Urban Human Settlement Environment (UHSE) transformed profoundly in the process of rapid industrialization and urbanization in China. By selecting 110 cities in the Yangtze River Economic Belt and constructing the UHSE evaluation model from four aspects: living environment, economic environment, social environment and ecological environment. Using the AHP and spatial autocorrelation method to evaluate and analyze the UHSE spatial pattern. The results show that: (1) There is significant spatial differentiation in the UHSE quality, the overall UHSE quality decreases gradually from east to west, and the UHSE quality in Central cities are higher than other cities. (2) In each subsystem, the living and economic environment quality of the citis in Yangtze River Delta and the provincial capitals are higher than other cities; areas with a high-quality social environment have central place orientation; the cities in Jiangxi-Anhui region have a best ecological environment quality, and the ecological environment quality in central and eastern cities are better than the western cities. (3) The UHSE exhibits have obvious agglomeration characteristics, the High-High cluster area is centered on the Yangtze River Delta, and the Low-Low cluster area is located in Yunnan-Guizhou-Sichuan region and north Anhui region.

Decomposing the driving effect of spatio-temporal differences in production water use and domestic water use in the Yangtze River Economic Zone is conducive to the smooth realization of the total water use control goal. In this paper, Logarithmic Mean Divisia Index (LMDI) is adopted to give consideration to both production water and domestic water. The spatio-temporal difference of water use is decomposed into production intensity effect, industrial structure effect, economic scale effect, domestic intensity effect and population scale effect. The results show that the production water use is the main source of the change of total water use in the Yangtze River Economic Zone and each province, and domestic water use on the increase of total water use is gradually enhanced. Production intensity effect and industrial structure effect are the primary and secondary factors to inhibit the increase of total water use respectively, while economic scale effect and domestic intensity effect are the primary and secondary factors to promote the increase of total water use. Population scale effect is relatively weak in promoting the increase of total water use. Economic growth in agriculture and industry has contributed to the increase in total water use, especially in agriculture. The general decline in the water intensity in agriculture and industry and the decline in the proportion of agriculture added value have contributed to the decline in total water use. Production water use is the main source of spatial difference of total water use among provinces, and the driving factors of spatial difference in total water use between each province and Jiangsu and Chongqing are different. Therefore, all provinces should implement high-quality development, change the mode of economic growth, and focus on saving water in production link and taking into account of living conditions. We will also continue to reduce the intensity of industrial water use，optimize and upgrade the industrial structure, strengthen the management of domestic water quotas and raise people’s awareness of water-saving. The provinces can take Jiangsu and Chongqing as the reference objects and fully explore feasible water-saving paths according to the driving factors of spatial difference of total water use.

With the development of economic globalisation and the intensifying of regional integration, an urban agglomeration is becoming an important platform for international competition and cooperation. During this process, the transport facility, especially high-speed rail (thereafter HSR) acts as an essential medium for regional connectivity while generating essential impacts on the formation and optimisation of the regional spatial pattern. Using railway time data of 2008 and 2018, this paper studies the railway passenger transport service capacity of Yangtze River Delta urban agglomeration by comparing accessibility and linkage intensity level between traditional rail and high-speed rail. Based on the above investigation, this research attempts to measure how the network pattern and operational organisation mode of HSR work to reshape and develop urban spatial structure. The results are demonstrated as follows. (1) HSR has substantially shortened the travel time between cities and improved the accessibility of transport services by generating a “time-space convergence” effect, thereby leading to a shrinkage of space and time. Generally, the HSR has improved the overall railway passenger transport service capacity in the research area. The highest level of accessibility centres on the Shanghai-Nanjing channel and is declining from the core area to the peripheral region in Yangtze River Delta urban agglomeration. (2) Shanghai, Nanjing, Hangzhou, Hefei, Ningbo have formed different daily communication areas, which expand along the HSR, causing the overlapping area to increase. (3) The linkage intensity pattern in the Yangtze River Delta urban agglomeration can be characterised as multi-level and multi-core, boosting a networked regional structure. (4) By influencing urban spatial linkage, the HSR promotes regional spatial reconstruction to a large extent. The spatial structure of Yangtze River Delta urban agglomeration is expanded from the “one body two wings” structure with Shanghai as the core to the “golden triangle” structure which connects Shanghai, Nanjing, and Hangzhou. The implementation of HSR has accelerated the flow of factors, enhanced transport efficiency and promoted multi-level integrations within the agglomeration. In the future, the construction of railway corridors in marginal areas should be strengthened to expand the coverage of railway service and thus to bridge the gap in accessibility. Furthermore, it is crucial to attach importance to optimising the spatial organisation of HSR in the core area with the aim of enhancing passenger transport capacity, and encouraging the optimal allocation of resources in the region.

