As an important part of the national environmental governance and supervision system, government environmental audit is of great significance to promote the green development of the Yangtze River Economic Belt. Taking 110 prefecture-level cities in the Yangtze River Economic Belt as the research scale, the green effect and mechanism of government environmental audit were tested from multiple perspectives. The research showed: (1) Government environmental audit has a significant direct effect on the green development of the Yangtze River Economic Belt, and the breadth of government environment audit is slightly greater than the intensity of government environmental audit; (2) The green effect of government environmental audit in upstream and downstream basins is better than that in midstream basins, and the green governance efficiency of government environmental audit in non-key environmental protection cities is higher than that of key environmental protection cities. In the strengthening phase of the government’s environmental audit work after 2009, its service performance was better than the previous phase; (3) Local government competition, green technology innovation, and industrial structure upgrading are the three major mechanisms for government environmental auditing to indirectly promote the green development of the Yangtze River Economic Belt. The indirect promotion of the intensity of government environmental audit is higher than the breadth of government environmental audit, and the green governance effect exerted by the green technological innovation mechanism is even higher.

It is very important to explore the coordinated development between industrial ecologicalization and ecological industrialization for promoting the high-quality development of the Hanjiang River Ecological Economy Belt, at the background of improving the level of ecological environment governance across the whole country. This paper takes nine cities of Hanjiang River Ecological Economy Belt as the research object， and adopts entropy method and coupling coordination model to measure the level of industrial ecologicalization and ecological industrialization, according to the data from 2011 to 2019. The evolutional features of coupling and coupling coordination degree of industrial ecologicalization and ecological industrialization are analyzed by using the method of GIS. The study shows that: firstly, the overall level of industrial ecologicalization is on the rise, the pattern of gradient distribution gradually indicates ongoing increase in upper, middle and lower reaches of Hanjiang River Ecological Economy Belt. Secondly, the level of ecological industrialization shows a steady growth, the pattern of gradient distribution presents gradually diminishing in upper, middle and lower reaches of Hanjiang River Ecological Economy Belt. Thirdly, the coupling degrees of industrial ecologicalization and ecological industrialization are on the rise，the coupling type is in the transition from runin stage to highlevel stage. Fourthly, the couplingcoordination degrees of industrial ecologicalization and ecological industrialization are showing a rapid growth, the coordination type has been developed from reluctantly couplingcoordination to good couplingcoordination. Suggestions are put forward including boosting the green development of agriculture and industry, constructing a multiplelevel system of resource saving and reusing, and elevating the coordinated development between industrial ecologicalization and ecological industrialization in Hanjiang River Ecological Economy Belt synergistically.

As the largest strategic freshwater resource bank and an important ecological barrier in the upper reaches of the Yangtze River, the Three Gorges Reservoir faces dire challenges in terms of uncoordinated water resources utilization and supple and demand imbalance of water resources. Water resources carrying capacity is an important index of measuring the sustainable development in a region. Studying the features of dynamic water resources carrying capacity in the Three Gorges Ecological and Economy Corridor of the Yangtze River can go a long way towards promoting water conservation and ecological civilization construction across the reservoir area. Adopting entropy weight method and the TOPSIS method, and based on the system theory and supplyanddemand theory, the paper conducts an analysis of the dynamic changes and regional differences of water resources carrying capacity in 11 districts and counties between 2015 and 2019. The results find that the water resources carrying capacity in the 11 districts and counties in the Three Gorges Ecological and Economy Corridor of the Yangtze River on the whole presented an upward trend, and the carrying capacity basically maintained at a low level, with the ecological subsystem and the social economic subsystem making the biggest contribution. The central and local governments play a leading role in the conservation and protection of water resources in the reservoir area. And the imbalance of supply and demand of water resources in each district has been slightly eased. As such, the paper proposes that the macro management should continue to be brought into full play to further enhance the green upgrading of the industrial structure, water resources utilization and quality government in the reservoir area.

