In traditional economic theory, the object laws of economics focus on explaining the differences among regions in their economic development. However, the important role of political and social factor has been ignored. From the perspective of space production theory, this article uses Beijing and Shanghai as cases to make a deep comparison between the central city and its peripheral region, and analyze their different strategic interaction process and regional spatial development performance. The results show that, Shanghai and its peripheral region are able to grow into a highly integrated area, due to the sustained strategy interaction between regional actors; While, Beijing’s peripheral region has been become "Metropolitan Shadow Area" due to divergent interactive strategy between Beijing and peripheral areas since a long time. From the perspective of promoting regional strategy, the article proposes the possible measures to dissolve metropolitan shadow area.
Against the context of high-speed economic growth in China, the number of South Koreans who have expatriated to China soared over the last two decades. This increase has made China the third largest destination for South Korean Transmigrants among all nations, following only USA and Japan. The South Korean transmigrants mainly lived in major metropolises such as Beijing, Guangzhou and Shanghai. With the population growth of South Korean transmigrants in Chinese cities, now many South Korean enclaves have established and attracted attention both in China and abroad. However, compared to the foreign enclaves in Beijing and Shanghai coming from immigration policy and specific districts such as the economic and technological development zone, and embassy District, Yuanjing Road in Guangzhou got rid of the mark of impoverished urban village (Tangxia village) in Baiyun district, and transformed into a South Korean enclave mainly resided by South Korean traders. Based on the theory of production of space, this research sheds light upon the Yuanjing Road, taking it as a case to examine the production of space of this South Korean enclave, and first-hand data were gathered from questionnaires and interviews in February, May,October 2015 and September 2016. In the context of commodity chains and regional divisions of labor in an age of globalization, and transnational entrepreneurialism booming in Guangzhou, the local government took advantage of the situation that some South Korean traders have assembled in Yuanjing Road, and then put forward the construction of a Korean town at Yuanjing Road. Also, the local government, associating with investors, reconstructed the material space of the Yuanjing Road. At the same time, the South Korean traders strengthened their living and working foundation in the Yuanjing Road through three factors: the location advantage (next to some wholesale trade markets), social network connected to transnational trade chain, and Korean ethnic economy. Therefore, the South Korean traders succeed in occupying the space of the Yuanjing Road, and in redeveloping the social relations there. In summary, this study found that the Yuanjing Road’s transformation from an urban village to a South Korean enclave is a joint product of the local government, investors, and South Korean traders. As the result of production of space, the Yuanjing Road has become the place of transnational trade chain between China and South Korea, also the living space of diversify groups including the South Korean transmigrants, villagers, and migrant populations. The production of space of South Korean enclave in the Yuanjing Road, gives us a valuable lesson of the urban villages’ reconstruction in China, and also introduced ideas for immigration management to Guangzhou.
Under the background of globalization and localization, the gateway city has become important geographical unit which links the global production network and the gateway function of the cities, and attracts more and more people's attention. From the perspective of geographical space, this article attempts to portray the city's gateway function and explore its driving mechanism, and consider the passenger and cargo flow of three dimensions consisting of water, land and air transport. Based on the data of the main gateway cities in the Yangtze River Delta Region (YRDR) during 2004-2014, the spatial pattern and evolution of the gateway function in YRDR is analyzed by using the comprehensive evaluation index, the Gini coefficient and the standard deviation ellipse. The main results can be summarized as follows: 1) On the whole, the gateway function of cities in YRDR increases clearly. Shanghai, Ningbo, Nanjing and Hangzhou always have strong gateway function in YRDR, and the gateway function pattern of this region has changed from “one pole three strong” to “one pole four strong” with the rapid advancement of gateway function in Suzhou since 2010, which also reflects that the spatial pattern of gateway function in YRDR has the stability and significant path dependence. 2) The spatial differentiation state of international gateway function is obviously larger than that of the comprehensive and domestic gateway function, but the distribution pattern of the three kinds of gateway function tends to be equilibrium in space. The main reason for the spatial differentiation of gateway function in YRDR is the difference between the two gradient cities. 3) The international gateway function of the eastern region is stronger than that of western region, but the discrepancy between them is narrowing. In the meanwhile, the spatial patterns of all the three types of gateway function are transforming from the pattern of south-north distribution to the pattern of east-west distribution. 4) The pattern of gateway function and its evolution in YRDR are driven by multiple factors. Through the fixed panel regression model, the economic and social environment factors such as population density, industrial structure and informationization level all play significant roles in promoting the comprehensive and domestic gateway function, while the improvement of the international gateway function is more closely related to the economic behavior factors. At the same time, financial development level has no significant impact on the domestic or international in YRDR.