Researchers have contributed many theories and approaches to figure the boundary of agglomerations and draw the urban agglomeration a reasonable scale, but few studies have quantitatively defined the spatial scope of urban agglomeration from the perspective of integration, which cannot cure the “urban agglomeration disease” such as forming groups blindly and join an urban agglomeration untimely. This study first positions the urban agglomeration as a spatially and temporally variable “community of interests” that cooperating and competing with other systems while internal individuals sharing resources. Then, authors launch a dynamic coupling relationship model of integration of urban agglomeration to test the interactions (include strengths and directions) among the central city and lower-tiered cities around it; applying the theory of metal valence bond that describes the atomic interaction by exchanging electrons internal and external, consistent with the principle of mutual attraction of element allocations among cities. On this basis, defining “coupling distance” and corresponding formula to express the direction and intensity of that interaction, to calculate the integrated region and boundary range of the urban agglomeration. Resort to this theoretical frame, authors first analyze the spatial-temporal changes of blocking effects of the urban agglomeration in different spatial distances. Second, calculating the spatial-temporal changes of the coupling distance among the cities, and then judge the situation and level of urban agglomeration integrating to conclude the suitable spatial scales of the urban agglomeration. In this paper, authors conduct an empirical study on the urban agglomeration along the Middle Reaches of the Yangtze River that including urban agglomeration of Pan-Wuhan, Ring of Changsha-Zhuzhou-Xiangtan urban agglomeration and theurban agglomeration around Poyang Lake, and the analysis results show that:(1) Urban agglomeration of Pan-Wuhan and Ring Changsha-Zhuzhou-Xiangtan urban agglomeration can develop the radius of the integrated regions up to 100 kilometers and 150 kilometers respectively, and the urban agglomeration along the Middle Reaches of the Yangtze River cannot expand the boundary radius exceeds 200 kilometers at present.(2) In terms of the hierarchical system, Ring of Changsha-Zhuzhou-Xiangtan urban agglomeration is second to urban agglomeration of Pan-Wuhan and both exceed the urban agglomeration around Poyang Lake; but the urban agglomeration along the Middle Reaches of the Yangtze River has no heart yet.(3) Analysis of Maturity shows that Ring of Changsha-Zhuzhou-Xiangtan urban agglomeration surpasses the other two as several depressions exist in the middle of urban agglomeration of Pan-Wuhan and two cities are away from the urban agglomeration around Poyang Lake.(4) The members of the urban agglomeration along the Middle Reaches of the Yangtze River are Wuhan, Huanggang, Xiaogan, Changsha-Zhuzhou-Xiangtan urban agglomeration and Yiyang, is smaller to a quarter of the original planning; and “Wuhan & Changsha” will shape into an integrated center.These results offer a scientific reference to the integrated development planning of the urban agglomeration along the Middle Reaches of the Yangtze River.

The evolution process of rural industrial land in southern Jiangsu is the core content of regional rural transformation and development. We detect the spatio-temporal distribution characteristics of rural industrial land since the new millennium. The results show that: (1) From 2000 to 2016, the area of rural industrial land in Jiangyin City increased significantly, with a net increase of 2 543.28 hm2; The concentration of rural industrial land distribution characteristics increased continuously and the regional differences were significant; the main traffic road has gradually strengthened the layout of rural industries, and the directivity of rivers and townships to the layout of rural industrial land declined. (2) The intensity of rural industrial land expansion was high in the north; the rural industrial land in each township experienced different expansion degrees from 2000 to 2016, with an annual expansion index between 0.46% and 1.12%. (3) The expansion mode of rural industrial land was mainly contagious mode, supplemented by shrinkage and filling mode, accompanied by partly enclave mode. The intensity of rural industrial land expansion affected the expansion mode. Excessive expansion intensity inhibited the spread of rural industrial land. The spread and filled expansion area of rural increased industrial land with the weakening intensity.

Huangshan City, which is located in Anhui Province, China, was selected as the pilot of eco-compensation mechanism in 2012. Difference-in-Difference (DID) method is taken to analyze whether the mechanism offsets the decline on economic, which is caused by ecological protection in Huangshan City. The results show that, ecological protection reduces the per capita GDP in Huangshan City at the level of 2.93%, regardless of the compensation from the government. In addition, the policy reduces the lagged value of per capita GDP at the level of 2.15%. Further studies suggest that, changes in industry structure could explain for the consequence. The proportion of secondary industry has been declining, while the value of tertiary industry fails to make up the opportunity cost that Huangshan City paid for ecological protection. From the perspective of policy evaluation, the implement of watershed ecological protection is at the cost of sacrificing the benefit of the upstream area. Besides, the eco-compensation mechanism could not take effect immediately and completely. Therefore, attention should be paid to the balance of economic, ecological, and society during the development of environmental governance.

