In the context of tightening constraints on water resources, the panel data from 2005 to 2014 of 26 cities in the Yangtze River Delta Urban Agglomeration is adopted, and SBM model is used to measure the industrial water use efficiency in this region. Then, the spatial differences of the industrial water use efficiency in the Yangtze River Delta Urban Agglomeration are analyzed by the decomposable Theil index. The results show that the industrial water use efficiency level of the Yangtze River Delta Urban Agglomeration is low: the 10years average industrial water use efficiency is 0591 8 when the undesirable outputs are not considered, and it is 0519 7 when the undesirable outputs are added. The within group difference of industrial water use efficiency is the main source of the total difference and it has the trend of increasing with time. The contribution rate of Zhejiang Province to the within group difference is the largest, followed by Anhui Province, and Jiangsu Province has the lowest contribution rate. Although the differences of industrial water use efficiency between the cities in Jiangsu Province is not very big, the overall level is still low, Shanghai’s industrial water use efficiency is a little higher and on a steady rise. Therefore, narrowing the within group differences is an important way to realize the overall increase of industrial water efficiency in the Yangtze River Delta Urban Agglomeration

How to reduce the dimension of multi-dimensional data becomes more and more important in the era of big data. The traditional method of data dimensionality reduction can not understand all the dynamic trends at the same time, therefore has certain limitations. This paper adopts the dynamic factor method designed for panel data, and take the measurement of urbanization quality of Yangtze River Delta urban agglomeration as the case to carry out the dimensionality reduction experiment of multi-dimensional social data It is found that this method can more accurately identify the “latent variables” which can affect multiple variables at the same time in multi-dimensional data, and can describe the variation trend of  “latent variable” of each individual sample along with time and that of the whole sample. Combined with the results of case study, this research found that the Yangtze River Delta urban agglomeration also exists the problem of incongruous between population urbanization and land urbanization, which needs to accelerate the construction of New-type urbanization and focus on improving the quality of urbanization.

Using the impulse response function, this paper analyzed the impact of urbanization on the institutional transformation of all the cities in Jiangsu Province between 2000 and 2015 by three dimensions (decentralization, marketization and globalization). Then three indices, the proportion of local governments’ fiscal decentralization, the proportion of the non-state-owned and non-state-controlled industrial gross outputs value in the total industrial value, and the ratio of total import and export value to GDP, were chosen to measure decentralization, marketization and globalization, respectively. The results showed that: ① Urbanization greatly promoted the improvement of decentralization in Jiangsu Province, especially for the north part of Jiangsu; ② Urbanization played a little role in marketization, but it showed a positive effect on marketization in the three cities , Suzhou, Wuxi and Changzhou; ③ Urbanization also exerted significant influence on globalization, and the labor force raised by rapid urbanization has brought tremendous economic benefit in the foreign trade; ④ In general, the impact of urbanization on the three dimensions of institutional transformation was more pronounced in less developed stages and less developed areas.

Based on multi-temporal remote sensing images from 1980 to 2016, we extracted land use information in Nanjing with the hierarchical land use information extraction method based on knowledge and rule. The grid method, equal fan analysis method and shared boundary analysis method were used to analyze the intensity, direction and types of the long cycled and multi-period urban construction land expansion. The result revealed that the rate of urban expansion in Nanjing was very quick and the urban construction land area has increased 574.73 km2 during the last 36 years. The construction land expansion has obvious characteristics-expanding along the Yangtze River and transportation-oriented development. The rising of development zones and university town is the main reason for construction land expansion in Nanjing. In different periods and directions, the intensity and types of urban spatial expansion are quite different. 2008-2012 is the fastest period of urban expansion, with an average annual growth of 55.28 km2. The intensity of expansion in the south and northeast were the highest, urban expansion has changed from single center to multi center pattern. The infilling expansion mainly occurred within the main city and some areas with certain development foundation; The spread expansion was not only from main city to surrounding areas, but also included the expansion of areas which used to be enclaves; The enclave expansion was more dispersed and affected by the location of the development zone and the university town. The study also showed that the expansion of urban construction land in Nanjing has experienced the process of low speed expansion, accelerated expansion, high speed expansion and slow change. Expansion of urban construction land in Nanjing has been transformed from extensive to connotative, and more attention was paid to the adjustment and integration of internal space structure. Urban development in Nanjing should shift from flat expansion to vertical expansion, fully develop and utilize the aboveground and underground space, accelerate the integration of the urban internal space structure.

