorithm to reveal the evolving features of community structure of city clusters in middle reach of the Yangtze River(MRYR) at county scale, based on 2000, 2007 and 2014 producer services firms’ database of city clusters in MRYR. Furthermore, this article introduces the Quadratic Assignment Procedure(QAP) to uncover the proximity mechanism and other influencing factors. The main conclusions are as follows: According to the results of network modularity and PageRank, city clusters in MRYR could be divided into three city communities, including Wuhan community, Changsha community and Nanchang community, and community structure has significant heterogeneity, which reflects in the inequality of both intra and inter communities. At city clusters’ level, geographical proximity, cultural proximity and administrative proximity have dramatic effects on community structure of city clusters in MRYR, but provincial administrative proximity causes dominant effects. Additionally, progress in communications technology and financial resources of the clustering and diffusion spur on connections intra and inter communities of city clusters in MRYR. Once inside communities’ level, geographical proximity plays a key role in the process of cities’ interacting within city community. Moreover, some influencing factors have different effects on different city communities, which provides us some beneficial policy enlightenments.
The rapid development of China’s urbanization process has prompted people to deconstruct, adjust and reconstruct urban spatial identity continously. This is a new problem that cannot be ignored in the development of urbanization in China. Urban spatial identity is an important theme in the era of urban cultural pluralism. Taking Web of Science (WoS) citation database as data source, this paper analyzes and reproduces the researches of urban spatial identity conducted abroad. The essence of urban spatial identity is the collection of people′s social and economic identity, cultural identity, collective identity, individual identity and emotional identity in urban development. As an important type of national consciousness, the theme of urban spatial identity is a great concern to foreign scholars. The research in this field is essentially a knowledge representation of humanistic space demands in urban spatial practice. In the study of foreign urban spatial identity from 2008 to 2017, the United States, Britain, Australia and other countries have obvious advantages. The international cooperation research networks are mainly in America-Europe, Europe-Australia, and between Australia and Europe and America. Most of the highly cited literatures on urban spatial identity abroad focus on the discussion of ‘spatial multicentricity’‘locality and continuity’‘urban community’‘urban citizenship’‘space gentrification’ and ‘localism’. In the future, the study of urban spatial identity will turn to focus on new themes such as ‘identity’‘space’‘city’‘geography’‘politics’‘place’ and ‘community’. In contrast, there is a lack of research on urban spatial identity in China. With the development of urban space practice in China, it is necessary to strengthen the ‘theoretical consciousness’ of urban space identity research. China’s urban space research needs a global perspective. Although there are differences between China’s urbanization development and western developed countries, foreign research on urban space identity can provide reference and inspiration for China’s urban space practice and healthy development in the new era.
Sea salt production was an important part of coastal economy; China’s sea salt industry had a long history. Since the 13th century, sea salt economy had a rapid process of development and became the center of China’s salt industry. Under the background of industrialization and urbanization, sea salt production gradually declined and salt area gradually reduced. How to improve the sustainable development of China’s coastal salt industry and enhance its international competitiveness is one of important issue of coastal economic development in the current. Based on historical documents analysis and within the perspective of sea salt production, we analyzed spatial and temporal variations of sea salt production and the driving mechanism through combing historical process of coastal salt industry development, and discussed the impacts of regional environmental differences and management policy. This study is helpful to better understand the current historical stage of coastal salt development and the environment impact, and to provide theoretical and historical reference for coastal development and planning. In this paper, the coast was divided into three areas, i.e., north, east and south coast. Through geographical approach and according to a variety of historical documents and local chronicles associated with sea salt industry during the 13-20th centuries, we evaluated sea salt industry development and its evolution mechanism, and revealed spatial-temporal changes of sea salt industry and its driving factors. The research shows that: 1) Sea salt industry in historical periods was characterized by decocted salt production had become the focus of salt industry for a long time, which was gradually replaced by the solar salt industry; the evolution process was significant differences in different salt area: the northern salt area had the fastest progress than eastern salt area and southern salt area. 2) The focus of sea salt production had a migration changes from eastern to northern coast, and the Huainan saltworks of eastern salt area was the sea salt production center during the 13-19th centuries. 3) Natural and social-economic factors were the important driving factors resulted in the changes of spatial-temporal distribution of sea salt production; the differences of coastal natural environment promoted the different evolution process of salt production, and the monopolistic management policy in salt industry was the key to changes of sea salt industry. Thus, follow the regional difference, coastal development need to break through the limit of local interests and improve efficiency of sea salt production in coastal area with the resources and ecological advantage, and promote production agglomeration from disadvantage coast to advantage coast. This is not only the result of sea salt industry of long-term historical development in China, but also the current urgent need of the international competitiveness of coastal development. In addition, on January 1, 2017, China began formally implement the salt industry management system reform, and the old salt management system lasted for more than two thousand years will gradually open. It was predictably that the reform will have a profound impact to sea salt industry and coastal development, which the location and resources advantages will be highlighted, and will also improve the international competitiveness of China’s sea salt industry. The sustainable development of future sea salt industry will depend on management policies based on resources and ecological constraint in coastal region.
