Water Environmental Pressure Research Articles

Overloading risk assessment of water environment-water resources carrying capacity based on a novel Bayesian methodology

Water environment-water resources carrying capacity (WERCC) is a sustainability indicator, rendering it significant to measure the water systems covering the water environment and water resources. Currently, water environment carrying capacity (WECC) accounting and assessment mostly tend to the deterministic results of a single element under a design hydrological condition. However, the WERCC, as well as its components WECC and water resources carrying capacity (WRCC), is a random variable with a certain probability distribution. To account for that, we established a Bayesian network-based WERCC overloading risk assessment method system. It can calculate the water system carrying state and its corresponding probability after determining the WECC and WRCC probability distributions. Among them, the probability distributions of the WECC and WRCC were determined by the Bayesian formula, and the spatiotemporal law, respectively. Additionally, based on the above quantitative uncertainty analysis in the basin, a Bayesian network-based WERCC overloading risk assessment path was built by modeling the causal chain of the WERCC internal impact mechanism, and the risk assessment results were obtained by the software Netica. Taking the North Canal Basin in China as an example, the results of WERCC overloading risk zoning showed that CU6 and CU9 were severe risk areas; CU2, CU7, CU8, and CU10 had moderate risks; and the remaining 40% control units were slight or mild risks. According to the overloading risk characteristics, the uncertain quantitative assessment has provided a scientific basis for ensuring the sustainable development of the North Canal from the perspective of reducing the water environment pressure (WEP) and improving the WERCC.

Evaluation of the Ecological Status of Wetlands of International Importance in China

An international assessment of wetlands is important for quantifying the current state of development of international wetland structure and function. At present, the management department and public lack a comprehensive understanding of the ecological status of internationally important wetlands in China. Here, using annual ecological monitoring data and hierarchical analysis, an evaluation index system was constructed with water environment, biological environment, biodiversity, and disturbance pressure as influencing factors, and an evaluation of the ecological status of 63 wetlands of international importance (WOII) in China was carried out, it is helpful to formulate technical plans for the ecological management of wetlands of international importance (WOII). The results showed that the average ecological status score of these wetlands was 0.714 ± 0.075, and there were differences in this score between different regions. The ecological status of wetlands in northeastern and northern coastal areas were mostly evaluated as ‘excellent’ and ‘good’, while some wetlands in other areas of China were evaluated as ‘poor’. The type and protection level of wetlands have an important impact on their ecological status. The ecological status of wetlands according to type were ranked swamp wetlands > coastal wetlands > river wetlands > lake wetlands, while those with national level protection were ranked higher than those with provincial level protection. The ecological status of WOII in China is generally good, but is adversely affected by human activities, alien species invasion, and other factors. Hence, there needs to be a focus on improving the protection and management mechanisms for WOII, promoting improvements in the ecological status of these wetlands, and transforming ecological product value.

Numerical Study on the Influence of Tidal Inlet Restoration on Water Exchange in Wanning Lagoon

Wanning Xiaohai is the largest lagoon in Hainan Province. In recent years, the body of water in Xiaohai has been polluted due to the untreated discharge of domestic sewage and aquaculture tailwater directly into Xiaohai. In order to improve the water quality of Xiaohai and relieve the pressure on the water environment, it was decided to restore the tidal inlet of Xiaohai. In this study, the water quality module of the finite volume ocean model was applied to simulate the change of pollution concentration using the Eulerian advection diffusion equation to analyze the half life time and tidal prism before and after the restoration project of the Wanning Xiaohai tidal inlet. The research results showed that after the restoration of the tidal inlet, the half life time of Xiaohai water body changed from 64 d to 58 d, shortened by 6 d, and the tidal prism increased from 8.8×106 m3 to 9.6×106 m3, which can well enhance the exchange between Xiaohai and external water bodies, improve the water quality of Xiaohai and relieve the pressure of water environment.

