Based on the frequency data of high-speed rail services from the 12306 Chinese Timetable website and the complex network theory, this paper analyzes the spatial distribution characteristics of the high-speed rail network in the Yangtze River Delta in detail by investigating some indexes, such as dominance index, the service frequency of the stations as starting station, the time distribution of train services, and so on. The result firstly shows that the degree distribution of high-speed rail network has a two-tier hierarchical structure, and the stations can be divided into two types, “degree greater than 60” and “degree less than 60”. Secondly, the high-speed rail exerts a promoting effect on the commuting between Shanghai, Nanjing, Hangzhou and their surrounding cities. Thirdly, a great difference in the grade of stations is found, three high-speed railway stations, Shanghai Hongqiao, Nanjing South and Hangzhou East are the dominant among those stations. Then this paper divides the study area into four closely related communities, and the organizational structure of those communities can be described as multi-level network, sparse network, group network and group with typical core. Finally, the formation mechanism of the above conclusions is discussed.

Automobile industry is one of the leading industries in the Yangtze River Delta Urban Agglomeration. It is meaningful to study the spatial agglomeration characteristics and performance problems of this industry. This paper applies the methods of kernel density estimation and Ripley’s K to explore the spatial agglomeration patterns of automobile industry in the Yangtze River Delta Urban Agglomeration, based on the data of automobile enterprises from Chinese industrial enterprises database; and then use the quantile regression model to distinguish the relationship between spatial agglomeration and the development performance of automobile enterprises. The results show that: (1) The spatial distribution patterns of the automobile industry in the Yangtze River Delta Urban Agglomeration show the evolution of polarization and re-equilibrium. In general, it has experienced three stages: sporadic dispersion aggregation-M-type agglomeration-M-type clustering. (2) The spatial agglomeration and diffusion of automobile enterprises coexist. The scale of agglomeration first expands and then stabilizes, while the intensity of agglomeration rises first and then falls. (3) The role of spatial agglomeration in the performance of automobile enterprises has the orientation of enterprise development level; in general, the localized economy is very important for the improvement of the development performance of automobile enterprises, however, the role of urbanization economy is negative or insignificant.

The purpose of this study is to explore the UGB delimiting method, which can address concerns on both policy planning and the pattern of natural development. Taking Yubei district of Chongqing as the case study area, the study is based on the data of land-use, social economy and multiple spatial planning, and the urban land demands in three different industrial transformation speeds scenes are calculated by the method of “Marginal land-use”. Then based on the idea of “anti-planning”, the Multi-plan integration and FLUS model is introduced to explore the land-use distribution, and the rigid UGB, short-term and long-term flexible UGB in three industrial transformation scenes are delimited. The result shows that：1) Artificial initial land-use, which combines Multi-plan integration and land-use status, make the UGB delimiting result adapt to the demand of development planning. 2) Industrial transformation slows down the urban-land expansion in Towns of Xinglong, Gulu and Shichuan, and the long-term flexible UGB delimitation result shows a moderate diminish. 3) The rigid UGB in Yubei district distributes along the three mountains, and the area of remaining land that can be developed beyond the rigid UGB is 59 52072 hm². The areas of short-term and long-term flexible UGB in three scenes are 35 781780, 48 34361, 44 73133 and 41 061.13 hm², respectively. The remaining land neither in rigid UGB nor in flexible UGB mainly distribute in towns of Luoqi, Gulu and the airport area in Shuangfengqiao Street. The methods used in this study take the rigid and flexible concept of UGB into consideration and combines the Top-down politic factors and Down-top natural pattern factors effectually. The UGB delimiting results would make it effective to achieve ecological security and urban smart growth.

