The ocean is an important strategic resource in coastal countries and regions. The coastal area has the largest population, the biggest population density, and is the most developed area in China as in other coastal countries. Bohai Sea Ring Area and the Changjiang River Delta, Zhujiang River Delta are the three economic growth poles in China coastal area. With the great growth of economy and society, the contradiction between supply and demand of land resources has become increasingly prominent, marine resources have been predatory exploited, marine environment has been seriously polluted. Carrying capacity is an important study on coordinating development of resources, environment, and economy. Marine carrying capacity is generally be defined as the capacity or limit of the harmonious development of population, environment, and socio-economic that the ocean can carry in a certain period without damaging the sustainable development of marine resource and environment, and ensuring a certain living standard. Marine carrying capacity assessment is of great significance for the sustainable exploitation of marine resources, the environment protection and the coordinated development of regional economy and society in coastal areas. In this context, evaluation on carrying capacity of Bohai Sea Ring Area is of great significance to the sustainable development of the Bohai Sea economic circle. Since marine resources system has mobility, renewability and other characteristics, marine carrying capacity has openness, dynamics and complexity, it is difficult to accurately quantify the population, environment and socio-economic development or limits that marine carrying capacity can support. But by constructing indicator system, we can measure the dynamic change trend and relative marine carrying capacity then guide the development of marine economic activities. The fuzzy comprehensive evaluation method is based on the fuzzy mathematics principle, to analyze and evaluate the situation of the membership level of things to be judged from multiple factors. Marine carrying capacity assessment is a comprehensive evaluation issue which related to multiple factors, and there are a lot of uncertain, fuzzy factors, so it can be evaluated by fuzzy comprehensive evaluation method. In view of the shortage of previous studies, this article applied Weber-Fischna law to determine classification standards of assessment indexes, and used D-S evidential theory to combine the subjective factor weights and objective weights, in order to make integrated weight more reliable and accurate. Information diffusion technique was used to determine the information distribution of small sample indexes value on the domain, and then determine the degree of membership. Finally used the fuzzy comprehensive evaluation method to assess marine carrying capacity in the Bohai Sea Ring Area, and used Natural Breaks to express the spatial distribution. The results show that although the marine carrying capacity from 2000 to 2011 of 17 coastal cities in the Bohai Sea Ring Area had fluctuations but it had an upward trend on the whole and continuously improve. But level characteristics values are all between 1.8 and 4, which means marine carrying capacity are not high. There is an obvious regional spatial difference and peak effect in marine carrying capacity.
The paper, using spatial econometric model to study the provinces TFP in China from 1990 to 2011, found, that from the aspects of global and local spatial autocorrelation, China’s provincial TFP represents spatial autocorrelation in most years, and that the provincial TFP is not completely in a random state but affected by other regions in the last 22 years. Using a spatial econometric model, the article further discusses factors influencing the regional TFP from space dimension. From the research, we draw the following conclusions: the higher the economic agglomeration level is, the more significant improvement TFP will achieve. Human capital not only plays a remarkably positive role in the increase of economy and efficiency, but also exhibits a certain degree of overflow. Moreover, human capital can promote domestic technological innovation, which contributes to productivity growth. Governmental intervention and industrial structure has a negative impact on TFP, indicating the government should reduce intervention in economic activities; It also means that something unreasonable may exist in China’s industrial structure. Therefore, the government needs to continue to transfer economic growth mode, adjust the industrial structure, and develop modern services. The effects posed by the informational level and infrastructure level on TFP are positive. And increasing information level can reduce the cost of enterprise information, promote exchanges and cooperation between enterprises, and thus improve the efficiency of the economy. It should be noted that the effects of infrastructure level on TFP is not statistically significant, which may be related to the selected indicator, for only one indictor can not reflect the condition of the infrastructure completely and accurately. The rise in the proportion of privatization has a number of significant improvements over TFP. Privatization allows decentralization of power in enterprises which helps improve technical efficiency. The level of open economy has largely increased China's regional TFP. Because economic exchanges can introduce some advanced foreign management experience, which will be conductive to improving inter-regional competition and efficiency. The study also found that the investment scale of land in some provinces of China is too large, which causes diseconomy of scale. Altogether, the research finds the evidence that TFP has spillover effect in different regions. Therefore, during the development of regional economy, local governments should not only consider actual conditions of development of local economy, but also break the boundaries of administrative region economy, which will help achieve cross-regional coordination and cooperation, create a win-win situation, and ultimately improve TFP in all regions.