The analysis of spatial differentiation and it’s influence factors of traditional villages can provide theoretical support for the overall protection and zoning protection of traditional villages, and also provide a scientific basis for formulating protection policies. Taking 550 traditional villages in Hunan, Hubei and Jiangxi Provinces as research objects, this paper use the methods of spatial analysis and mathematical statistics to analyse the spatial differentiation and it’s influence factors of traditional villages. The research is carried out from two scales of prefecture and county. The results showed that the traditional villages in Hunan, Hubei and Jiangxi Provinces are characterized by widespread distribution and partial concentration. The distribution pattern is a type of agglomeration and the agglomeration characteristics of county scale are more obvious than prefecture scale. The plain of Jianghan-Dongting lake is a low-low agglomeration district and the distribution of traditional villages is sparse. The number of traditional villages is positively related to the average elevation and average annual rainfall. It is negatively correlated with river density, average annual temperature, highway density, urbanization rate, per capita GDP and population density. The average elevation, highway density have a significant impact on the distribution of traditional villages at the prefecture scale. The average annual temperature, average annual rainfall and per capita GDP have a significant impact on the distribution of traditional villages at the county scale. The natural geographical factors are the environmental basis for the formation of traditional villages, and affect the preservation of traditional villages by affecting social and economic activities in Hunan, Hubei and Jiangxi Provinces.

Based on the PSR (Pressure-State-Response) model, the evaluation index system of poverty alleviation process in counties at deep poverty levels is constructed. The entropy method is used to quantitatively analyze and comprehensively evaluate the poverty alleviation process, such as poverty alleviation pressure, poverty alleviation and government response. This paper takes Sichuan Province as an example for empirical analysis. Results show that: (1) By 2020, the goal of alleviating poverty in Sichuan’s counties at deep poverty levels will have been achieved; (2) Counties at deep poverty levels are different in endowments to which poverty alleviation is closely related and in poverty-alleviating progress, and the poverty alleviation process showcases the distributional feature of “concentration and dispersion”. (3) Inside counties at deep poverty levels, the process of poverty alleviation is uneven. Poverty alleviation faces potential challenges. Counties with better endowments should accelerate the transition from poverty alleviation speed to poverty alleviation quality, and introduce risk identification and prevention mechanisms, while paying special attention to “temporary poverty alleviation” trap, as well as putting emphasis on stabilizing poverty alleviation, consolidating poverty alleviation outcomes and poverty alleviation quality. The Liangshan Yi Minority Area with weak endowments still needs to focus on poverty alleviation speed at this stage, relying on the pro-poor effect of economic development to break the deep-level poverty trap. While focusing on supporting counties at deep poverty levels, it is also necessary to subdivide the internal differences in this area, avoiding the “averageism” tendency and action convergence, and improving policy targeting.

The Gan-Jiang River is an important tributaries in the mid-lower reaches of the Yangtze River (Chang-Jiang in Chinese), and its aquatic ecological security is directly related to the sustainable and green development of the Yangtze River Economic Belt. In recent years, however, impacts from multiple human activities have been increasing in the Gan-Jiang River Basin. In this paper, we reviewed related literature by December 2017 and synthesized the current situation of aquatic environment, fish resources, and human disturbances in the Gan-Jiang Basin. We found that the current aquatic environment of the Gan-Jiang Basin was in moderate pollution, organic pollutants increased but inorganic pollutants did not change significantly. A total of 124 fish species, belonging to 10 orders and 32 families was recorded. According to the statistics of fish resources in the past 10 years, there are 7 orders, 35 families, 120 fish species in the Gan-Jiang River Basin, including 22 fish species of 4 orders and 14 families in the upper reach, 82 fish species of 6 orders, 28 families in the middle reach, and 91 fish species of 7 orders, 28 families in the lower reach. In the whole basin, a total of 33 fish species have not been found over the past ten years, such as Acipenser sinensis, Macrura reevesi, Coilia ectenes, Fugu oceliatus, Oryzias latipes, A. taenisnalis, A. barbatulus, E. oxycephaloides, Toxabramis swinhonis, P. semifasciolatus, and Pseudogrinocheilus  prochilus. The three major human disturbances were hydropower dams construction, industrial and agricultural pollution, and navigation, and sand mining. These activities led to an increase in nutrient and organic pollutants in the water column, degraded aquatic habitat, and then threatened fish survival. With the planning and construction of several more mega hydropower dams, we suggest that more related studies should be conducted to assess the impacts of hydropower development on aquatic environment and fish resources, initiate ecological restorations, strengthen habitat protection, control water related activities strictly, improve the ecological compensation system, and secure green development in the Gan-Jiang River Basin.