Ecological environment health assessment of lake water ecosystem system based on simulated annealing-projection pursuit: A case study of plateau lake

• A DPSR framework model was proposed and covers 26 multi-scale indexes. • Ecosystem health assessment was built from environment, ecology and socioeconomic system. • Ecological health, environmental pollution and water resources were combined to system. • Simulated annealing projection pursuit was introduced as assessment method. • The key factors affecting the Ecological environment health were identified. A lake ecological environment health assessment index system is constructed based on DPSR (Driving forces-Pressure-State-Responses) framework. The simulated annealing projection pursuit (SA-PP) algorithm, which can analyze high-dimensional data, is introduced and provides a new way for lake ecological environment health evaluation and decision-making. Qionghai, a typical plateau lake in Sichuan, China, is taken as an example to introduce the application of this assessment system. The results suggest the water ecological environment of Qionghai basin is in a relatively healthy state from 2017 to 2020. The state subsystem has the largest weight, and the important influencing factors affecting the health of lake water ecological environment are the water environment characteristics, ecological characteristics and pressure subsystem in the State subsystem. Zooplankton Simpson diversity index, chlorophyll a, NH 3 -N and total nitrogen are the main influencing factors of lake ecosystem health in the lake ecosystem health system. The restriction factor of the pressure subsystem is per capita daily domestic water consumption. Therefore, improving water quality and controlling water consumption intensity become important factors to improve the health of water resources and water environment in Qionghai basin. This study provides a new way for lake ecological environment health evaluation and decision-making.

Study on cooperative constraint zoning of water environment.

This study comprehensively considers two elements of water environmental sensitivity and pressure using the combination of qualitative analysis and quantitative calculation. And it puts forward the water environmental collaborative constraint zoning method and focuses on the construction of the water environmental collaborative constraint zoning evaluation index system using the fuzzy optimization programming model to determine the index weight. This study takes the Liaohe River Basin in Liaoning Province as a study area through two-dimensional quadrant analysis of water environmental sensitivity and pressure; it is divided into four types of areas: high-pressure and high-sensitivity area (HP-HS area), high-pressure and low-sensitivity area (HP-LS area), low-pressure and high-sensitivity area (LP-HS area) and low-pressure and low-sensitivity area (LP-LS area), respectively. The results show that the proportion of HP-HS area is 28.4%, the proportion of HP-LS area is 10.1%, the proportion of LP-HS area is 22.2% and the proportion of LP-LS area is 39.3%, respectively. The evaluation results are in line with the actual situation of the Liaohe River Basin in Liaoning Province. According to the results of different zoning, this research puts forward the optimization and adjustment scheme of industrial layout to achieve the comprehensive and coordinated sustainable development of population, economy, society, and environment in the study area. The research results also have been applied to the formulation of '14th Five-Year Plan' for water ecological environment protection of key river basins in Liaoning Province.

Water environmental pressure assessment in agricultural systems in Central Asia based on an Integrated Excess Nitrogen Load Model

Agricultural runoff is the main source of water pollution in Central Asia. Excessive nitrogen (N) inputs from overuse of chemical fertilizers are threatening regional water resources. However, the scarcity of quantitative data and simplified empirical models limit the reliability of grey water footprint (GWF), particularly in undeveloped regions. In this study, we developed an Integrated Excess Nitrogen Load Model (IENLM) to calculate excess N load and evaluate its potential water environmental pressure in Central Asia. The model optimized the biological N fixation and atmospheric N deposition modules by involving more environmental variables and human activities. Results showed that N fertilizer application contributed over 60% to total N input and was mainly responsible for 42.9% increase of total GWF from 101.5 to 145.0 billion m3 during 1992 - 2018. Water pollution level (WPL) increased from 0.55 in 1992 to 2.41 in 2018 and the pollution assimilation capacity of water systems has been fully consumed just by N load from agriculture since 2005. GWF intensity and grey water pollution – efficiency types in all Central Asian countries have improved in recent years except for Turkmenistan. N fertilizer application and agricultural economy development were the main driving factors induced N pollution. Results were validated by riverine nitrate concentrations and the estimates from prior studies. In future, combining the N fertilizer reduction with other farm management practices were projected to effectively improve the WPL. The modeling framework is favorable for N pollution research in data-scarce regions and provides a scientific basis for decision-making for agriculture and water resource managements.