As a sustainable development strategy that advocates higher urban efficiency, compact urban is of great importance to China cities when it faces a great deal of problems at the stage of fast growing, such as the sprawl of construction land, the short supply of housing residents in urban and incompatible relationship between urban and rural area. To interpret the spatio-temporal characteristics of China cities, the comprehensive evaluation index system is built up based on six dimensions, which are land-use compactness, economic compactness, population compactness, infrastructure compactness, public service compactness and eco-environment coordination. Entropy method was used to calculate the weights of each evaluation index, which the weights of eco-environment coordination and economic compactness are higher than other index. And then we calculate the urban compactness of 280 cities at the prefecture level and above in 2001, 2005 and 2009 based on those weights. The result show that urban compactness elevates slightly overall, and the disparities between cities decreases gradually, which the high scores of urban compactness grow small and the low score of that promote slightly. As to the spatial pattern of urban compactness, the eastern part ranks highest, and follows by the central part and western part of China, which implies the score of urban compactness is relative higher in east and relative lower in west, and that spatial pattern is similar to the spatial pattern of regional economic development. While, referring to the evolvement of urban compactness, the score of the east decreases gradually, and that of central and western part of China elevates step by step. And it is obvious to notice the spatial heterogeneity of urban compactness, the high and low compact cities cluster in different regions. The low value mainly agglomerates in northeastern, central and western China, while the high value mainly locates in eastern China where are Beijing-Tianjin-Hebei area, Changjiang River Delta and Zhujiang River Delta to be more exact. Moreover, that proportion of hierarchies grows even larger with the evolvement, which shows an even more eminent spindle-sized pattern. As to the scale-size characteristics of urban compactness, the megacities have the highest value of compactness that is higher than super cities, large cities and middle-sized cities, and the value of small cities ranks last. It seems to be a strong correlation between urban compactness and urban size, then correlation analysis was used to investigate the result which shows the correlation coefficient between urban compactness and municipal population is below 0.5, which implies a weak correlation.
Based on the individual-level event-history data from a random sampling questionnaire survey of 2 977 migrants in Fujian Provinces in 2009, this article examines patterns of the floating population′s spatial distribution, their choices of the spatial types of their destinations, and factors determining such choices, in their first-time migration, from a gender perspective, and using the multinomial logistic regression model. The results show that patterns of the floating population′s spatial distribution and their choices of the spatial types of their destinations in their first-time migration exhibit strong tendency of spatial clustering, and are rather close to the average spatial patterns and choices of member of the floating population at different migration stages, which have been revealed by existing studies based on aggregate migration data. In fact, such patterns and choices establish the basis for the spatial distribution and destination choices of the floating population at their later migration stages. However, the results also demonstrate that not all members of the floating population will experience a one-step migration process, and that some of them will move to other destinations, or return to the places of origin, leading to the fact that the floating population′s spatial distribution and choices of the spatial types of their destinations at later migration stages are often at variance with those in their first-time migration. The results further suggest that the floating population′s choices of the spatial types of their destinations in their first-time migration are not only the combined effects of their human capital selection mechanism and their family decisions, but also affected by other factors, including the floating population′s social networks, their community environment, and the general institutional context. It is particularly noteworthy that the characteristics of sending areas and families, and the status of the floating population′s families in the communities, which are often neglected in the existing migration research, stand out in the floating population′s choices of the spatial types of their destinations in their first-time migration. Compared to male members of the floating population, there is a stronger tendency for spatial clustering of female members of the floating population in their first-time migration, who are also more likely to reach the current destinations by a one-step process. While equally affected by human capital selection mechanism, social networks, and community environment, as with their male counterparts, the choices of the spatial types of destinations for female members of the floating population are more constrained by family- and institutional-related factors.