Based on a survey of 2 496 migrant workers in 9 cities of the eastern and central China, this article investigated the impact of local factors on social integration of migrant workers. A multiple-level regression model was applied to analyzing and revealing the differential impact of local factors, including level of economic development, intelligibility of local dialect, population share of migrants, and cost of rent. The cities, with more difficulties to join the local endowment insurance, the better the economic development, the greater gap between the earnings of the migrant workers and urban capita income, the higher rent, the more difficult urban dialect to master and the higher proportion of urban immigrant population, have a lower integration. The results find: 1) each city’s uniqueness produces some specific positive and negative effects. The positive effects can reduce the social distance between the migrant population and the urban residents. The sense of inclusion may become a source of pride in promoting the effective integration of migrants. However, the negative effects may serve to marginalize and alienate the migrant population. In cities that are not conducive to social integration, the migrants have a lower degree of recognition. 2) the differences between cities are selective in attracting migrant populations. Different cities attract different types of migrants, so that their migrant populations are structurally different. The abilities of the migrant populations to adapt and integrate are also different in different cities. Therefore, cities differ significantly in their levels of social integration. Recognition of these differences is an important basis for making urbanization policies that fit the local conditions. Given the large variety of cities, it was suggested that localized social policies are promoted to ease the integration of migrant workers in urban communities. To facilitate migrant workers’ social integration, priority should be given to promoting social integration within a province and at cities with high proportion of migrant population. Migrant workers should also be given the benefits of local social programs such as public housing rental assistance, especially in cities with a high level of rental cost.
The relative land acreage and GDP as the influence factors on Chinese population distribution, while the relative land acreage is composed of land yield and multiple crop index. It is very useful to measure the contribution of land and GDP by using Standard regression coefficient method. This research shows the relative productivity land and regional domestic product is high-closely related to the Chinese population distribution. Land accounted for 87.8% for Chinese population distribution in 1952. However, it changed while GDP accounted for 59.5% for Chinese population distribution in 2013, and economy plays a more and more important role in Chinese population distribution. For a very long time before reform and opening, Chinese population was land-oriented and now it is economy-oriented. But the overall population distribution is not changed while the role of influence factors changed. It is impossible to change Chinese population distribution line, the Hu’s line whatever by the potency of land product or by the economic product. It still need to according to the space sequence from east to west, south to north to accomplish China New-type Urbanization strategy. For now, it is easier for the east of China to increase it urbanization population. It needs a long period to accomplish the urbanization strategy for harmonious interregional development.
Based on patent and dissertation database of China’s 287 cities, the evaluation system of urban innovation capability was established in the perspective of innovation output, which is concerning the temporal-spatial evolution of innovation in China during 2001-2014. Then the article constructed the spatial econometric model to analyze influencing factors. The results are as follows: from 2001 to 2014, there are great differences of regional innovation output in China, and the output weakened from east to west, which showed an obvious trend of strengthen of western. The Gini Index of regional innovation capability in China raised at first, then decreased, which indicated that the innovation spatial patterns has evolved from polarized development to balanced development. The Gini Index of eastern where innovation output mainly concentrated in showed little change, in contract, the Gini Index of western showed declined. High level innovation hotspots widely distributed in developed cities, and the cities in the innovation secondary level are distributed in the form of agglomeration. Spatial dependence characteristic of city innovation level was significant, and further strengthen over time. H-H cluster areas are mainly distributed in Beijing-Tianjin-Hebei, the Yangtze River Delta and the Pearl River Delta, and the central and western provincial capital cities as regional innovation, didn’t have obvious driven effect to neighboring city and had limited radiation effect. Economic base, human capital, education level, FDI scale, institutional factors and infrastructure could promote the development of regional innovation. Especially, economic base and human capital were the most important factors, followed by education level and institutional factors.