This paper collects the sustained land data from the Department of Homeland, for studying the influence of scale change on urban expansion. We extract urban land for the corresponding annual central city by using ArcGIS10.2 software, and then change the data scale from 50m to 1000m and take 50m for the step size. The urban expansion scale, fractal characteristics and expansion model are analyzed in different scales. It shows that 350 m is the optimal study scale. Based on optimal scale, the characteristics of urban land expansion from 1996 to 2014 are studied. The results show that: (1) Expansion rate of 1996-2005 is obviously higher than 2005-2014. Its scale is in accordance with industrialization and urbanization period.(2) The type of expansion acts as obvious periodicity and regularity. Early expansion mainly includes spread expansion and enclave expansion, and then significant filling expansion emerges. There are gradient moves in all directions. (3) In the past 20 years, the urban fractal dimension has been growing. Convex graphics indicates that the city center would expand again in the future and has been becoming more complex. In the last part of this paper, we provide some suggestions for the management of urban expansion, and expected to make references for the similar regions or studies.

Based on the data of the minimum travel time between every two provincial cities and the comprehensive index of socioal economy, we used weighted average travel time indicators, modified gravitational model, geostatistical analysis, spatial exploratory analysis and spatial econometric model to explore the urban accessibility and spatial connections of Central Plains city group. Results are shown as follows: First, the spatial pattern of the regional accessibility forms a cross axis shape like ‘十’, the accessibility of cities along the north-south direction is superior to that of east-west cities. Locally, The statistical of Moran’s I shows the characteristic of spatial clustering, and the significant spatial association types are dominated by significant HH and significant LL. Secondly, economic linkages present a three-dimensional network shape like a diamond, which structure not only has an obvious hierarchy feature, but also be characterized by gathering small groups, close ties within the group, as a whole is relatively loose links. The local space pattern highlights the radiated characteristics of central cities such as Zhengzhou, Shangqiu and Luoyang. Thirdly, the urban size, urbanization level, transportation condition, urban location and resource circulation capacity would account for the intensity of economic connections and spatial relationship in Central Plains city group.

Revealing the relations of intrinsic spatial link characters of urban agglomeration by scientific method is the key to analyze the problems and optimize the strategies for the achievement of sustainable development. Based on the evaluation system of urban comprehensive quality index and accessibility analysis, this paper explored an empirical analysis on the spatial linkages of the urban agglomeration around Changsha-Zhuzhou-Xiangtan city group from three aspects of spatial interrelation, external service ability and internal agglomeration ability since 2006. The results showed that the spatial interaction of Changsha-Zhuzhou-Xiangtan urban agglomeration presents inner structure; it is obvious that the effect of traffic science and technology on urban spatial relation and the pattern of spatial connection network appear to be further expanded. External service ability is high in the north; low in the south, but the degree of regional disparities has been greatly improved, which is showing the coexistence of Changsha as the core and Changde as the secondary center, also Yiyang and Loudi under the low concentration of urban internal agglomeration. The ability of urban agglomeration on inner agglomeration is distributed and expanded along high-speed railway lines. After the opening of the Chang-Kun passenger dedicated Line, the core area began to show the trend of westward shift. At last, it is suggest that strengthen regional industrial collaboration, optimize the strategic policy and improve the integrated transportation system.