Based on the data of the 5th and 6th censuses, factor and cluster analysis and other methods were used to study the evolution trend of social spatial structure in the central city of Chengdu from 2000 to 2010. It is found that the main factors, social areas and structural patterns of urban social spatial structure in Chengdu have changed significantly in the past 10 years. The evolution characteristics of the main factors can be summarized as follows: the factors of general wage earners, professional and technical personnel and industrial workers show great changes; while the factors of immigrants and living conditions, highly educated population and minority population show certain stability and sustainability. The evolution characteristics of social areas can be summarized as the optimization of spatial structure and upgrading of function orientation in the old urban areas, and the evolution towards “three descent and two mention”; the expansion of intellectuals’ residential areas and the separation from minority agglomeration areas, showing a trend of residential differentiation; the gradual migration of foreign population to secondary and tertiary industries and the expansion of agglomeration areas; and the agglomeration districts of agricultural population gradually become suburbanized and the prominence of blue-collar population areas. The pattern of social spatial structure has evolved from the single and homogeneous “circle + fan” structure in 2000 to the “circle + fan + multi-core + multi-group” pattern in 2010. Various types of spatial regions have expanded and the spatial heterogeneity has become clearer.

The carbon emission right trading policy is an important measure for achieving the transformation of the low-carbon economy in China. This paper takes panel data of 30 provinces in China from 2007 to 2016 as research object. The difference-in-differences model is applied to explore the effectiveness of the carbon emission right trading policy, and the mechanism of the policy is analyzed from the perspective of inter-provincial differences in the construction land carbon emission intensity. The study shows that: (1) The average value of construction land carbon emission intensity in the pilot area and the non-pilot area has same variation trend during the study period, with the carbon emission intensity value of pilot area a general decline and the non-pilot area a slight rise, which shows that the effect of implementing the carbon emission trading policy is more effective than that of mandatory emission reduction policy. (2) The results of the difference-in-differences model confirm that carbon emission trading right policy significantly reduced the construction land carbon emission intensity under the circumstances of controlling other variables. Moreover, the control variables such as the average land GDP, energy intensity, and industrial structure have significant effects on the construction land carbon emission intensity. (3) Through further investigation of the mechanism of carbon emissions trading policy, we found that the carbon emission right trading policy will ultimately serve to curb construction land carbon emission intensity with a relative decline of energy intensity.

Water is the important natural resource for the development of human society. Under the background of water scarcity in China, it is very important to create more welfare growth with less water consumption and seek sustainable development of water resources. Based on the logic of ecological well-being performance, this paper constructs an evaluation system of water well-being performance to measure the sustainable utilization of water resources of 31 provincial-level regions in China. To solve the problem that the intertemporal outcomes computed from traditional DEA methods are not comparable, this paper adopts the generalized DEA method to measure the water well-being performance of 31 provincial-level regions in China from 2006 to 2015, and analyses the spatial agglomeration of the sustainable utilization of water resources in China using the global Moran’s I index, the Moran scatter plot, the local Moran’I index, and the LISA cluster plots. The study found: ①The water well-being performance of 31 provincial-level regions in China is on the rise from 2006 to 2015 , and the eastern region is the best, followed by the west, and the central region is the worst. There are still significant differences between the 31 provincial-level regions. The water well-being performance of Beijing is the highest, and the water resource welfare of Ningxia is the lowest.②The water well-being performance in China has spatial agglomeration effect and has been increasing year by year and passes the significant test since 2009. During the observation period, the spatial evolution path of the sustainable utilization of water resources in 31 provincial-level regions in China includes four states: positive spatial agglomeration, negative spatial agglomeration, negative spatial overflow and spatial differentiation. As time goes on, more and more provinces are affected by the negative influence of the neighboring provinces and enter low-low concentration areas. The provincial government must not only pay attention to the improvement of their own water resource welfare performance, but also should pay attention to the trends of the sustainable use of water resources in neighboring provinces in order to prevent negative spatial effects.③The Beijing-Tianjin-Hebei region has long been stable in high and high agglomeration areas, while the provinces near Pearl River valley such as Hunan and Guangdong have long been stable in low-low concentration areas. The water well-being performance in water-scarce areas is better than that in rich water areas, which provides a warning for the rich water areas.