Recyclable laccase by coprecipitation with aciduric Cu-based MOFs for bisphenol A degradation in an aqueous environment

Copper-based MOF (Cu-PABA) was selected to immobilize laccase (Lac) at optimum pH because of its favorable acid resistance. Cu-PABA@Lac biocomposites were synthesized in situ by the one-step method under moderate conditions (water environment and normal temperature and pressure). Cu-PABA@Lac had great potential to maintain stability due to the protection of the Cu-PABA shell and reasonable conformational changes. In addition, Cu-PABA@Lac could be used repeatedly by centrifugation, as confirmed in the degradation experiment of bisphenol A (BPA). Because of the synergistic effect of copper ions between laccase and Cu-PABA, the Km value decreased (from 0.0024 to 0.0014 mM); therefore, the affinity between laccase and guaiacol was enhanced. In conclusion, the system provides a choice for immobilized acid-resistant enzymes and a solution for environmental BPA degradation.

Decoupling water environment pressures from economic growth in the Yangtze River Economic Belt, China

China's economic development is gradually transforming from an extensive expansion mode to a green development mode that pursues environmental quality and environmental benefits. To achieve economic growth and reduce environmental pollution at the same time is the essence of decoupling. This paper combines the Tapio decoupling model and the Stochastic Impacts by Regression on Population, Affluence, and Technology (STIRPAT) model to analyze the decoupling performance and driving factors of economic output and water environment pressure of provinces and cities in the Yangtze River Economic Belt from 2004 to 2018. The results show that the overall water environment pressure and economic growth of the Yangtze River Economic Belt have shown a positive trend (from weak decoupling to strong decoupling). Strong decoupling areas were identified in the upper reaches of the Yangtze River (Sichuan, Guizhou, Yunnan, and Chongqing), the middle reaches of the Yangtze River (Jiangxi, Hubei, and Hunan), and the lower reaches (Shanghai, Jiangsu, Zhejiang, and Anhui). When compared with decoupling in the middle and lower reaches, the decoupling state of the upper reaches is unstable and tends to deteriorate. The driving factors of water environment pressure indicate that population size and urbanization are the main factors influencing wastewater discharge. The direction and size of the industrial structures are affected by policies and markets. Then, economic growth, fixed asset investment, and trade openness have had a positive impact on wastewater discharge. Technological progress and environmental regulations are important factors in controlling wastewater discharge. However, their current effect on wastewater discharge is not ideal. Therefore, while controlling the reasonable flow of population, each region should carry out industrial optimization and technological upgrading, and increase the management, capital, and technical support for the underdeveloped provinces of the Yangtze Economic Belt. This is necessary to achieve green economic development.

