Evolution and Determinants of Population Agglomeration in Less Developed Metropolitan Areas:A Case Study of the Taiyuan Metropolitan Area,China

It is of importance to enhance the urban areas'capacity for population aggregation in underdeveloped regions,aiming to rectify the imbalanced and insufficient pattern of economic development in China.Taking the Taiyuan Metropolitan Area(TMA)in central China as a case study,this paper examines the evolutionary process and characteristics of population agglomeration from 2000 to 2020,and identifies factors associated with agglomeration and their spatial effects.The findings indicated that:1)against the background of sustained population shrinkage in the provincial area,the TMA showed a demographic trend of steady increase,albeit with a decelerated growth rate.In the metropolitan area,urban population size continued to grow rapidly,whereas the rural areas endured sustained losses.Disparities in city size continued to widen,and the polarization of concentrated population in the core cities kept increasing.2)Agglomerations in both secondary and service industries had significant positive effects on local population agglomeration,with the former effect being stronger.Regional economic development,government fiscal expenditure,and financial advancement all contributed to facilitating local population clustering.From a spatial spillover perspective,service agglomeration and financial development promoted population agglomeration in surrounding areas.Conversely,fiscal expenditure inhibited such agglomeration.As for industrial agglomeration and regional economic development,their spatial spillover effects were non-significant.The results obtained reveal several policy implications aimed at enhancing the population agglomeration capacity of the metropolitan area in underdeveloped regions during the new era.

Coordination Mechanism and Empirical Research on Marine Science Technology Innovation and Marine Eco-civilization:A Case Study of Coastal Areas of China

Marine science technology innovation provides power and guarantees for marine eco-civilization construction,which provides direction and material support for marine science technology innovation.Therefore,the coordinated development of the two is of great significance to the marine economy sustainable development in China’s coastal areas.On the basis of clarifying the connotations of marine science technology innovation and marine eco-civilization in China’s coastal areas from 2006 to 2019,the mechanism for their coordinated development was analysed.A comprehensive indicator system based on the connotation of the two was constructed,and the coordinated development relationship was empirically tested using the coupled coordination model and the panel vector autoregressive(PVAR)model.The results show that:1)the level of China’s coastal marine science technology innovation continues to improve,gradually forming the core of the development of marine science technology innovation in the north,east and south of Shandong,Shanghai and Guangdong;the level of marine eco-civilization development fluctuating upward trend,showing obvious spatial differentiation characteristics.2)The degree of coordination of marine science technology innovation and marine eco-civilization is growing over time.There is no causal relationship between marine science technology innovation and marine eco-civilization in the northern marine economic circle,but there is a two-way causal relationship between the two in the eastern and southern marine economic circles.3)Marine eco-civilization shows a significant positive and continuous impact on marine science technology innovation,and marine science technology innovation shows a long-term,continuous,fluctuating,and lagging impact on marine eco-civilization.The overall role of marine eco-civilization on marine science technology innovation is dominant,and there are significant differences in the impact effects of the two major marine economic circles.

Influence of lithospheric thickness distribution on oil and gas basins,China seas and adjacent areas