Urban vulnerability refers to the ability of resisting internal and external interference from natural and human factors including resource, ecological environment, economy, social development etc. in the city evolution process. When the resistance to the adverse disturbances is lower than a certain threshold value, city will enter vulnerable state. Urban vulnerability generally includes resource vulnerability, eco-environment vulnerability, economic vulnerability and social vulnerability, and it is the comprehensive embodiment of the four kinds of vulnerability. Daqing is a typical resource-based city with obvious vulnerability characters. The articleused the method of system analysis and composite-index assessment to study the dynamic evolution characteristics of each subsystem’s vulnerability and the urban comprehensive vulnerability. The result showed that: 1) in 1990-2012, the resource vulnerability of Daqing presented an increasing tendency, while the vulnerability of other three subsystems contain eco-environment, economic vulnerability, social vulnerability showed a declining trend. This mainly because Daqing is a resource-based city whose leading industry is oil development and machining; 2) in 1990-2012, the urban comprehensive vulnerability of Daqing experienced three different stage, in sequence of ‘rapid decrease-wavelike decrease-accelerated decrease’. At present, Daqing is in the transition station from mid-vulnerability to lower-vulnerability; 3) The urban vulnerability of Daqing has already changed from economy-leading vulnerability to resource-dominated vulnerability and Daqing is in the important stage of city development. In future, we should pay more attention to the vulnerability of resource-based cities, summarize the mechanism and law of urban vulnerability, and provide scientific basis for the transition and sustainable development of the city.
The spatial land use changes of coastal economic zone are closely associated with the future sustainable development of the regional industries. The research chose Dalian new urban as study area due to its typical characters of coastal economic zone with highly accumulated port industries. Using TM remote sensing images and DEM spatial data over a two-decade period, the logistic regression models on the construction land changes were built with 2 000 random samples. The models were aimed to analyze the spatial variables embodied in the evolution process with focus on the composition of driving factors and involvement levels, effects and impacts of each remarkable factor. In order to reflect the spatial change mechanism comprehensively, not only natural but also social-economic, especially industrial factors were all imported into the independent variable index in the models. By extracting urban spatial changes, it was found that the construction land in Dalian new urban has expanded by nearly 30 times in 20 years. To explain such huge land changes, the regression results show that the significant variables in coastal economic zone not only contain the distance to CBD, to nearest district, villages and towns, as the finding in similar urban sprawl regressions, but also include the distance to nearest main ports, coastal lines and port industry zones with strong specific coastal attributes. The variables both on urban spatial distribution and on coastal related conditions are thus confirmed as driving factors of land use spatial changes in this coastal economic zone. The driving factors are all playing critical roles in shaping urban patterns jointly. Through the comparison between the regression models in the period of 1990-2000 and 2000-2010, it can as well known the categories and impacts of the proposed explanatory variables in different stages varied. In the first period, as a newly developing stage, the urban spatial growth was mainly promoted by inward space filling with the distance to district, villages and towns and the ports as the most important significant factors, representing obvious spatial attraction. While in the second period, the spatial pattern was formed by outward sprawl with an addition of the coastal elements (distance to ports, port industry zones and coastal lines, etc.) as determining factors. Along with the rapid development of port industries, the spatial effects of port and port industries were increasing. These findings suggest a future trend of construction land expansion in the area adjacent to port, port industry accumulation zones in the circumstances of coastal economic flourishing, and therefore in need of paying more attention on how coastal related natural, social and industrial factors change during urban planning. The regression models in the study passed through the Logistic tests and the received verification findings confirmed the effectiveness of the designed research methods. It is considered the driving factor analysis based on Logistic regression can deepen the understanding in land use changes of coastal economic zone and provide decision-making support for coastal urban planning and spatial forecasting as well. The methodology can be applied to researches of a similar nature.