北方寒冷干旱地区内陆湖泊生态安全评价指标体系研究——以呼伦湖为例

呼伦湖作为我国北方寒冷干旱地区内陆湖泊的典型代表，在涵养水源、调节气候、防风固沙及维系呼伦贝尔草原生态系统平衡乃至我国北方生态安全屏障等方面发挥着不可替代的作用。准确识别呼伦湖流域主要生态安全问题、完善其生态安全评价指标体系对于科学研判呼伦湖生态环境状况、维持区域可持续发展及精准实施底线管控政策具有重要意义。在遥感影像、地面调查、实验模拟等多尺度数据分析基础上，结合历史资料收集、专家咨询、部门访谈等方式分析识别了呼伦湖区域生态安全问题及成因：（1）气候暖干化及超载放牧等因素使得草地退化显著，土地沙化、盐碱化面积扩大；（2）草原退化增加了干草入湖、大气干湿沉降及水土流失等水环境污染负荷；（3）气候暖干化造成湿地萎缩，加之长期的过度捕捞等人类活动使得渔业资源枯竭、鱼类小型化特征显著，水生生态系统稳定性下降，蓝藻水华频发。在全面诊断分析区域生态安全问题的基础上，以山水林田湖草系统方法论为理论指导，以改善呼伦湖流域生态环境质量为核心目标，依据评价指标的针对性、科学性、可操作性及系统性原则，采用压力-状态-响应（Pressure-State-Response，PSR）模型，以气象条件、人口、水资源、水环境压力及人类活动等5个一级指标构成的压力子系统，以水环境状况、水生态状况、陆域生态状况、生态系统服务功能和敏感性、景观格局及生态风险等6个指标构成的状态子系统，以生态治理措施及生态治理投入等2个指标构成的响应子系统，共同组成了一套包含13个一级指标38个二级指标的天空地一体、陆湖统筹的生态安全评价指标体系，以期为呼伦湖及北方寒冷干旱区类似湖泊的生态安全评价研究提供借鉴。;Hulun Lake, as a typical representative of inland lakes in the cold and arid areas of northern China, plays an irreplaceable role in water conservation, climate regulation, windbreak, and sand fixation. This lake maintains balance in the Hulun Buir grassland ecosystem and even the ecological-security barrier of northern China. Thus, identifying the main ecological-security problems in Hulun Lake Basin and improving its ecological-security evaluation index system are highly significant. The obtained data can be used for the scientific research and assessment of the ecological environment status of Hulun Lake, the maintenance of regional sustainable development, and the accurate implementation of bottom-line management and control policy.Based on remote-sensing imagery, ground survey, experimental simulation, and other multi-scale data analyses, this paper aims to analyze and identify the ecological-security problems of Hulun Lake area and their causes by combining historical data collection, expert consultation, and department interview. The results are as follows:(1) warm and dry climate, overgrazing, and other factors induce significant grassland degeneration, so land desertification and salinization area expand. (2) grassland degradation increases water-pollution load, such as hay into lake, atmospheric dry and wet settlement, and soil erosion. (3) climate warming and drying cause wetland shrinkage. Long-term overfishing and other human activities lead to the depletion of fishery resources and significant fish miniaturization. Consequently, the stability of aquatic ecosystem is reduced, and blue-green algal blooms occur frequently. Based on the comprehensive diagnosis and analysis of regional ecological-security problems, together with theoretical guidance by the methodology of mountains, rivers, forests, fields, lakes, and grass-system methodology, and improving the ecological environment quality of Hulun Lake basin as the core goal, the pressure-state-response (PSR) model is adopted in the present study according to the principles of focalization, scientific nature, operability, and systematicness of evaluation indices. The pressure subsystem comprises five first-class indicators, namely, meteorological conditions, population, water resources, water environment pressure, and human activities. The state subsystem comprises six indicators, namely, water environment, water ecology, land ecosystem, ecosystem service function and sensitivity, landscape pattern, and ecological risk. The response subsystem comprises two indicators, namely, ecological-management measures and ecological-management investment. Then, they jointly form an ecological-security evaluation index system with the integration of sky and land and the overall planning of land and lake, which includes 13 first-class indicators and 38 second-class indicators, to serve as a reference for studying the ecological-security evaluation of Hulun Lake and similar lakes in cold and arid areas.