The distribution of oil and gas resources is intricately connected to the underlying structure of the lithosphere.Therefore,investigating the characteristics of lithospheric thickness and its correlation with oil and gas basins is highly important.This research utilizes recently enhanced geological–geophysical data,including topographic,geoid,rock layer thickness,variable rock layer density,and interface depth data.Employing the principles of lithospheric isostasy and heat conduction,we compute the laterally varying lithospheric thickness in the China seas and adjacent areas.From these results,two pivotal parameters for different types of oil and gas basins were statistically analyzed:the minimum lithospheric thickness and the relative fluctuation in lithospheric thickness.A semiquantitative analysis was used to explore the connection between these parameters and the hydrocarbon abundance within the oil and gas basins.This study unveils distinct variations in lithospheric thickness among basins,with oil and gas rich basins exhibiting a thicker lithosphere in the superimposed basins of central China and a thinner lithosphere in the rift basins of eastern China.Notably,the relative fluctuations in lithospheric thickness in basins demonstrate significant disparities:basins rich in oil and gas often exhibit greater thickness fluctuations.Additionally,in the offshore basins of China,a conspicuous negative linear correlation is observed between the minimum lithospheric thickness and the relative fluctuation in lithospheric thickness.This study posits that deep-seated thermal upwelling results in lithospheric undulations and extensional thinning in oil and gas basins.Concurrently,sustained deep-seated heat influences sedimentary materials in basins,creating favorable conditions for oil and gas generation.The insights derived from this study contribute to a quantitative understanding of the intricate relationships between deep lithospheric structures and oil and gas basins.These findings provide valuable guidance for future oil and gas exploration in the studied areas.

Integration of Multiple Spectral Data via a Logistic Regression Algorithm for Detection of Crop Residue Burned Areas:A Case Study of Songnen Plain,Northeast China

The burning of crop residues in fields is a significant global biomass burning activity which is a key element of the terrestrial carbon cycle,and an important source of atmospheric trace gasses and aerosols.Accurate estimation of cropland burned area is both crucial and challenging,especially for the small and fragmented burned scars in China.Here we developed an automated burned area mapping algorithm that was implemented using Sentinel-2 Multi Spectral Instrument(MSI)data and its effectiveness was tested taking Songnen Plain,Northeast China as a case using satellite image of 2020.We employed a logistic regression method for integrating multiple spectral data into a synthetic indicator,and compared the results with manually interpreted burned area reference maps and the Moderate-Resolution Imaging Spectroradiometer(MODIS)MCD64A1 burned area product.The overall accuracy of the single variable logistic regression was 77.38%to 86.90%and 73.47%to 97.14%for the 52TCQ and 51TYM cases,respectively.In comparison,the accuracy of the burned area map was improved to 87.14%and 98.33%for the 52TCQ and 51TYM cases,respectively by multiple variable logistic regression of Sentind-2 images.The balance of omission error and commission error was also improved.The integration of multiple spectral data combined with a logistic regression method proves to be effective for burned area detection,offering a highly automated process with an automatic threshold determination mechanism.This method exhibits excellent extensibility and flexibility taking the image tile as the operating unit.It is suitable for burned area detection at a regional scale and can also be implemented with other satellite data.

Evolution and Governance of the Structure of Marine Economic Networks in China’s Coastal Areas: Based on Sea-related A-share Listed Companies

Data on discrete,isolated attributes of the marine economy are often used in traditional marine economic research.However,as the focus of urban research shifts from internal static attributes to external dynamic linkages,the importance of marine economic net-work research is beginning to emerge.The construction of the marine economic network in China’s coastal areas is necessary to change the flow of land and sea resources and optimize regional marine economic development.Employing data from headquarters and branches of sea-related A-share listed enterprises to construct the marine economic network in China,we use social network analysis(SNA)to discuss the characteristics of its evolution as of 2010,2015,and 2020 and its governance.The following results were obtained.1)In terms of topological characteristics,the scale of the marine economic network in China’s coastal areas has accelerated and expan-ded,and the connections have become increasingly close;thus,this development has complex network characteristics.2)In terms of spatial structure,the intensity of the connection fluctuates and does not form stable development support;the group structure gradually becomes clear,but the overall pattern is fragmented;there are spatial differences in marine economic agglomeration radiation;the radi-ation effect of the eastern marine economic circle is obvious;and the polarization effect of northern and southern marine economic circles is significant.On this basis,we construct a framework for the governance of a marine economic network with the market,the government,and industry as the three governing bodies.By clarifying the driving factors and building objectives of marine economic network construction,this study aims to foster the high-quality development of China’s marine economy.