It is widely agreed that the spatial infection of real estate bubble exists in China. However, it is difficult to further investigate the issue in detail by using economic methods. To demonstrate spatial infection of real estate market bubble from perspective of geography in China, we conduct a case study of 35 metropolises by developing the method of symbolic vector data, spatial autocorrelation models, and spatial interpolation model based on GIS. The results indicate that the spatial infection of real estate bubble exists between Chinese cities. Moreover, its spatial infection capability becomes stronger than before. And the capability has a hierarchy decrease from the eastern areas to northwestern areas in China. Secondly, three source cities of infection (Beijing, Shanghai, Guangzhou) is identified in 2006, but only Guangzhou is identified in 2014. It suggests that a spatial transfer of source cities of infection has happened in recent years. Finally, the government should adopt some hierarchy strategies to stop the spatial infection of real estate bubble between Chinese cities under the background of “new normal” economic.

Aiming at the problems existing in the ecological environment impact assessment, such as partial evaluation indexes selection and difficulties in determining the standard value, taking Chaohu Lakeside’s regulation projects for flood control as an example. Based on the theory of pressure—state—response model, an evaluation index system was established which took consideration of the characteristics and degree of ecological environment impacts. The weights were determined using the entropy method. In order to enhance the comparability of different evaluation units, selecting grey model to make quantitative evaluation of the ecological environment impacts of Chaohu Lakeside’s regulation projects for flood control during the construction period. The comprehensive index method was used for comparative verification. Results showed that: 1) The approaching degrees of different evaluation units were different, the corresponding eco-environmental quality grades of Feixi County, Baohe District, Feidong County, Chaohu City and Lujiang County were good, good, general, general and poor. 2) Harnessing the waste discharged actively and increasing the input of environmental protection funds could achieve good results for Feixi County where the pressure layer had a higher approaching degree than that of state and response layer. The situation in Baohe District, Feidong County, Chaohu City, Lujiang County was just the opposite, so it would be useful to make reasonable arrangements for the construction site and time to reduce the emission of waste and improve the region’s ecological environment quality.

In order to provide reference for the improvement of regional ecological environment and rational utilization of land, this paper analyzed the characteristics and spatial evolution of land ecosystem service value during the four periods from 1990 to 2016 in Wuhan. Based on Landsat TM image interpretation data, this paper used adjusted equivalent factor valuation model of ecosystem service to compute ecosystem services value and further utilized spatial analysis tools to explore spatial features of the value changes. The results showed that: (1) The ecosystem services value in Wuhan showed a trend of first decreasing and then increasing. The ecosystem services value of rivers and lakes was always the highest in all periods, followed by that of farmland, pond and wetland. These three types of ecosystems provided Wuhan More than 85% of ecosystem service value. (2) The spatial distribution of the total value of ecosystem services in each township was characterized by spatial agglomeration and the degree of correlation tended to increase. (3) The spatial correlation of the ecosystem service value change rate in each township was weakened continuously. In the later stage, discrete effect appeared. (4) The unbalanced spatial distribution of ecosystem services in central urban areas tended to spread to the suburbs. The location conditions of townships as well as the proportion of rivers and lakes were closely related to the changes of the total value of ecosystem services in urban areas. The research showed that the spatial distribution of urban ecosystem services value was greatly influenced by the urban expansion directions and the change of land use structure. Rivers and lakes played an important role in improving urban ecological environment.