基于灰水足迹的中国城市水资源可持续利用综合评价

随着城市化的快速发展，中国城市水资源面临着水资源短缺与水环境恶化等挑战，因此加强城市水资源可持续利用对于中国可持续发展具有重要意义。基于灰水足迹核算对2016年中国地级市水资源可持续利用情况进行综合评价。研究结果表明：（1）中国城市灰水足迹水平差异大，平均值为23.40×10⁸ m³，主要集中在20.00×10⁸ m³以下。中国城市农业源灰水足迹比例占比主要在70%以上，工业源比例占比主要在20%以下，而生活源比例占比在40%以下；（2）全国灰水经济生产率在12.45-857.31元/m³范围内，地区差异明显。33%城市灰水足迹荷载系数均大于1，全国地级市灰水足迹荷载系数平均值为1.16，城市水资源利用已对水环境产生污染压力，用水不可持续；（3）城市水资源开发率与灰水足迹荷载系数呈一定程度的正相关关系，说明了城市发展对水资源利用的"量"和"质"的压力作用具有一定的协同关系；（4）水资源可持续利用程度呈现大型城市 > 特大型城市 > 超大型城市 > 中小型城市，城市发展一定程度上有助于水资源的可持续利用，但发展规模过大可能会造成用水高产而护水低效的现象。因地制宜的实行水资源循环经济发展模式以及适时纳入灰水足迹核算与管理体系，是当前城市化大背景下实现水资源可持续利用的重要途径。;With rapid urbanization in China, urban water resource utilization is facing up to growing challenges brought by the water shortage and pollution. Thus, it is greatly significant to strengthen the sustainability of urban water resource utilization for China's sustainable development. The indicator of grey water footprint, which provided a metric measurement for the integrated assessment of water resource scarcity in terms of water pollution, was applied in assessing the sustainability in water resource utilization of the prefecture-level cities in China in 2016 (the data of country-level city, as well as Hongkong and Macao special administrative region and Taiwan region was not included). The results showed that (1) the urban grey water footprints of prefecture-level cities were significantly different with an average of 23.40×10⁸ m³, most of which were less than 20.00×10⁸ m³. The percentages of agricultural grey water footprints accounted for more than 70% in majority cities, and those of industrial and residential grey water footprints accounted for lower than 20% and 40%, respectively. (2) The economic productivity of urban grey water ranged from 12.45-857.31 yuan/m³ with significantly regional differences. The cities under great water environmental pressure with grey water footprint load coefficients higher than 1 accounted for 33% of overall cities assessed. The average coefficient of the assessed cities was 1.16, indicating that current urban water resource utilization was unsustainable and had negative impacts on water environment. (3) This study discussed the relationships between urban water resource utilization and protection, and found that there exited synergic relationships between urban water resource exploitation rates and grey water footprint load coefficients in terms of the impacts of urbanization on the quantity and quality of urban water resource. (4) The degrees of sustainable water resource utilization decreased in the order:big city > megapolis > megacity > small and medium city. Urban development to some extent contributes to the sustainability of water resource utilization, but excessive sprawl of economy and population sizes may degrade environmental-friendly water economy, which inclines to balance the achievements of economic efficiency and environmental protection in water resource utilization. Finally, suggestions for sustainable water resource management are summarized. Taking advantage of regional geography, promoting the water resource circulation economy, and incorporating the grey water footprint accounting and management system are important ways to achieve sustainable water resource utilization under the background of rapid urbanization, contributing to nationally fulfilling the 17 Sustainable Development Goals stipulated by United Nations 2030 Agenda, in terms of urban water resource utilization.

Attaining Sustainable Water Resource Utilization in Lake Basins Using Progressive Operational Scenario Analysis

There is a severe conflict between water resource exploitation and protection of the aquatic environment of lakes with rapid urbanization. Sustainable water resource utilization is urgent for sustainable development. The present study introduced a progressive operational scenario analysis (POSA) method for water resource regulation in lake basins. The application processes of POSA in Dianchi Lake, Erhai Lake and Fuxian Lake were described in detail. The effectiveness of the POSA method and scenario analysis method in achieving sustainable water resource utilization were compared and analysed, and the improvement in the efficiency of water resource utilization in lake basins due to the two methods was discussed. The results showed that implementation of POSA can effectively achieve sustainable water resource utilization in Dianchi Lake, Erhai Lake and Fuxian Lake and reduce the aquatic environmental pressure. Compared with business-as-usual, this method reduced the water use efficiency indicators of Dianchi Lake, Erhai Lake and Fuxian Lake by 2%–8%, 1%–25% and 8%–35%, respectively, and the water environmental pressure in Dianchi Lake, Erhai Lake and Fuxian Lake decreased by 28.51%, 29.70% and 69.39%, respectively. POSA has been proven to be an excellent tool for managing the aquatic environments and regulating water resources in lake basins.