Phytoplankton community characteristics are a basic information of aquatic ecosystems. The Three Gorges Reservoir (TGR) is an important area of environmental protection in the Yangtze River Economic Zone, however the basic information for the phytoplankton community characteristics in the whole reservoir and the influencing factors are rarely reported. To fill this gap, the field survey, including 17 transects (51 sites) in 484km main channels of TGR and 22 tributary bays (122 sites), was carried out in April 2015 to investigate the fundamental information of the water environment and phytoplankton community. A total of 61 species, belonging to 39 genera in 7 phyla were identified. Specifically, for the richness, Chlorophyta (26 species) is the most important component, accounting for 42.62% of the total species number; followed by Bacillariophyta (16 species) for 26.23%, and Pyrrophyta (7 species) for 11.48%. For abundance, Bacillariophyta dominated in all phyla, accounting for 34.26% of the total abundance; followed by Cryptophyta for 23.72%, and Cyanophyta for 20.96%. For biomass, Pyrrophyta is the most important component, accounting for 44.18% of the total biomass; followed by Cryptophyta for 29.92%, and Bacillariophyta for 14.32%. The abundance and biomass of phytoplankton for each site in the Three Gorges Reservoir ranged from 2.22×104-5.12×107 cells/L and 0.001 8-120.99 mg/L, respectively. In addition, we found that i) both the values of abundance and biomass were increasing from the dam of TGR to the upper reache of the Yangtze River ii) the Shannon-Wiener diversity index of phytoplankton in the tributary bay was significantly higher than that in the main channel (Mann-Whitney U test, P < 0.001). Further, redundancy analysis showed that water temperature and dissolve silicate were the main environmental factors affecting the phytoplankton community in the main channel (P < 0.001); while, nitrate and water temperature  were the main factors determining phytoplankton community in the tributary bays (P = 0.002). The results of this study give us a comprehensive understanding of the community structure of spring phytoplankton and the influencing factors in the TGR. Meanwhile, it also has some values for ecological protection and water resources management for the TGR.

To enrich awareness of ichthyotoxic fishes for people, the species, distribution pattern and feeding habits of ichthyotoxic fishes in the Jialing River were studied according to our 8 years investigation results and the existed data. 18 species from 17 genera, 6 families and 4 orders of ichthyotoxic fishes were found in the Jialing River. With the changes of the taxonomy level (from order, family, genus to species), the proportion of ichthyotoxic fishes decreases gradually. Coreius guichenoti and Siniperca chuatsi are absent in the upstream, but the other ichthyotoxic fishes were distributed in whole mainstream of the Jialing River. Analysis of the Jaccard’s similarities indicated that ichthyotoxic fishes were homogeneous distributed in upstream, midstream and downstream in the Jialing River. No significant difference (p>0.05) were found for the distribution pattern of ichthyotoxic fishes by Chi-test. There were two species of ichthyootoxic fishes, one species of ichthyohemotoxic fishes, nine species of ichthyogallotoxic fishes and seven species of acanthotoxic fishes among the 18 ichthyotoxic fish species. The catfish (Silurus asotus) belongs to both ichthyootoxic and acanthotoxic fishes. The ichthyogallotoxic fishes were all from Cyprinidae (Cypriniformes). No ichthyocrinotoxic fishes were found in the Jialing River. Seven trophic guilds were included of the 18 ichthyotoxic fish species, the omnivorous and carnivorous were the dominant trophic guilds, accounting for 38.89% and 33.33% of the ichthyotoxic fish species, respectively. According to our study, we can know that ichthyotoxic fishes are widely distributed in the Jialing River, and there are many species and categories of the ichthyotoxic fishes were found. This study has promoted the understanding of ichthyotoxic fishes and laid the foundation for further study of them in the Jialing River.

In order to study the reproductive status of drifting egg-producing fish in the lower reaches of Jinsha River, and to provide scientific basis for the fish conservation, the fish resources surveys of early life history stage were carried out in the Qiaojia section, the lower reaches of the Jinsha River during May to July in 2017 and 2018. The results showed that there were at least 14 species (subspecies) of fish bred in the lower reaches of the Jinsha River, including 12 species with drifting egg and 7 endemic fishes in the upper reaches of the Yangtze River. The amount of drifting eggs laid by fish was estimated 6 949.73×104  individual in 2017 and 11 056.17×104  ind. in 2018, among which 3 861.44×104 ind and 5 338.16×104  ind was produced by the endemic fishes, respectively. Five peaks of spawning activities (two in 2017 and three in 2018) were detected during the surveys, with a spawning amount of 7 942.02×104 ind, accounting for 42.67% of the total spawning scale in two years. Pearson Correlation analysis showed that the discharge of fish eggs was significantly and positively correlated with water temperature (p < 0.01) in 2018. The peaks of spawning activities for the endemic fish species such as Coreius guichenoti, Leptobotia elongata and Jinshaia sinensis all appeared when the flow velocity increased. The spawning grounds of fish with drifting eggs ranged from the reaches of Qiaojia County to Panzhihua City. Specifically, In 2017, the spawning sites mainly located in the reaches of Qiaojia County, Huize, Huidong and Jiaopingdu. Besides, Wuding section was found in 2018 as well.Compared with the previous results, our study indicated that the spawning egg abundance maintained stable and spawning grounds were more disperse in the lower reaches of the Jinsha River although the number of endemic fish species increased in our surveys.It is suggested that the study on resources of drifting eggs in the lower reaches of Jinsha River should be strengthened, especially on artificial propagation technology of endemic fish species. Meanwhile, ecological operation of dams should be conducted scientifically, which, particularly, are suitable to meet the demand of fish spawning in the lower reaches of the Jinsha River.