In this study, three reanalysis products (i.e. CRU, ERA-Interim and JRA-55) are evaluated using in situ measurements at 33 weather stations over the Three Gorges reservoir area for 1991-2006. The measurement variables include monthly air temperature and precipitation at all stations. Some approaches, including timing analysis, correlation analysis and percentage deviation, are utilized to quantify the relative performance of reanalysis data with respect to each variable. The results show that the monthly temperature from all reanalysis data are overall in better agreement with in situ observations compared with the precipitation. However, three types of data all underestimate the temperatures in each season, and the significant differences are seen in winter. As for precipitation, ERA-Interim data largely overestimate the overall precipitation in the Three Gorges reservoir area, and in winter, both ERA-Interim data and JRA-55 data show a marked underestimation of precipitation, with a deviation of about -40%. On the whole, at monthly scale, CRU is superior to others in air temperature and precipitation for the Three Gorges reservoir area. Based on the result, CRU was selected to analyze the characteristics of climate changes in the Three Gorges Reservoir before and after the impoundment by using trend analysis and ensemble empirical model decomposition (EEMD) After the impoundment, the significantly rising trend of the temperature in the Three Gorges reservoir area turns to a slight downtrend. No obvious changes are found in spring, summer and annual averaged precipitation. However, affected by the impoundment, autumn precipitation has notably increased and winter precipitation decreased. Moreover, strength of warming to the north of the Yangtze River like Chongqing and Beibei is greater than their adjacent regions. Impacts of impoundment on the spatial distribution of precipitation changes are not identical in different regions and seasons. In addition, the EEMD results indicates that quasi-periodic variations with about 2 to 3 years, 5 years and 7 to 8 years in both temperature and precipitation in the Three Gorges reservoir area. It also shows that the annual averaged temperature in this area undergoes slow trend in recent years, but may increase more obviously in future.

The flow regime is regarded to be the key driver of structure and function of riverine ecosystems. To assess eco-hydrological regimes alternation in the lower reaches of Three Gorges reservoir, the change characteristics of flow regime were evaluated by using the Mann-Kendall statistical test, the cumulative departure and moving T detected method based on daily flow series at Yichang gauge station from 1952 to 2014, while the hydrologic regime alteration degree and ecological effect of Three Gorges reservoir on the variation of 32 hydrological indexes were also analyzed by the range of variability approach and hydrologic regime alteration degree method. The results show that annual average flow of the Yangtze River has shown a decreasing trend during 1952 to 2014. Yichang gauge station has an obvious decreasing degree with the confidence degree of 90%. The abrupt junction of annual average flow is 2003 year, which means the significant effect of Three Gorges reservoir on the flow regime. The overall degree of hydrological alternation belongs to moderate alternation. The alternation degree of Yichang gauge station was 61%. Three Gorges reservoir has caused the flow regime alternation of the Yangtze River and altered flow regimes have influenced river habitat alternation, aquatic biodiversity decreases and fish population structure alternation. The study provides a scientific reference for the ecological protection and reservoir eco -operation in the middle and lower reaches of the Yangtze River.

The urban-rural gradient is an effective technique to examine spatial pattern and processes of urbanization. Quantitative studies on interaction between landscape pattern and function of urban ecosystem have become the core issues of landscape ecosystem in city. Based on remote sensing images, geographic information system (ArcGIS 10.2) and landscape pattern analysis (Fragstats 4.2), four indicators commonly used including physical variables and landscape metrics were calculated in this paper. Principal components analysis and multiple linear regression analysis were used to build the urban-rural gradient model to assess the urbanization level of central Kunming in a direction and the differentiation of landscapes. The results showed as follows: (1) Urbanization indicators can be used to describe the level of urbanization. The gradient of urban-rural showed spatial differentiation. (2) With the change of urban-rural gradient, the index values of urbanization showed a decreasing trend. The proportion of impervious underlying surface area (80%), density of road network (14 km/km2), landscape shape index and Shannon diversity index were the highest in the urban region. (3)The average of urbanization index UI in district of Kunming was showed that: Guandu＞Wuhua＞Xishan＞Panlong, and the variation coefficient was smallest for Guandu ,and largest for Wuhua. (4) The development of urban area in central Kunming is more concentrated, the dividing line between the suburbs and the city is not obvious. The main reason may be restricted by orographic factors.