Improving agricultural water use efficiency is of great significance for agricultural sustainable development and food security. Thus it is the premise of the strategies to improve agricultural water use efficiency which analyzes the status and spatial distribution characteristics. The super efficiency Data Envelopment Analysis method is applied to calculate the efficiency of agricultural water use in 31 regions of China. Results show that the regional difference of agricultural water efficiency is obvious and the overall value is low. In order to explore the deeper causes of agricultural water use efficiency, geographically weighted regression is used to analyze the spatial heterogeneity and contribution degree of factors, and some factors are observed including annual precipitation, agricultural water consumption ratio, diversity of agricultural products, water saving irrigation area and irrigation costs per acre. The conclusions are follows: The effective measures to improve the efficiency of agricultural water use in Xinjiang are to adjust the structure of water use and the planting structure; Strengthening the engineering construction such as water storage project, water interception project and water-saving project is the most effective way in South China; Heilongjiang should focus on the development and application of water saving technology; Shandong, Henan, Tianjin, Hebei, Beijing, Jilin, Liaoning and Shanghai need to take consideration of the natural endowments, water consumption structure, planting structure, water saving technology and economic factors together; It is inappropriate to raise the average irrigation fee per acre in southwest and northwest regions to improve water use efficiency. In a word, the research results are helpful to formulate different countermeasures for agricultural water use efficiency in different regions.

In view of the deficiencies in the researching methods of urban distribution pattern in China, taking national garden counties as a special example, using methods of ESDA and imbalanced index to characterize the evolution of the number of provinces in the distribution pattern; Stepwise regression model, GWR and GeoDetector are also be applied to explore the influencing factors of its distribution and its spatial heterogeneity and interaction on the provincial scale. The results show that: (1)The distribution of national garden counties has been characterized by significant global and local spatial autocorrelation. The spatial heterogeneity of the counties has remained stable, but the number of the counties has become more discrete among provinces as a whole. (2)Total investment in fixed assets, green space ratio in built-up area of county, number of (Autonomous)Counties/Banners and local general public budget revenue are the significant factors leading to the spatial differentiation of the number of national garden counties. In case of the direction affected, these factors are all positive except for the last one. (3)The effects of each factor demonstrate obvious spatial non-stationarity, but the spatial distribution patterns of their effects are different; The influence is also not independent, there are two kinds of interaction, including nonlinear enhancement and bi-factor enhancement, the influence of which is greater than that of factors acting alone, and green space ratio in built-up area of county has the most promoting effect on other factors.

Promoting the development of the Yangtze River economic belt is a major strategy that concerns the overall development of China. As one of the strategic core areas of national resource security protection, the shale gas, manganese, vanadium, titanium, tungsten, tin, antimony, rare earth, lithium, phosphorus and some other minerals in the Yangtze River Economic Belt occupy an important position in China, but as it has been affected by the long time high-intensity exploration, the development of mineral resources in the Yangtze River Economic Belt is faced with several problems, such as the layout and structure is not always reasonable, the scale and intensification level and The overall utilization efficiency is generally low, furthermore, the contradiction between mineral resource development and environmental protection is relatively prominent. Under the strategic guidance of “grasping the major protection and no large-scale development”, it is imperative to optimize the spatial pattern of mineral resources development and promote the growth of high-quality mining industry in the Yangtze River Economic Belt. Starting from the perspective of functional zoning, based on the analysis of the characteristics of the mineral resources in the Yangtze River Economic Belt and the above problems, this study considered factors such as the mineral resources background, the importance of the ecological environment, the degree of transportation dominance and water shortage, and the needs of regional economic development. A functional zoning indicator system targeting to optimize the spatial pattern of the mining industry has been constructed. Taking county-level administrative units as the unit, and using the discriminant method, the Yangtze River Economic Belt has been divided into five functional zones, namely key avoidance zones, poverty alleviation development zones, mining mitigation zones, restricted development zones, and moderate development zones. Environment protection, resource poverty alleviation, high-end guidance, overall coordination, and green transformation are the main tasks of the five functional zones to promote the optimization of the spatial structure. In addition, in response to the characteristics of each kind of functional zone, this paper put forward different policy proposals.

