Evaluation,prediction, and protection of water quality in Danjiangkou Reservoir,China

The water quality in the Danjiangkou Reservoir has attracted considerable attention from the Chinese public and government since the announcement of the Middle Route of the South to North Water Diversion Project(SNWDP), which commenced transferring water in 2014.Integrated research on the evaluation, prediction, and protection of water quality in the Danjiangkou Reservoir was carried out in this study in order to improve environmental management. Based on 120 water samples, wherein 17 water quality indices were measured at 20 monitoring sites, a single factor evaluation method was used to evaluate the current status of water quality. The results show that the main indices influencing the water quality in the Danjiangkou Reservoir are total phosphorus(TP), permanganate index(COD Mn), dissolved oxygen(DO), and five-day biochemical oxygen demand(BOD5), and the concentrations of TP, BOD5, ammonia nitrogen(NH3e N), COD Mn, DO, and anionic surfactant(Surfa) do not reach the specified standard levels in the tributaries. Seasonal Mann e Kendall tests indicated that the COD Mn concentration shows a highly significant increasing trend, and the TP concentration shows a significant increasing trend in the Danjiangkou Reservoir. The distribution of the main water quality indices in the Danjiangkou Reservoir was predicted using a two-dimensional water quality numerical model,and showed that the sphere of influence from the tributaries can spread across half of the Han Reservoir if the pollutants are not controlled.Cluster analysis(CA) results suggest that the Shending River is heavily polluted, that the Jianghe, Sihe, and Jianhe rivers are moderately polluted, and that they should be the focus of environmental remediation.     

DEVELOPMENT AND APPLICATION OF A EUTROPHICATION WATER QUALITY MODEL FOR RIVER NETWORKS

The Preissmann implicit scheme was used to discretize the one-dimensional Saint-Venant equations, the river-junction-fiver method was applied to resolve the hydrodynamic and water quality model for river networks, and the key issues on the model were expatiated particularly in this article. This water quality module was designed to compute time dependent concentrations of a series of constituents, which are primarily governed by the processes of advection, dispersion and chemical reactions. Based on the theory of Water Quality Analysis Simulation Program （WASP） water quality model, emphasis was given to the simulation of the biogeochemical transformations that determine the fate of nutrients, in particular, the simulation of the aquatic cycles of nitrogen and phosphorus compounds. This model also includes procedures for the determination of growth and death of phytoplankton. This hydrodynamic and water quality model was applied to calculate two river networks. As illustrated by the numerical examples, the calculated water level and discharge agree with the measured data and the simulated trends and magnitudes of water quality constituents are generally in good agreement with field observations. It is concluded that the presented model is useful in the pollutant control and in the determination of pollutant-related problems for river networks.     

MODEL OF CALCULATING WATER QUANTITY NEEDED TO DILUTE AND PURIFY POLLUTANTS IN RIVER NETWORK AND ITS APPLICATIONS

Based on the analysis of dilution capacity and self-purification capacity of water body, the dilution, dispersion, entrapping and purification principles of pollutants in river system at river network area were discussed in this paper. Also, the one and two dimensional models of water quantity needed for improving water environment quality and pollutant concentrations were developed for rivers and lakes respectively. The calculation method for the quantity of water transfer was given and the forecasting evaluation of the effect of water transfer was carried out. It was took the project, water transfer from Yangtze River to improve the water quality of rivers in Zhangjiagang City, as an example, and changing principles of water quantity and quality were observed in rivers and lakes through site water transfer experiments. The theory of estimating parameters in inverse problem was used to determine parameters in water quantity and quality models. The water quantity and quality coupled models in river system were applied to calculate the minimal water transfer quantity. The theoretical and technical support for the improvement of water environmental quality in Zhangjiagang City and the project ＂water transfer form Yangtze River to Taihu Lake＂ were provided.     