Referring to the provincial panel data from 2002 to 2016, we took non-point source pollution caused by chemical fertilizer, non-point caused by farmyard manure, carbon emission during irrigation process and pesticide loss as the undesired output in the agricultural water resources utilization process. We constructed a water resources analysis framework centering on blue water and green water, and investigated the green technology progress of China's agricultural water resources utilization process by employing the SBM model and the Malmquist-Luenberger index. Moreover, adopting the spatial panel model, it examined the influences of the green technology progress and the agricultural economic development level while utilizing the water resources on the pollutant emission. The results showed that non-point source pollution caused by chemical fertilizer and pesticide loss all showed the characteristics of spatial aggregation. Given same input and desired output, promoting the green technology progress in agricultural water resources utilization could alleviate agricultural pollution. The environmental technology efficiency regarding the pesticide loss as the undesired output was more effective in reducing environmental pollution. The relationship between the agricultural economic development level and the aforementioned four types of pollution emissions were as follows respectively: inverted N-type, inverted U-type, N-type and inverted N-type. With the agricultural economy develops, most areas in China are still in the rising stage of inverted N-type use of pesticides and chemical fertilizer, and the situation of pesticide loss pollution and non-point source pollution caused by chemical fertilizer are exacerbating. The separation caused by agricultural economic development level and non-point source pollution caused by farmyard manure has gradually disappeared, while the carbon pollution generated by agricultural water resources utilization is unoptimistic.

Based on the data of chemical fertilizer application intensity and recommended amount of formula fertilizer, the paper used environmental risk assessment model to evaluate the environmental risk of chemical fertilizer application of three major food crops in 2016 in China. The results showed that: (1) The phenomenon of chemical fertilizer over-application existed generally in three major food crops in China, and there was a significant difference in the degree of excessive application of nitrogen, phosphorus and potash between different regions. The spatial scope and degree of excessive application of chemical fertilizer of wheat and maize were higher than that of rice on the whole. (2) The environmental risk of chemical fertilizer application among three major food crops demonstrated significant different patterns of spatial distribution in China, and the regions which were at the same risk level showed certain spatial proximity. (3) The environmental risk of chemical fertilizer application for three major food crops in China was generally low, but the environmental risk of wheat planting in Inner Mongolia, Xinjiang and Jiangsu and maize planting in Inner Mongolia, Gansu and Hubei had reached a moderate or severe risk level, which should be the focus of attention. Targeting at the current problems of chemical fertilizer over-application in China, the government should speed up the popularization and application of formula fertilizer for three major food crops, introduce policies and measures to encourage enterprises to produce formula fertilizer according to large formula, guide enterprises to sell the formula fertilizer in suitable areas, formulate subsidies policies to improve farmers' enthusiasm for selecting formula fertilizer, and carry out scientific guidance and technical services to improve farmers' scientific fertilization ability and cognitive level.

The study of regional symbiosis ecosystem with the regulation of food chain material flow as the core is an important research content in the field of sustainable development. Based on the material flow analysis method and system dynamics modeling platform, evaluation framework for nitrogen flow effect in regional food chain was constructed. Nitrogen flow in regional food chain was analyzed and simulated in Qingpu district of Shanghai. The results indicate that: (1) From 2000 to 2014, the input and output of food chain nitrogen experienced a sharp decline to gradually stable process without regional self-sufficient in nitrogen products. (2) Under the baseline scenario, the negative effects of nitrogen flow in food chain on environment are generally small, but the agricultural production capacity in 2020 can not meet the demand of local population for nitrogen in meat and aquatic products. (3)Under the optimized scenario, the input of fertilizer nitrogen was reduced by 53.75%, and the agricultural production met the consumption needs of the local resident population. The amount of nitrogen products in outside region was reduced by 2 245.16 t, the comprehensive nitrogen cycle efficiency was increased to 25.54%, and the impact of agricultural production on water environment was reduced. The optimized scheme not only guarantees food security, but also protects the environment from the impact of intensive agricultural production. The research results can provide methods and ideas for nitrogen nutrient management in regional food chain.