Tourism integration is a trend of regional tourism economic development and cultural integration. The evolution of transportation network has an important impact on regional tourism integration. This influence is more obvious with the enhancement of accessibility. Taking the Poyang Lake area with the most concentrated distribution of tourism resources in Jiangxi Province as an example, this paper takes the evolution of the transportation network pattern in the region and its national tourism resources above Grade 3A as the research object, and carries out the evolution of the regional transportation network and its accessibility level. Based on the quantitative analysis, the grey relational coupling model is used to analyze the relationship between the communication network accessibility and the tourism economy. The study believes that: ①The degree of coupling between the accessibility of the transportation network in the Poyang Lake area and the tourism economic system is relatively high. The evolution and accessibility of the transportation network are crucial to the evolution of the tourism economy and the regional tourism integration pattern. There is a mutual feedback mechanism between the accessibility of the transportation network and the tourism economic system; ②The evolution of transportation network and the development stage of communication are different. The development and integration of regional tourism corresponds to different stage modes. It can be divided into point core mode, point axis corridor mode, multi-center ring axis mode and network integration mode. ③At present, tourism integration in the region has entered the primary stage of implementation. The focus of future development should focus on cooperation between tourism enterprises across administrative regions and the establishment of a unified tourism management coordination agency to provide reference for the development of regional tourism integration.

This paper analyzes the spatial-temporal heterogeneity of tourism poverty alleviation efficiency and the influencing factors in 24 national-level poverty counties in three contiguous destitute areas of Hubei Province from 2006 to 2016, using Super-SBM model, mean square deviation decomposition method and LS regression model.The results show that:(1) The efficiency of tourism poverty alleviation in Hubei Province had achieved a steady and rapid growth from 2006 to 2016, but the overall level was still relatively low, which basically presented the spatial differentiation pattern of “Qinba Mountain Area > Wuling Mountain Area > Dabie Mountain Area” and high-effciency counties located in the Qinba Mountain Area and Wuling Mountain Area.(2) The overall difference between the efficiency of tourism poverty alleviation in Hubei Province and the internal differences in the study area tended to be narrow, but the regional difference was in a discrete state. And the internal differences among Dabie Mountain, Wuling Mountain and Qinba Mountain were the main reasons for the differences in the efficiency of tourism poverty alleviation in Hubei Province.(3) From the perspective of Hubei Province as a whole, the positive driving effect of structural and economic dynamics on tourism poverty alleviation efficiency was the most obvious. From the regional perspective, the dominant factors in Qinba Mountain Area are economic power and traffic power, as for the Wuling Mountain Area, the efficiency of tourism poverty alleviation was mainly driven by economic power and structural power, and the leading ingredients that affected the efficiency of tourism poverty alleviation in Dabie Mountain Area are traffic dynamics and information power. Therefore, it is suggested that different tourism poverty alleviation policies should be adopted to expand the benefit of poverty alleviation industry in profiting and reducing povertyin different regions, and the efficiency of tourism poverty alleviation should be promoted.

The liability sharing of carbon emission reduction is the foundation to formulate the carbon emission reduction policy and also the important process to perfect the carbon trading market system. In order to define the liability of regional carbon emission reduction in a reasonable manager, the IFCAM was constructed by beginning with the regional difference of carbon emission in land use and giving considerations to the principles of fairness and efficiency. The liability of carbon emission reduction in each county and district was divided under the carbon emission reduction targets of Wuhan Urban Agglomeration in 2020. And it was conducted the feasibility test, hoping to provide reference for liability sharing of carbon emission reduction in Wuhan Urban Agglomeration and relevant areas. The findings showed that:（1）The proportion of carbon emission of urban land use in Wuhan megalopolis exceeds 70%, showing the core-peripheral diminishing distribution. Each region had the obvious difference;（2）Even if 3D apportion model improved fairness of carbon emission in the megalopolis, the overall carbon emission efficiency was only 0.54, which was reduced by 30.77% comparing with 2015, thus it should be further improved;（3）The entire efficiency maintained by the IFCAM was 1, which gave considerations to 3E equity principle on the basis of no decay, thus areas with the higher economic development would reduce the pressure of carbon emission reduction, while areas with the lower economic development would increase the pressure of carbon emission reduction;（4）The inspection findings indicated that based on the IFCAM, the decrease amplitude of carbon emission intensity in each county and city of Wuhan Urban Agglomeration in 2020 could reach the standard. The decrease amplitude of average carbon emission intensity was 19.27%, which exceeding the target(18.78%) distributed by the Hubei Provincial Government. Moreover, the variable coefficient of apportion results was smaller and average carbon emission efficiency was enhanced. The distribution of fairness and efficiency could be solved effectively, showing the feasibility and scientificity.