Evaluation of urban river landscape design rationality based on AHP

An evaluation model for the rationality of the landscape design of urban rivers was established with the analytic hierarchy process （AHP） method so as to provide a foundation for updating the landscape design of urban rivers. The evaluation system was divided into four layers, including the target layer, the comprehensive layer, the element layer, and the index layer. Each layer was made of different indices. The evaluation standards for each index were also given in this paper. This evaluation model was proved tenable through its application to the landscape design rationality evaluation of the Weihe River in Xinxiang City of Henan Province. The results show that the water quality, space, activity, facility, community, width of vegetation, sense of beauty and water content are among the most influential factors and should be considered the main basis for evaluating the rationality of the landscape design of urban rivers.     

R/S method for evaluation of pollutant time series in environmental quality assessment

The significance of the fluctuation and randomness of the time series of each pollutant in environmental quality assessment is described for the first time in this paper. A comparative study was made of three different computing methods： the same starting point method, the striding averaging method, and the stagger phase averaging method. All of them can be used to calculate the Hurst index, which quantifies fluctuation and randomness. This study used real water quality data from Shazhu monitoring station on Taihu Lake in Wuxi, Jiangsu Province. The results show that, of the three methods, the stagger phase averaging method is best for calculating the Hurst index of a pollutant time series from the perspective of statistical regularity.     

STUDY AND APPLICATION OF STEADY FLOW AND UNSTEADY FLOW MATHEMATICAL MODEL FOR CHANNEL NETWORKS

Based on the Preissmann implicit scheme for the one-dimensional Saint-Venant equation, the mathematical model for one-dimensional river networks and canal networks was developed and the key issues on the model were expatiated particularly in this article. This model applies the method of three-steps solution for channel-junction-channel to simulate the river networks, and the Gauss elimination method was used to calculate the sparse matrix. This model was applied to simulate the tree-type irrigation canal networks, complex looped channel networks and the Lower Columbia Slough networks. The results of water level and discharge agree with the data from the Adlul and field data. The model is proved to be robust for simulating unsteady flows in river networks with various degrees of complex structure. The calculated results show that this model is useful for engineering applications in complicated river networks. Future research was recommended to focus on setting up ecological numerical model of water quality in river networks and canal networks.     

INTERVAL FINITE VOLUME METHOD FOR UNCERTAINTY SIMULATION OF TWO-DIMENSIONAL RIVER WATER QUALITY

Under the interval uncertainties, by incorporating the discretization form of finite volume method and interval algebra theory, an Interval Finite Volume Method (IFVM) was developed to solve water quality simulation issues for two-dimensional river when lacking effective data of flow velocity and flow quantity. The IFVM was practically applied to a segment of the Xiangiiang River because the Project of Hunan Inland Waterway Multipurpose must be started working after the environmental impact assessment for it. The simulation results suggest that there exist rather apparent pollution zones of BODs downstream the Dongqiaogang discharger and that of COD downstream Xiaoxiangjie discharger, but the pollution sources have no impact on the safety of the three water plants located in this river segment. Although the developed IFVM is to be perfected, it is still a powerful tool under interval uncertainties for water environmental impact assessment, risk analysis, and water quality planning, etc. besides water quality simulation studied in this paper.     

Water level updating model for flow calculation of river networks简

Complex water movement and insufficient observation stations are the unfavorable factors in improving the accuracy of flow calculation of river networks. A water level updating model for river networks was set up based on a three-step method at key nodes, and model correction values were collected from gauge stations. To improve the accuracy of water level and discharge forecasts for the entire network, the discrete coefficients of the Saint-Venant equations for river sections were regarded as the media carrying the correction values from observation locations to other cross-sections of the river network system. To examine the applicability, the updating model was applied to flow calculation of an ideal river network and the Chengtong section of the Yangtze River. Comparison of the forecast results with the observed data demonstrates that this updating model can improve the forecast accuracy in both ideal and real river networks.     