Since China’s reform and opening up, development zones (DZs) has achieved remarkable results in promoting the growth of total economic volume. Under the background of transformation and efficiency enhancement, the realization of an economic growth model supported by total factor productivity (TFP) is an inevitable trend for the development of DZs. Improving the TFP of in zone firms has also become the basic way for DZs to achieve high quality economic development. Based on the perspective of TFP, the article uses micro-firm data to study the agglomeration status and productivity levels of firms in the development zone of Nanjing and Suzhou, and analyzes its heterogeneity. Research indicates: (1）Firm agglomeration and industrial clusters have formed in DZs of the two cities. The characteristics of firms gathering in DZs are obvious, and its agglomeration situation is increasingly strengthened. Industrial agglomeration in DZs already has a considerable scale; （2)In zone firms have certain productivity advantages. Advantages of DZs are mainly reflected in the small number of low efficiency firms and the increase of the number of high efficiency firms. In addition, there are differences in productivity levels between zones and in zone firms with different characteristics. The research aims to provide scientific reference for improving the productivity of in zone firms and promoting the transformation and upgrading and sustainable development of DZs.

The agglomeration development of rural tourism has played strong significance in stimulating rural tourism efficiency, enhancing regional tourism competitiveness, and revitalizing the development of rural industries. Under normalized epidemic prevention and control, rural tourism in urban marginal areas becomes a hotspot. Using the methods of network dimensional analysis, Ripley’s K, and kernel density analysis, this paper selects four years (2005, 2010, 2015 and 2020) and takes Wuhan as an example to analyze the evolution characteristics of spatial agglomeration pattern of rural tourism destinations in urban fringe from the perspectives of agglomeration form, agglomeration scale and agglomeration mode. Based on 2 km*2 km micro-scale unit, rural tourism spatial agglomeration factors are quantitatively analyzed geodetector, and the spatial coupling distribution of spatial agglomeration level and influencing factors are discussed. The results show that there is basic fractal feature of regional unequal probability distribution, which is linearly distributed and spreads to the periphery in Wuhan. The intensity of spatial agglomeration has a normal distribution with the agglomeration scale increasing, and the spatial scale of the peak agglomeration intensity increases from 8 km to 18 km.Spatial agglomeration evolves in a multi-core hierarchical point-axis diffusion pattern, forming multiple scale core and sub core agglomeration areas. Natural ecology, social economy, high-grade scenic spots and policy regulation factors jointly affect the spatial agglomeration pattern. According to the level of explanatory power, the influencing factors are high-grade scenic spots, road network density, distance around the city, river system, population density, mountain resources and land use types. Among them, natural factors lay the resource foundation of spatial agglomeration, social and economic factors affect the market size of spatial agglomeration, high-level scenic spots are the core growth pole of spatial agglomeration, and government regulation strengthens the regional grounding of the agglomeration. The influence of the two-factor interaction is higher than that of the single-factor, resulting in two effects of nonlinear enhancement and two-factor enhancement. In addition, policy regulation factors play a role in enhancing the “embeddedness of agglomeration areas”.

Research on the change trend and sustainability of farmland productivity is of great significance for the assessment of the requisition-compensation balance and the sustainable use of farmland resources. In the past 20 years, afforestation projects and urbanization have had important impacts on the distribution and productivity of farmland in the Han River Basin. Based on time series land cover and MOD17A3 NPP datasets derived from the Google Earth Engine cloud platform, this study investigated the spatial and temporal change trends, stability, and sustainability of net primary productivity (NPP) of farmland in the Han River basin from 2001 to 2019 using trend analysis, coefficient of variation, Hurst index, and GIS spatial analysis. The state of requisition-compensation balance for farmland productivity and their regional differences in the Han River Basin were discussed as well. Firstly, the farmland NPP generally showed a fluctuating upward trend in the Han River Basin from 2001 to 2019, and the growth trend from 2001 to 2010 was significantly faster than that from 2011 to 2019. Secondly, the farmland NPP in the Han River Basin showed a distribution pattern of high in the west and low in the east. 79% of the farmland had NPP values between 400 and 600 g C·m^-2·a^-1, which was concentrated in the valley basins of middle and upper reaches. Moreover, 53.20% of the farmland presented a significant increase in NPP and was mostly distributed in the valley basins of upper-middle reaches and the Nanyang Basin, while only 1.06% of the farmland got a significant decrease in NPP. Thirdly, farmland areas having a stable change in NPP were mainly concentrated in the upper valley basins and the lower reaches such as Jingmen and Yingcheng, while unstable areas were mostly located in Yunyang, Xiangyang and the urban expansion areas of the downstream urban expansion areas of Hanchuan, Tianmen and Wuhan. Furthermore, farmland NPP in the Han River Basin will be in a continuous increasing trend in the future. Besides, 0.56% of the farmland in the Han River Basin was transferred in and 4.70% was transferred out from 2001 to 2019, with significantly less farmland transferred in than transferred out. Farmland productivity in the Han River Basin and its third-level sub-basins all showed a more significant negative balance of requisition and compensation, and was most prominent in the Tangbai River Watershed.

