Water-carbon nexus is one of the important research fields of regional sustainable development. Studies on industrial carbon and water footprint efficiency from the perspective of water-carbon coupling not only help reveal the impact mechanism of the resource consumption intensity and efficiency on industrial carbon emissions, but also have great significant practical meanings for reducing water and carbon emissions in regional industrial transformation under the background of globalization. By the method of input-output analysis, input-output table of Henan in 2012 and industrial water and energy consumption data were applied to discuss industrial carbon and water footprint efficiency in this paper. The conclusions are as follows: (1) Carbon and water footprints of different industries are unmatched. The agricultural water footprint is the largest, which is 2333 times of the water footprint of lumbering. The carbon footprint of extractive industry is the largest, which is 273 times of food industry. (2) There are obvious differences among industrial water and carbon footprint efficiency. In general, the water/carbon footprint efficiency is lower in the industries with higher water/carbon footprint. (3) The different water/carbon footprint efficiency among different industries were mainly influenced by industry attribute, water and carbon consumption intensity, energy structure, technological level and relationship between industries, etc. (4) In the future, Henan province should make differentiated water-saving and carbon emission reduction policies in industrial development by combining the characteristics of different industries and the water-energy nexus, strengthening institutional constraint and legal supervision, promoting water and energy efficiency of enterprises, and enhancing regional adaptation and mitigation capacity under climate change.
Studying the Chinese provincial carbon emission reduction potential and the path of emission reduction based on the coordinated perspective of fairness and efficiency is most significant to measuring the regional potential of carbon emission reduction and to formulating the regional carbon emission reduction path for China, so as to better promote the development of green low carbon economy. First, we measure the carbon reduction efficiency by the Super-SBM model, and measure the equity of regional carbon emissions by per capita carbon emissions. Then we calculate the carbon club convergence index of efficiency and fairness based on Markov model frame so as to analyze the importance of carbon reduction potential in China and the emphasis in carbon emissions. Then we recalculate the carbon emission potential of each province based on the coordinated principle of fairness and efficiency. Finally, the carbon emission reduction path is designed on the basis of the two dimensional matrix diagram of carbon emission fairness and efficiency based on the coordinated principle. The results show that: (1) The carbon club convergence degree of China's regional carbon emission efficiency is higher, and the curing problem of "long-term low efficiency" of carbon emissions is more serious than the "long-term unfair". (2) China's carbon emission potential is underestimated, which will affect the country's allocation of carbon rights and the sharing of emission reduction responsibility. (3) Based on the coordinated perspective of fairness and efficiency in carbon emissions, the 29 provincial-level administrative districts in the mainland of China fall into four categories. Policymakers should focus on supporting the regions of "low-efficiency & low-emission" type and improve the efficiency of their carbon emissions, so as to achieve carbon emission reduction under the coordinated perspective of fairness and efficiency.
The analysis on the intensity of land development and utilization is of great significance to improving the efficency of land development and utilization and promoting ecological and environmental protection work. Taking the Tampa Bay watershed of Florida, USA as the study area, based on the information of four TM/OLI remote sensing images of 1985, 1995, 2005 and 2015, this paper constructs a series of models of land-use dynamics, conversion matrix, land development and utilization intensity and land-use structure with GIS technology. Then, it conducts research on spatial and temporal pattern of land development and utilization intensity in Tampa Bay watershed. The results showed that: (1) Construction land and woodland are the dominant types of land use in the watershed. The area of construction land mainly converted from cultivated land increased most, with the ratio being 53.74%. (2) The relative change rates of all types of land use have obvious spatial differences and those of rivers and lakes have the greatest. The change speed of unused land is the largest, with the highest single dynamic degree of up to 1.11%. The average annual growth rate of construction land is steady at about 0.30%. The size with the highest dynamic degree was decreasing from the northern and southern polar nuclei outward, and the areas with higher dynamic degrees were gradually converted into the lower dynamic areas. (3) Information entropy slightly decreased, the land use structure heterogeneity constantly decreased. Area of the land-use composition is listed in the order of Construction Land>Wood>Cultivated Land and Pasture>Rivers and Lakes>Tidal Flat and Marsh> Unused Land. (4) The intensity of land development and utilization is the highest in the Coastal Pinellas county and Tampa city. The area of development is much larger compared with the adjustment period, and the intensity of land development and utilization was obviously strengthened.