Beyond the on-site negative consequence, soil erosion has off-site negative impacts as a result of sediment delivery. The spatial decoupling between soil conservation services provision and beneficiaries is common. In previous assessments involving soil conservation services, the on-site soil erosion prevention usually is used as proxy to the soil conservation services, or a constant sediment delivery ratio is employed in estimating sediment delivery to external areas. The former approach ignores the difference between provision of soil conservation service and soil conservation services delivered to beneficiaries, and lead to an overestimation. The latter approach overlooks the spatial variation of sediment delivery ratio, and leads to great uncertainty in soil conservation services quantification. It is fundamental to understand the process-effect-function-service cascade in estimating soil conservation services provision and delivery. Fortunately, spatially distributed sediment deliver model that integrated the sedimentological connectivity concept provides an opportunity. In this study, a spatially explicit approach based on the cascade mode of soil conservation formation was employed to assess the soil loss prevention and sediment reduction services in neighboring areas of Dongting Lake in Hunan Province. The supply capacity of soil loss prevention service and sediment reduction service are integrated. Following the framework of this study, that ecosystem services supplying areas are coupled with the beneficiary areas through the ecosystem services flow. This study shows an effective avenue to coupling the ecosystem service supply and demands.

The ecological environment protection of the Yangtze River Economic Belt is a common concern of the whole society. Land consolidation is an important means to protect the orderly ecological system for mountains, rivers, forest, farmland, lakes and grassland, but at present, in most areas the land consolidation mainly focuses on the improvement of agricultural production conditions, which lacks consideration of key environmental issues such as soil erosion. This study take Jintan and Liyang city as the reach areas which are the typical land consolidation areas in Ning-Zhen-Yang hilly area, based on the quantitative evaluation of land consolidation and the accurate estimation of soil erosion, we have focused on the key factors and mechanisms of land consolidation works on soil erosion. The results of this study:(1) Land consolidation significantly reduced the degree of regional soil erosion, and the amount of soil erosion in the project area dropped to 43.1% after remediation.(2) Land flatness, investment intensity and field rule degree have the most significant effect on regional soil erosion control, and contribution rates to reduce soil erosion amount are 41.5%, 28.1% and 13.2% respectively.(3) In areas where soil and water loss is serious, we should increase investment in land consolidation, strengthen land leveling works, and intensify the fragmentation and regularization of plots.

Land use change in metropolitan fringe area occurs frequently. It is of great significance to analyze the impact of land use change on the habitat quality from a perspective of ecological network and species. We took Ezhou City, a metropolitan fringe area in central China, as a case study, and selected Alcedo bengalensis, Rufous-Backed Shrike, Chinese Pond Heron as target species, and constructed the ecological networks based on the habitat conditions and migration distance of the target species. Based on the two scales of landscape pattern and the connectivity of ecological network, we evaluated the impact of land use change on habitat quality from 2004 to 2014.The results indicate that, the area of construction land in Ezhou increased, the area of forest land increased significantly during 2004-2009, the water decreased significantly during 2009-2014, and the land use was continuously fragmented. From the perspective of the patch, habitats quality showed a downgrading trend. Forest habitats quality represented first increased and then decreased shape, and water habitat quality downward was more obviously. Habitat quality showed an inverted "U" structure which first increased and then decreased from the perspective of connectivity. Patch plays an important role in maintaining network connectivity and habitat quality. The construction of new urban area and infrastructure result in the segmentation of forest land and water，which is the major reason for the surrounding quality change of the typical patch. Therefore, urban planners should pay more attentions to the protection of large habitat patches, which should be prohibited and restricted as the development zone. Meanwhile, in order to improve the ecological environment quality of metropolitan fringe area, “stepping-stones” patches should be protected to maintain network connectivity.