The standard and apportionment responsibility are the core issues of cross-basin ecological compensation. Based on the principle of “who benefits, who compensates”, the ecological compensation model is established from the perspective of water quality and water quantity, which provides the compensation standard for Danjiangkou reservoir area. Then, the total amount and the amount of ecological compensation that should be borne by each water-receiving area are calculated and a two-way ecological compensation mechanism between the reservoir area and the water receiving area is established. The results show that: (1) The total ecological compensation required in the reservoir area from 2016-2019 is 2.879 billion yuan, and compared with the raising of special funds, there is a gap of 575 million yuan; (2) According to the calculation results of each water receiving area, Beijing, Tianjin, Hebei and Henan bear the ecological compensation amount of 915 million yuan, 452 million yuan, 729 million yuan and 783 million yuan respectively; (3) The total amount of water compensation is 1.139 billion yuan more than the total amount of water quality compensation, and the water receiving area values water quantity more than water quality, showing a high demand for water quantity.

Promoting the green transformation of agricultural production with the marketization of factors is an important way to realize the development of China’s agricultural modernization. This paper, focusing on the fertilizer product market, uses survey data from 781 rice farmers in Hubei, Jiangxi, and Zhejiang provinces, to examine the impact of factor marketization on the adoption of soil testing formula fertilization technology, and the heterogeneous effects of factor marketization under different resource endowments. The results show that the promotion of soil testing formula fertilization technology in the sample areas is far behind expectations, and the adoption rate of rice farmers is only 27.5%. Then, n the dimension of factor marketization, product diversity and product availability have a significant positive impact on rice farmers’ adoption of soil testing formula fertilization technology. What’s more important, egardless of whether it is based on grouping regression based on specific endowments or general endowments, product diversity has a more significant promotion effect on rice farmers in the highlevel resource endowment group, but there is no significant difference in product availability. Thus, it is recommended to continue to strengthen the improvement of the agricultural production factor market, and give full play to the role of grassroots agricultural material distributors in product sales and information dissemination, so as to realize the coordinated development of factor marketization and green agriculture.

Based on the panel data of 108 cities in the Yangtze River Economic Belt from 2009-2018, this paper selects indicators from atmospheric environment, water environment and energy consumption to construct an environmental pollution index, and uses the location quotient index to measure the level of manufacturing agglomeration. On the basis of clarifying the mechanism of the environmental effect of manufacturing agglomeration, this paper uses benchmark regression model and threshold regression model to empirically test the impact of manufacturing agglomeration on environmental pollution in the Yangtze River Economic Belt. The results show that: (1) From 2009 to 2018, the manufacturing agglomeration level in the lower reaches of the Yangtze River Economic Belt was the highest, followed by the middle reaches, and the upper reaches was the lowest. (2) The overall environmental pollution level of the Yangtze River Economic Belt shows a downward trend, and the improvement of urban environmental pollution in the lower reaches is higher than that in the middle and upper reaches. (3) The whole Yangtze River Economic Belt and the middle and lower reaches of the Yangtze River show an “N” curve relationship between manufacturing agglomeration and environmental pollution, which first promotes, then inhibits and then intensifies. However, the manufacturing agglomeration in the upper reaches is still in the stage of aggravating pollution. We should balance the benign relationship between manufacturing agglomeration and environmental pollution, continuously increase the investment in environmental protection science and technology, strictly enforce environmental regulations, and formulate the differentiation policy of manufacturing industry agglomeration in the Yangtze River Economic Belt.