The Northeast is a complete and independent geographical and cultural region in northern China. Since the founding of the People's Republic of China(1949), the administrative division pattern in Northeast China has changed a lot. The administrative division adjustment is mainly divided into the following five stages: In 1949-1955, the provincial-level administrative districts were adjusted frequently. In 1955-1969, the provincial-level administrative district was stable, the prefecture level and county-level administrative districts were frequently split and merged. In 1969-1979, the eastern region of Inner Mongolia was allocated to the three provinces (Liaoning, Jilin and Heilongjiang) of Northeast China; In 1979-1996, the prefecture-level and county-level administrative districts were adjusted frequently. Many counties changed to cities and municipal districts. From 1997 to the present, this stage was relatively stable, administrative divisions were adjusted less. The counties and cities were mainly changed to municipal districts. Factors such as the level of economic development, traffic conditions, history and culture, physical geography conditions, and policies or standards have had important impact on the pattern and adjustment of administrative divisions in the Northeast China. Finally, the article analyzes the main problems of the administrative divisions in Northeast China, and proposes the optimization path of administrative division adjustment. The authors put forward the following suggestions: At the provincial level, four prefecture-level cities in eastern Inner Mongolia will be built separately and named Xing'an Province. At the prefecture-level, the Jiagedaqi and Songling District will be placed under the Daxinganling Area, and chang the Daxinganling Area to a prefecture-level city. At the county level, the counties and the mega-towns with good development conditions will be changed to county-level cities for increasing the number of small cities. At the township level, continuing to promote the "township merger", and townships around the big city will be changed to street offices.
：This article measures the marine ecological efficiency of 11 coastal regions in China with the SBM model considering the undesirable output. The center of gravity model is applied to projecting and visualizing the evolution of spatial pattern of marine ecological efficiency from 2001 to 2015. On this basis, the VAR model is introduced to explore the dynamic relationship between spatial evolution of marine ecological efficiency and its influence factors.The results showed that: 1) The marine ecological efficiency of coastal provinces is generally low but shows an upward trend. Among them, the marine ecological efficiency of Tianjin, Shanghai, Jiangsu, Fujian and Guangdong jumped from relatively ineffective to relatively effective, and Liaoning,Shandong and Hainan rose from relatively ineffective to relatively inefficient, while Hebei, Zhejiang and Guangxi remained relatively ineffective. 2) The transition process of the gravity center of marine ecological efficiency can be divided into "northeast migration phase from 2001 to 2006" and "southwest migration phase from 2006 to 2015", however, the movement range of of the center of gravity is mainly located in the Yangtze River Delta region. 3) By analyzing the influence factors on the evolution of spatial pattern of marine ecological efficiency, we can find out that the impact of marine industrial structure on marine ecological efficiency has fluctuations between positive and negative but mainly positive. As the industrial structure is continuously optimized, the negative effect is weakened over time. Marine science and technology have a significant positive effect and sustained benefits on marine ecological efficiency, especially in the initial stage of the change of marine ecological efficiency. As a terminal treatment, the effect of environmental regulation on the marine ecological efficiency is not significant.