Taking the Huainan City as a case, the article, combined all previous status information of the urban planning land and industrial development data, using the GIS technology platform, has researched the urban spatial form of Huainan City with the method of comparative study of superposition in different inspection points, measures the compact degree index, expansion speed and expansion intensity index of the urban spatial expansion form in different periods, and inspects the evolution process and features of the urban spatial form in Huainan City from the aspects of time and space. The result indicates that the urban spatial extension of Huainan City, as a coal city, demonstrates significant spatial orientation and structure characteristics of layers, with 7 stages including scatter development, node cluster expansion, enclaves expanding, axial extension, interior filling, integration and optimization, and location reengineering. In the process of spatial expansion, under the control of the coal resource, the drive of the coal industry and the expansion of the coal enterprise, the development of urban space experiences a changing process from compact to decentralized form and then back again under the influence of gradual filling and optimization adjustment. In different periods, West, North, East, South of the city became the main directions of urban spatial expansion in turn. From the macro level, the urban spatial structure, which has free space, presents binary spatial structure—"urban-industrial areas". Instead, it is the dissimilated band structure. Along the main traffic arteries, there are residential areas, commercial areas, office area on both sides and the factory sector outward side. From the micro level, residential areas are around the coal enterprise center layout. The urban spatial structure presents ternary structure, including management area, office-residential area and coal mining area. In addition, the expanded speed and strength of urban spatial is greater different in different historical periods. Before the mid 1980s, it expanded slowly. From the mid 1980s to the mid 1990s, it kept medium speed. Since the mid 1990s, it expanded rapidly. And the urban spatial expansion of three main directions (North, West, and South) is faster than the East. The analysis concludes that, the dominant factors of urban spatial expansion are different at different stages of evolution of Huainan City. At the formative period, resource and the occurrence of the city commuting are the dominant factors led the urban spatial form change. At the growing period, the long-term national energy strategies and transportation drives the growth of the city. At the mature period, the industrial structure succession is the dominant factor. At the transition period, it is led by the interaction of the space economy and planning regulation.
To face the aviation market liberalization all over the world, Chinese government and airlines have prompted a series of strategies from the 1990s. Hainan Airline as one of the four biggest airlines in China, has reconstructed some small airlines from 1993, which largely reflects the interactions of national strategies and market patterns. Till to 2004, Hainan Airline has recombined Chang'an Airline, Xinhua Airline, Shaanxi Airline, and all these four airlines adopted “HU” as their flight signal and were called “four recombined airlines of Hainan”, which stands for the completing of the first stage of airlines recombined. In 2004-2012, Hainan Airline has restructured Tianjin Airline, Western Airline, Changjiang River Express Airlines and so on. Until 2012, Hainan Airline has owned 111 domestic nodes and 415 domestic airlines, compared to these in 2004, the nodes increased 33 and the airlines increased 97. The restructure of airlines leads to the expansion of Hainan airlines, while how these influence the structure of Hainan airline network is not clear. Therefore, this article will analyze the impacts of its reconstruction, acquisition and expansion on the aviation network structure and aviation hub of Hainan Airline for nearly 10 years. To have a clear understanding of the reconstruction pattern, the article studies the changes of the distribution of aircraft network and the flights they own. Through this study, we get several conclusions: Hainan Airline expends its network to north significantly, and the average flight distance has a downward trend; flights are concentrated in a few navigable cities and routes, but the gathering trend decline; the network presents two special patterns, which are “hub-spoke” and “point to point” patterns, while the aviation hubs changes from Beijing, Xi'an, Haikou to Beijing, Xi'an; the first contact of the network decreased significantly, which reflects the network tends to be balance.