Scientific evaluation of the carrying capacity of the ecological environment was theoretical prerequisite for formulating reasonable ecological protection measures. It was of great significance to the promotion of ecological civilization construction. However, there were difficult to quantify threshold value of ecological carrying capacity and the pressure value of human activities on ecological environment. So this article was based on ecological data from 2009 to 2017 in the Yangtze River Economic Belt, Learned lessons from “Dynamic Evaluation Method of Ecological Environment Quality Index”. It was transformed the quantitative measurement value of the ecological environment carrying capacity into the study of the ecological environment carrying capacity operation status. To achieve the purpose of evaluating the carrying capacity of the ecological environment of the Yangtze River Economic Zone. The results showed that: (1) During the evaluation period, the quality of the ecological environment in the Yangtze River Economic Zone is on the rise, The ecological environment is generally in bearable state and Among the 11 provinces and cities, Shanghai, Zhejiang, Hubei, Hunan, Chongqing, Sichuan, Yunnan and Guizhou are in the loadbearing state, What’s more, the Guizhou has the largest improvement in Ecoenvironmental quality index, reaching 86.844. Jiangsuand Jiangxi provinces are in overload condition, while Anhui province is in the basic state of carrying capacity. (2) Per capital GDP, tertiary industry, science and technology investment accounted for the proportion of GDP, environmental governance investment, green area, and the ecological environment quality index of the Yangtze River Economic Belt increased and decreased at the same time, and the impact was large, respectively 7.33, 6.92, 8.28, 6.71, 7.21. (3) The natural population growth rate, urbanization level, population density, energy consumption per unit of GDP, and power consumption per unit of GDP are negatively correlated with the Ecoenvironmental quality index of the Yangtze River Economic Zone. Among them, energy consumption per unit of GDP and power consumption have the greatest negative impact on environmental quality. It is 6.57 and 6.26.

Air quality is closely related to human health and sustainable social and economic development. It is of important theoretical and empirical significance to explore the factors affecting the changes in air pollutant concentration in the context of different land use patterns. This study took the middle reaches of the Yangtze River as an example. We adopted a spatial regression model, in which we used forestland coverage as the benchmark factor, and took the forestland landscape pattern as the key factors to explore the driving mechanism of PM_2.5. Integrated with the regional socio-economic and natural conditions, we selected influencing factors from the three aspects of PM_2.5 namely source, diffusion and removal. The comprehensive influencing factors of PM_2.5 with different forest coverage were explored, compared and analyzed. The results show that: (1) The influencing factors with different forest coverage affect PM_2.5 in similar patterns, yet with different path and magnitude; (2) The spatial heterogeneity of PM_2.5 is obvious. With the increase of forest coverage, the PM_2.5 concentration is greatly reduced; (3) Decreasing the of the fragmentation degree of forest patches is beneficial to reduce the PM_2.5 concentration; (4) DEM is the main factor affecting PM_2.5. It is shown that with the increase of forest coverage, the weakening effect on PM_2.5 increase. Based on the results, it is recommended to strengthen the refined control of air pollution in the middle reaches of the Yangtze River basin according to the characteristics of different forest coverage areas, and combine the spatial spillover characteristics of PM_2.5 to strengthen joint prevention and control among the regions.

With the development of the economy and society, human beings have a strong ability to transform the structure and function of the city water environment system. In addition to natural factors, the state of the water environment is a concentrated reflection of human pollution behavior and governance behavior. To analyze the effect of the city water environment, this study takes Taihu Basin as an example. Based on the PSR model, the water environment status of each city in the basin from 2010 to 2018 is measured and its spatial correlation is tested. The study focuses on using the Dubin model to analyze the impact of social and economic development factors on the city water environment and its spatial spillover effects. The results show that the water environmental status of cities in the Taihu basin has been improved in varying degrees from 2010 to 2018. The water environmental status of Jiaxing and Shanghai, which are located in the lower reaches of the basin, is worse than that of other cities. There is a positive spatial spillover effect in the water environment between cities, which shows the phenomenon of “sharing prosperity and loss”. Population agglomeration has a negative effect on the local water environment, while economic development and foreign direct investment have a significant positive effect. In terms of the impact on surrounding areas, the negative spillover effects of population agglomeration, technological innovation and cultivated land area are significant, while the construction land area and industrial agglomeration are positive spillovers. The development of industrial agglomeration of cities in the Taihu basin tends to be more mature, which can realize the coordinated development of the economy and environment. However, the non-point source pollution from agriculture is a non-negligible factor restricting the improvement of the water environment. Finally, according to the results of the study, some policy recommendations for the improvement of the city water environment are put forward, such as strengthening cross-regional cooperative governance, guiding the city’s land developed efficiently and intensively, and improving rural water environment governance.