As a basic component of comprehensive three-dimensional transportation corridor of the Yangtze River economic belt, railway plays an important role in building transport channel, accelerating the flow of socio-economic elements, promoting the development of the whole area. Based on the railway passenger transport network, this paper analyses the spatial pattern of railway passenger accessibility by using rail-travel time index in the age of fast-speed and high-speed. And then, the impact of railway traffic change on the development of urban tertiary industry is analyzed by using the market panel data model. Results are shown as follows. 1) Railway passenger transportation in the Yangtze River economic belt has been greatly enhanced by the operating speed acceleration and transportation capability expansion of existed railway lines and the opening of high-grade new lines. However, the spatial density and time gradient during railway construction cause spatio-temporal compression of railway accessibility change unbalanced. With the development of the high-speed railway from east to west, the gap between the three zones has gradually narrowed. 2) The disequilibrium of time and space compression in the economic belt is brought by railway construction and "channel effect" is evident. On the basis of the former Jing-Guang channel, the high accessibility area has expanded to Hu-Kun channel and Hu-Han-Rong channel with the construction of the express channel from east to west. With the strengthening of the north-south channel, network development is realized. The main reason for the difference of railway traffic location is changing from presence of railway to the differences of the construction standard during the study period. High-speed railway redefines passenger services. The low-travel time network is being strengthened in major urban areas and interzone high accessibility network convergence appears along main interregional communication channels. The east-west high-speed railway corridors prop up the most obvious traffic location advantage areas. Fast connections between central cities through the "core - network" model reconstruct original discrete urban spatial organization form and drive the changes of traffic location among cities, which achieve integrated development of urban agglomerations and network communication from east to west. At the same time, the development mode may cause a greater imbalance between the core and the periphery. People and factors continue to cluster in the Yangtze River delta, Wuhan, Chang-Zhu-Tan and other economically advanced regions. 3) Railway passenger transport is one of the most important tools for long-distance personnel transportation and has great social and economic effects in the evolution of railway accessibility. Railway construction and accessibility promotion promote urban tertiary industry development and factors concentration, which shows the pattern of the Middle and the East higher, the West lower. Industry and elements tend to cluster and expand in the direction of railway channels. By using the advantage of railway traffic location, cities of Strong positive effect function, including railway channel node cities, cities along the traditional railway main channels and cities along the new railways attract elements in a relatively competitive environment.
Along with the economy development goes into a new normal in China, the economic structure imbalance becomes one of highlighted economic problems, especially in Northeast China. This phenomenon has attracted wide attention from scholars and society. The state government points out that the adjustment of economic structure and the transformation of economic development mode, are not only important measurements to promote healthy development of national economy, but also vital methods to prosper the economy in Northeast China. Therefore, it is of important academic significance and practical value to analyze economic structure imbalance and its influence on economic growth. Based on this, this study establishes an evaluation index of economic structure imbalance, including industrial structure, investment and consumption structure, financial structure, regional economic structure and international payments structure, explores level of economic structure and its spatial-temporal characteristics of 34 cities in Northeast China from 2003 to 2015 by using factor analysis method and ArcGIS spatial analysis method. Due to the spatial effects of per capita GDP, then the paper sets up spatial econometrics models (including spatial lag model, spatial error model and spatial Durbin model) in order to explore the impact of economic structure imbalance on economic growth in Northeast China, which are different from traditional regression models ignoring space factors. The results show that: 1) Generally speaking, the economic structure in Northeast China is in imbalanced condition, but the level of imbalance is continuously decreasing. There is spatial heterogeneity in the level of imbalance, and the high level of imbalance area mainly concentrates in resource-based and old industrial cities. 2) High-value areas with imbalanced level of economic structure are surrounded by low-value areas, presenting a typical "core-periphery" distribution pattern in space. 3) Among three spatial econometrics models, the regression result obtained by spatial Durbin model is more convincing than the other two. The model reveals that the impact of economic structure imbalance is of a periodic characteristic. In the period of 2003 to 2008, it inhibits economic growth and generates significantly negative spillover effects. However, from 2009 to 2015, it promotes economic growth, that is “imbalance but growth”. The reasons for this seemingly contradictory are as followings: on one hand, from the previous analysis, the imbalance level of economic structure has been declining after adjustment, and appears a trend towards equilibrium. According to the principle of evolutionary economy, when the economic structure changes from imbalance to equilibrium, new drivers emerge and promote economic growth. On the other hand, in the Northeast China, the main driving forces for economic growth origin from the secondary, tertiary industry and investment, structure imbalance within a certain range can still stimulate economic growth weakly.