Health care is an important part of the public service. Scholars from human geography, medicine, public health, sociology and other fields pay wide attention to its accessibility studies. A variety of methods have been emplyed to measure health care accessibility, including the distance or time to the nearest medical facility, the ratio of supply to demand in a certain radius, the gravity model, the kernel density method, and two-step floating catchment method to measure the relationship between supply and demand in a region. Among the different methods mentioned above, the attractiveness of the facilities is one of its core elements, which is mainly related to the amount and scope of services. The impact factors are mainly related to hospital size, rank, service population, traffic accessibility and so on. The reasonableness of these assumptions mentioned above directly affects the reliability of the results, and it is important to test these hypotheses. Current testing methods and data acquisition are limited, which make such kind of researches exile. GPS data of floating car provide a solution to the problem. This article test the indicators commonly used in medical facilities’ accessibility by introducing GPS floating car data. The indicators include endpoint characteristics such as hospital rank, size, whether or not covered by medicare, characteristics of service endpoint such as population in service areas, and environmental factors such as the number of other medical facilities, population and road accessibility, etc. Results showed that hospital size and population within 1.5 km have positive effects on the amount of attraction of the hospital. Other indicators commonly used in the accessibility models, such as hospital rank, whether or not covered by medicare, population and high-need population in the main service radius, road accessibility and population in the surrounding area, and the number of competitors are not significant in this article. Population within 1.5km has negative effects on the main service radius. Other indicators have no significant effect in the test of this paper. Data in this paper is mainly from the GPS data of floating car. Other transportations like walking and public transit and so on are not studied in this paper. The test of the indicator is mainly the reflection of the floating car mode. Despite the limitations, the method and main conclusion of this paper which depend on mass data of GPS have positive significance on deepening the research on accessibility.
While the issue of cultural identity is highlighted under the circumstance of globalization and modernization, there is still lacking particular research on sports events'impacts on cultural identity. Thus more attention should be paid to the socio-cultural impacts in order to utilize more fully of the positive impacts of sports events. 2010 Asia Games opening ceremony in Guangzhou is not only part of the sports event, but also an independent cultural event. The article, through participant observation and interview, described the Lingnan Culture in Guangzhou Asian Games opening ceremony and interpreted the cultural symbols in it. The relationship between the ceremony and the culture of the host city was discussed by analyzing the attitude of local residents to the event with local cultural characteristics. Possible changing tendency of cultural identity in the context of the opening ceremony was also discussed. By expounding event as a liminal phase, event as cultural performance, event as a connection of traditional and modernity, event as a booster of local awareness, how the cultural identity would be was revealed in the context of events that represented by the Asian Games opening ceremony in this article. It indicates that: 1) the relationship between events and cultural identity is reflected on the different levels of cultural identity. Ontological identity is showed in the emotions that aroused by events. Events also offer a way to learn about the cultural symbols and different cultures integrate with the stimulation of events; 2) the participation of local people plays an important role in the proceeding of culture identity affected by the event. The stimulations generated by the event can be lasting and finally affects cultural identity only when the people turn the provisory emotion into a more positively thought and cognition. Meanwhile, we also need to identify how events influent cultural identity on a long time scale and attention also should be paid to the post-event development of the culture.
Urban growth model was the simplification of the urban area, which was expected to present and simulate the dynamic processes of urbanization through the mathematical methods, and provide a very useful analysis tool to understand and capture the characteristics of urban growth. The Logistic-CA model was widely used in the existing researches of the urban growth simulation, while it was difficulty to reflect the nonlinear and dynamic characteristics of the urban growth for its static coefficients. To deal with this deficiency, a variable-coefficient urban growth model was developed through the error feedback control in this artcle. Firstly, four pixel types were generated according to the comparison between the simulation result and real situation, which includes the Omission Error (OE) pixels, Commission Error (CE) pixels, Urban Correct (UC) pixels and Non-urban Correct (NUC) pixels, then the simulation error was mapped into the urban growth model to modify the coefficients through the linear programming method. Finally, the variable-coefficient urban growth model was built based on the error feedback control. To validate the effect of the variable-coefficient model, both the Logistic-CA and variable-coefficient model were used to simulate the urban growth process of Beijing City from the year of 1997 to 2009. The results showed that the accuracies of Logistic-CA model in 2001, 2005 and 2009 were 73.842%, 64.704% and 63.953%, respectively, while these values of the variable-coefficient urban growth model were 75.624%, 66.537% and 69.142%, which were 1.782%, 1.833% and 5.189% greater than the former. It can be demonstrated that the variable-coefficient model could present the real situation of urban growth and obtain a better simulate results. The results of this article had a high theoretical and practical significance, for it could provide a new method and view to guide the research of urban growth simulation, but also provide an ancillary evidence for the urban planning and decision.