In order to investigate the microplastic pollution of continental fish in Shanghai, this study investigated the detective rate, abundance, physical characteristics, chemical composition and differences of microplastics in digestive tract of five fish species in Dianshan Lake, Huangpu River and Suzhou River. The results show that 845 microplastics were detected in 639 fish. The average detective rate of microplastics was 59.78%, and herbivorous fish had significantly higher detective rate than omnivorous and carnivorous fish (p<0.05). The average abundance of microplastics was 1.32±1.92 items/individual, and not only the herbivorous fish was higher than the others (p<0.05), but also the downstream, tributaries and upstream of Suzhou River were significantly higher than Dianshan Lake and the upstream of Huangpu River (p<0.05). There are four microplastics shapes were detected, fiber (80.47%), films (13.73%), fragments (4.14%) and particles (1.66%). Black, transparent, blue, red, yellow and green microplastic colors were dected, accounting for 29.59%, 28.99%, 15.86%, 10.53%, 8.52% and 6.51%. 60.12% of microplastics were smaller than 1mm. A total of eighteen chemical components types were dected. The majority of the microplastics were cellophane (39.42%), polyethylene terephthalate (20.19%), polyamide (11.54%) and ethylene-vinyl acetate copolymer (9.62%). The research shows that the microplastic pollution of fish in Shanghai's main rivers mainly comes from the packaging materials or discarded items in daily life. The average detective rate and abundance are below the medium level, which has a correlation with the pollution degree of the habitat water.

Black and odorous phenomenon of river is the most intractable environmental problem in the construction of urban ecological civilization. In order to better understand the distribution and potential sources of heavy metals in black and odorous river in Wanjiang City (Wuhu), the black and odorous river in Baoxinghan was selected as the research object. Through the outdoor collection and indoor analysis combined with the modified potential ecological risk index (MRI) method, the contamination status of heavy metals in sediments is evaluated and the correlation analysis and principal component analysis is used to explain potential sources. The results show that: (1) In the river, the content of heavy metals presents the characteristics of Fe>Zn>Mn>Cr>Cu>Cd, which is significantly higher than the soil background value in Anhui Province and Cd is the most enriched among them. Except for Cd, the other five heavy metals all show the characteristic that their content in rainy season are higher than that in dry season. (2) Morphology studies show that heavy metals tend to be desorbed from the surface of particulate matters and released into the overlying water during the rainy season and the proportion of heavy metals in the residue state increases. (3) MRI results show that ecological risk of Cd pollution accounts for the vast majority of the totals (contribution rate> 90%), so the pollution of Cd should be focused to solve. (4) The source appointment results show that Zn, Cu and Cr are affected by surrounding industrial activities, Fe and Mn are mainly affected by the mixture of natural and industrial sources and Cd is most likely to be affected by regional agricultural non-point sources. 

