基于相关系数定权的集对分析法在湖泊富营养化评价中的应用

为有效处理浮游植物型湖泊富营养化评价中各评价指标、评价级别以及各级别对应的水质标准浓度的不确定性,将集对分析理论运用于湖泊富营养化的水质评价中。在确定各指标权重时,将统计学中的相关关系理论引入该模型,通过计算各评价指标与叶绿素的相关关系来计算各水质评价指标在富营养化评价中所占权重,建立了基于相关系数定权的集对分析模型。最后通过国内5个湖泊的水质实测数据,将该模型与模糊评价方法,灰色评价方法进行比较验证,说明该模型简单实用、评价结果合理。     

湖泊富营养化综合评价的距离测度模型

湖泊富营养化评价标准中的分级指标为区间数.区间的下界点值和上界点值差异很大.近似呈指数变化.基于该认识,提出了一个湖泊富营养化综合评价的新模型--相对距离测度模型(RDMM).首先,对评价标准分级指标界值及待评湖泊水质指标值进行对数变换,以降低评价系统的非线性化程度:其次,定义评价标准与待评湖泊单一指标之间的相对距离测度,利用兼顾功能性与协调性的评价函数及Monte Carle模拟计算综合相对距离测度.综合距离测度最小值对应的类别即为待评湖泊的富营养化程度.文中给出了由5个湖泊组成的富营养化综合评价实例.     

基于属性识别模型的湖泊富营养化评价

为合理地确定湖泊的富营养化状态,从属性识别理论出发,建立了湖泊富营养化评价的属性识别模型,并结合熵权法确定的权重系数对东昌湖的富营养化状态进行评价。评价结果为各湖区全年均属于富营养化级别,并且7月份的富营养化程度最高,12月份次之,4月份最低,这与集对分析法和模糊识别方法评价的结果一致。表明该模型的评价结果是合理的;同时该模型简便、易懂,可作为湖泊富营养化评价的一种可行方法。     

基于投影寻踪的湖泊富营养化程度评价模型

针对湖泊富营养化评价指标的不相容性以及现有方法对等级的分辨率较粗略等问题,基于我国湖泊富营养化评价标准构建了投影指标函数,引入粒子群算法优化投影指标函数寻求最佳投影方向,应用最佳投影方向计算投影值,从而建立了评价湖泊富营养化等级的投影寻踪模型。同时引入混沌变量解决了采用随机生成样本系列的方法确定分段函数端点值存在的困难。实例应用结果表明,基于混沌映射的投影寻踪评价模型以投影值为单指标,采用分段函数的模型形式解决了湖泊富营养化的多指标综合评价问题,且该模型对湖泊富营养化等级的分辨率较高。     

人工鱼群算法在湖泊富营养化综合评价中的应用

提出了一种对多项指标都能普遍适用的湖泊水质富营养化评价的逻辑斯谛模型,将人工鱼群算法应用于逻辑斯谛曲线模型中的参数优化,并用优化后的逻辑斯谛曲线模型对湖泊富营养进行综合评价。对我国5个湖泊富营养化实测数据进行评价实例研究,并与其他多种评价方法进行比较,结果表明该模型具有实用性和可行性。     

湖泊富营养化综合评价的五元联系数法

针对湖泊富营养化的评价问题,从集对分析理论出发,建立了湖泊富营养化评价的五元联系数模型,利用置信度准则来确定富营养状态等级,避免了不确定系数取值的难题。利用五元联系数法对2005年8月至2006年7月洪湖不同区域的富营养化状态进行了评价。结果表明入湖区、养殖区、开阔区、保护区及全湖的富营养化状态依次为轻富营养、轻富营养、中营养、中营养和中营养,与模糊数学评价法的评价结果一致,与可拓学方法的评价结果一致或仅差一级。评价结果说明五元联系数模型用于湖泊富营养化评价是可行的,评价结果是可信的。     

基于MATLAB的神经网络在湖泊富营养化评价中的应用

以MATLAB为工具,建立评价湖泊水体富营养化状态的BP神经网络模型,应用此模型对我国9个湖泊富营养化程度进行评价。将此评价结果与用分级评分法、模糊数学法、Fuzzy Grey决策法的评价结果进行比较分析,得出较一致的结论。同时表明用MATLAB构建神经网络简洁、高效,具有更好的通用性和实用性。     

基于可变模糊模式识别模型的湖泊富营养化评价

针对湖泊富营养化评价中存在模糊性的特征,应用可变模糊模式识别模型对湖泊富营养化进行评价。通过对传统模糊数学得到的结果进行比较,表明可变模糊模式识别模型考虑到各指标值优劣方面对评价结果的影响,避免了最大隶属原则评价可能出现的偏差。     

湖泊富营养化数学模型研究进展

随着经济发展,水污染日益加剧,水体污染最突出的问题是富营养化.联合国环境规划署(UNEP)的一项调查表明,全球范围内30%～40%的湖泊和水库都有不同程度富营养化.湖泊富营养化通常呈现发展快、危害大、治理难、修复历时长等特点,而数学模型可以综合反映系统特征,因此建模是湖泊管理中特别有用的手段.综述了国内外湖泊富营养化数学模型的研究进展情况.将模型按照从简单到复杂分为4种类型分别进行评述,概述了各类模型的发展情况、优缺点及发展趋势.最后指出湖泊富营养化数学模型的发展趋势.     

