In this paper, comprehensive evaluation indicators were constructed for the evaluation of economic development, urbanization, social security and eco-environment, and the coupling degrees of 36 cities in the middle reach of Yangtze River during 2011-2013 were calculated by means of the coupling degree model. The GIS technique was used to analyze spatial distribution of values of 4 systems and coupling degrees of 36 cities. The results showed that the 36 cities were very similar in terms of development levels of economy, urbanization and social security, and had similar spatial distributions in terms of these three systems. The three systems were positively correlated with each other. Particularly, the average values of the three systems were low, while their variation coefficients were very high. It indicated that there were huge and significant differences in economic development, urbanization and social security among the 36 cities. However, regarding eco-environment, the 36 cities had high average values and low variation coefficients. In terms of spatial distribution, there were three obvious clusters of high coupling degrees, i.e.. Chang-Zhu-Tan city cluster, Wuhan-Nanchang economic belt (including Ezhou, Huangshi and Jiujiang), and 4 cities in the North Hubei Province (Shiyan, Xiangyang, Yichang and Jingmen). Finally, the difference of coupling degrees of the 36 cities seemed to show a declining trend.

There is a great difference between resource endowment, energy consumption and economic growth form in China, which makes energy intensity significantly differ between regions. It is important to reveal whether the presence of energy intensity level of each regional economic growth in China is similar to the convergence of nature, whether a certain club convergence phenomenon for the implementation of energy policy differentiation exists. In this paper, the specific data of energy intensity level in 30 provinces in China from 2000 to 2014 were taken as the starting point. First, the spatial correlation of energy intensity level in China was explained theoretically. Then we constructed the correlation model to carry on the empirical research and the examination to the existence of China's comprehensive and sub-provincial energy intensity convergence clubs from 2000 to 2014. At the same time, the effects of the secondary industry output value (SEN), fixed asset investment (TZ), R&D expenditure (R&D) and foreign direct investment (FDI) on energy intensity convergence were forecasted. The results showed that the energy intensity gap between provinces and cities in China was gradually reduced, and there was a spatial phenomenon of provincial energy intensity convergence of the club. It also showed that the effect of economic variables on energy intensity in different regions was different. Therefore, in the development of energy-related policies, we must consider the objective differences in different regions, which targeted the implementation of differentiated energy policy.

In rural planning studies, population scale is usually used to represent the whole scale of settlements, but obviously it is not comprehensive and need to be improved. It is necessary to have a deep analysis in function and scale of settlements for decision-making in rural planning and development policies. Therefore, by looking into the existing literatures, this paper clarified the connotation of scale and function in rural settlements. By drawing lessons from coupling theory, we established the evaluation system about coupled and coordinated development of scale-function in township settlements. Using the Entropy Method, coupled and coordinated index analysis, and the ESDA methods, we analyzed the developing status about coupling system of scale-function in towns and streets in TongNan District. Results showed that economic scale was the main factor that influenced the scale of township settlements, while the second important factor was population scale, and the least impact factor was land scale. The tertiary industry was the main influencing factor of production function of township settlements, with education and medical service of living function, and afforested area of built-up district of ecological function. The coupling development level of township settlements of TongNan District had obvious characteristics of the single nuclear structure in space. Counties with Zitong street and Guilin street as the core took the leading position in scale expansion, function construction and scale-function coupling coordinated development degree. The regional development presented high inequality. The function and scale of township have significant correlations, forming a natural coupling system. The very essence of coordinated development about scale-function coupled system is a type of development that function and scale are both in synchronous and high-level development state in township settlements. The scale-function coupling system of most towns and streets of TongNan District are in antagonistic state, with scale and function both at a low level. We suggest that the sub-growth pole should be cultivated in order to diminish the inequality of regional development, and more attention should be paid to the status of economic scale of township settlements in rural planning for a more reasonable forecast of the scale of the residential area and more scientific planning and construction of residential function.