Based on information data of patent applying and cooperative patent of petroleum equipment manufacturing industry in Dongying during 1985-2013, patent information service platform of SIPO and the data, the author interviewed 17 petroleum equipment manufacturing industry in Dongying, and did an analytical research on innovative network evolution of Dongying petroleum equipment manufacturing industry from multidimensional proximity perspective with social network analysis in virtue of software tools such as Ucinet, Arcgis etc. Then we get some result. Firstly, multidimensional proximity factor has great influence on Dongying innovative network development and the predominant proximity factor is different on different network development stages. In breeding stage, the cooperation between network main bodys mainly in enterprises belong to state-owned Shengli Group in which organization is proximity to predominant factor; in early stage, cooperation mainly occurs in enterprises having industry chain cooperation relationship which in order to reduce communication transportation costs which become the consensus of cooperation main body when geographic proximity factor become dominant; in growth stage, cooperation occurs mainly in enterprises with similar technical level knowledge foundation which in the pursuit of horizontal cooperation when cognitive proximity factor plays a leading role. On the one hand, that confirms relevant multidimensional proximity theoretical hypothesis of Boschma, and points out different relevance between multidimensional proximity factor and Dongying cooperative innovative network evolution on the other hand. Secondly, universities and large state-owned enterprises are knowledge source and organizers of Dongying innovative collaborative networks. China University of Petroleum (East China) and Shengli Oilfield conglomerate plays a leading role which is different with the foreign situation that small and medium-sized enterprises play a leading role.
The coupling coordination between urban smart development and ecological environment is the important strategic objective in forming conservation-oriented spatial pattern and sustainable developments. Based on the statistics of Harbin-Changchun City Group from the pre-period Year 2006 of "the eleventh five-year plan"to the later-period Year 2014 of “the twelfth five-year plan”, we should take a further consideration about smart development degree of urban performance within the Harbin-Changchun City Group from the following dimensions such as spatial development dimension, welfare development dimension, consumption development dimension and management development dimension. According to the construction of the coupled coordination model, it analyzes the overall coupling and coordinated development degree, spatial coupling coordination characteristics of Harbin-Changchun City Group is also included. As a result, it shows that: 1) During “the eleventh five-year plan”, the comprehensive development level and coupling coordination degree of urban performance and ecological environment in Harbin-Changchun City Group, both of them realize the gathering spatial distribution in western areas. To the contrast, the comprehensive development level in eastern regions needs to be improved and the coupling coordination should be balanced. During the period of “the twelfth five-year plan”, the comprehensive development level of the two is still dominated by western areas. The degree of coupling coordination shows a decentralized layout again. 2) In the study period from 2006 to 2014, it reveals that the comprehensive development level of urban performance and ecological environment in Harbin-Changchun City Group takes the trends of a little falling and then increasing except Changchun City, Jilin City and Suihua City. However, the coupling coordination degree appears to take an obvious decline and the two coordinating relations are actively promoting only in Siping City, Liaoyuan City, Harbin City and Qiqihar City. 3) In the whole Harbin-Changchun City Group, the comprehensive development level, coupling strength and coordination degree are not of great advantages, in the other hand, it is relatively different in regional distributions. There is a certainly spatial correspondence between comprehensive development levels and coupling coordination degrees. And it makes a benign resonance in the space as a whole. Smart development is an inevitable choice for China’s sustainable development under the background of tight resources and environmental problems. Judging from the degree of coupling coordination in the study area which is regarded as the core corridor and pivot of China’s trade facing towards Russia and Northeast Asia, Harbin-Changchun City Group is also in close cooperation with the Beijing-Tianjin-Hebei region and other vertical hinterlands at the same time. We can make a conclusion that the smart development degree of urban performance is of significant regional difference. Therefore it is particularly important to achieve harmonious and sustainable development of urban performance as well as the ecological environment in order to gradually take pace in smart development path and push forward economic and social new normal development actively especially in Harbin-Changchun City Group.