Human Carrying Capacity of Rangeland Resources in China′s Mountain Areas

Based on analysis of the development potential of rangeland resources in China＇s mountain areas, the paper makes analysis and forecast in human carrying capacity of rangeland resources. It provides some reference for drawing up the development strategy in mountain areas.

Do farmers care about climate change? Evidence from five major grain producing areas of China

Using a logistic model,this paper empirically investigated farmers’perception of climate change and its determinants based on a field survey of 1 350 rural households across five major grain producing provinces in China.The results show:i)There is an apparent difference in perception levels for long-term temperature and precipitation changes.Specifically,57.4%of farmers perceived the long-term temperature change correctly,but only 29.7%of farmers perceived the long-term precipitation change correctly;ii)The factors influencing the farmers’perceptions are almost completely different between precipitation and temperature,the former are mostly agriculture related,while latter are mostly non-agriculture related,except for farm size;and iii)Farmers are not expected to pay more attention to long-term precipitation changes over the crop growing seasons,because less than 30%of farmers can correctly perceive long-term precipitation change.Therefore,to improve the accuracy of farmers’perceptions of climate change,the government is recommended to:i)enhance education and training programs;ii)speed up land transfer and expand household land farm size;iii)develop farmer cooperative organizations;iv)invest more in agricultural infrastructure,specifically in major grain producing regions;and v)improve the agricultural environment and increase farming income.

Numerical Simulation of the Regional Ocean Circulation in the Coastal Areas of China

The regional ocean circulation in the coastal areas of China (including a part of the western PacificOcean, the South China Sea and the Bay of Bengal et al.) is simulated by using the improved Princeton University ocean circulation model (POM). Compared with the modeling results obtained by the large-scaleocean general circulation model (OGCM), the basic ocean circulation features simulated by the regionalocean circulation model al-e in good agreement with that simulated by OGCM and some detailed characteristics such as the regional ocean circulation, sea temperature, salinity and flee sea surface height have alsobeen obtained which are in good accord with the observations. These results indicate that the regional oceancirculation model has good capability to produce the legional ocean circulation characteristics and it can beused to develop coupled legional ocean-atmospheric model systems.

Rocky Land Desertification and its Driving Forces in the Karst Areas of Rural Guangxi,Southwest China

With a subtropical climate,Guangxi Zhuang Autonomous Region has a typical karst landscape.Rocky desertification has become a serious environmental issue due to its high vulnerability caused by the joint effect of natural settings and human activities,because of which its eco-environment has been deteriorated in recent years,and farmland has been disappearing sharply at the same time.This,in turn,has exacerbated the poverty level in the rural areas of the region.In this study,we monitored the spatial distribution of rocky land desertification and its temporal evolution using Landsat TM/ETM images of 1985,1995,2000 and 2005.We also analyzed the driving forces of the desertification and its expansion.Through constructing regression models by using all the relevant variables and considering the lagged effects as well as fixed effects,we quantified the exact role of different factors causing rocky land desertification in the study area with some new findings.The new findings in this study are greatly helpful for preserving,restoring and reconstructing the degraded mountain environment in Guangxi and other karst areas in Southwest China,and also for alleviating poverty in the rural areas in the future.

Study on Size Distributions of Airborne Particles by Aircraft Observation in Spring over Eastern Coastal Areas of China

The authors studied the size distributions of particles at an altitude of 2000 m by aircraft observation over eastern costal areas of China from Zhuhai, Guangdong to Dalian, Liaoning (0.47-30 μm, 57 channels, including number concentration distribution, surface area concentration distribution and mass concentration distribution). In these cities, the average daily concentrations of PM10 are very high. They are among the most heavily polluted cities in China. The main pollution sources are anthropogenic activities such as wood, coal and oil burning. The observed size distributions show a broad spectrum and unique multi-peak characteristics, indicating no significant impacts of individual sources from urban areas. These results are far different from the distribution type at ground level. It may reflect the comprehensive effect of the regional pollution characteristics. Monitoring results over big cities could to some extent reflect their pollution characteristics.