Vegetation is an important component of tourism attractiveness. Studying the change of Normalized Difference Vegetation Index(NDVI) in scenic spots is crucial to the sustainable development of scenic spots. Taking Lushan Scenic Spots, the first batch national key scenic spots, as the research area, the trend analysis was used to analyze the spatial-temporal change characteristics of NDVI based on the nearly 30 years Landsat NDVI data. Then, the potential influence factors of NDVI change were discussed from the aspects of climate, topographic and tourism activities. The results showed that: for nearly 30 years, the NDVI in Lushan Scenic Area showed a downward trend in the overall fluctuations. Among them, the two periods of 1988-2001 and 2002-2017 showed a trend of decreasing first, but the end of the rally was lower than the beginning level. In terms of space, the regional distribution of NDVI decreased significantly around the major scenic spots and tourist routes, while NDVI increased significantly was in the high-density forest cover region. Among the influencing factors, for the climate factor, due to the limited region of the research area, the spatial distribution of temperature and precipitation was small, and the correlation between temperature and precipitation and NDVI was not significant. Climate factor was not the main influencing factor of NDVI changes. For terrain factor, higher elevation and slope was distributed with major scenic spots and tourist distribution, where the interference of human factors was relatively large, and the value of NDVI was relatively low. Compared with the shady-slope, the sunny-slope was more abundant in light resources. In addition, the shady-slope was mostly a region with strong human activities such as scenic spots and tourist routes, and the NDVI was higher in the sunny-slope. For tourism activities, with the number of tourists and tourism activities increased year by year during the research period, the construction land and bare land around scenic spots, visitor centers and tourist routes also increased significantly, leads to downward trend of NDVI. Tourism activities were the main influencing factors of NDVI changes.

Species composition, distribution, fauna similarity and threatened factors of freshwater molluscks in the Gan River Basin were analyzed based on the systematic investigation from 2016 to 2017. In addition, we also provided some strategies to protect freshwater molluscks. The results showed that 62 species of freshwater molluscks were identified, belonged to 29 genera, 14 families and 2 classes, and included a new record species-Lithoglyphopsis ovatus. Among which that 29 species belonged to 16 genera and 11 families of Gastropoda, 33 species belonged to 13 genera and 3 families of Bivalvia. There were 27 endemic species to China(Gastropoda had 6 species and Bivalvia had 21 species), and 23 threatened species to China(Gastropoda had 4 species and Bivalvia had 19 species). From the frequency of occurrence of species, Corbicula fluminea, Limnoperna lacustris, Unio douglasiae, Anodonta woodiana woodiana, Bellamya aeruginosa, Bellamya purificata and Pomacea canaliculata were widely distributed in the Gan River Basin. From the perspective of fauna similarity analysis, distribution of freshwater molluscks between the main stem and tributary of the Gan River Basin was significantly different, and species richness of the main stem was higher than tributary. Due to the effect of human activities, especially sand mining, water pollution and overharvesting, freshwater molluscks resources in the Gan River Basin had declined rapidly, which should attract much attention and strengthen protection.