Based on over ten thousand pieces of relative-seeking data from a certain online public platform, the basic laws of crime activities of trafficking in children in China during 1980-2015 were examined through a variety of analytical methods like GIS and SPSS from the perspective of geography of crime. It was found that: 1) The main purpose of trafficking is for forced adoption, and the total trafficking amount of the male is more than that of the female. High trafficking frequency occurred at low ages. The female were trafficked more at adolescence stages while boys were trafficked more at baby, infant and children stages. It can be divided into four trafficking types: “family control type”, “adoption tricking type”, “integrated transition type” and “pre-adult labor type”. 2) The amount of crime since 1980 presented a “Pour Spoon” pattern of fluctuations and reached the peak stage during 1989-1998. The crime was significantly affected by the strike policy and population policy with a “seesaw” type of response. Compared to promulgation of legal foul, a direct blow from the public security department was still the most effective way to curb. 3) The number of monthly changes in criminal cases showed two-inverted “U” pattern, with two peak stages from May to August and from October to January. Seasonal variation was not obvious. The crime occurred more frequently during the winter half-year (summer and autumn) than the winter half-year (winter and spring), which indicated temperatures could promote the occurrence of the crime. 4) The crime presented “centralized supply/trafficking-out from the west while decentralized demand/trafficking-in to the east” features: the core area of supply concentrated in Sichuan and Guizhou of Southwest China while the core area of demand concentrated in Fujian, Guangdong, Shandong and Henan. The whole migration pattern of “trafficking from the west to the east” had a linkage to the “push-pull” mechanism resulting from the regional economic difference between eastern and western areas. 5) The crime presented the main “field-flow” features of the spatial pattern as “three-area and two-route” and the two crime flows were formed between the three crime areas with certain driving effect: the south route’s flow was from Yunnan, Guizhou and Sichuan to Fujian with a certain collateral flow in Guangxi, and the north route’s flow was from Yunnan, Guizhou and Sichuan to Shandong, Henan and Hebei with a certain collateral flow in Shaanxi. 6) With the time went on, the spatial concentration degree of the crime of trafficking in children presented a descending trend. Gradually in future, the crime was sure to be developed from a regional crime to a national crime, and “Hollow Village” and “Urban Village” would be the potential high-risk areas, which would be a big challenge for future prevention and control. Several research prospects from the perspectives of data, contents, theories, methods and comparison are figured out.
Currently, western region’s rural tourism resources in China over a broad area, tourism services spread all over, make rural tourism spatial organization efficiency lower and seriously hindered the development of rural tourism. To this end, it is urgent to find out the characteristics of rural tourism spatial organization and reconstruct the tourism spatial structure. Based on the traditional gravity model, this article constructed the tourism space interaction model, taking 47 rural tourism development focused village of Lanzhou as an example, using social network analysis method, analyzed the characteristics of Lanzhou rural tourism network center, put forward countermeasures to optimize the Lanzhou rural tourism network structure. The results showed that each village centrality values are higher than betweenness centrality, betweenness centrality values are higher than the center vector, and urban area surrounding the village center is generally higher than Yongdeng County of southern and northern Yuzhong County and other counties under the jurisdiction of the village center. The majority central of the Lanzhou rural tourism is the second level of the village, the first level of the village is in urgent need in order to supplement the core nodes in the tourism network. Lanzhou rural tourism network system has not formed yet, the spatial structure of the local compact, the overall sparse and uneven development characteristics. Finally, it puts forward the countermeasures to optimize the structure of rural tourism network in Lanzhou.
This article sets up the concept and connotation of river tourism from the perspective of the complexity of tourism and regional system. It analyzed three tradition, including aesthetic and gardening tradition, humanism and post industrialization tradition and pilgrimage tradition, and it also researched the significance to the present study of three tradition on the basis of clarifying the tradition of its origin. In fact, these tradition has not been lost in the concept of modern tourism and the health and entertainment function of the river is more and more important, and the river itself is endowed with great religious significance under the cultural background of the river basin as the source of civilization. The most important thing of this article is to come up with two conceptual systems, and the first continuous concepts from four dimensions are constructed according to the form degree of the use of the main body of the river from the perspective of ontology, including completely close, partial close, partial alienation and complete alienation on the basis of the main factors and their interactions of river tourism usage, and the second constituted continuity concepts of four dimensions include non-intervention (natural rivers), weak intervention, strong intervention and totally intervention (artificial river) from the degree of artificial intervention to the object of the river. As a result, it built the main conceptual system of river tourism. The connotation of river tourism can be explained deeply when the two conceptual systems are folded. In essence, river tourism is the same as other forms of tourism activities, which can be regarded as the interaction and co-construction process of tourism subject and tourist object (river tourism land) in a certain time and space. Then the article found that in the context of postmodern or post industrialization, the construction of river research system should be based on the subjective experience and the regional system, and this result should be in the conceptual system which the research sets up. The purpose of the article is to explore the way of participating in the river tourism based on different experience types, to analyze "process-structure-mechanism" of development evolution of river tourism system, to pay close attention to the transformation and influence of river utilization mode under the dominance of recreation and entertainment functions, and to focus on the status of recreational activities in the integrated development of the river basin. Also this research content system combing with traditional regional research can be used to clarify methodology and technical means deeply.