Agricultural Production Structure Optimization: A Case Study of Major Grain Producing Areas, China

A large number of mathematical models were developed for supporting agricultural production structure optimization decisions; however, few of them can address various uncertainties existing in many factors （e.g., eco-social benefit maximization, food security, employment stability and ecosystem balance）. In this study, an interval-probabilistic agricultural production structure optimization model （IPAPSOM） is formulated for tackling uncertainty presented as discrete intervals and/or probability distribution. The developed model improves upon the existing probabilistic programming and inexact optimization approaches. The IPAPSOM considers not only food security policy constraints, but also involves rural households’income increase and eco-environmental conversation, which can effectively reflect various interrelations among different aspects in an agricultural production structure optimization system. Moreover, it can also help examine the reliability of satisfying （or risk of violating） system constraints under uncertainty. The model is applied to a real case of long-term agricultural production structure optimization in Dancheng County, which is located in Henan Province of Central China as one of the major grain producing areas. Interval solutions associated with different risk levels of constraint violation are obtained. The results are useful for generating a range of decision alternatives under various system benefit conditions, and thus helping decision makers to identify the desired agricultural production structure optimization strategy under uncertainty.

Three Types of Spatial Function Zoning in Key Ecological Function Areas Based on Ecological and Economic Coordinated Development: A Case Study of Tacheng Basin, China

Three types of spatial function zoning is an effective measure for regional environmental protection and orderly development.For ecological and economic coordinated development, spatial function zones should be divided scientifically to clear its direction of development and protection. Therefore, based on ecological constraints, a beneficial discussion would be about the key ecological function areas adopting the concept of ecological protection restriction and supporting socioeconomic development for spatial function zoning. In this paper, the researchers, taking Tacheng Basin, Xinjiang of China as an example, choose township as basic research unit and set up an evaluation index system from three aspects, namely, ecological protection suitability, agricultural production suitability, and urban development suitability, which are analyzed by using spatial analysis functions and exclusive matrix method. The results showed that: 1) This paper formed a set of multilevel evaluation index systems for three types of spatial function zoning of the key ecological function areas based on a novel perspective by scientifically dividing Tacheng Basin into ecological space, agricultural space, and urban space,which realized the integration and scientific orientation for spatial function at the township scale. 2) Under the guidance of three types of spatial pattern, the functional orientation and suggestions of development and protection was clearly defined for ecological protection zones,ecological economic zones, agricultural production zones, and urban development zones. 3) A new idea of space governance is provided to promote the coordinated and sustainable development between ecology and economy, which can break the traditional mode of thinking about regional economic development, and offers a scientific basis and reference for macro decision-making.

Characterization of Air Pollution in Urban Areas of Yangtze River Delta,China

The hallmark of development in the Yangtze River Delta(YRD) of East China has been sprawling urbanization. However, air pollution is a significant problem in these urban areas. In this paper, we investigated and analyzed the air pollution index(API) in four cities(Shanghai, Nanjing, Hangzhou and Ningbo) in the YRD from 2001 to 2012. We attempted to empirically examine the relationship between meteorological factors and air quality in the urban areas of the YRD. According to the monitoring data, the API in Shanghai, Nanjing, Hangzhou slightly declined and that in Ningbo increased over the study period. We analyzed the inter-annual, seasonal, and monthly variations of API, from which we found that the air quality had different temporal changes in the four cities. It was indicated that air quality was poor in winter and spring and best in summer. Furthermore, different weather conditions affected air quality level. The wind direction was considered as an important and influential factor to air pollution, which has an impact on the accumulating or cleaning processes of pollutants. The air quality was influenced by the different wind directions that varied with seasons and cities.