Tangxun Lake is the largest urban lake in China, which is greatly affected by human activities. In order to investigate the pollution status of polycyclic aromatic hydrocarbons (PAHs) in Tangxun Lake, a total of 23 surface sediment samples were collected in August 2020, and the contents of 16 PAHs were detected by GC-MS. The results showed that the concentration of PAHs in the surface sediments from Tangxun Lake ranged from 219.13 to 3917.36 ng·g^-1, with a mean of 715.58±809.80 ng·g^-1, the pollution degree of the outer lake was higher than that of the inner lake. The PAHs concentrations were significantly positively correlated with the total organic carbon (TOC) content in sediment, and the correlation between TOC and high molecular weight PAHs was more significant.The 4-6 rings PAHs were the main components in the surface sediment, accounting for 78.05% of the total PAHs, and Fla, Phe, Pyr, BghiP and Chr were the highest components. Compared with other domestic lakes, the PAHs pollution of Tongxun Lake was at a medium level. PAHs source analysis were carried out by a isomerratio method and principal component analysis and multiple linear regression (PCA-MLR), and the results showed that the PAHs were mainly originated from combustion sources (petroleum combustion, coal combustion and biomass combustion), and a small part of PAHs came from petroleum product leakage. The contribution ratio of traffic emission sources were 62.62%, and the contribution ratio of mixed sources of coal and natural gas combustion and oil leakage were 37.38%.The results of sediment quality standards(SQSs) showed that the overall level of ecological risk of PAHs in sediments of Tangxun lake was relatively low, and there were some areas with medium risk. The relevant departments should strengthen monitoring and treatment of the medium polluted areas.

The Tuojiang River watershed is located in the middle of Sichuan Basin where the human and water environment frequently interact with each other. In recent years, the water environment pollution and degradation of ecosystem services are becoming more and more seriousowing to rapid population growth, fast economic development and accelerated urbanization process lead to in this watershed. This study adopted the assignment of ecosystem service value per unit land use area and export coefficient as approaches, then estimated the ecosystem service values and pollution loads of 28 counties in Tuojiang River watershed, and finally revealed their matching relationships from spatial scale toto provide suggestions for water environmental management and ecological conservation. The results included following aspects:（1）Comparing individual pollutant emitted amounts, the COD emission was largest, TP emission was lowest, and the maximum values of COD, NH3-N, TN and TP pollution loads were 71 067.51 t, 111 08.76t, 21 320.08 t and 3 073.99 t, respectively. The distribution of pollution load had great spatial heterogeneity in this study watershed. The pollution load in the upstream was smaller, the pollution load in the middle reaches was larger, and the pollution load in the downstream was lower than that in the middle reaches.（2）The spatial differentiation of the four types of ecosystem service values in the basin was obvious. The larger ecosystem service values of provisioning, regulating, supporting and cultural ecosystem services values occurred in upstream of study watershed. The spatial distribution pattern of total ecosystem service value was very similar to that of supporting ecosystem service.（3）The spatial differentiation of the matching relationship between ecosystem service value and pollution load in Tuojiang River watershedwas also obvious.The higher values of spatial differentiation appeared in the middle and downstream of watershed. Therefore, it is necessary to build a reasonable ecological compensation mechanism and effective pollution load reduction strategies to improve the water environment and ecosystem service functions in these districts.The study on spatialrelationships between pollution loads and ecosystem services values not only deepens the understanding of the relationship between ecosystem services and pollution loads, but also enriches the research case of water environmental management in the watershed. It provide the basis of water environmental management and ecological construction. 

Coal is an important energy source, but the surface subsidence formed after coal mining, especially in the subsidence areas, has caused significant damage to cultivated and construction land on the plain areas, impacting food production, vegetation cover and the production, housing and living conditions of residents in the subsidence areas. We used Landsat MSS, TM, ETM+, and OLI images to obtain outlines of coal mining subsidence areas in Huaibei over 6 periods from 1973 to 2020 through visual interpretation. We also extracted land use information over 5 periods through supervision classification and visual correction. The spatio-temporal changes in coal mining subsidence and their impacts on landuse and vegetation cover were analyzed. Although the subsidence areas are being continuously reclaimed, the number and total area of the subsidence areas have been increasing in the past ~50 years. In 2020, there are 243 coal mining subsidence areas with a total area of ~12 000 hm². The collapsed land is mainly cultivated land, followed by construction land, and the area of collapsed cultivated land shows an increasing trend. The scale of land reclamation in the subsidence areas continues to expand. After reclamation, it is mainly used as construction land, followed by cultivated land. The collapse has caused farmers to lose their land, people to relocate, and reduction of grain production. At the same time, it also has damaged the vegetation. The results could be used to support the management, development and exploitation of collapsed land.