The physiecological responses of Microcystis aeruginosa to different concentrations of phenanthrene (Phe) with different exposure time were studied. Results indicated that the growth rates of M. aeruginosa were stimulated under the lower doses of Phe with the range of 005-02 mg/L; compared to the control, the stimulation effects under 02 mg/L Phe was significant (P＜005).Growth rates were significantly inhibited under the higher concentrations of Phe (05-10 mg/L) (P＜005). Potential internal mechanisms were further investigated by analyzing several typical physiological parameters such as the photochemical efficiency (Fv/Fm), superoxide dismutase (SOD), glutathione reductase (GR) and malondialdehyde (MDA). Under the lower exposure concentrations (005-02 mg/L), the associated increase of the enzyme activities of SOD and GR, and the decrement of MDA contents would improve the photosynthesis and stimulate the growth rates.While for the higher exposure concentrations (05-10 mg/L), the growth rates were inhibited mainly by the decrement of SOD activities, GR activities and photosynthesis as well as the increase of MDA contents. The EC50 of Phe (1dayEC50 and 12dayEC50 were 127 mg/L and 065 mg/L, respectively) on the inhibition of the growth indicated the inhibition increased with the exposure time. Therefore, the development and maintenance of phytoplankton community dominated by M. aeruginosa, would more or less affected by the continuous inputs of Phe. Moreover, such physiological properties as SOD and GR could be used as efficient biomarkers of Phe pollution because of their high sensitivity

The greenhouse gas produced during rice planting is the main source of agricultural greenhouse gases. Effectively promoting the lowcarbon rice production among farmers is an important way to reduce agricultural greenhouse gas emission and to realize the green sustainable development of agriculture in China. In this study, the theoretical framework for the mechanism of lowcarbon production behavior in rice planting was established, which is based on the interpersonal behavior improvement theory. Then, SEM model was employed to analyze the impact of farmers' behavior and its influence. The low carbon willingness and ability  were the direct driving factors to stimulate their lowcarbon production. Behavioral attitudes, social norms and environmental emotions could indirectly affect lowcarbon production behavior by affecting the lowcarbon willingness. Moreover, the coefficient of behavioral attitude is the greatest (0555), indicating the main impact factor, followed by social norms (0232) and environmental emotion (0153). Promotion condition played an importantly moderating role in the transformation process of willingness-behavior and ability-behavior. The further multiplegroup analysis found that there were significant differences in the adjustment effect among different groups divided by education, family income and farm scale. In rice cultivation, encouraging farmers to expand the rice farm scale, improving the subsidies for the agricultural green production and strengthening lowcarbon production education specially in professional technical training are effective methods to enhance the lowcarbon cognition of farmers and behavioral willingness, and to guide farmers to engage in lowcarbon production 。

Large national protected area in Yangtze river basin, various types of protection, in order to achieve the overall protection and management of natural resources in Yangtze river basin, the purpose of global scale from analysis of the spatial distribution characteristics of corridor is the study of the Yangtze river national park to build the important basis. In this paper, through mathematical statistics and ArcGIS spatial analysis, combined with the natural geography and human geography property in China, the existing 8 classes in Yangtze river basin spatial distribution characteristics totally of 996 nationallevel protected area are studied, the results show that (1) The national protected areas in the Yangtze River Basin are collectivity distribution, forming the Sanjiang source region, Three Parallel Rivers region, High alpine plateau area in Western Sichuan, the middle Qinling region, the basin area of West Chongqing, Dongting lake area, Poyang lake area, Huangshan area, ring Taihu area nine concentrated area; (2) The areas of national protection in the Yangtze River Basin are mainly concentrated in the region, where focused on middle cut high mountain aera, as well as low hill,hill and plain area in the middle and lower reaches, interconnected waterways, waterrich resources, a variety of evergreen plants, soil fertile, high accessibility, moderate population density and high level of economic development of eastern and central regions. Based on the national protected area spatial distribution characteristics of the Yangtze river, this paper proposed a space strategy for the corridor of the Yangtze River National Park, which are “the Yangtze river sourceentrance to the sea” important protection nodes, “Dongting lake, Poyang lake, Chao lake, Taihu lake” important protected area, “Wudang mountainHuafu mountainDaliang mountain, Wu mountainWuling mountain, Yao mountain” important protective belt “three importances” mode of protection zone, and “national park first areasnational reserve accumulationnatural, social, economic advantage areanative plants and animals background ” “four level system” with the combination of the Yangtze river national park corridor space strategy