RELATIVE SEA LEVEL RISE AND ITS EFFECTS ON ENVIRONMENT AND RESOURCES IN CHINAS COASTAL AREAS

Due to global climate warming and natural and man-made land subsidence etc., relative sea level rise in the coastal plains of China will exceed 2-3 times over the golbal mean value during the first half part of the 21st century. It will result in a series of adverse impacts on evolution of natural environment and socioeconomic development of the coastal area. This paper analyses environmental and resource effects induced by relative sea level rise in China's coastal areas on the basis of rough estimate of future relative sea level rise. These effects include inundating tidal flat and wetlands and increase in inundated risk of coastal habitable land,exacerbating storm surge. coastal erosion, flooding and salt water intrusion hazards.as well as endangering land. water. tourism and living resources and their utilization.

Spatiotemporal evolution of land transportation networks and accessibility in inland mountainous areas 1917-2017:A case study of Southwest China

Located in the western hinterland,Southwest China is a typical mountainous area covered by plateaus,mountains and hills.Its ruggedness hinders regional internal and external connections,and its poor transportation infrastructure has long constrained the socioeconomic development of Southwest China.Based on the GIS transportation database,this paper explored the spatiotemporal evolution and characteristics of the land transportation networks and the accessibility of Southwest China from 1917 to 2017.Regional accessibility in Southwest China has significantly improved,and transportation infrastructure has gradually integrated the transportation circles of the52 central cities.The transportation network has followed an evolutionary process from a"hub-spoke pattern"to a"network pattern",while the construction of a high-speed railway(HSR)has brought about significant spatial polarization.We argue that innovation in transportation technology is one of the most effective factors for promoting a significant change in regional accessibility.In addition,the spatial distribution and evolution of accessibility in Southwest China presents a verticalcharacteristic that distinguishes it from the plains,as the spillover effects of new transportation infrastructure on accessibility improvement are partly offset by the mountainous terrain.Additionally,in Southwest China,there is significant"path dependence"in the evolution of the transportation network,since a large portion of the population is concentrated along transportation corridors in mountainous areas.

AN OBSERVATIONAL ANALYSIS OF A TORRENTIAL RAINSTORM IN THE WARM SECTOR OF SOUTH CHINA COASTAL AREAS

On May 20 th 2007, a brief but severe downpour rainstorm occurred in the coastal areas of Maoming and Yangjiang with rainfall of 115 mm per hour. Data from NCEP/NCAR reanalysis with 1°×1° resolution, Doppler weather radar, conventional surface observations, high-altitude radiosonde and wind profiler radar were used to analyze characteristics and contributions of synoptic scale and mesoscale systems during this torrential rainstorm. The results showed that:(1) the storm was caused by a quasi-linear mesoscale convective system(MCS) and the slow-movement of this system was the primary trigger of the torrential downpour;(2) water vapor was abundant, nearly saturated and in steady state throughout the atmosphere before the storm; intrusion of the weak dry and cold air in the middle level and a striking "dry above and wet below " structure had increased the atmospheric instability;(3) low-level southwesterly airflow from a low pressure(trough) at the Beibu Gulf provided abundant water vapor at the onset of the rainstorm; a deep dry layer was formed by dry and cold air behind the high-level trough, which facilitated latent heat release;upper-level divergence and low-level convergence circulations also provided vertical uplift for warm and moist air at the lower level;(4) Topography only played a minor role as the MCS developed and strengthened over relatively flat coastal terrain. Low level density flow induced by convection triggered new convective cell generation at the leading edge of the convective system, thereby playing a key role in the change of temperature gradient at lower layers, and resulting in strengthening atmospheric instability.