Macrozoobenthos specimens were sampled in the Doushui Lake Basin from June 2016 to May 2017, which were identified into 40 genera(species), 28 families and 6 classes. The number of Arthropoda was the greatest(18), accounted for 45.0% of the total, followed by Mollusca(15), accounting for 37.5%, Annelida was the lowest(7), accounted for 17.5%. The dominant species were Limno drilus hoffmeisteri, Branchiura sowerbyi, Radix swinhoei, Bellamya purificata, Semisulcospira libertine and Corbicula fluminea. The cluster analysis showed that macrozoobenthic fauna in the Doushui Lake Basin was clearly divided into reservoir and river. The mean density(476.64±28.91 ind./m2) and mean biomass(46.706±15.293 g/m²)of macrozoobenthos in the river were greater than reservoir(mean density was 452.34±78.45 ind./m², mean biomass was 1.569±0.209 g/m²). The analysis of diversity index showed that species diversity of macrozoobenthos in the river was higher than the reservoir. The results of canonical correspondence analysis(CCA) indicated that spatial distribution of macrozoobenthos was correlated with total phosphorous(TP), chemical oxygen demand(CODcr) and ammonium(NH4⁺) in the Doushui Lake Basin.

The impact of the Three Gorges Dam on aquatic ecosystem and environment in the Three Gorges Reservoir Area (TGRA) has received international attention. Water quality is an essential factor to the ecological security and sustainable socioeconomic development for TGRA. By setting Zhutuo section in Chongqing as inflow and Nanjinguan section in Yichang, Hubei province as the outflow of the TGRA, the Mann-Kendall method was applied to test the inflow and outflow water quality trend with  the monitoring dataset (DO, CODMn, NH3-N) published by the ministry of environmental protection of the People's Republic of China from 2004 to 2017. The results showed that DO of the inflow and outflow sections remained class I and under a not significant upward trend. CODMn of inflow was under an upward trend while NH3-N was under a downward trend, either maintained class Ⅱ in recent years. CODMn and NH3-N of outflow had a significant downward trend and remained class Ⅱ in recent years. Compared to the inflow, the water quality of outflow was better and gradually improved. The mutation trend analysis showed that the water quality monitoring factors of inflow had a non-significant mutation, mainly occurred in 2005 and 2008. No mutation in outflow which indicated the water quality of outflow remained more stable than inflow. The concentration of DO, COD_Mn and NH₃-N are closely related to the characteristics of water situation, the production and lifestyle in the reservoir area. With the rising water level, declining water flow speed and sediment deposition, pollutant is sinking into the sediment effectively. In order to maintain and improve water quality of the Three Gorges Reservoir, the control and reduction in agricultural non-point source pollution, industrial sewage, urban sewage emissions and shipping emissions are in need.

In order to explore the source of CO₂ in karst cave and the relationship between cave pCO₂ and cave environment, a constant cave monitoring study(including air temperature in and out the of cave, local precipitation, soil pCO₂, cave air pCO₂, and the relative humidity of cave air) had been carried out during 2012-2016 A.D, in Furong Cave, Chongqing, Southwest China. The results showed that ⅰ) The mean cave air temperature was stable at 16.4±0.4℃ at “Great Hall” in the deep of the cave, while the mean temperature was 19.1±1.0℃ and the changing amplitude of monthly average cave air temperature was about 5℃ at the monitoring site named “Lotus Guanyin”, approximately 150 m from the entrance. It was explained that ventilation effect was stronger near the entrance than the deep of cave. ⅱ) The air relative humidity changed from 95% to 100% at “Great Hall”. In contrast, the average relative humidity was 94% and was lower in summer and higher in winter at “Lotus Guanyin” which was in line with the seasonal variation characteristics out of the cave. ⅲ) There was a seasonal change in cave air pCO₂, with maximum cave air pCO2 values in autumn and the minimum values in winter. The peak values of cave air pCO2 were measured in October or November, lagging 1-2 months behind the peak of overlying soil pCO2. It was considered that the local meteoric precipitation and the thickness of overlying bedrock were the main factors. ⅳ) The effects of overlying soil pCO₂, cave temperature and relative humidity on pCO₂ at different areas of cave were different because the cave shape, structure and tourist activity had spatial differences. Consequently, it is important to pay attention to the cave spatial structure in the process of cave monitoring and discussing the influencing factors of cave pCO₂.