The spatial distribution and highresolution morphological of riverbed micromorphology were observed using a RESON 7125 multibeam during September 2016. Bathymetric data of the Zhangjiazhou reach in 1998 and 2013 were also used to analysis the channel volume change. Results show that: (1) strong riverbed erosion was experienced in the Zhangjiazhou segment and the net erosion volume was 176×106m3 between 1998 and 2013. Several erosional holes were found in the South Zhangjiazhou Waterway which reach up to 9 m. (2) Medium grain size of the channel sediment sampled in 2016 changed from 1491 μm to 223 μm were coarser than history before 2003. (3) Approximately 829％ main channel developed dunes while 140％ of the main channel developed erosional holes. The mainly reason of the strong erosion occurred in the Zhangjiazhou segment because of the sediment supply reduced. The river channel control engineering affected the river morphology and stabilized the river regime. The water was forced by these manmade projects to return to the river trough and exacerbated the erosion phenomenon. With the sediment supply reducing in the future, the main channel of the South Zhangjiazhou Waterway may erosion further.

Based on the classification data of landuse pattern from Landsat, nighttime light image data, automatic meteorological stations data and atmospheric boundary layer (ABL) sounding data, the representative stations of urban area, rural area, and lake were chosen for the urban heat island (UHI) analysis. The characteristics of UHI in Suzhou in January 2015 were studied in this paper. The result showed that: (1) UHI intensity was weak at daytime, which was less than 10℃ from 09 am. to 05 pm., with the minimum of only 02℃. UHI intensity was strong at night, which maintained above 12℃, with the maximum of 17℃. (2) The temperature difference between urban area and lake was positive at daytime and negative at night. Temperature variation rate of urban stations was about 02℃/h faster than that of lake stations. (3) The shape of heat center was irregular and has a large range at daytime, and the temperature difference between urban and rural area was small in Suzhou. However, at night the temperature difference between urban and rural area maintained at about 15℃,and a single, closed and stable heat center was formed, which was in correspondence with that in downtown area. The northwest wind was prevalent on the ground in winter, and Taihu lakeland wind was obvious in Suzhou. The combined action of lakeland wind and prevailing wind jointly transferred the urban thermal plume to the southwest. (4) The difference of virtual potential temperature profiles between urban and lake was small, and unstable ABL developed both in urban and lake area at daytime. However, at night, unstable ABL profiles were still maintained in urban area, and stable ABL profiles developed in lake area. In the meantime, the phenomenon of wetisland near ground surface was obvious. (5) The influence of UHI in vertical direction has significant diurnal variation, which was less than 40m at daytime, and more than 200m at night.

Studying the change and response of lake water quality driven by natural and human factors can provide a scientific basis for water environmental management. This study accessed the effects of different scenarios of pollutions reduction on water quality using the combination methods of twodimension water quality numerical modelling and greymode identification accessing. Based on measured topography, hydrological, meteorological data and water quality in 2012, as well as the quantitative results of pollution resources, a twodimensional hydrodynamic and water quality coupling model of Honghu Lake was established. The pollution resources were generalized to surface runoff, aquaculture activities and atmospheric deposition. The results showed that, during the model calibration and validation periods, the average water level RMSEs were respectively 0.10 m and 0.08 m, the concentration RMSEs of total nitrogen, total phosphorus, ammonianitrogen and permanganate index were respectively 0.171 mg/L, 0.009 mg/L, 0.110 mg/L, 0.627 mg/L and 0.191 mg/L, 0.020 mg/L, 0.079 mg /L, 0.689 mg/L. The simulation results meet the accuracy requirements of water quality model. The water quality change under different scenarios of load reduction revealed that under 50% reduction of inflow loads, the decreasing rates of total nitrogen, total phosphorus, ammonianitrogen and permanganate index concentration were largest, which were respectively 37.2%, 35.1%, 37.3% and 37.2%. The comprehensive water quality index were decreased from the baseline (2.84) to 2.44. The areas of grade V water quality did not exist. The percentage in areas of grade IV water quality decreased from 15% (baseline) to 10%. The areas of grade III water quality accounted for 90% of the whole lake area. it concluded that the water quality deterioration primarily was owing to nonpoint pollution from upstream Sihu watershed brought by runoff. We should vigorously develop nonpoint source pollution control in the upstream and carry out the ecological restoration in the northeast and northwest of Honghu Lake.