Urbanization and real estate investment are important influencing factors of carbon emission in a region. Therefore, it is necessary to systematically analyze and test the internal impact mechanism of urbanization and real estate investment on carbon emission. Combining the deformation of Kaya identity and LMDI decomposition, this article decomposes the carbon emission changes of 30 provinces in China (due to data limitation, the data of Hong Kong, Macao, Taiwan and Tibet are not included in the study area) from 1997 to 2015. The spatial evolution characteristics of carbon emissions in Chinese provinces are described by Moran’s I index and LISA spatial agglomeration map. This article further uses the spatial panel data model to empirically test the effects of urbanization and real estate investment on carbon emission from both direct impact and spatial spillover effects. The results are as follow: First, from the time trend, China’s carbon emission has maintained a growth trend from 1997 to 2015. From the perspective of the decomposition factors of carbon emission, the carbon emission coefficient of real estate investment is the main driving factor to curb carbon emissions, while the intensity of urban real estate investment, the level of urbanization and the change of total population in the region have positive effects on carbon emission, and the effects are increasing year by year. Second, from the spatial distribution characteristics of carbon emission, there are significant differences for the carbon emission in the provincial-level, and the distribution characteristics are generally expressed as higher carbon emission in the east and lower in the west. The spatial concentration of provinces with less carbon emission has increased, and the regional differences among them have been shrinking. Third, from the regression results of the spatial panel data model, the direct impact of urbanization on carbon emission is significantly negative, but the spatial spillover effect is significantly positive. The direct effect of the intensity of urban real estate investment on carbon emission is positive, but its spillover effect is not significant. The direct effect and spatial spillover effect of the interaction between urbanization and the intensity of urban real estate investment are significantly negative. The direct effect and spatial spillover effect of economic development on carbon emission are significantly positive. The direct impact of government investment on carbon emission is significantly negative, but the spillover effect is not significant. Industrial structure has no significant direct effect on the carbon emission, but its spatial spillover effect is negatively negative. The degree of opening to the outside world has a significant negative direct effect on the carbon emission, but it has a positive effect on the carbon emission in the adjacent areas. With the improvement of the level of urbanization and economic development, there is a significant U-shaped and inverted U-shaped curve relationship between the two and carbon emission, respectively. This article further proposes countermeasures and suggestions to improve regional carbon emission reduction from the perspective of urbanization and real estate policies.
With the rapid development of economy, the number of China's motor vehicle rises sharply. The rapid development of the auto industry promotes the social civilization, and drives the sustained economic growth. Cars improve the efficiency of people’s traveling, at the same time, they bring some problems such as traffic congestion, environmental pollution, energy consumption, which directly threat to human health and the sustainable development of social economy. To explore the temporal variation characteristics of civilian cars under the background of China’s rapid economic growth ownership is the basis to solve the problem such as traffic congestion, traffic accidents, car exhaust, it is also the premise of auto industry development and applicable policy. This article reveal the temporal variation characteristics of Chinese civil car ownership and differences, explore the relationship between the civil car ownership change and economic development. With the the number of civil car ownership, gross regional product, household consumption level, highway mileage and provinces population data in 31 provincial level administrative region in mainland China from 1996 to 2015, the empirical research is conducted by adopting Theil index, the linear trend estimation indicates, Mann - Kendall test and panel data mode, respectively, based on the national, the eight economic regions, and 31 provinces three spatial dimensions. The preliminary results shows that: 1) The scope of research and the continuous growth of China's car ownership can be divided into two stages: the first stage, 1996-2005, for the slow growth; The second stage, from 2005 to 2015, is for rapid growth; 2) From 2000 to 2015, China's civil car ownership regional differences declined obviously in 2000-2005, the differences of China’s civil car ownership in 31 provinces regions are determined by differences of within-region, and differences in Northern coastal areas are the main cause of regional differences; The differences of between-region were greater than the differences of within-region in 2006-2015; 3) In the research time range, the gross regional product, residents' consumption level, and highway mileage can improve the number of civil car ownership, and there are significant differences in the influence of three factors on the civil car ownership.