Based on the daily precipitation data of 11 meteorological stations in Hengshui City, Hebei Province from 1961 to 2015, StarDex extreme precipitation index and SPEI drought index were used to analyze the spatial and temporal characteristics of precipitation and drought in the city. The results showed that:(1) the Max no. consecutive dry days (PXCDD) and the mean of dry spell lengths (PDSAV) show an upward trend, while Max no. consecutive wet days (PXCWD) and annual precipitation decreased. (2) From the perspective of spatial distribution, there was a trend toward drought in the western and northern regions. (3) SPEI indicated a significant increase in the occurrence number of drought after the 1990s. Annual, summer and winter series tend to develop toward drought. Droughts occured more frequently in the west and north. (4) The extreme precipitation index correlated well with SPEI. SPI and SPEI had good consistency at the 12-month scale, but there were differences on the degree of drought. The extreme precipitation index and SPI performed well in typical drought years of different degrees. In general, the drought in Hengshui City was becoming more and more severe, which was characterized by frequent occurrence in summer and winter, and severe disaster in the west and north. 

Based on the comprehensive meteorological drought index (CI) calculated from 98 meteorological stations and the MODIS enhanced vegetation index (EVI) data from 2000 to 2012 in the Dongting Lake Basin, we analyzed spatial and temporal variations of drought intensity and EVI during growing seasons. We also analyzed spatial distributions of drought intensity and EVI in spring, summer and autumn of typical dry and wet years as well as the correlation between drought intensity and EVI. We aimed to answer the question whether variations in EVI can reveal large-scale meteorological drought events, and to explore the potential of EVI as an indicator of dry and wet conditions in this basin. The results showed that (1) the lowest value of EVI occurred in 2001, 2005 and 2009, while the highest value of drought intensity also appeared in these three years. For drought intensity, high values were mainly distributed in summer and autumn, while low values were present in winter and spring. For EVI, the maximum and minimum values were present in summer and winter, respectively. (2) The drought intensity, EVI and forest coverage that have been corrected for inter-annual and seasonal effects during the growing season showed significant inter-annual fluctuations. The year with high drought intensity was consistent with that with low forest coverage. (3) The spatial distribution of high drought intensity matched well with that of low EVI in typical drought years. The correlation coefficients between drought intensity and EVI in summer and autumn of dry years were statistically significant (P<0.01 and 0.1 for summer and autumn, respectively). (4) The spatial distribution of drought intensity and EVI anomalies did not match in spring, summer and autumn in wet years. No significant correlations were found between drought intensity and EVI anomalies during these time periods. Our results suggested that growth of vegetation can well reflect large-scale meteorological drought in the Dongting Lake Basin.

Based on the daily average temperature, maximum temperature, minimum temperature, average relative humidity and average visibility data of Shapingba station in Chongqing from 1987 to 2017, the inter-annual variations of meteorological elements and the similarities and differences before and after impoundment are analyzed. The results showed that the average temperature and the maximum temperature have an increasing trend, and the minimum temperature had a weak decreasing trend from 1987 to 2017. Meanwhile, the average relative humidity decreased significantly, and the average visibility increased. Among them, the maximum temperature, relative humidity and visibility are tested by α=0.01. According to the mutation test, the mutation points of mean temperature, maximum temperature, minimum temperature and visibility were 2009, 2001, 2012 and 2010, respectively. The multi-year seasonal average maximum temperature increases in all seasons, the multi-year seasonal average temperature and the multi-year seasonal mean minimum temperature decreases in winter, and increases in spring, summer and autumn. The inter-annual variation of annual average relative humidity increases after water storage, and the multi-year seasonal and monthly mean relative humidity decreases after water storage. The multi-year seasonal average visibility increased before and after water impoundment. The monthly average visibility decreases by 0.212 km in June, and the other 11 months increases. The frequency cumulative percentage distribution of five meteorological elements is consistent with the annual and seasonal characteristics before and after water storage.