This article realizes the classification of urban system structure and the division of economic zone in Horqin by improving the breaking point model based on spatial interaction model and GIS platform. First of all, it introduces a model improving method which replaces the urban population with the centrality strength and combines the weighted Voronoi Diagram. Then it builds and completes the centrality strength computing index system by introducing the concepts of weighted average distance friction index of towns and cost weighted distance, etc. The urban system structure has been classified into central towns, secondary central towns and common towns. Finally, by comparing two space division solutions of regular Voronoi diagram and weighted Voronoi Diagram, it can be found that the latter has been determined to be the final solution of urban influenced regions. By merging and searching the sub-regions step by step, this article divides the study area into three economic zones—east economic zone, middle economic zone and west economic zone. The results reflect the current situation and the tendency of development of urban system and provide theoretical basis for the sustainable development of urban system in Horqin Left Middle Banner.
Migration flow caused by migrant workers′ employment outside their hometown has an increasingly important impact on the overall socio-economic development. Analyzing the law of migrant workers′migrant location choice from a geographic perspective is the base of understanding the principles of this migration flow. By the analysis on relevant literature home and abroad, we find that there are less direct researches on employment location of migrant workers and the theoretical construct is weak. There is more indirectly related literature, but most of them come from sociology, economics and management science, etc. At present, the researches in China focus on the choice mechanism of employment location, the law of work distance distribution, the selection of location type on city and town and the influencing factors of employment place choice, etc. On the employment location selection mechanism, the migrant workers′ cluster, the infection model, the four-process decision-making mechanism of spatial behavior and the social capital theory offer a reasonable explanation. On the distribution of work distance, the “U” type distribution effect, the proximity effect, the job opportunity effect and the income maximization effect provide a better explanation. The principle of selecting high-grade urban areas and income effect sheds light on the selection of employment location type. The rural community factors, personal factors, family factors, distance factors, destination factors, etc., constitute the major factors influencing the employment location selection. The foreign indirect researches are concentrate on the field of permanent migration, such as immigration location, immigrant spatial structure, etc. However, researches on choice location of non-permanent migration are rather few. The theory of permanent migration is subject to certain restrictions when it is used to temporary migration due to the fact that they differ in migration time, migration purposes, migration motivation, etc. The important position of China′s migrant workers makes the issue a key research field of scholars today and for a long time. In future, geography researchers should strengthen the research in the field of migrant workers′ employment location, summarizing its general laws on the basis of case studies in different regions. As for research methods, the model analysis and quantitative analysis should be strengthened to reveal the characteristics and laws of the employment location of migrant workers more precisely. This also requires relevant government departments strengthening the statistical work on migrant workers.