Aiming at studying the mechanism of curtain weirs and controlling algal blooms of Xiangxi Bay in the Three Gorges Reservoir, based on the field data collected from January to December 2010 in Xiangxi Bay, this study analyzed the temporal and spatial variations of water temperature with and without curtain weirs by using CEQUALW2, a laterally averaged two dimensional hydrodynamic and water quality model. The results showed that the performance of curtain weirs was varied for different heights, different locations and different seasons. The curtain weir can change the water temperature of its upstream, especially the surface water temperature, the greater the height of the curtain weir was, the more the days when water temperature decreased would be, moreover, the greater the average daily water temperature difference would be, the influence of curtain weirs on water temperature was more obvious in summer and autumn, and reduction of water temperature was in the same period; the performance was more obvious as the curtain weir was installed further downstream and the height of it was greater, and in autumn, the change of water temperature in different layers compared with the scenario without curtain weirs was greater, especially in the layers close to the water surface; the curtain weir can change the flow, on one hand, the upstream inflow would flow down and mix with water in lower layers around the curtain weir, on the other hand, the intrusion flow from the Three Gorges Reservoir would be changed and mix with water in lower layers or shallower layers around the curtain weir, meanwhile, the curtain weir would promote vertical mixing, then make the water temperature in certain water areas tend to be uniform, finally weaken the water temperature stratification. CEQUALW2 model was suitable for the simulation of curtain weirs in Xiangxi Bay, and the study of curtain weirs would provide technical support for algae control in the tributaries of the Three Gorges Reservoir.

Slope erosion is one of the main sources of sediments in middle and upper reaches of the Yangtze River. The quantitative study of soil detachment process in middle and upper reaches of the Yangtze River has an important theoretical and practical significance in revealing soil erosion mechanism and preventing and controlling the soil and water losses. The scour experiment in this paper was carried out in a flume with a variable slope. We studied the relationship between soil detachment rate and slope, flow quantity and other main hydrodynamic parameters, aimed to find out the optimal parameters which can better simulated the soil detachment process. The results show that the soil detachment rate is positive correlated with flow quantity, slope and multiple hydrodynamic parameters. The power exponents of slope and floware all greater than one, indicate that these two parameters have a superimposed increasing effect on soil separation rate in the determination range. The coefficient of determination between stream power and soil detachment rate is the highest (R2=0.93), which means that more effective information can be obtained when using stream power to fit soil detachment rate. When unit stream power is larger than 0.280 7 m/s, the soil detachment rate begins to increase.However, the calculation of runoff shear stress (R2=0.83) only needs slope and depth as input parameters. The calculation of stream power value should not only rely on data such as slope and water depth, but also need data such as current velocity that relatively difficult to obtain.Therefore, it is more convenient to use the runoff shear stress to fit the soil detachment rate than using the stream power, but using stream power to fit the rate of soil detachment will be more accuracy.