DEVELOPMENT OF COUPLED 1D-2D MATHEMATICAL MODELS FOR TIDAL RIVERS

Some coupled 1D-2D hydrodynamic and water quality models depicting tidal water bodies with complex topography were presented. For the coupled models, finite element method was used to solve the governing equations so as to study tidal rivers with complex topography. Since the 1D and 2D models were coupled, the principle of model coupling was proposed to account appropriately for the factors of water level, flow and pollutant flux and the related dynamical behavior was simulated. Specifically the models were used to probe quantitative pollution contribution of receiving water from neighboring Jiangsu and Zhejiang Provinces to the pollution in the Huangpu River passing through Shanghai City. Numerical examples indicated that the developed coupled 1D-2D models are applicable in tidal river network region of Shanghai.     

Simulation of Non-Point Pollutants Evolution in Coastal Plain Island-A Case Study of Chongming Island

The coastal plain region usually shows the agricultural dominated industry mode, so more and more attention is paid to non-point pollutants discharge. In this study, the method for assessing the influence of non-point pollutants discharge on river water quality is probed which is concluded as follows： （1） Considering the costal plain island is characterized as nearly even elevation, the conventional gravitational runoff confluence method based on eight-point gravitational flowing directions （DS） is unable to compute the runoff confluence received by the surrounding rivers, so a new method of triangular confluence based on three-points of grid center and the river segments is presented. Further the equations of non-point pollutants loads estimation and non-point pollutants confluence on rivers are presented. （2） The integration mode of non-point pollutants model and river water quality model is presented so as to further assess the non-point pollutants contribution to river water quality. （3） With the Chongming Island, the third largest island in China, as an example, the above-mentioned equations are specified. For this island, the non-point pollutants loads are estimated and linked to the developed water quality model of the river network in the island, and further the non-point pollution evolution in river network is simulated. In this scenario, the non-point pollution contribution to river water quality over the whole island is clearly displayed, and the area where the river water quality is seriously influenced by non-point pollutants discharge is distinctly depicted. This scenario also shows the water quality contribution ratio of non-point pollution to point pollution can be in the range of 55.5% to 44.5% which proves the importance of non-point pollution control in costal plain islands.     

常用水质评价方法的选择

水环境质量的综合评价方法很多,特点各异.在重点分析最差因子判别法、有机污染综合指数评价法、主分量分析法和基于模糊理论的贴近度综合评价法这4种方法特点的基础上,以上海市若干水质监测点的监测成果为例,利用这4种方法分别进行了综合评价.评价结果表明,最差因子判别法评价的水质较差,而贴近度综合评价法评价的水质又过于乐观.有机污染综合指数评价法需要多次计算,多次比较,比较繁琐.主分量分析法充分考虑了各参评因子的权重,评价过程只需要通过一次计算,就能得出一个判别式和判别标准,以后评价时可以直接使用,而且评价结果符合实际情况,因此是一种比较好的评价方法.     

水环境质量评价三种方法应用浅析

本文从众多水质评价方法中选取地图重叠法、评分制法、水质指数叠加法三种方法，并通过运用这三种方法对１９９８年浑江源头至东村段水质评价为例，经过分析，发现水质指数叠加法是三种方法中一种较好的水质评价方法。     

基准剂量法在水质基准中的应用

基准剂量法作为一种新的确定参考剂量的方法,在运用于水质基准风险评价中制订非致癌物的可接受水平时,弥补了以往采用未观察到不良效应水平(NOAEL)作为指标的不足。该方法能从数理统计学的角度解释和发展剂量反应关系,体现了显著的科学性,已成为毒理学界确定参考剂量(RFD)的一种有效方法。首先,从水质基准的定义、分类、水质基准和水质标准的区别及水质基准方法学4个方面阐述了水质基准的相关概念。其次,详细总结了水质基准的国内外相关研究。然后,介绍了我国饮用水水质基准值的计算公式。再次,运用统计学知识详细阐明了基准剂量法的原理。最后,结合我国水环境质量标准管理体系的现状,提出了我国水质标准需要进一步完善的方面,以及开展我国水质基准研究的重要性和迫切性,并对下一步研究重点做出了展望。     

湿地水质监测技术与方法

湿地是水陆相互作用形成的特殊自然综合体.具有巨大的水文和元素循环功能,是生物多样性的“基因库”.但由于人类活动和自然因素,使其受到不同程度的污染,特别是水质污染令人担忧.文章对湿地水质监测技术、因子及方法,作了介绍.     