The high-resolution morphological data of riverbed were observed by RESON 7125 multi-beam system during August 2015 and September 2016. Before that, few scholars used high resolution multi-beam data to study the subaqueous topography in Nanjing segment. The data of flow velocity and sediment samples were synchronously collected by an Acoustic Doppler Current Profiler (ADCP) and a sediment sampler. Bathymetric data of the Nanjing reach of the Yangtze River in 1998 and 2013 were used to analyze the change of erosion/deposition in this area. The results show that: 1) The net erosion volume of riverbed was 5.6×107m3 between 1998 and 2013. In this period, the envelope area of 0 m has reduced 5.0×106m2, and that of -2 m, -5 m and -10 m increased 1.0×106m2, 3.0×106m2 and 9.0×106m2 respectively. The width of the river channel was narrowed, but the riverbed erosion occurred. Thus the navigation condition has been improved. 2) Dunes generated over approximately 97.09％ of the downlink navigation channel , while only was 52.09% of the uplink navigation channel existed dunes. According to the standard classification of subaqueous dunes proposed by Ashley, the very large dunes, large dunes, medium dunes and small dunes were observed in the Nanjing reach. The mean flow velocity over small dunes and smooth bed floor was 0.79 m/s, while over very large dunes reached 1.41 m/s. The subaqueous steep slope was observed in both two sides of the river bank and the maximum slope (Slope height/length) of the subaqueous steep slope was up to 0.34. 3) Human activities have an important influence on the evolution of riverbed micro-morphology and river regime in the Nanjing reach: the Channel Renovation Projects leads to the more stable bank lines and the deeper channel; the construction of bridge engineering results in the local scour surrounding the bridge foundations. However, smooth bed floor existed in the upstream of the bridge foundation, while the downstream developed very large dunes. 4) Due to construction of the Three Gorges Dam and the other human activities, the sediment load is increasingly decreasing according to the real-time monitoring data of Datong hydrological station. At the same time, the calculation results of field measured data in the study area show that the bed shear stress are 0.42 N/m2 and 0.38 N/m2, however, the critical shear stress of channel is one magnitude less than the bed shear stress, they are 0.09 N/m2 and 0.05 N/m2. It means that the riverbed sediment will be in a state of frequent transport for some time to come, and it also investigates that the channel depositional environment will be in erosion in the future. The analysis of grain size of riverbed sediment which were collected in the field show that the median grain size of sediment in 2015 was coarser than it in 2008. All of the results show that the Nanjing segment would experience significant riverbed erosion in the future, and it would be a serious threat to the safety of the wading project.
：Revealing the county poverty pattern and its influence mechanism of cultivated land in resource-rich area can provide a scientific basis for us to carry out accurate poverty alleviation, regional development and rural revitalization. In this study, choosing Lanxi County where in Heilongjiang Province as the study area, the townships as the statistical units, using geostatistics and the basic methods of statistics to analysis the spatial poverty pattern of Lanxi County and in-depth analysis of the impact of cultivated land use on rural poverty mechanism. Some conclusions are drawn as follows: Firstly, a characteristic called gradient decrease, it shows the rate of poverty incidence in Lanxi County decrease from the northwest to the southeast. Secondly, poor households rely heavily on cultivated land. In 2015, the per capita income of poor households in Lanxi County was 3 983 yuan, of which 2 388 yuan was relied on cultivated land utilization. The sources of income were farming, agricultural subsidies and property income. Thirdly, among the various affecting factors of cultivated land, national grade, utilization grade, economic grade and per capita cultivated land area have an impact on the incidence of poverty. Correlation between reclamation rate and incidence of poverty is weak with little impact. In terms of performance, the better the quality of cultivated land is, the lower the poverty incidence; the more cultivated land per capita, the higher the incidence of poverty. Fourth, the dependence mechanism of cultivated land resources and the utilization mechanism of cultivated land resources are formed due to the quantity and quality difference of cultivated land per capita owned, leading to the pattern of poverty and furthering affects the scale of poverty in Lanxi County and the incidence of poverty. Fifth, the strategy of the poor counties with relatively abundant cultivated land resources are as listed below. Strengthening land consolidation and improving the natural quality and ecological value of cultivated land are of great importance; increase the intensity of agricultural input and promote the upgrading of agricultural; adjust agricultural production relations to realize the organic combination of modern agriculture and poor households; make the full use of potential and advantages of featured agriculture, organic agriculture and ecological agriculture to ensure the sustainable development of agriculture and poverty alleviation.