The Mekong River Commission is the only international intergovernmental organization in the Mekong River basin engaged in water resources development and management, but its institutional system effectiveness has been questioned. Especially the "Procedures for Notification, Prior Consultation and Agreement" concluded in 2003, which was successively applied to the Xayabury, Don Sahong and Pak Beng hydropower stations in Laos, not only failed to reconcile the differences of interest and contradictions of member countries, but also caused great controversy. As the mainstream hydropower development accelerates, the objective environment for China to participate in the development and management of water resources in the sub-regions is also changed. There is an urgent need to strengthen relevant theoretical foundation and practical research to promote basin development cooperation and sustainable development. Therefore, this paper mainly introduces the institutional framework, management mechanism and operating process of the MRC prior consultation mechanism, while objectively analyzes its achievements and problems based on the three practices, and then puts forward suggestions for improvement in four aspects, such as supplementing an explanatory document, making provisions for benefit compensation and public participation, as well as perfecting the process of prior consultation. Finally, we discuss the impact of the MRC prior consultation mechanism on China's participation in the whole basin management and effective countermeasures, which will provide reference and enlightenment for China's water resources development and cooperation policy under the Lancang-Mekong cooperation framework.
China's national parks aim to promote conservation and improve public welfare. This research took tourists as one of the key ecosystem services beneficiaries. It used an ecosystem services approach to identify social perceptions and willingness to pay regarding different ecosystem services in the Wusyishan National Park Pilot, in order to find ways to optimise tourism to promote conservation and to improve public welfare in the establishment of the national park system. A social survey was conducted using questionaires focusing on the assessment of the importance of ecosystem services and the willingness to pay, and the data were analysed using weighted scoring, multiple correspondence analysis and optimal scaling regression. Results showed that most respondents recognised the importance of various cultural services, including eco-tourism which is high in practicality, activities to have cultural experience which is rather abstract and enjoying the beautiful scenery; however, there were trade-offs among specific ecosystem services. Tourists thought highly of maintaining air quality and it was the only regulating service that ranked the top five. In addition, they did not choose any provisioning services among the top five important ecosystem services. Under the entry tickets fee waiver hypothesis, more than 90% respondents were willing to pay for maintainance of the ecosystem services, but the average payment of 165.9 yuan/person was less than current ticket price. Willingness to pay was significantly affected by education level and career; together with the impact of age and personal income, clustered groups with certain willingness to pay were identified. These findings indicate that in the development of tourism in national parks, managers should focus on securing typical cultural ecosystem services regarding trade-offs in demand from different tourist groups. They also should improve the public's awareness of the chracteristics of ecosystems to facilitate their active participation in conservation.
As one of the protected areas, the wetland park has played an important role in protecting the wetland habitat. On one hand, the wetland park can be an important infrastructure for ecosystem research on exploring the contradiction between the vulnerability of ecologically fragile areas and the maintenance of original habitat of wetland, which shows both theoretic significance and practical value for systematic research on wetland parks. On the other hand, spatial analysis of the wetland park is an important basis for systematic construction of wetland parks. It can not only visualize the current spatial structure of wetland parks, but also reflect the wetland resources utilization and wetland management efficiency, which can provide the scientific basis for the spatial construction of wetland parks. Therefore, based on ArcGIS visualization technology, the spatial pattern characteristics of National Wetland Park (NWP) was analyzed from the perspective of time and space and its location relationships with the cities was explored by using Standard Deviation Ellipse, Point Pattern Analysis, Statistical Analysis and other methods. Results show the following four points: (1) China's NWP has gone through three stages, the starting stage, the rapid development stage and the standard development stage from time series. The amount of NWP is unevenly distributed in different provinces, and the correlation between the development of quality and quantity is not synchronized. Till now, Official National Wetland Park (ONWP) is at the beginning stage of standard development. (2) From multiple scale, an aggregated distribution pattern is emerging, supplemented by random distribution for ONWP. And the overall distribution pattern tends to be in a northeast-southwest direction, forming two high-density hot spots and three medium-density sub-hot spots. (3) From urban scale, the distribution of ONWP presents a large spatial heterogeneity and has the characteristics of being partial to the urban planning areas or being close to the urban planning areas. (4) At last, the distribution of ONWP presents the dominant characteristics of population pattern, which coincides with the guiding significance of Heihe-Tengchong Line.