Stable isotope methods are important tools for investigating the riverine hydrological processes and its variations, especially in the Yangtze Basin with densely staggered riverine network and complex hydraulic linkages. This study investigated the δ¹⁸O and δD in Yangtze River water and precipitation to reveal the spatiotemporal variations of isotopic compositions and their factors during the wet and dry seasons. The results showed that the δ¹⁸O in precipitation experienced an evident spatial variation in the Yangtze River Basin. Low δ¹⁸O values were found in the Yangtze sources and become decreased from the upper reaches to lower reaches of Yangtze River, which was closely associated with its moisture source and altitude. The δ¹⁸O and δD of river water in the dry season showed greater than those in wet season attributing to weaker evaporation enrichment and greater precipitation recharge in the wet season. Despite of the wet and dry seasons, the stable isotopic contents exhibited an increase trend from the upstream to downstream mainly attributing to the recharge of tributary and lake along the Yangtze River. In addition, this study also revealed that the effect of impoundment and drain by Three Gorges Reservoir on the river isotopic compositions was greater in the dry season than those in the wet season. These findings will provide the scientific evidences on recognizing the precipitation-river-lake hydraulic linkages and investigating the rational utilization and management of water resources in the Yangtze River Basin.

The spatial-temporal distribution characteristics of the concentrations of air pollution factor and AQI of urban agglomeration in Yangtze River Delta (YRD) were studied using spatial interpolation technique, correlation analysis and GIS. By extracting the spatial distribution data of urban agglomeration in the YRD according to the State Council's latest plan, the current study area were divided into ‘a core area and five metropolitan areas’. We analyzed temporal variation characteristics of AQI, spatial distribution of AQI and primary pollutants, and quantitatively evaluated the relationships between AQI and their influencing factors. The results showed that seasonal variation of air quality in the urban agglomeration in YRD was the best in summer and the worst in winter; the mean concentration of each month was the highest in January; AQI reached the maximum value in the second half of the week from the weeks mean change. The spatial gradient of AQI significantly changed in the spring, autumn and winter, showing a distribution pattern in which AQI was high in the north area and low in the south, while the AQI in summer had little change in the spatial gradient, and the spatial variation was not obvious. The primary pollutants in the Yangtze River Delta were PM_2.5 and O₃. The main pollutant in Shanghai and Ningbo metropolitan area was O₃. The main pollutant in Su-Xi-Chang area and Hefei metropolitan area was PM_2.5. The spatial distribution of PM_2.5 in the 26 cities of the Yangtze River Delta city group was similar to that of AQI and the distribution of O₃ was high in the east and low in the west in the YRD. From O₃ spatial distribution, we can see that the relatively high level of ozone in the city is relatively high. Finally, by correlation calculation, significant correlation was found between AQI and PM_2.5 and no significant correlation was found between O₃ and AQI. These studies provided the basis for the prevention and control of atmospheric pollution in the YRD.

Chongming Island is the largest estuary alluvial island in China. Its formation and development relate closely with the fluxes of water and sediment from the Yangtze River. There are records of reclamation or embankment in the Chongming Island in history. According to main seawalls constructed in the eastern part of Chongming Island during the last 60 years, the progradation rates along four transects in northeast, east and southeast directions respectively, and siltation area between seawalls of the eastern part of Chongming Island are calculated. The results showed that:(1) in the last 60 years, the progradation rate of the eastern part of Chongming Island was about 200 m/yr, and the average annual increasing rate of siltation area was 2.80 km²/a; (2) there were differences between the different transects in terms of progradation rate, and the progradation rate in the east was faster than that along every other transect; (3) there were differences in progradation rate for each transect in different time spans. Of all transects, the progradation rate in the 1990s was greater than those in other time spans. The trend of progradation of the eastern part of Chongming Island was coincident with that of variation of the annual sediment discharge from the Yangtze River from the 1950s to the 1980s. There was a difference between both trends for the heavy reclamation period in the 1990s. It is still rare to study the shoreline changes through the seawall. The method can provide a reference for studying the shoreline changes in long time scale.

Spatiotemporal characteristics of negative air ions concentrations and their relationships with meteorological factors in Pukou (Laoshan Forest, Nongzhaung, Pearl Spring, Shiqiaowancheng) were analyzed between Oct 2014 and Oct 2015. The results showed that:(1) The daily average concentration of negative air ions were 688/cm³ in Pukou (Nanjing), the maximum value of 986/cm³ appeared around 21:00; the minimum value of 610 appeared around 12:00; (2) The annual average concentration of negative air ions were 675/cm³ in Pukou (Nanjing), and the largest average concentration was 728/cm³ in summer, while the lowest was 728/cm³ in winter; (3) The negative air ions concentration was the largest in Nongzhuang, while the lowest in Shiqiaowancheng; (4) In different weather conditions, the relationships between negative air ions concentration and meteorological factors were different. In rainy, negative air ions were significantly correlated with precipitation, temperature and relative humidity (P < 0.01). In non-rainy days, negative air ions were significantly correlated with sunshine (P < 0.05).