With keeping a high-speed growth since reform policy, resource-based cities in northeast of China have encountered both social and economical changes caused by internal transition as well as external factors. It is important to strenghen research on resource-based cities development, to provide scientific supports for both resource allocation and policy making. From the pespective of long-run transition, this article uses H-P filter and a panel data model to explore resource-based cities’ economic spatial patterns and characteristics and investigate quantitative contribution of investment, tertiary industry, marketization, FDI and technique to economic transition in resource-based cities in the northeast in 2000-2014. It turns out that GDP keeps growing while business cycles are volatility which is coordinating with revitalizing policies and industry development. The results indicate that the transitional period falls into three stages, the first stage is from 2000 to 2003, in which the economic growth is mainly attributed to FDI, technology has no positive effects on economic development. In the second stage from 2004 to 2009, the economy is mainly driven by investment, technique development and tertiary industry ,in the mean time, FDI had negative influence mostly due to competition disadvantages. Marketization, FDI, technology and serving industry siginificantly improved the economic transition during the period from 2010 to 2014, in which serving industry made the most contribution, investment lost effectivemess. The periodical phenonmenon of resource-baesed cities in the northeast is related to revitalization of the northeast, many social, economic and environmental problems are not completely solved, in other words, transition development in resource-based cities in the northeast has not yet finished, the suggestions are: 1) Improving technology innovation ability to solve transition of development driving force; 2) Innovating the enterprises reform and encourging cooperations among various ownership economy; 3) Decreasing the poverty and increasing residents’ living level in northeast of China based on buliding infrustructure and eliminating environmental pollution. Firstly, these findings are uesful to integrate tranformation development in the northeast of China in different aspects. Secondly, according to the areal characters and its economic transition status, mathematical models should be explored in different areas. Thirdly, it is essential for the resource-based cities’ governments to change their traditional planning models, implement well-directed measures and upgrade management systems gradually and moderately by taking a sufficient consideration of the status and trend of both inside and outside circumstances.
Tourism has gradually become the world’s largest growth industry, being closely related to new urbanization. Through selecting 17 cities in Shandong Province as the research object and applying statistical analysis method, the article analyzed the characteristics and types of spatial-temporal differentiation of tourism urbanization response in Shandong Province from 2001 to 2014, by using measure indexes such as stand deviation, variation coefficient, static unbalance difference, relative development rate, deviation, ratio and so on. Major findings of this research are: the trend of the gradual increase from 2001-2009 and the decline from 2009-2014 in absolute and relative difference, announced the strength of tourism urbanization response in Shandong Province. There was a remarkable spatial differentiation phenomenon in the strength of tourism urbanization response of Shandong Province, which the certain gaps between the western and the mid-eastern region existed. For instance, positive increase of deviation （Di）and response coefficient ratio (Gi ) values were observed in middle cities such as Tai’an and Zibo and eastern cities such as Weihai and Linyi, whereas negative growth of deviation and ratio were observed in western cities such as Liaocheng and Heze. The certain differences on coefficient increase amplitude of tourism response in Shandong province can be proved by its gradual positive increase in 11 cities including Zibo, Tai’an, Linyi, Jining, Jinan, Weihai etc. And its negative increase in 5 cities including Liaocheng, Heze, Rizhao etc. According to the combination of time series variation and spatial differentiation, the tourism urbanization response strength of 17 cities in Shandong Province can be divided into 4 categories as strong, relatively strong, weak and special response regions. To maintaining an advantage in competition, the strong response regions including Rizhao, Tai’an and Weihai should support tourism infrastructure construction and coordinate the development of urban-rural area under the guidance of government, as to provide the support for tourism development. Targeted at the strong response regions and based on location and resources superiority, the relative strong response regions including Weifang, Yantai, Qingdao, Jinan and Laiwu should optimize the spatial industrial structure and raise the level of urban general planning to promote coordinated development between tourism and city. The weak response regions including Heze, Liaocheng, Dezhou, Binzhou and Dongying should maintain close ties with the strong response regions to promote own economic development, powering the tourism urbanization. As for the special response regions such as Zaozhuang, Jining, Linyi and Zibo, sustainable exploitation of special resources should be emphasized to promote the tourism industry transformation and upgrade.