Habitable Underwater Hyperbaric Facilities: Respiratory Balance in the Human Organism During Adapting to Saturation Nitrogen-Oxygen Hyperbaria

Abstract There were evaluated responses of the respiratory system to changes in the variables of the external environment under increased pressure. To the model of professional underwater human activity underwater served the conditions of full saturation in compressed air or nitrogen-oxygen gas mixtures. Technical devices were presented by a number of underwater laboratories, mounted at the bottom (Ikhtiander-66, 67 and 68), hyperbaric chambers, submersible drilling rigs (Bur-1 and 2), and an autonomous diving Ikhtiander-2 for a long stay in the water. Studies of respiratory gases mass transport conditions in man showed than within the pressure range of 0.25-1.1 MPa at density of moderate hyperoxic and nitrogen-helio-oxygen environment up to 14 kg/m3 oxygen and carbon dioxide regimes of the organism come to a new functional level which provides the adaptation to the extremal conditions. It is determined that an increase of physiological dead breathing space, a decrease of the rate of the O2 diffusion through the alveole-capillary barrier, intensification of unevenness of ventilator-perfusional relations in lungs and an increase of blood shunting in lungs are the main respiratory mechanisms which regulate mass transfer of O2 and CO2 in man under hyperbaria. The leading hemodynamic mechanism is the retention of volume blood circulation and cardiac output. It is studied how the compression rate, high partial pressures of oxygen and nitrogen, microclimate parameters in inhabited hypebaric chambers influence changes of functional breathing system. Absence of hypoxic state is proved in man (full saturation of man with nitrogen) under normoxia in nitrogen-oxygen environment with the density 6.34 kg/m3. These are also the data about accelerated rehabilitation of divers using the method of active adaptation o high altitudes. Basic directions in physiological studies of functional breathing system under increased pressure of gas and water environment are described.

Examining China's water pressure from industrialization driven by consumption and export during 2002–2015

Water depletion and pollution caused by industrialization have become major environmental concerns worldwide, which are further complicated by the urbanization and globalization. China has become an industrial powerhouse for the world, and its industrial activities-induced water pressure is no longer negligible. This study investigates China's industrial water pressure from final consumption and international export based on water footprint (WF) and dynamic structure decomposition analysis (SDA). The industrial blue and gray WFs with respect to rural consumption, urban consumption, and export are accounted for 2002–2015, and an advanced dynamic SDA model is developed and applied to examining the evolving WFs with 9 socio-economic drivers quantified. Results show that China's water resources pressure is intensified due to the increase of total industrial blue WF (by 47.4%) for 2002–2015, whereas a mitigation of water environment pressure is suggested by the decreasing gray virtual water outflow and total internal gray WF (by 31.9% and 36.4%, respectively). The SDA demonstrates that export scale and urban consumption level are two major drivers of water situation deterioration, which accumulatively contribute 38.3% and 33.0% to the evolving blue and gray WFs, respectively. In contrast, technology development is the dominant contributor alleviating China's water pressure, with absolute contribution proportions of 38.9% and 56.5%, correspondingly. Based on these, export regulation, consumption pattern adjustment and technological innovation are recommended for water policy making. The methodology used in this study can be extended to diagnosing the water issues in other nations/regions as well.

A dualistic water cycle system dynamic model for sustainable water resource management through progressive operational scenario analysis.