Based on a large number of research data on the environmental change events at 0.8 Ma B.P. and the 0.8 Ma B.P. terraces, this paper, which takes the Lanzhou Basin as an example, discusses the internal relationship between the 0.8 Ma B.P. terraces and the events of environmental change at 0.8 Ma B.P.. In the Lanzhou Basin, there are two river terraces, namely the Zaoshugou terrace and the Wuyishan terrace, which are selected respectively as the study terraces. For the Zaoshugou terrace, the altitude of gravel stratum is 80 m higher than the river level. The top of the gravel stratum is covered by at least 64 m eolian loess, and the paleosol S8 is at the bottom of the eolian loess. While for the Wuyishan terrace, the altitude of gravel stratum is 140 m higher than the river level. The top of the gravel stratum is overlain by about 100 m eolian loess, and the paleosol S8 is also at the bottom of the eolian loess. Through the paleomagnetic dating and loess-paleosol sequence matching, it is discovered that these two terraces have the same age, and both were developed at about 0.865 Ma B.P.. According to the analysis of sedimentary characteristics and the correlative literature of tectonic movement, these two terraces show significant attribute of the tectonic movement genesis. At the same time, they also have similar lithology that there is a paleosol developed on the top of fluvial silt. It shows that the Yellow River downcut during the transition from glacial to interglacial. Therefore, the 0.8 Ma B.P. terraces in the Lanzhou Basin were formed under the combination of tectonic movement and climate change. The main results show that: 1) With group-occurring and global characteristics, the environment change events at 0.8 Ma B.P. are mainly manifested in the climate transition, tectonic movement, loess expansion, biological evolution, astronomy meteorite and so on; 2) the Zaoshugou terrace and the Wuyishan terrace were formed at about 0.865 Ma B.P., which were developed under the combination of tectonic movement and climate change; 3) The universal existence of the 0.8 Ma B.P.P terraces in the Lanzhou Basin and other regions verifies that there was a large-scale river down cutting event which resulted in the formation of 0.8 Ma B.P. terraces; 4) The environment change events at 0.8 Ma B.P. are the direct cause of development of the 0.8 Ma B.P. terraces. The intensive tectonic movement provides the driving force for the development of river terraces, and the dramatic climate transition controls the time of river incision. Therefore, the 0.8 Ma B.P. terraces are the geomorphic response to the 0.8 Ma B.P. events of environment change.
Huangpu River Basin has experienced rapid urbanization since “reform and opening up”. Increasing human activities greatly changed the natural environment and flood risk characteristics in this area. This article presented a scenario-based study that investigated the flood dynamic risk in Huangpu River floodplain during the transitional period (1979-2009). A 1D/2D coupled flood inundation model (Flood Map) was firstly used to simulate the designed flood scenarios with 5 a, 50 a and 500 a return periods in 1979, 1990, 2000 and 2009. The flow hydrographs at the boundary gauging stations (i.e. upstream Mishidu and downstream Wusong) were derived using a simplified algebraic subtraction of the water levels with different return period which have been calculated in our previous studies and the maximum water level during the 9711 flood event where hourly stage hydrograph was available. The flood processes are only represented with 24 h stage hydrographs, including two rising and falling phases. 175 rectangular cross-sections were used as the 1D river channel model. The DEMs of 1979, 1990, 2000 and 2009 were generated based upon the 2005 DEM and land subsidence data of 1980-2009 for the study area. Roughness parameters of river channel and floodplain were represented by varying manning's. These provided the boundary conditions and the calibrated parameters for the model simulations. Furthermore, land use maps of the study area in various time points were used for vulnerability analysis and then they were categorized into four classes. On the basis of some relevant national standards and expert judgments, a flood risk matrix, which comprehensively considerate the relationship between flood inundation and vulnerability, was constructed for the analysis of flood dynamic risk variation in Huangpu River Basin during the transitional period. The results shown that over the past 30 years, the flood dynamic risk of Huangpu River Basin slightly increased between 1979 and 1990 due to rapid urbanization and land subsidence in floodplain but significantly reduced afterwards particularly in city center because the floodwall system along Huangpu River has been largely extended and reinforced. As expected, the flood risk obviously increased with the increasing return periods. Spatially, the flood risk appeared in most of riparian regions in 1979 and then it was gradually restricted to mid- and upstream. Finally, uncertainties and limitations were analyzed and some suggestions were presented for future researches.