Land-use optimization and spatial countermeasures are of great significance to control of non-point source pollution and improvement of water quality. In this paper, the gray linear programming method (GLP) and a minimum cumulative resistance model (MCR) were coupled to carry on risk control of non-point source pollution. (1) Taking the economic and ecological service value as the objective function, the gray linear programming model was built for the land use structure optimization at the regional scale. (2) The spatial zoning and countermeasure oriented to non-point source pollution risk control was discussed based on theMCR model. The Qingpu District located in the Taihu Lake Basin in a plain river network region was selected as a study case for this approach. The results showed that the Qingpu District could be divided into five parts, i.e., the delimiting water conservation zone, the key protection area of water resources, the general non-point source pollution control zone, the medium non-point source pollution control zone, and the core non-point source pollution control zone. According to the results of spatial-division, the specific countermeasures were put forward to lower the environmental risk. The annual load of total nitrogen will be reduced by 10.96%, and the load reduction of total phosphorus will be 41.33%. The economic benefits will be 46.13 billion yuan in 2020. Compared with 2012, the economic benefit will increase by 28.12%. In order to ameliorate the ecological environment and promoting the local social and economic development in area, land-use optimization and spatial zoning regulation mechanism were effective approach in risk control of non-point source pollution.

Stage-inflow relationship, which is affected by bathymetry of the lake, hydrodynamic connection between lake and surrounding rivers, is an important hydrological characteristic of a lake. Poyang Lake, located in the middle Yangtze River, presents significant floodplain features. This paper aims to explore the lake stage-catchment inflow relationship and the nonlinear characteristics of Poyang Lake. Cross wavelet transform (XWT) and wavelet transform coherence (WTC) were used to analyze the corresponding relationship between stage and inflow based on measured data of daily stage and catchment inflow during the period of 1960-2010. The stage-inflow relationship showed apparently three phases. In the first period, the phase difference between stage and inflow changed from 45 to 90 degree. A delay time of 2-9 days was detected between the two variables. In the second period, the phase difference was about 90 degree. The inflow decreased firstly while the stage remained increasing. The change of phase difference in the third period was almost the reverse of the first, which changed from 90 degree to zero. This paper conceptualized the lake stage-inflow relationship to three phases, which provides a new understanding of the hydrological characteristics of the lake-floodplain system. The results provide an important theoretical basis for describing and simulating the hydrologic processes of Poyang Lake and other similar lakes.

In freshwater lake ecosystems, change of water level will markedly affect the whole ecosystem. The Bang Lake, which is one of the most representative sub-lakes of Poyang Lake, was selected as study field in this study. Along with the gradient of water level elevation and vegetation succession, 6 sample plots were set up, and the diversity and distribution of microbial metabolic function from different plots were studied by using the Biolog-Eco method. Our results indicated that with the decrease of water level elevation, soil moisture was gradually increased, while vegetation coverage rate was gradually reduced. Soil organic matter content decreased firstly but increased afterwards. The soil microbial metabolic activity of carbon source was reduced as the water level elevated, and the preference and utilization rates of carbon source types were significantly different. Further results from distance-based redundancy analysis (dbRDA) showed that the carbon metabolic pattern of soil microbial communities from adjacent plots were more similar. There were several factors affecting the soil microbial metabolism of carbon source, including soil moisture, soil organic matter, pH, NH4-N and vegetation types. These findings would provide scientific guidance for reasonable management and protection of Poyang Lake wetland ecosystems.

Water temperature is one of the most important factors in the evaluation of water environment, which plays an important role in the physical, chemical and biological processes. In order to analyze the water temperature distribution in the Xiangjiaba Reservoir, the longitudinal/vertical two-dimensional water temperature model with CE-QUAL-W2 was constructed. The water temperature structure in the Xiangjiaba Reservoir was simulated by the model with the monitoring data. The results showed that seasonal stratification was present in the Xiangjiaba Reservoir, the upper middle water (60 m above) was heated quickly by the warming-up inflow water and the air temperature from April to June, followed by increasing temperature difference between surface and bottom water. The temperature difference reached 10℃ at the end of June, and the vertical stratification became more severe. As the flood discharge in July and August increased, the bottom temperature in the Xiangjiaba Reservoir rose rapidly and the middle isothermal layer increased as well, and the water temperature difference between the surface and the bottom decreased to 2℃. The main factors affecting the temperature distribution in the Xiangjiaba reservoir included inflow water temperature, meteorological, intake elevation and discharging patterns, which affected the whole aptitude, the surface water temperature and vertical temperature stratification structure, respectively.