The quantitative study on the impact of climate change on tourism in China is relatively weak, so it is urgent to learn from foreign experience. Therefore, based on the SCI/SSCI literature database, this article reviews the related research progress abroad from 1986 to 2017. The study finds that for more than 30 years, quantitative research on the impact of climate change on tourism in foreign countries has mainly used index methods, tourism demand models and selection analysis methods. Among them, the index method includes the single index method and the comprehensive index method. The tourism demand model includes the time series model and the cumulative demand model. The selection analysis includes the descriptive statistics and the discrete selection model. The indicator method is mainly used to study the environmental effects of tourism resources and environmental changes, changes in tourism climate conditions, changes in comprehensive factors, and the climate change response behavior of the main body of tourism. Due to the existence of offsetting effects of climate change, the comprehensive index method is more advantageous than the single index method. Although the comprehensive index method has difficulties such as computational complexity, it can comprehensively examine the impact of climate change on the comprehensive factors of tourism destinations, and is an important direction of development of indicators and methods. The indicator approach focuses on the changes in tourism destinations, and climate change responses need to understand the changes in tourism demand. Therefore, the use of tourism demand model has gradually increased. Among them, the time series method is mainly used to study the impact of weather conditions on tourism demand. The cumulative demand model is mainly used to study the structural impact of climate change on tourism demand and the impact of climate policy on tourism demand. With the development of computer technology and artificial intelligence, there is a great potential for future applications. The tourism demand model focuses on changes in the macro-tourism flow and ignores the heterogeneity of the tourism market. With the diversification and diversity of the tourism market becoming more apparent, the use of micro-individual-based selection analysis methods has increased. In related studies of selective analysis, descriptive statistics are often used to study the effects of climate change based on preference, behavioral willingness and climate change perception in the context of climate change. Discrete choice models are often used to study the influence of climate change based on preference and help to analyze the changes in the market structure of tourist destinations in the context of climate change. As more and more studies show that the impact of climate change on the tourism market is more reflected in the change in market structure, the application demand for discrete selection models has further increased. However, the basic theoretical assumptions of the discrete selection model still need to be studied in the correction of tourism scenarios. Combining the latest progress in the quantitative research on the impact of climate change on tourism in foreign countries, and linking with China's reality, future research needs to strengthen the application of cumulative demand models in tourism flow related research, the application of discrete selection models in tourism market structure research, and the use of systematic scientific methods and big data technologies in related research. In the future, we should enhance research on climate-sensitive tourism activities in China, and as relevant studies on "Belt and Road" countries and regions, as well as the Tibetan Plateau.