A reliable system simulation of the reciprocal mechanism between water resource utilization and dualistic water cycle is essential to the basin water resource sustainability management. In this study, a system dynamic model was built to simulate the water cycle change and lake water environmental pressure under the influence of water resources utilization, and the procedure of a progressive operational scenario analysis of how to relieve water environment pressure was illustrated. Dianchi Lake, which is the sixth largest and the most severely polluted freshwater lake in China, was employed as a case study to demonstrate the applicability of the model. The change of runoff components and pollution load of total nitrogen from 2000 to 2030 were discussed. Also, the sustainable water resource management was ultimately realized in the planning period through three progressive levels of water resource regulation scenarios. Compared with business-as-usual scenario, the TN pollution load into lake and total water demand decrease by 27.1 and 27.3%, and the domestic water use, industry water use, tertiary industry water use, and irrigation decrease 9.0, 16.8, 29.5, and 30% in the scenario 3.

Decoupling Analysis of Water Environmental Pressure and Economic Growth in Shanghai

While developing our economy, we also attach great importance to pollution prevention and control in order to improve the environmental quality. Water environmental pollution is an important part of environmental pollution. It is very meaningful to alleviate the pressure of water environment through the prevention and control of water environmental pollution. This paper uses decoupling theory to analyze the relationship between water environmental pressure and economic growth in Shanghai. The results show that, there is a strong decoupling between water environmental pressure and economic growth in Shanghai. The main reason is the transformation of industrial structure and the increase of investment in science and technology.

Regionalization of water environmental carrying capacity for supporting the sustainable water resources management and development in China

With the rapid economic growth and social development in China, conflicts over water resources between human and nature are continuously increasing which is attracting the attention of researchers. At the same time, discharge of water pollutants and exploitation of water resources pose a daunting challenge to the sustainable development of economy and society. China consists of 34 provincial administrative regions having similar or different characteristics in the levels of economic development, water resource endowment, water environmental capacity and water environmental pressure. Among these, it is meaningful to analyze spatial similarities and variations in water environmental carrying capacity (WECC), which contributes to carrying out different and scientific strategies for the management of water environment and for sustainable economic and social development in China. An index system is established to quantify WECC from the perspectives of carrying capacity, environmental pressure, vulnerability of water environment and exploitation and utilization potential. The k-means clustering method is applied to conduct the similarity combination based on the quantification of 4 integrated indicators using catastrophe progression method. The silhouette coefficient is introduced to measure the quality of clustering and to determine the optimal clustering number. The obtained results indicate that carrying condition of water environment becomes more and more better and exploitation and utilization potential of WECC is decreasing gradually from the east to the west in China, and there are more overload in the north provinces and less in the south. In addition, water environmental vulnerability in the west is higher than that of central and eastern provinces in China. The optimal clustering number is 4 obtained by calculating the silhouette coefficient. Also, 31 provinces are categorized into 4 sub-areas i.e. key protected area, controlled development area, optimized development area and prioritized development area. The suggestions on the corresponding bidirectional regulation to different sub-areas are also put forward to provide a scientific reference to rational distribution of economic development, elaborate management of water environment as well as regional sustainable development in the future.