Ecosystem service value (ESV) is not only one of the important parameters to study regional ecological economic harmony, but also a key indicator to improve the sustainable development. In recent years, based on remote sensing data, the ESV model has been gradually developed and widely used, whereas it is lacking in the application of regional ESV dynamic monitoring year by year. Here, the optimal spatial resolution and long time series of remote sensing data was selected by analyzing the scale effect, and regional ESV dynamic monitoring of year level was carried out on the pixel scale from 2001 to 2013 in Central Plains Urban Agglomeration region. The results showed that: 1) The range of the optimal spatial resolution was 30 m to 1 000 m for multi-source remote sensing data, and the relative deviation of the estimation results of different scales was less than 0.4%. With the demand of dynamic monitoring, the MODIS data products (spatial resolution was 500 m, and time scale was 1 year) were selected as the optimal data source for ESV model. 2) The total value of ESV in the study region showed a significant increasing trend from 2001 to 2013, with an increase of approximately 860 million yuan/a, but experienced three fluctuations in the continuous increasing process, and the performance was more and more intense. The dynamic change of ESV in the study region was uneven in the spatial distribution, and the growth area was slightly larger than the degraded area. Overall, the method of this article was simple and feasible, and the quasi-business operation of ESV remote sensing model was implemented.
Based meteorological data from 13 weather stations in the Yarlung Zangbo River Basin, the wind erosion climatic factor index was calculated using function given by the UN Food and Agriculture Organization and the basic features of wind erosion climatic erosivity were analyzed. The results showed that Yarlung Zangbo River wind erosion climatic factor indexes were in range of 4.2-31.9 and the average value was 14.7. On the spatial, wind erosion climatic factor indexes decreases from the west to the east. Wind erosion climatic factor indexes can reach to 40 in the west and reduced to about 5 in the eastern part of Gyaca - Mainling section. The wind erosion climate factor index has a significant seasonal variation. The largest value is in spring with the value of 8.5 and the second large value in winter with the value of 5.2. Summer and autumn show very small value. The trend of wind erosion climate factor index decreased significantly in Yarlung Zangbo River Basin on annual, spring, autumn and winter, while that of summer uptrend is not significantly. Analysis using Mann-Kendall test method shows that the wind erosion climatic factor index has abrupt change in 1987.
Based on the historical military topographic maps and Landsat TM/ETM+ remote sensing images, the spatial data set of river course evolution in Jingjiang River section of the Yangtze River from 1930s to 2015 reconstructed in this study. On this basis, the evolutionary process of river fractal dimension over the last 100 years calculated on ArcGIS 10.2 platform by using box counting dimension method. The results show that the Jingjiang River section of the Yangtze River has obvious fractal characteristics, and the river fractal dimension varies from 1.074 7 to 1.049 1 with an average of 1.061 3. The evolution of Jingjiang River section of the Yangtze River in the past 100 years can be divided into two stages: 1930s-1950s and 1976-2015, with the average fractal dimension of 1.074 3 and 1.052 6 respectively. In the past 100 years, Jingjiang River section of the Yangtze River has been in the process of gradually stabilizing. The fractal dimension and complexity of down Jingjiang River section over the past 100 years is higher than that of up Jingjiang River section in each time, and the change of fractal dimension of whole Jingjiang River section mainly depends on that of down Jingjiang River section. The main reasons for the decline of river fractal dimension in the past 100 years are the large-scale governance of Jingjiang River section and river cut off projects after 1949.