As it is closely related to the construction of new countryside and building a moderately prosperous society in China, the improvement of rural households’ livelihood and well-being status in ecological fragile area are of great research significance. Based on the sustainable livelihood framework and the application of statistical analysis and in-depth interviews, we divide the 293 households in the case village into three categories including pastoral households (sheep household, cattle household, cattle and sheep household, horse household), farm households, and off-farm households. In accordance with the total amount of livelihood assets, they are ranked into three levels: high, medium, and low. And then, the dependence relationship between livelihood assets and strategies of the rural households in different grades and types were analyzed. The results show that there are significant differences in mean value of livelihood assets, in which the pastoral household is highest for the value of 0.37. The livelihood assets of farm households and off-farm households are 0.25 and 0.21, respectively. Among them, the mean value of the assets of pastoral household is the highest in the aspects of labor, pasture, livestock, cash and loans. The mean value of farm machinery and cultivated land assets is the highest, while that of cash assets is the lowest of farm households. The off-farm households are with the highest social assets. It can be seen from the results that rural households in farming-pastoral area are still taking the dry farming and animal husbandry as the main livelihood. However, the agricultural and animal husbandry production faces a great pressure from the resources and environment. The off-farm households only occupies 15.3% of the total households, facing problems such as insufficient employment opportunities, lack of personal skills, language barrier and conflicts between farming time and employment time. Finally, the study puts forward the counter measures and suggestions to improve the income and livelihood of the rural households.
Shanxi Province has rich intangible culture in China. Intangible culture is not only historical accumulation, but also energetic culture, Shanxi Province intangible culture tourism is one of the essential parts in tourism development and pillar industry. Tourism industry of Shanxi Province has been changed from initial sightseeing tourism to leisure tourism. A conclusion is drawn by choosing Shanxi Province as a case study from the perspective s of type, spatial distribution, industrial gathering, urban spatial distribution characteristics, tourism response and temporal distribution characteristics: 1) Differentiation is obvious in the types of Shanxi intangible culture heritage. It covers maximum amount of traditional skills on the national level, provincial level of intangible culture heritage programs. Folk custom, traditional dancing, folklore literature has an advantage to upgrade from provincial level to national level as reserve resources. Dagu—Chinese ballad with drum accompaniment and story-telling, mainly in song, with musical accompaniment are both Chinese folk art forms, which are needed to be protected and developed. So does intangible culture heritage program of traditional medicine (including traditional Chinese medicine acupuncture and traditional Chinese medicine preparation). 2) Gathering distribution characteristics are national level distributed in Shanxi Province. Polar nuclei, highly dense , sub dense areas and zonal region are distributed at present. Even state is shown in the distribution of provincial level. 3) Intangible culture heritage is distributed in 11 districts and cities of Shanxi Province, but unbalanced distribution in types and numbers, it presents uneven spatial gathering distribution. 4) Temporal spatial pattern is presented different. The first and second groups of intangible culture heritage are mainly folklore literature, hand-made skills, traditional operas, and traditional arts. They are distributed in Linfen city and Yuncheng city, which are rich in culture. The third and fourth groups of intangible culture heritage are mainly traditional songs and dancing, Chinese traditional medicine, folk customs, which are distributed enlarge and varied. Rich heritage resources has more A-level tourist spots and on the high level; Poor heritage resources has less A-level tourist spots and on the low level. Significant positive correlation is shown in the intangible culture heritage and development of tourism in Shanxi Province.