It is of great significance to accurately and objectively evaluate the spatial and temporal variation characteristics of soil moisture in studies on the biochemical evolution process of the earth surface. Thus, the combination of model simulation and site observation is necessary to studying water and energy recycling at a regional scale especially. In this paper, based on daily soil surface (0-10 cm) moisture data of 82 monitoring stations in Beijing and GLDAS soil moisture products, the accuracy and consistency of CLDAS was evaluated and the spatio-temporal variability of soil moisture content in Beijing was examined. The root mean square error (RMSE) was used to identify the consistency of CLDAS products and observation values. Specifically, we compared and analyzed the accumulated values of CLDAS products and observation data in 1 day (8∶00, 20∶00), 7 days (8∶00, 20∶00), 15 days (8∶00, 20∶00), 31 days (8∶00, 20∶00), 61 days (8∶00, 20∶00), and 92 days (8∶00, 20∶00). The results showed that: (1) Although the data from CLDAS products were generally slightly higher than the measured data, CLDAS products and site observation data show a good consistency that RMSE in various countries was almost around 10; (2) CLDAS products could reflect the distribution characteristics of soil moisture in Beijing when the temperature was higher than 0 ℃, while there existed a bias in GLDAS products when the temperature was lower than 0 ℃; (3) Based on drought identification based on soil moisture data, we found that the drought area in Beijing was gradually expanding and one extreme drought center was spreading from Changping (soil relative moisture content < 30%) to other districts. Meanwhile, the other area with high soil relative humidity (soil relative moisture content > 50%), centered in Shunyi District, gradually decreased at a spatial scale; (4) In terms of temporal scale, soil moisture in Beijing gradually decreased with the decrease of precipitation that soil humidity at 20∶00 was all higher than that at 8∶00 in the same day (MEobs >0). When the temperature was lower than 0 ℃, soil humidity at 20∶00 and 8∶00 became significantly different. These conclusions would help us make effective use of GLDAS products in soil moisture related studies and would help us know the spatial and temporal variability of soil moisture content in Beijing.
Potential evapotranspiration (ET0) is one of the most critical parameters that are essential for evaluating regional vegetation water use and managing water and soil resources. However, accurate estimation of it is so difficult for many parts of China due to a limited number of weather stations. Weather data from nearby stations are available for most sites, but past relevant works mainly focused on ET0 predicting methods with local weather data and less work was done to investigate the approaches for estimating ET0 with data from other stations. Therefore, this study was conducted to test the reliability of estimating ET0 with weather information from nearby stations. Whether data of four weather stations located in Hetao Irrigation District of western Inner Mongolia were collected. The study area has an arid climate with annual rainfall and pan evaporation of 130-215 and 2100-2300 mm respectively. Three commonly used approaches, namely, FAO56 Penman-Monteith equation (PM56) with estimated weather data, the empirical formula corrected with meteorological data of nearby stations, and the artificial neural network model (ANN) developed using meteorological data from nearby stations, were compared for predicting ET0 when data are limited in this work. The results showed that: (1) When all of the necessary parameters were not measured at the study sites, weather data from nearby stations could be used directly, the average absolute error (MAE) of the ET0 calculation was 0.43-0.52 mm d-1, and the root mean square error (RMSE) was 0.56-0.63 mm d-1, and the error could be narrowed by correcting the radiation data using the latitude information of the stations; (2) When the maximum and minimum air temperature data were available, PM56 with estimated weather data performed the worst, and the performance of the ANN model is the best with the MAE and RMSE ranging between 0.14-0.22 mm d-1 and 0.17-0.29 mm d-1, respectively; and the results of the calibrated Hargreaves formula are intermediate with the MAE and RMSE values of 0.23-0.26 mm d-1 and 0.30-0.31 mm d-1, respectively; (3) When knowing the temperature and radiation data, the ANN model trained with meteorological data from nearby stations is still the best, with MAE and RMSE values of 0.13-0.19 mm d-1 and 0.17-0.25 mm d-1, respectively, and the other two methods have larger error and the performance is inconsistent among different stations. The results of this study demonstrated that we can estimated ET0 accurately using air temperature data in combination with weather data of nearby stations under arid conditions, and the reliability of the methods still need to be validated under other climatic conditions.