漕河水质的现状评价

采用综合指数法和灰色聚类法对漕河某河段的水环境进行水质评价。根据污水水质的特点,布设水质监测点,对污染源、水文地质等进行综合调查。选择主要的因子进行河水质量现状评价,用两种方法评价的结果大致相同,综合指数法在此更符合实际。河水的主要污染成分为COD和总汞。     

灰关联方法在水质评价中的应用

灰关联分析方法具有计算简单、要领直观的特点，而且其评价结果能够反映不同断面不同水质级别之间的序关系。文中应用灰关联分析方法对一处拟建水源地进行了综合评价，取得了很好的效果。     

中国地表水资源质量评价方法的研究

作者分析了我国现行水资源质量评价方法中存在的问题，介绍了国外该项工作的思路和作法。在此基础上，建立了一套基于水质项目环境影响的分区、分类、分级的多指标综合指数评价体系，克服了国内传统评价方法的假达标、一票否决，不能描述级内优劣等弊病。对全国160个重点站进行的计算结果表明，该方法基本实现了与国际接轨，更为科学合理。     

基于水质综合指数法的亚热带水源型水库水质评价

为了解亚热带水源型水库——茜坑水库水质状况,基于2016年1月至2020年12月对水库pH值、高锰酸盐指数、五日生化需氧量、粪大肠菌群、氨氮、硝酸盐氮、总氮、总磷、硫酸盐、氯化物、氟化物、铁和锰等13个主要水质指标每月1次的监测数据,通过计算水质综合指数评价了水质状况,并通过多元线性回归优化水质综合指数模型。结果表明:水库水质整体较好,pH值和高锰酸盐指数受浮游植物繁殖影响,部分时段超标,总氮质量浓度偏高,总磷质量浓度和粪大肠菌群数部分时段较高,铁质量浓度的上升趋势应重点关注;表层监测难以全面体现分层对水质的影响,应增加垂向监测,全面掌握水库水质风险;利用由总磷、铁、高锰酸盐指数、氨氮和硝酸盐氮组成的主要污染指标水质综合指数模型可有效进行水质评价和管理。     

南水北调东线（江苏段）水质变化趋势分析

为科学指导调水工作,全面掌握南水北调东线江苏段地表水资源质量状况及其水质变化趋势,应用季节性Kendall检验法,选取溶解氧、高锰酸盐指数、五日生化需氧量、氨氮、石油类、挥发酚6项污染指标,对2001-2012年南水北调东线(江苏段)14个控断面水质变化进行分析评价,从污染物类型、河流级别和行政区域三个方面对水质变化结果进行分析比较。结果表明:2001-2012年间,1按污染物种类分,南水北调东线江苏段研究区域内6项水质评价指标均呈变好趋势;2按河流级别分,支流水质呈变好趋势,输水干线水质除石油类指标趋势变差外,其它均呈变好趋势;3按行政单位分,扬州段BOD5、淮安段石油类、宿迁段溶解氧和CODMn水质变差外,其它段均呈变好趋势。     

单因子法与可变模糊法在水质评价中的应用

基于2019、2020年在辽河、大辽河入海河段及辽河口的水质监测数据,分析河流、河口水质指标的时空变化规律,并运用单因子评价法、可变模糊评价法对水质状况进行评价。整体而言,基于可变模糊评价法的水质评价等级优于单因子评价法;河流的主要污染指标为DO、高锰酸盐指数和总磷,基于单因子法的评价结果为Ⅳ类、劣Ⅴ类,可变模糊法评定等级为Ⅰ～Ⅲ类;河口监测点的主要超标污染物为无机氮,单因子评价结果为Ⅳ、劣Ⅳ类,可变模糊评价法为Ⅱ、Ⅲ类;单因子法基于最差指标的区间评定,可变模糊法综合权衡各指标的影响,在水环境管理中可根据目的不同考虑采用不同评价方法。