Through detailed field investigation, palaeoflood slackwater deposits (SWDs) were identified from loesspalaeosol profiles in the upper reach of Huaihe River Basin. Through detailed observations and sampling, the samples were analyzed based on particle sizes and geochemical elements, and dating in optically stimulated luminescence. These data were further compared with global El Nio events recorded since the beginning of the Holocene. The results show that flooding occurred at least six times during the last 8,500 years in the upper reach of Huaihe River Basin, and those occurrences correlate well with El Nio. By comparing the contents of different grain fractions of sediments, SWD is considered as the dominant component in the range of coarse grain size, whereas the loesspalaeosol is the dominant component in fine grain size range. The difference between the SWDs and loesspalaeosols is apparent. Thus, palaeoflood SWDs can be identified effectively based on particle size characteristics. The geochemical analysis shows that the elements in the sedimentary units of this profile have distinct differences; SiO2 and Th contents are significantly lower and Fe2O3, CaO, MgO, P, V, Sr, and Nb contents are more enriched in the SWDs than in the loesspalaeosols, although Al2O3, Na2O, K2O, Cr, Zn, and Rb contents did not show significant differences between profile layers. Palaeoflood SWDs can also be well identified based on geochemical compositions. We identified the palaeoflood SWDs, and get the palaeofloods data in the upper reach of Huaihe River Basin since the early Holocene. The results also show that these floods are closely related to the global El Nio phenomenon.

Based on the 96 gauges’ long series of rainfall data from 1956 to 2016 in the Hanjiang River Basin, the spatiotemporal variability characteristics of flood season precipitation are diagnosed in terms of mathematical statistics. The study found that no statistically significant trends of the flood season rainfall for the whole basin were tested, but there was a strong mutation in 1989 with major shock cycles of 22, 8 and 3 years. Affected by climate and topography, the spatial distribution of precipitation in flood season is uneven. The southwest of upper reaches of basin and downstream of basin are regularly the rainfall centers. It is easy to form three kinds of spatial distribution patterns, including “radiation type”, “northsouth type” and “northeastsouthwest type” with variance contribution rates of 41.1%, 12.4% and 7.6%. In recent years, precipitation in the southwest (e.g.,Hanzhong, Ankang and Shennongjia areas)and downstream(e.g.,Tianmen and Xiantao regions) of Hanjiang River Basin have significant upward trends, while the precipitation in the northeast(e.g.,Shangzhou, Fengzhen)and Tangbaihe watershed have significant downward trends. The “northeastsouthwest” spatial distribution patterns of flood season rainfall is likely to be more significant. Spatiotemporal distribution and evolution characteristics of rainfall are directly related to the rational development and utilization of water resources. Through this research, we further deepen the understanding of the rainfall variation in the Hanjiang River Basin, and some results could be used as a reference for the watershed flood disaster response, rainfall flood resouces utilization and optimal allocation of water resources.

Using PM2.5 data from 1998 to 2013 that is inversed from satellite remote sensing images, and employing the methods in geospatial analysis, geographical weighted regression(GWR) and geographic detectors, this paper analyzes the relationship between urbanization and PM2.5 in ChengduChongqing urban agglomeration. The results shows as follows: (1) From 1998 to 2013, the urbanization of ChengduChongqing urban agglomeration has been rapid, and the PM2.5 average value in urban area is obviously higher than that in nonurban area, which indicates that urbanization has certain influence on PM2.5; (2) In recent 16 years, the center of gravity of PM2.5 and the city both generally move toward southeast, and their annual fluctuations in the longitude is basically opposite; (3) The nighttime light data has a good consistency with PM2.5 in the spatial distribution in ChengduChongqing urban agglomeration, and the global R2 of GWR is between 0.86-0.95. The urbanization and human activities in the study area have a significant impact on the distribution of PM2.5; (4) Geographical detection analysis shows that different urbanization factors account for PM2.5 concentration. From 2006 to 2013, the density of urban population and greening coverage of builtup areas have gradually become the main factors affecting the PM2.5 distribution in ChengduChongqing urban agglomeration.