Poyang Lake is the largest fresh water lake in China. Seasonal fluctuation of water level is a typical hydrological feature of Poyang Lake. And Poyang Lake wetland is one of the most important international wetlands and the largest habitat for wintering birds in East Asia. Since the beginning of the 21st century, the hydrological drought trend of Poyang Lake that emerged in autumn and winter seasons has not only posed serious threats to the local freshwater/wetland ecological security, but also attracted wide attention from the public. It is therefore of great significance to precisely monitor hydrological changes in the study lake and reveal the underlying drivers. Some studies suggest that the drought trend of Poyang Lake is related to the decrease of precipitation in the basin or the running of Three Gorges Dam (TGD) displaced in the middle reach of Yangtze River. Lai et al. argued theoretically that the drought trend in Poyang Lake was caused by sand minning in the lake. In this study, we used the long term records of LANDSAT images to locate and analyze sand mining in Poyang Lake during 2000-2016. On this basis, long time-series hydrological data were used to analyse hydrological changes. Finally, we combined these two datasets to investigate the impact of sand mining on the drought trend of Poyang Lake. Our results showed that: (1) During 2000-2016, an increasing number of vessels involved in sand mining was observed in the lake, and the sand mining has been extended to the whole lake region, including its southernmost tip and ecologically sensitive areas; (2) The drought period of Poyang Lake tended to be prolonged, and a decreasing water surface gradient and an increasing outflow from Poyang Lake into Yangtze River at similar water level happened in these years; (3) Sand mining, causing river channel connecting Poyang Lake with Yangtze River becoming deeper and wider, contributed to the hydrological drought in autumn and winter of the lake. (4) Three Gorges Dam (TGD), which reduced the water level in downstream, and weakened the backwater effect to Poyang Lake drainage from Yangtze River, could also be one of the reasons for hydrological change in Poyang Lake. In recent years, Jiangxi provincial government has been promoting Poyang Lake Water Conservancy Project to deal with the drought trend. We should urge the departments concerned to formulate a comprehensive management scheme for Poyang Lake according to the main causes for hydrological changes.
In the process of rapid urbanization, urban agglomeration development was promoting regional economic competition and cooperation, but also causing the intensification of contradictions between human and land, decline of ecosystem services level to a certain extent. In order to quantify the impact of urbanization on natural capital and reveal the influence mechanism of ecosystem service in human resource consumption process. In this study, Southern Fujian Urban Agglomeration (SFUA) is taken as an example, which is the typical rapidly urbanized area, emergy analysis method and GIS technology are used to analyze the spatial and temporal evolutions of renewable resources in the SFUA from 2000 to 2015, the evolution of eco-environment value and natural capital loss in the process of urbanization and land conversion. The results show that: (1) The renewable resources of SFUA presented a fluctuant decreasing trend in time, and gradually increasing trend in space; (2) The area proportion of urban land presented a significant increase trend in high environmental quality level, increased from 0 to 10.63%, the loss of regional eco-environment value caused by human activities was gradually rising; (3) Due to urbanization in the process of urban expansion, part of the natural land and agricultural land was converted to urban land, the total loss of natural capital caused by the conversion was 1.27E+22 seJ, and the currency value was more than 6.3 billion yuan. This study can help improve the research of eco-environmental effects due to urbanization, and provide decision-making reference for the urban agglomeration or regional eco-environment management and restoration.