湘江流域城市化与水资源环境交互耦合机制研究

为研究湘江流域城市化与水资源环境的耦合协调机制，本文利用流域内8个市州2000~2014年的统计数据，在建立城市化与水资源环境系统综合指标体系的基础上，构造耦合协调模型、灰色关联模型，揭示两系统的交互耦合机制，并运用ArcGIS的Jenks分类法分析流域耦合协调度的时空演变态势。结果表明：1) 湘江流域15年来城市化与水资源环境的协调关系总体趋向良性发展，耦合协调度从0.65波动上升至0.92。2) 流域内各市州城市化与水资源耦合协调度表现出复杂的空间分异特征，随着各市州经济状况、自然条件的差异而有所不同。3) 水资源本底条件是影响水资源环境的决定因素，人口规模、结构和科技水平则是水资源环境的主要胁迫因素；经济要素在城市化进程中起关键作用，供水设施和环境压力为城市化水平的主要约束因素。流域内城市化与水资源系统间驱动机制错综复杂，与各城市经济发展模式存在较大关联。 Based on the comprehensive index system between urbanization and water resource & environment of the Xiangjiang River basin, a coupling coordination model and GRA (Grey Relational Analysis) model were established to analyze quantitatively space-time dynamics of urbanization and water resources environment by coupling coordination degree, and to reveal the interactive coupling mechanism of two systems. The results are: 1) In the last 15 years, the coupling coordination between urbanization and water resources & environment in the Xiangjiang River basin trends upward totally while the internal mechanism remains to be optimized. 2) The coordination degrees of these cities show characteristically spatial differentiation, which is related to the economic development and natural conditions. 3) The driving mechanism is extremely complicated. As a whole, the background of water resources is the main determinant of water resources and environment while the population structure is the main stressor of that. Economic urbanization is the main determinant of the urbanization level of a river basin while the water supply facilities and environmental pressure primarily constrain the process of urbanization. However, the driving mechanism of each city shows pertinent regional differences, which is closely related to the urban economic development model.

Improving the sustainability of agricultural land use: An integrated framework for the conflict between food security and environmental deterioration

In rapidly developing countries, intensive agriculture faces the conflict between food security and environmental deterioration. To improve the sustainability of agricultural land use, this paper proposes an integrated framework for risk assessment and conflict coordination to cope with these salient challenges at the administrative unit level. This framework is demonstrated using a case study conducted in the Dongting Lake area in China. Drawing upon diverse sources of statistical data concerning agricultural inputs and outputs, water resources and natural hazards as well as questionnaire surveys conducted at the household level, this paper uses the Cobb-Douglas production function and the water environmental pressure index to assess food insecurity risk and environmental risk from food production, respectively. A double matrix method is used to characterize the degree of sustainability based on the risk assessment. The results indicate that the overall food security of the region can be maintained in the negligible-risk range. However, rising agro-environmental risks from grain production in the coming years are likely to threaten the sustainability of agricultural land use in most administrative units. It is suggested that optimization of land use patterns and mitigation of natural hazards could be effective approaches to improve the sustainability of local agricultural land use.

A Study on the Water Environmental Impaction Mechanism of Huaxi Wetland Park in the Process of Urbanization

In order to investigate the impact mechanism of urbanization on waters, Huaxi district environment, the analysis was carried out on the watershed forest cover, precipitation, stream water quality, wastewater discharge and treatment, such as river pollution investigation on the influencing factors of water environment. As a result, the influence mechanism and its protection counter measures of water environmental problems were drawn up. Urban development led to a series of soil and water environmental problems on the great pressure of urban water environment in the process of urbanization, due to the fragility of its environment in karsts area, especially in Huaxi. With the urban land expansion of Huaxi country, it was increasing of new immigration residents that mainly varied impact degrees of the wetland water environment.

Urban water security evaluation based on similarity measure model of Vague sets

The urban water security is an important part of urban ecological security, which is directly related to the sustainable development of urban society and economy. A comprehensive evaluation of the urban water security is a complex, vague and multi-level evaluation process. This paper presents a Vague set-based water security evaluation method and establishes a similarity measure model of Vague sets. AHP and Delphi methods are used to conduct index weighting in order to evaluate the level of urban water security assurance. The empirical study is done on the case study of Chengdu, China. Among the nine indexes of the city water security evaluation, the index values for socio-economic environment and socio-economic pressure are 0.24 and 0.41 respectively, which indicates that there is a relatively greater pressure on the city's social, economic and environmental pillars. The WSAI values of water resource index and water environment pressure are 0.94 and 0.96 respectively. These relatively higher values show that the city's water resources are relatively fully exploited and its environment is relatively well-protected. The similarity measure evaluation model of Vague sets can be used to quantitatively evaluate the degree of urban water security support.