The accurate green water simulation is very important for the crop growth, agricultural drought monitoring, food security and rational allocation of water resources. Now, there are three methods which can be used to get greenwater: field observation, remote sensing calculation and hydrological model simulation. The field observation can not get the accurate simulation result of catchment green water at large scale because of complicated spatial heterogeneity; the remote sensing calculation method can only get the instantaneous simulation result at a large scale region. Compared to the two methods above, the hydrological model can get the continuous green water simulation results in large scale catchment. But, because hydrological models have different structures and characteristics, different simulation results can be got when inputting the same simulation data in the same region. In order to comprehensively utilize the simulation results of different hydrological models, the data assimilation method is a good choice. In this study, the Distributed Time Variant Gain Model(DTVGM) and Distributed Evapotranspiration Process Model(DEPM) were used to simulate the hydrological process in the catchment controlled by the Yan’an station in the Yanhe River Basin based on their structures and characteristics, and the Extended Kalman Filter(EKF) data assimilation algorithm was used to assimilate the green water (actual evapotranspiration) simulated by the two models to optimize the green water in the study area. The statistical indexes show that the simulation result of DTVGM is applicable to simulate the hydrological processes in this study area, the Nash-Sutcliffe coefficient(NSCE) is 0.83 and the relative water balance is -1.97% in the whole simulation period. The water balance relative index of DEPM is -1.81% in the whole simulation period, which shows that DEPM can model the water balance well at the study area.Besides, the simulation results show that the green water in 2010 simulated by the two models is 378.52 mm and 375.55 mm, respectively. There are not obvious difference for the mean simulation results of two models and the spatial distribution pattern are also similar, but there is more spatial variable information for result simulated by DEPM model than that of DTVGM. Compared to the observed green water, the NSCE of green water simulated by DTVGM and DEPM is respectively 0.76 and 0.59, but the spatial distribution of green water simulated by DEPM has more change information. Then, the green water simulation result of DEPM was used as “observed value” to assimilate the green water simulated by DTVGM based on the EKF data assimilation method in order to optimize the green water simulation result.The average green water simulated by DTVGM after data assimilation is 376.42 mm and the NSCE is 0.78 when comparing to the observed green water. The Standard Deviation(SD) for the green water simulation becomes 40.37 mm after assimilation, which is significantly increased by 7.79 mm than the original modeling results. The green water in spatial distribution shows more spatial change information and is more reasonable in this study area.
The water line is the demarcation line between land and sea areas. It is important interaction zone for global ecosystem conservation. As a result, it is vital that the rapid, accurate, real-time extraction of water line. Remote sensing solutions using Synthetic Aperture Radar (SAR) are playing an increasingly important role in monitoring water line and have getted much more attention from scholars and related department around the world. The sensor has two types: satellite SAR and airborne SAR. Satellite SAR has many advantages, for instance wide range observation, timely data available and all weather operation. As a result, it is a most suitable sensor for monitoring water line in marine environments. At present, the commonly used satellite SAR sensors for this purpose including Seasat SAR, Jers-1 SAR, Sentinel-1 SAR, and so on. In the SAR images, water line usually shows the edge characteristic, so the edge detection based algorithms are the most commonly used in coastline extraction. The classical edge detection operators including Canny operator, Sobel operator, Roberts operator, Prewitt operator and Laplacian operator, and so on. The operators have some advantages such as simple, fast speed, but they always effected by speckle noise inherent in SAR images, as a result, they can not obtain accurate water line results. So noise is a major issue for the task of boundary detection by the SAR images. Instead of combating the noise, we use a technique for boundary detection in SAR images based on the statistical properties of speckled data. The G0 distribution is a special form of G model, its parameters are very sensitive to the surface roughness and succeeds in characterizing a wide range of areas as sea, mountain chain and urban areas in speckled images. And the parameters required for boundary detection is extracted with moment estimation. Moreover, relative to G distribution, G0 distribution does not include the complex Bessel function, and is a kind of simple statistical distribution model with less parameter. According to the estimated parameters of G0 distribution, the marine and land areas can accurately be separated. In order to extract the water linefrom SAR image, a G0 distribution based algorithm is proposed in the article. First, the domain of SAR image is divided into a set of sub-blocks with the same size, and the grayscales of pixels in each sub-block are assumed to be identical and independent G0 distribution. The roughness of each sub-block and scatter shot parameters of the distribution are obtained with moment estimation. By thresholding the roughness parameter, the rough sea area can be divided, and then its geometric center is determined. On the rays started at the geometrical center, the cut-off points between sea and land are located with likelihood function. Consequently, the water line is formed by linking all the cut-off points. To prove its feasibility, a process of water line extraction has been tested with simulated and real SAR images by the method. Qualitative and quantitative results show that the proposed method can extract water line from SAR image effectively and efficiently.