In the context of the new era, it is of great theoretical and practical significance to promote urban-rural integrated development and rural vitalization by means of studying the urban-rural scale system. The concept of urban-rural scale system had three essential characteristics of size, structure and distribution, therefore the three-dimensional analytical method had been established. This paper explored the evolution characteristics and driving mechanism of urban-rural scale system, based on both the land change survey data and remote sensing data in 1995, 2005 and 2015, using the well-developed Zhangjiagang city of Jiangsu province as a case. Several conclusions can be drawn as follows: (1) The number of urban-rural settlements was continually decreasing, but the scale of built-up areas showed the opposite trend during 1995-2015. (2) The type of city-town-village scale structure changed from "stele-pattern" to "pyramid-pattern", then to "olive-pattern" from 1995 to 2015. The number and built-up area of high grade settlements were increasing, and those of low grade settlements were decreasing. There was close correlation between the growth speed of settlements and their size-classes. Zipf's index of settlements size was generally high, with the decreasing growth rate of it, and the outcomes of model fitting conformed to the law of rank-size as a whole. (3) The spatial differentiation of urban-rural scale system had become increasingly obvious during the study period. However, the speed of polarization had decreased in the 10 years. There existed significant characteristics of spatial agglomeration of settlements, and distribution of cluster centers developed toward the direction of equalization. The spatial and temporal changes of urban-rural construction land were remarkably different in different regions, but the land-use change was mainly found in the urban areas. (4) This paper constructed a "four-wheel" driving mechanism of urban-rural scale system, including four driving factors. More specifically, geographic location was the fundamental factor limiting the development of urban-rural scale system; regional economy was the internal motivity impelling the settlements to evolve toward an advanced one; transport network was a kind of important catalyst in the process; institution and administration had become the indispensably external driving forces. These four factors, just like the four wheels of a car, interacted each other and together impelled the evolution of urban-rural scale system.
Estimation of the effect of grain production adjustment on the consumption of water and land resources will help to formulate the strategy for sustainable agricultural development. Since the mid and late 1990s, the proportion of corn in China's grain production has been obviously improved. Taking grain cropping structure without adjustment as the base scenario, and under certain grain output, the actual grain production adjustment in China during 1996-2015 has brought about the savings of water and land resources, accounting for about 4.2% and 3.7% of current demand in grain production respectively. The adjustment of grain production comes from grain demand structure change, which helps to alleviate the consumption pressure of water/land resources in grain production to some extent, though China's dietary transformation requires more agricultural resources. At the regional level, from the effect of structural adjustment on the demand for planting area, the savings in northern regions with relatively abundant arable land resources are significantly higher than those in the south. The area saving effect is higher in the northeast and northwest regions, and the least in southeastern coastal areas. From the effect of structural adjustment on the demand for water resources, the savings in northern regions are generally higher than those in the south, the highest in the northwest region with the highest drought degree, and the water saving effect in the middle and lower reaches of the Yangtze River is minimal. During the period, the output of regional grain crops has been widely affected by the change of cropping proportion, which is the indicator of the planting benefit and implies the change of consumption demand. Feed grain demand has increased more than rice and wheat rations, making the northern region suitable for corn planting become China's main grain production area. In the southern rice region, the demand for rice is relatively limited, and the regional production advantages of wheat, corn and soybeans are also lacking, which causes the relative stagnation of grain production in the south. To this end, in southern China, the recovery of grain production and full utilization of the potential of water/heat resources mainly depend on the consumption demand for rice and farmers' planting benefit. For the northern region, in order to reduce the amount of groundwater irrigation, it is necessary to rationally control the cropping area of rice and wheat and to adjust farming system according to the law of precipitation as far as possible.
The land cover change and the non-point source pollution output risk in Nansihu Lake Basin during 1990-2015 were analyzed based on the land use data and statistical data. The method of output risk model, CA-Markov model and Regression Model were used, and combined with GIS technology, the land use pattern and the export risk distribution in 2020 were simulated. The results were as follows. In the 25 years, farmland and arable land were the main land use types in the study area, accounting for more than 85% of the total area. The TN and the TP risk changes were significantly different. The TN output risk value ranged between 0-0.65, and the TP output risk value was 0-0.12. N was the main pollutant. The TN risk increased gradually from 1990 to 2005, decreased significantly during 2005-2005, and increased sharply during 2010-2015. The TP risk decreased gradually during the 25 years. The low risk areas were mainly distributed in the eastern part of Nansihu Lake basin, while the high risk areas were mainly in the west part of the lake basin. The land use change in 2020 was predicted. Compared with 2015, the arable land is increasing, the area of unused land is unchanged, and the other types are reducing to different degrees. The TN risk is reducing slightly. TP risk is unchanged. It is necessary for the local government to focus on improving the agricultural science and technology and reducing fertilizer use so as to control the status quo of non-point source pollution in Nansihu Lake Basin.