Straw-checkerboard barrier is a mainly mechanical method of controlling desert in the Qinghai Lake,according to the yearly monitoring of erosion and deposition, and sharp measure of concaves of six kinds of dimensions,it can be concluded that the dimension of 1.5 m×1.5 m is the most locally feasible one with the best comprehensive benefits both in ecological effects and economical cost. Basically, this norm is easy to form a balanced concave, and will change little in the erosive and cumulate depth afterwards. Whereas small dimensions with one meter space in east-west direction will cause serious sand-bury hazard which their accumulated intensity will surpass 15 grams per one square centimeter, and their accumulations last for the whole year and gradually become placid. Meanwhile, the big dimensions with 2 m space will be corroded severely in their centerand southerly parts, and the erosive intensity will reach to 10 grams per square centimeter and their sand-fixing effect just be confined to 60% . In the aspect of seasonal changes of different norm concaves, the small ones present a medium accumulation from autumn to early winter, then a serious sand deposition in late winter and spring, and a light accumulation in from summer to autumn. Unlikely, these trends may be converted to erosive states with different degrees, especially in the winter and spring. As to the medium norms, the balanced concaves will have formed before the coming of winter, and later on the concave will keep a relatively stable shapealternately in weak erosion and deposition.In detail, the northwest and southwest part of each checkerboard are mainly depositional positions with the most marked extent among the four seasons, the center part is controlled by omnibearing wind directions resulting to be a erosive part for some medium and large norms. Besides, an integrated protection index of each dimensional straw-checkerboard showed that the medium norms have the largest value about 0.65 which means the best comprehensive protective benefit, including the longest duration, superior sand-fixing and wind-preventing effects and moderate economic costs. While the small norms are greatly troubled by the expensive cost so that they are unworthy to select in fact, but the large ones may become the candidate norms relying on their economic cost and long protection terms, even though the ecological benefits are not the most obvious. Compared comprehensively, the 1.5 m×1.5 mnorm should be selected as the most suitable dimension for this areal sand barrier, and the other dimensions should follow the principle of adjusting to local conditions and performing their functions best in practical application.
Clouds are a visible manifestation of thermo-dynamic processes in the atmosphere. Clouds have a strong influence on climate as a component of water cycle and through radiation budget. Surface based observation of cloud amount is a valuable source of information for the interpretation of the surface radiation budget and for the validation of satellite based retrievals of cloud and radiation properties. The correlation between cosmic rays and low cloud amount (LCA) variations, which led to the introduction of a new scientific subject-‘cosmoclimatology’, was found more than 10 years ago. Although much evidence implying correlations between low cloud amount variations and solar activity, the physical phenomenon explaining this is still poorly pronounced. In this article, we try to analysis spatial and temporal distribution characteristics, annual trend, and seasonal change of cloudiness over the northwest of China. In addition, the correlations among low cloud amount and climate factors, cosmic rays, NOI index and sunspot were discussed, respectively. With trend analysis method, the spatial-temporal variation of low cloud amount is analyzed for 177 stations on the Northwest China during 1960-2005. Analysis of these data reveals that the annual low cloud amount is characterised by high year-to-year variability and shows a weak, statistically significant increase in 1960-2005. A more pronounced increase in 1997-2005 is evident. Analysis indicates that the annual low cloud amount decreases from the southeast to the northwest of the Northwest China. A strong positive correlation is found among low cloud amount and rainfall, annual average temperature, relative humidity and annual low temperature, while a strong negative correlation is found among low cloud amount and average wind speed, diurnal temperature range and Sunshine Duration. The low cloud amount of Jaunary is positive with the relative humidity. However, the low cloud amount of July is positive with the average low temperature, and is negative with average wind speed, diurnal temperature range and sunshine duration, respectively. The cross wavelet transform method is adopted to study the time-frequency characteristics and multitime scale correlations among low cloud amount, cosmic rays, NOI index and sunspot was discussed, respectively. Results show that there are significant periods at scales of 2-4 a, 6 a and 11 a in low cloud amount over Northwest China. There are significant syntonic periods of 5-8 a between low cloud amount and the cosmic rays in 1982-1993, while the multi-time scale correlations between the low cloud amount and NOI index are 2-4 a, 5 a and 11 a syntonic period in 1960-2005 within the 95% of the red noise test, respectively. The low cloud amount and the sunspot number has a significant a syntonic periods 9-11 a, also within the 95% of the red noise test. A strong correlation was found between low cloud amount and cosmic rays, NOI index and sunspot, while the strongest correlation was found between low cloud amount and NOI index.