Existing observational evidence has revealed the characteristics of low probability and high risk in event-based extreme precipitation (EEP), which means that the occurrence of an EEP is uncertain. We identified the pattern of extreme precipitation in the Yangtze River Basin, i.e. early, after, balance-phase, and 1-day EEP. Based on the high-resolution (0.5°×0.5°) gridded daily precipitation dataset (V2.0) in 1961-2019 obtained from Chinese Meteorological Administration, we investigated the spatiotemporal variation of extreme precipitation in the Yangtze River Basin. Meanwhile, the response of EEP to ENSO (El Nio-Southern Oscillation) events during recent 59 years was analyzed by using correlation analysis. The results are as follows: (1) the early EEP in the Yangtze River Basin showed increasing and then decreasing trends, while the EEP in the after and balance-phase experienced a stable fluctuation over the past 59 years, and 1-day EEP kept growing. (2) Spatially, the pattern of early, after EEP increased from northwest to southeast across the Yangtze River Basin, and 1-day EEP shows the ‘center-periphery’ structure, which has a higher frequency in middle areas and lower in periphery areas. For the balance-phase EEP, the high-value areas are distributed in the Jinsha River and Poyang Lake Basin. (3) The EEP in the Yangtze River Basin and its subregions is positively correlated with El Nino, and the proportion is 79.2%. That is to say, while the sea surface temperature of Nino 1+2 or Nino 3.4 is abnormally high in the preceding winter, the volume of extreme precipitation for the four types in the Yangtze River basin will be increased. Moreover, EEP in the Yangtze River Basin and its subregions show a more positive correlation with Nino 1+2 than Nino 3.4. (4) For the flood induced by EEP over Yangtze River Basin in 1998, the dominant type is the early EEP. Specifically, the early EEP between July 20th to 26th was the core cause of the 1998 summer flood over Yangtze River Basin. This study can provide a reference to understand the lasting extreme precipitation of the monsoon region in China.

Based on the daily precipitation data in Hubei Province from1961 to 2018, this paper analyzed the characteristics of extreme daily precipitation events by using the Percentile method. And, it also divided large-scale circulation of the extreme precipitation events from 1981 to 2018 into three main types with the method of PCT.The results show that:（1） The distribution of the threshold of extreme daily precipitation at different levels is similar to that of its climate state in this region, which is larger in the south and east than in the north and west.And the thresholds of these two factors overlap at the center.（2）Relative to the 99 percentile and 90 percentile,95 percentile makes the greatest contribution to summer rainfall. （3）Three PCT types are obtained,which is consistent with previous research: Southwest Low Trough and Northeast high Pressure Ridge in 500 hPa，Southwest Vortex and Northeast anticyclone in low-level for Type I; Jianghuai Trough, Northeast weak Ridge in 500 hPa, Southwest Vortex and Bohai Sea anticyclone in low-level for Type II; deep Northeast Trough and shallow Southwest trough, which formed inclined trough from the northeast to the southwest in 500 hPa, Southwest cyclone and northeast cyclone in low-level for Type III. Comparing the above-mentioned three circulation types,the circulation types reflected in the extreme daily precipitation events occurred in Hubei ProvinceRiver on July 6-7, 2020, is Type III which can be offered as an subjective approach to classification and prediction of extreme precipitation events in the future.

In recent years, the problem of urban waterlogging has threatened more and more cities. The paper adopts a coupled rain and flood model to simulate the flooding state of Zhaoyang New City in Nanchang City when it encounters 1, 3, 5, 10 and 20 a rains during the return period. The complete process of the formation and recovery of urban waterlogging under different return periods of rainfall is studied, combined with the elastic analysis method, and also studies the flood resistance and recovery ability of the Zhaoyang New Town area of Nanchang City. At the same time, it analies the land use situation of the study area in three different years, and explores the impact of the development of urbanization on the defense and recovery ability of the study area after being attacked by rainfall. The results show that the development of urbanization and the increase of the return period of rainfall will lead to the reduction of the research area's ability to resist and recover from floods. The research results will help to formulate scientific and reasonable anti-disaster strategies faster and accurately in the future flood prevention and drainage work, in the meantime,it enables humanity to understand more intuitively the impact of the urbanization process on regional defense and resilience.