With industrialization and urbanization, the economic gap between rural areas and urban areas is widening. The rural decline has become a problem facing most of the countries. Under this background, the policy of industrial integration development was proposed by the central government of China, aiming at propelling rural economic development. The policy attracted researchers from different disciplines to conduct research from different perspectives. However, most studies have just explored the theories of industrial integration in rural areas, and the quantified case studies are still hardly found. Especially for the Important Agricultural Heritage System (IAHS) Sites as a special rural area, how to promote the development of industrial integration and how to quantify the integration level among primary, secondary and tertiary industries is poorly documented. Thus, in this study, considering the characteristics, resource features and protection demands of IAHS sites, we proposed the concept and connotation of industrial integration development in IAHS sites, and set up an evaluation methodology consisting of industrial integration degree (IID) and labor integration degree (LID) and calculation methods. Taking the eight towns in the Honghe Hani rice terraced systems site, Yunnan as an example, we evaluated the IID and LID of each town. The results are shown as follows. The more balance among the sub-indices of IID and LID of each town, the higher the industrial integration level; all the sub-indices of IID and LID of each town are very small, and a huge development space exists for every town. In the eight towns, Xinjie Township has a highest IID and LID due to the biggest contribution from the tertiary industry; a highly positive correlation is between the IID and the LID of each township (r=0.67), which is below 10% in significance level (P=0.069<0.1). In conclusion, in IAHS sites, integrated industrial development can enhance the employment percentage of local people.
As the center of economic development in northern China, the coastal areas around the Bohai Sea (Bohai Rim region) have greatly boosted the development in this region. However, in recent years, there are many inharmonious conditions in this region due to various reasons. Applying the three-stage of DEA model, this paper has calculated the eco-efficiency of 17 cities in the Bohai Rim. Combining the standard deviation ellipse and gravity center transfer method, this paper has concluded the evolution law of ecological efficiency space transfer in the 17 cities of the study region. Therefore some conclusions can be drawn as follows: (1) Based on the eco-efficiency result measured by the three-stage DEA model, the eco-efficiency of the 17 cities in the Bohai Rim region is generally above average, and the efficiency value continued to rise from 2006 to 2015. Among the 17 cities, Tianjin, Tangshan, Qingdao, and Dalian rank the top four in the efficiency, and for the rest of the 17 cities, the eco-efficiency is lower than the average, which indicates that there is a significant regional difference. (2) The result of the standard deviation ellipse is in the northeast-southwest direction and has a tendency gradually towards the southwest. On the whole, we have not found an obvious transfer of the eco-efficiency center in the Bohai Rim. (3) There are significant provincial differences in the study region, as well as a big difference between the highest and lowest values. Among them, several provinces with the lowest values have remained unchanged in the ecological efficiency for a long time, and the restrictive factors of different provinces are quite different.
The remote location of resource-based cities is considered to be an important factor restricting the transformation and sustainable development of resource-based cities. With the rapid development of high-speed rail, has the location of resource-based cities been improved? In this paper, with the State Council identifying 126 resources-based cities as the case cities, taking the provincial capital cities of resources-based cities located in these provinces and three regional central cities of Beijing, Shanghai, and Guangzhou which are closely linked to resources-based cities as the reference objects, using the calculation method of time distance, the location of resources-based cities was evaluated among different development types and different regions. The research shows that: (1) From the perspective of overall sample, due to the impact of high-speed railway, the location of resource-based cities has deteriorated. Compared with D-series trains, the impact of G-series trains is even more pronounced. (2) D-series trains and G-series trains have a consistent effect on the locations of resource-based cities. To a certain extent, D-series trains and G-series trains have an overlapping layout in spatial distribution. (3) From the perspective of resource types, the mature resource-based cities are not only the cities with the most obvious improvements of locations, but also the cities with the most obvious deterioration of locations. (4) From the perspective of different regions, the central region is the region with the most obvious improvement of locations, and the western region is the region with the most obvious deterioration of locations.