In order to explore the hydrochemical change and its influencing factors of epikarst zone under human disturbances in the Southeast Yunnan peak forest-lake basin, we investigated physical and chemical properties of the two spring area in a hydrological year. Results showed that for the Caihuaqing spring, seasonal dynamics of physicochemical indicators had a large amplitude. The water temperature was 4.6 degrees Celsius, the conductivity was 302 μs/cm, pH was 0.66, water turbidity was 255.1. For the Huobadong spring, the seasonal dynamics of the physical and chemical indicators had relatively small variations. The water temperature was 3.3 degrees Celsius, the conductivity was 225μs/cm, pH was 0.5, water turbidity was 9.8. Under normal weather conditions, air temperature and water temperature, conductivity and pH were positively correlated for the Caihuaqing spring. While for the Huobadong spring, air temperature and water temperature were positively correlated, but water temperature was negatively correlated with conductivity and pH. Under the condition of heavy rainfall, the Caihuaqing spring presented peaks of water temperature, conductivity and turbidity while low pH value at the early stage of rainfall. At the late stage of rainfall, the conductivity increased significantly in 6 hours from 189μs/cm to 405 μs/cm, and then maintained a stable upward trend, pH showed a downward trend after the peak. The relationship between water temperature and conductivity, pH was positively correlated with the water temperature in the Huobadong spring, which showed the peak during the period. After 10 hours of rainfall duration, pH and electrical conductivity showed a downward trend. Under the condition of weak rainfall, the Caihuaqing spring and Huobadong spring presented small amplitudes of physicochemical variations. At the early, middle and late stages of rainfall, pH and conductivity of the two springs appeared dilution effect curves.

Palaeoflood hydrological studies were carried out in the upper reaches of the Hanjiang River valley. Four bedsets of palaeoflood slackwater deposit (SWD) was found in the eolian loess-soil profile at the LJT site at the riverbank near the Luojiatan Village in the Xunyang County. After detailed field observations, a series of sedimentary samples were taken from the profile. Grain-size distribution and magnetic susceptibility were analyzed in the laboratory. The results showed that these SWD consist of sandy silt, originated from the suspended sediment load of the palaeo-floodwater. Each bedset of the SWD represented one group of palaeoflood event. According to the OSL dating in combination with the archaeological dating and pedo-stratigraphic correlations, these palaeoflood events occurred during 8 500-8 400 a B.P. (SWD1), 4 200-4 000 a B.P. (SWD2), 3 200-2 800 a B.P. (SWD3), and 1 800-1 700 a B.P. (SWD4), respectively. The palaeoflood peak discharges were calculated by using hydrological models. They were estimated to be between 26 500 and 46 800 m³/s. Improvement of the frequency curve estimation was made by the use of gauged flood data from 1935 to 2010; historical floods of 1583, 1867, and 1921 at the Ankang hydrological station; and Holocene palaeoflood discharges. These results have the archives of flood data extended to a time-scale of 10 000 years in the Ankang-Xunyang reach in the upper reaches of the Hanjiang River. Thus, the data generated from palaeoflood hydrology allowed us to refine the flood frequency-peak discharge curves and potentially increase its accuracy. From the frequency plot, we conclude that the flood discharge was 46 900 m³/s, with a return period of ten thousand years; 37 800 m³/s with a return period of one thousand years; and 28 900 m³/s with a return period of one hundred years, respectively. These results are of great significance for mitigating flood disasters and hydraulic engineering. These results are also very important for water conservancy construction and flood hazard mitigation.

Concentration of polycyclic aromatic hydrocarbons (PAHs) in organic film on window glass surface were quantitatively analyzed by GC-MS. The results showed that with increasing floors, the density of PAHs on the residential buildings presented an increasing-decreasing trend, where the highest and lowest density appeared on the third floors and the ninth floors, respectively. While the density of PAHs of 17 floors apartment block showed a trend with first decreasing then increasing pattern, the highest and lowest density appeared on the ninth floor and the sixteenth floor, respectively. The analysis for the relations between TOC and PAHs suggests that the abundance of PAHs on the glass surface is also influenced by other factors apart from TOC. The 10 floors residential building mainly presented 3 rings and 4 rings PAHs, while the 17 floors apartment mainly presented 4 rings PAHs. The PAHs density on the outdoor glass surface was much higher than that in the indoor surface, and the outdoor glass surface mainly presented Phe, Pyr, Chry, Fluo and Fl. The ratio of low rings PAHs on the indoor and outdoor surface was close to 1, while the ratio of high rings was almost less than 0.6. Although TEQ values were lower, but we still need to pay attention to the ecological risk of PAHs in organic film on glass surface.