Impacts of formal credit on rural household income:Evidence from deprived areas in western China

Financial support is a crucial part of China's poverty alleviation effort.Thus,it is vital to understand how formal credit impacts income growth in rural households.In 2012,2015,and 2018,a survey was conducted to obtain a panel dataset of 592 rural households from 6 poverty-stricken counties in western China,including counties in Guizhou,Yunnan,and Shaanxi provinces.We use the data to examine the effect of formal credit on rural household income and the mechanism that underlies this effect.We find that formal credit can significantly increase rural households'income in deprived areas in western China.Furthermore,formal credit promotes the reallocation of household labor from the agricultural sector to the non-agricultural sector and changes rural households'decisions about investment-consumption behavior.These are the drivers of changes in the amount and structure of household income.Further analyses show that formal credit may widen income inequality among rural households in western China's deprived areas.The individual characteristics of rural households,such as different levels of material capital,human capital,and social capital,bring about differences in the effects of formal credit on income growth.This study emphasizes that the implementation of formal credit is an essential strategy for poverty alleviation in underdeveloped areas,but policymakers should not excessively interfere with the financial market.

Monte-Carlo Method for Coalbed Methane Resource Assessment in Key Coal Mining Areas of China

Monte-Carlo method is used for estimating coalbed methane （CBM） resources in key coal mining areas of China. Monte-Carlo method is shown to be superior to the traditional volumetric method with constant parameters in the calculation of CBM resources. The focus of the article is to introduce the main algorithm and the realization of functions estimated by Monte-Carlo method, including selection of parameters, determination of distribution function, generation of pseudo-random numbers, and evaluation of the parameters corresponding to pseudo-random numbers. A specified software on the basis of Monte-Carlo method is developed using Visual C＋＋ for the assessment of the CBM resources. A case study shows that calculation results using Monte-Carlo method have smaller error range in comparison with those using volumetric method.

Discussion on the dextral movement and its effect in continental China and adjacent areas since Cenozoic

Continental China has moved dextral Eastward since Cenozoic time,driven by the collision of the Indian with the Eurasian plate.Evidence for this comes from landscape evolution,the distribution of earthquake epicenters,Cenozoic sedimentary and volcanic rocks,and the measurement of GPS velocity vectors,the distribntion of crustal stress,paleomagnetic data,and deep mantle structure,among others.This movement commenced around 40 Ma,coupled with thickened lithosphere and widespread stress release along strikeslip faults that bound the continental Chinese block.Because of continued Northward subduction of the Indian plate,manifestation of the dextral movement has intensified since 25 Ma.Far-reaching effects include extensive strike-slip movement on the Tan-Lu fault in Eastern China,formation of the Dabie ultrahigh pressure metamorphic terrane,extensive thrust faults in East China,delamination and thickening of the lithosphere of South China,a possible tectonic doubling of the Middle-Lower Yangtze Valley metallogenic belt,and the formation of the Japan,Huanghai (East China),and South China Sea.

Influence of the Moho surface distribution on the oil and gas basins in China seas and adjacent areas

Owing to the strategic significance of national oil and gas resources,their exploration and production must be prioritized in China.Oil and gas resources are closely related to deep crustal structures,and Moho characteristics influence oil and gas distribution.Therefore,it is important to study the relationship between the variation of the Moho surface depth undulation and hydrocarbon basins for the future prediction of their locations.The Moho depth in the study area can be inverted using the Moho depth control information,the Moho gravity anomaly,and the variable density distribution calculated by the infinite plate.Based on these results,the influences of Moho characteristics on petroleum basins were studied.We found that the Moho surface depth undulation deviation and crustal thickness undulation deviation in the hydrocarbon-rich basins are large,and the horizontal gradient deviation of the Moho surface shows a positive linear relationship with oil and gas resources in the basin.The oil-bearing mechanism of the Moho basin is further discussed herein.The Moho uplift area and the slope zone correspond to the distribution of oil and gas fields.The tensile stress produced by the Moho uplift can form tensile fractures or cause tensile fractures on the surface,further developing into a fault or depression basin that receives deposits.The organic matter can become oil and natural gas under suitable chemical and structural conditions.Under the action of groundwater or other dynamic forces,oil and natural gas are gradually transported to the uplift or the buried hill in the depression zone,and oil and gas fields are formed under the condition of good caprock.The research results can provide new insights into the relationship between deep structures and oil and gas basins as well as assist in the strategic planning of oil and gas exploration activities.