The farming willingness of rural youth is highly related to the development of agricultural management, to the training of novel skilled farmers and to the national food security of China. Based on the data of 597 questionnaires obtained in Henan Province, we explore the farming willingness and its impact factors of rural youth in the near and long term, respectively. We use the push-pull theory as well as the binary logistic regression analysis model in this work. The results show that the farming willingness of rural youth will decrease in the far future compared with the results in recent years. There are similarities and differences between the short-term and long-term reasons of the “two generation” farming willingness. The farming experience, family type and life stress in the rural aeras have significant effect, along the same direction, on the short-term and long-term farming willingness of rural youth, while the requirements of farming skill and daily family expenditure have influence on the short-term and long-term farming willingness with opposite directions. However, some factors only affect the farming willingness of short-term or the long-term farming willingness of rural youths. Factors such as peasant household characteristics and rural thrust play an important role in both the short-term and long-term farming willingness of rural youths. In addition, the pull force in rural areas has a significant effect on the short-term farming willingness, while the pull force in urban areas has a significant effect on the long-term farming willingness. According to the impact factors of the farming willingness of rural youth, we show some specific policy suggestions to provide comments for local governments to formulate their policies.

Based on the survey data of rural households in the contiguous area of Liupan Mountain, the paper comprehensively considers the bias and heterogeneity of sample selection, and analyzes the transfer decision to the household poverty index and the per income. The results show that: 52.97% of households participated in the transfer of agricultural land. The land transfer can significantly reduce the multidimensional poverty index of peasant households. Through further counterfactual hypothesis research, it was found that if the households who rent out the land do not rent out of farmland, the household’s multidimensional poverty index will increase by 22.16%. If the non-transferred households have the opportunity to rent out the land, the household’s multidimensional poverty index will drop by 30.22%. Although land transfer can reduce the family’s multidimensional poverty index, it is constrained by the ideological consciousness of relying on the land for the livelihood. Concentrated farmers in contiguous destitute areas cannot make reasonable decisions.

To address the problem of changes in river water and sediment fluxes into the ocean, the Yangtze River was used as a subject of this study based on the field measurements of water, sediment and rainfall data at Datong station and its components from 1950 to 2017. By analyzing the processes of changes of the water and sediment entering the ocean and the various components and their contributing ratios, the principal contributing components were determined, and the trends of changes in water and sediment fluxes into the ocean were predicted. The results show that: (1) The annual runoff of each component and the rainfall had not changed much for many years, and as a consequence, the change in annual runoff from Datong station into the ocean had been unobvious. The contribution of Yichang station to the annual runoff to the ocean was 48%. (2) The intra-annual process of water flux from Datong station into the ocean gradually became more evenly distributed, with Yichang station as the primary contributing component, and the average contributing ratios during the flooding and low water seasons were 233.79% and 80.36%, respectively. The primary contribution of Yichang station reflects the smoothing effect of the upstream cascade reservoir group on the process of water flux from Datong station to the ocean. (3) Basin reservoir construction tends to maintain the flattening effect on the intra-annual process of water flux from Datong station into the ocean and the stabilization of the annual runoff. (4) The annual sediment load at Datong station had decreased significantly since 1985. The sediment at Datong station was primarily from Yichang station before the impoundment of the Three Gorges Reservoir, and the contributing ratio was 116.04%. After the impoundment of the Three Gorges Reservoir, the sediment at Datong station was mainly replenished from the riverbed along the reach between Yichang and Datong, and the contributing ratio was 53.29%. The gradual reduction in riverbed replenishment downstream of the reservoir and the prolonged reservoir sedimentation time are expected to prevent the average sediment load entering the ocean from exceeding 1.5 × 108 t/a for a long period of time (> 300 years).

Eutrophication is an urgent problem faced by lake manager，it is necessary to study lake eutrophication and its limited factors for lake management. In order to assess the eutrophic status and understand its influencing factors, field investigation of water quality was carried out at 109 sampling sites in five impounded lakes (Lake Gaoyou; Lake Hongze; Lake Luoma; Lake Nansi; Lake Dongping) in the east route of South-to-North Water Transfer Project in April 2018 (water non-diversion) and October 2018 (water diversion) separately. Water samples were collected for determination of permanganate index (CODMn), total nitrogen (TN), total phosphorus (TP) and chlorophyll a (Chl a), and transparency (SD) was measured in situ．The comprehensive trophic level index TLI (∑) was used for eutrophic status assessment, and multivariate statistical analysis was used to analyze the eutrophication characterization and limited factors. The results indicated that water quality parameters were varied among impounded lakes in the same water period, and water quality of impounded lakes in water non-diversion period was better than that in water diversion period, which were mainly affected by total nitrogen and total phosphorus. The comprehensive trophic level index of Lake Gaoyou, Lake Hongze, Lake Luoma, Lake Nansi and Lake Dongping were 54.43 and 49.74、55.00 and 48.50、54.14 and 38.30、53.41 and 40.57、52.86 and 40.77, implying that these lakes were light eutrophication level during water diversion and mesotrophic level during water non-diversion. The correlation coefficients between TLI and SD and Chl a were -0.51 and 0.46 in water diversion period and -0.73 and 0.82 in water non-diversion period, indicating that SD and Chl a were the limited factors for eutrophication of implouded lakes.