Using historical and scenario simulation results from three CIMP5 climate models, NCEP/NCAR reanalysis data and observed precipitation data over Yangtze River Basin, the summer extreme precipitation event frequency over the middle-lower reaches of Yangtze River (YRF) has been simulated and estimated by using the statistical downscaling method. First, the predictors that significantly influence YRF have been extracted by correlation analysis. The predictors with high predictive power were selected from high correlations between observation YRF and other variables. Then the downscaling models were established by using the multi-linear regression method. Cross-validation test showed that the downscaling models have high skill for YRF and ensemble results of three downscaling models can further improve the simulation skill. Finally, the statistical downscaling model was applied to three scenarios of CMIP5 to construct future climate change of YRF. For future climate change scenarios, the YRF increases during following several decades, and the increased amplitude for high emission scenarios is higher than that of low emission scenarios during middle and later 21th centuries.

Based on the daily precipitation data of a high-resolution regional climate model (COSMO model in Climate Mode, CCLM) simulated for the period 1961-2100 and the 90 meteorological stations observed during 1961-2005 over the mid-lower reaches of the Yangtze River Basin, four typical extreme precipitation indices, i.e. annual precipitation, intensive precipitation, heavy rain days, and contribution ratio of intensive precipitation, were calculated separately. The spatiotemporal variations of extreme precipitation under the global warming of 1.5℃ and 2.0℃ were analyzed in detail. The results showed that:(1) In the 1.5℃ warming period, annual precipitation in the mid-lower reaches of the Yangtze River Basin will decrease by 5%, but intensive precipitation, heavy rain days, and contribution ratio of intensive precipitation will increase by 7%, 33% and 4%, respectively, relative to the reference period (1986-2005). The probability density curves showed that under the global warming of 1.5℃, the mean value of annual precipitation will decrease, but intensive precipitation, heavy rain days, and contribution ratio of intensive precipitation will increase, and the variances of extreme precipitation will increase, relative to the reference period. Compared with extreme precipitation in the reference period, the spatial distribution of annual precipitation, intensive precipitation, and heavy rain days show an increasing trend in the southern part of the mid-lower reaches of the Yangtze River Basin and a decreasing trend in the northern part, however, contribution ratio of intensive precipitation has the opposite result in the 1.5℃ warming period. (2) In the 2.0℃ warming period, annual precipitation will decrease by 3%, but intensive precipitation, heavy rain days, and contribution ratio of intensive precipitation will increase by 15%, 46% and 15%, respectively, relative to the reference period. The probability density curves showed that under the global warming of 2.0℃, The mean value and variance of annual precipitation will decrease and increase respectively, but intensive precipitation, heavy rain days, and contribution ratio of intensive precipitation will increase significantly, relative to the reference period. The region of annual precipitation reduction is located in the north of the mid-lower reaches of the Yangtze River Basin, but intensive precipitation, heavy rain days, and contribution ratio of intensive precipitation show that extreme precipitation will increase in most areas. (3)With a global warming of 1.5℃ to 2.0℃, annual precipitation, intensive precipitation, heavy rain days, and contribution ratio of intensive precipitation will increase by 3%, 7%, 10% and 11%, respectively, relative to the reference period. The mean values and variances of extreme precipitation are projected to increase with the rising of temperature, by analyzing the probability density curves. The area and scope of extreme precipitation with increasing trend in a 2.0℃ warming will expand to larger than that of the extreme precipitation with same reference period in a 1.5℃ warming. Aforementioned findings revealed that compared to the extreme precipitation in a 2.0℃ warming, the temperature will be controlled strenuously at 1.5℃ warming that is of great significance to reduce the adverse effects of extreme precipitation.

Based on the Landsat images during 1987 to 2014, this paper interpreted the hazard areas of debris flow fans, analyzed their evolution characteristics in the Jiangjia and Dabaini catchments in Xiaojiang Basin, and further discussed the variation of influenced area in Jiangjia and Dabaini catchments, as well as their influential factors of the variation. It revealed that (1) the damaging ranges of debris flow fans have shrunk during the recent 30 years; (2) the development of debris flow fans in Dabaini basin was at the mature stage with lower amplitude of shrinkage, while in Jiangjiagou basin, their development were at the over-mature stage with higher amplitude of shrinkage and stable situation; (3)water, sediment provenance and human activities are the main factors of that influence variation of debris flow fans.