The concentration and distribution of soil heavy metals in the peri-urban ecosystem and their transfer and enrichment features in the soil-plant systems are key issues in soil security. In this study, Fritillariae Thunbergii Bulbus was selected to study the heavy metal migrations in soil-plant system. The concentrations of heavy metals including Cr, Cu, Zn, As, Cd and Pb in soil and plant samples were analyzed in Zhangxi watershed of Yangtze River Delta in eastern China. Results of this study showed that average concentrations of Cu, Zn, As, Cd and Pb in cropland soil were higher than the background values of soil in Ningbo. The spatial distribution of heavy metals had high spatial variability and varied with different heavy metal types. Comparison of heavy metal concentrations in different tissues of Fritillariae thunbergii showed that concentrations of heavy metal in leaves and stem were significantly higher than those in bulb. The concentrations of heavy metal in leaves were 5~10 times than those in bulb. This suggested that leaves of Fritillariae thunbergii was more likely to absorb heavy metals than bulb. Analysis of transfer factor in Fritillariae thunbergii plant indicated that Cr, Cu, Zn, As, Cd and Pb were mainly enriched in aboveground tissues. The migration and enrichment abilities of heavy metals in soil-plant system were varied with metal types. Results also showed the aboveground tissues had low enrichment ability for Cr, As and Pb, but had strong enrichment ability for Cu, Zn and Cd. Both the low migration and enrichment abilities of heavy metals in bulb and the integrated pollution evaluation showed the bulb was not contaminated by soil heavy metals.

Under the influence of topographical factors, the spatial characteristics of the vegetation system in the western Sichuan plateau are obviously different in the vertical direction. Taking MODIS EVI remote sensing data as the vegetation dynamic monitoring index, the variation law of EVI along the elevation gradient in the western Sichuan Plateau from 2000 to 2015 was analyzed. Then based on the air temperature and precipitation data from 39 meteorological stations in and near the western Sichuan Plateau, the response of vegetation EVI to climate change was studied. The results showed that: (1) In the recent 16 years, the vegetation EVI showed a fluctuated increasing trend with a rate of 0.8%/10 a and increased along the altitude gradient at first and then decreased. The vertical distribution was significantly different. (2) The change trend of vegetation EVI in the western Sichuan Plateau is in a stable state as a whole, and the improvement area is more than the degenerated area. In the low altitude area (<1 000 m), the vegetation EVI degenerated seriously due to the disturbance of human activities. In the middle altitude, the hydrothermal conditions are sufficient, which is conducive to vegetation growth, and the vegetation is gradually improved, but some local area is slightly degraded. In the high altitude area (>4 000 m), the fluctuation of vegetation EVI is relatively low, and the EVI tends to be stable. (3)Vegetation EVI changes in different altitudes are affected by climate in different ways. The growth of vegetation in the high-altitude area of the western Sichuan Plateau is mainly controlled by temperature, while that in the medium-altitude area is greatly affected by precipitation. (4) At the significance level of 0.05, the vegetation EVI change in the western Sichuan Plateau is driven by non-climatic factors with a wide area distribution of about 84.22%, while the proportion of area driven by climate factors is 15.78%. And the driving force of air temperature on vegetation growth and distribution is stronger than precipitation.

The total nitrogen (TN) and total phosphorus (TP) contents in the lake water are widely used to estimate the eutrophication levels of the lakes. However, the laboratory analyses results might be not always reliable and accurate because the analyses procedures are often affected by many factors, i.e., the storage method, duration and conditions, especially when a large number of water samples need to be analyzed. To the TP and TN content analyses of the lakes that mostly developed in Karst area in Yunnan, especially to the large lakes and remotely located lakes, the long transportation distance and large water sampling numbers make it difficult to complete the analyses in a limited time duration. Considering theses actual situations, we selected the Lake Fuxian, in that with a very low TP and TN contents, the Lake Yangzong with a middle level of TN and TP contents, and also Lake Dian (Dianchi) with a relatively high TN and TP contents, to test how the TN and TP contents, and also the dissolved TN and TP would change when the water samples are transported and stored under low-temperature condition. Then to fix the optimal storage time to complete the laboratory analyses procedures. The test results indicate that: 1. The total nitrogen and phosphorus contents of the water sample that obtained immediately after sample taken from Dianchi is the highest, of which the TN content is 2.44  mg/L, with the dissolved nitrogen content is 1.47 mg/L that accounting for 60% of total nitrogen, and the TP content is 0.13 mg/L, with the dissolved phosphorus content is 0.02 mg/L that accounting for 15% of total phosphorus. To the water samples taken from Lake Yangzong, the TN contents is 0.73 mg/L, with the dissolved nitrogen content is 0.60 mg/L, accounting for 82% of the TN, the TP contents is 0.04 mg/L, with the dissolved phosphorus content is 0.03 mg/L, accounting for 75% of the TP. The water samples taken from Lake Fuxian show the lowest TN and TP contents, with the TN content of 0.32 mg/L and dissolved nitrogen content of 0.28 mg/L, that accounting for 90% of the TN, the TP contents is 0.02mg/L, with the dissolved phosphorus content of 0.01 mg/L, accounting for 50% of the TP. 2. Along with the low-temperature storage duration increase, the TN and TP contents of the water samples decrease. The total nitrogen and total phosphorus contents of the water samples taken from Lake Yangzong and Dianchi decrease more than that from Lake Fuxian. 3. With the filtration pretreatment procedure, the TN and TP contents in the lake water samples taken from Lake Yangzong and Dianchi also show a significant decrease, but the difference is not so much in the water sample taken from Lake Fuxian. Our findings indicate the storage duration exert a stronger impact on the higher eutrophication level lake water than that on the lower eutrophication level lake water.In particular, on the water samples with higher contents of detrital nitrogen and phosphorus. Our study result suggests that due to the existence of various forms of nitrogen and phosphorus in water samples and the different nutrient levels in lakes, the storage duration and the occurrence state of nitrogen and phosphorus should be considered when determining the nitrogen and phosphorus contents of water samples.

The vegetation ecosystem of the Qinghai-Tibet Plateau is very sensitive to climate change. In this study, the spatial-temporal evolution patterns of net primary production (NPP) and its driving mechanisms in the Qinghai-Tibet Plateau from 2000 to 2015 were analyzed and discussed by using the gravity center model and other relative models. Subsequently, the relative effects of climate change and human activity on the process of NPP change were quantitatively distinguished. The results have been listed. (1) From 2000 to 2015, the annual mean NPP in the Qinghai-Tibet Plateau showed a decreasing trend from southeast to northwest. In terms of interannual changes, the annual mean NPP of different subregions showed a fluctuating upward trend. (2) During the past 16 years, the gravity center of NPP in the Qinghai-Tibet Plateau moved southwest indicating that the increment and growth rate of NPP in the southwestern part were greater than those in the northeastern part. (3) The regions with significant correlation between NPP and precipitation were mainly located in the central and southeastern parts of the Qinghai-Tibet Plateau and the middle and lower reaches of the Yarlung Zangbo River Basin. The regions with significant correlation between vegetation NPP and temperature were mainly located in southern Tibet, northern Hengduan Mountains, and central and northern Qinghai-Tibet Plateau. (4) The relative effects of climate change and human activity on the process of NPP change in the Qinghai-Tibet Plateau had significant spatial-temporal differences with a spatial pattern of “four lines-five regions.” The research results can provide theoretical and methodological support to reveal the response mechanism of regional ecosystems to global change in the Qinghai-Tibet Plateau.

Extreme precipitation events have the characteristics of low probability and high risk. The use of high resolution dataset is helpful to understand the real situation of extreme precipitation. Based on the dataset of China's hourly precipitation from 1961 to 2013, the characteristics of the intensity and frequency of extreme precipitation in China were analyzed by various mathematical statistics methods. The results showed that: Firstly, the intensity of hourly extreme precipitation in China at different return periods had obvious spatial differentiation characteristics of high in southeast and low in northwest. The hourly extreme precipitation thresholds in China under different percentiles also had the spatial differentiation characteristics of high in southeast and low in northwest. Secondly, the trend of hourly extreme precipitation frequency in China from 1961 to 2013 under different percentiles were mainly increasing, and with the increase of percentiles, the increasing trend tended to decrease and concentrated in the Yangtze River Basin. The fluctuation of hourly extreme precipitation frequency in China showed a spatial pattern of small fluctuation in the southeast and large fluctuation in the northwest. With the increase of percentiles, the areas with large fluctuation expanded from the northwest to the east and south, while the western areas gradually showed a mosaic pattern of fluctuation small and large. EOF analysis of China's hour extreme precipitation frequency under 90% and 95% percentile showed that the hourly extreme precipitation frequency in China had distinct temporal and spatial variation modes, and the first two modes could reflect the main temporal and spatial variation modes of the hourly extreme precipitation frequency in China. The two methods of super threshold sampling reflected the temporal and spatial characteristics of the Yangtze River Basin.