一种改进的集对分析法在湖泊富营养化评价中的应用

将构建的湖泊富营养化评价标准集合和"比较标准"集合组成一个集对,并针对集对分析中联系数表达式的差异度系数i取值的不确定性,采用遗传算法对i的取值进行优化。将优化后的集对分析联系数表达式用于我国若干湖泊富营养化评价,其评价结果与用其他多种方法的评价结果基本一致,亦与湖泊富营养化实况相符合,为i值的确定和湖泊富营养化评价提供了一种可行的方法。     

HYDRODYNAMIC CHARACTERISTICS OF LAKE YANAKA

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Assessment of impact of water diversion projects on ecological water uses in arid region

In arid regions, large-scale water diversion from rivers leads to significant changes in river flow regimes, which may have large impacts on ecological water uses of river-dependent ecosystems, such as river, lake, wetland, and riparian ecosystems. To assess the integrated impact of water diversion on ecological water uses, we proposed a hierarchy evaluation model composed of four layers representing the evaluation goal, sub-areas of the influenced region, evaluation criteria, and water diversion schemes, respectively. The evaluation criteria for different types of ecological water uses were proposed, and the analytical hierarchy process was used for the integrated assessment. For a river ecosystem, the percentage of mean annual flow was used to define the grade of environmental flow. For a lake ecosystem, water recharge to the lake to compensate the lake water losses was used to assess the ecological water use of a lake. The flooding level of the wetland and the groundwater level in the riparian plain were used to assess the wetland and riparian ecological water uses, respectively. The proposed model was applied to a basin in northern Xinjiang in northwest China, where both water diversion and inter-basin water transfer projects were planned to be carried out. Based on assessment results for the whole study area and two sub-areas, an appropriate scheme was recommended from four planning schemes. With the recommended scheme, ecological water uses of the influenced ecosystems can be maintained at an acceptable level. Meanwhile, economical water requirements can be met to a great extent.     

Wind Shielding Impacts on Water Quality in an Urban Reservoir

This study applied an atmospheric Computational Fluid Dynamics (CFD) model and a three-dimensional hydrodynamic-ecological lake model to investigate the impacts of variable wind forcing on lake hydrodynamics and water quality. The CFD model was used to predict the wind field over the lake surface which served as the meteorological forcing for the lake model. The study was carried out for the Marina Reservoir in downtown Singapore where field measurements of the wind field showed that temporal and spatial differences in wind field were found to be significant. By comparing simulations using uniform and spatially variable wind inputs in terms of thermal stratification, Richardson number, vorticity, and spatial gradients, this study demonstrates that the variability in wind forcing in urban lakes that arise from shielding and seasonal effects can have significant impacts on the hydrodynamics and water quality in the reservoir.     

基于BP神经网络在白洋淀水质综合评价中的应用

选用2012年为现状年,应用BP神经网络建立白洋淀水质综合评价模型,用训练好的BP神经网络模型对白洋淀各监测断面的水质现状进行类别评价。结果显示,与单因素评价法相比,BP神经网络法是一种更加客观、有效和实用的环境质量评价方法。     

Response of Hydrodynamics and Water-quality Conditions to Climate Change in a Shallow Lake

Lake water resources operation and water quality management come up with higher challenges due to climate change. The frequency and intensity of extreme hydrological events are increasing under global warming, which may directly lead to more uncertainty and complexity for hydrodynamic and water-quality conditions in large shallow lake. However, studies about effects of climate change on lake hydrodynamic and water-quality conditions are not enough. Thus, a coupled model is es-tablished to investigate the potential responses of lake water level, flow field and pollutant migra-tion to the changing climatic factors. The results imply that water flow capacity and self-purification in the Hongze Lake can be improved by west, northwest, north, south and southeast winds indi-cating wind filed change has a great effect on the hydrodynamic and water-quality conditions in large shallow lake. It is further observed that both hydrodynamics and water quality are more sensitive to rainfall change than to temperature change; compared to the effect from temperature and rainfall, the effect from wind field appear to be more pronounced. Moreover, the results verify the feasibility of coupling basin hydrological model with lake hydrodynamic and water quality model. To the best of knowledge, the coupled model should not be used until independent calibra-tions and verifications for hydrodynamics and water quality modeling, the hydrological model and the coupled model.

     

基于集对分析多元模糊法的湖泊水质评价

针对湖泊水质评价中存在模糊性的特征,应用集对分析多元模糊法建立湖泊水质评价模型,并对西湖和青海湖的水质进行评价,西湖和青海湖的水质分别为Ⅴ类和Ⅲ类。应用实例表明该模型严谨、简洁方便、有效可行,能较好地应用于生产实际。     

浅水湖泊群连通与调水的二维水动力-水质藕合模型研究

将湖泊群连通并进行引清调水的水环境污染治理模式在浅水湖泊分布比较集中的地区逐渐受到人们的关注.为了探究独立湖泊群相互连通引水后各湖区的水动力水质变化情况,以武汉大东湖生态水网工程的建设为背景,建立了湖泊群二维水动力-水质耦合模型.采用适合复杂边界的非结构化网格,考虑湖底地形和气候条件,考虑污染物的输入、迁移和转化,以及蓝藻等浮游生物的生长条件,分别利用东湖2006年6月和2007年6月的野外数据对所建模型进行参数的率定和校核,并利用2012年6月实测数据对3种引水方案与3种连通模式组合情况下湖泊群的BOD5,TP,TN以及Chl-a等生化指标的变化情况进行模拟,对稳定运行30 d后的模拟结果进行比较分析.结果表明:引水工程中,对于水域面积较大的湖泊,风力作用依旧是影响流场的主要因素;同样的引水流量下,不同的调水方案对水质改善结果有较大差别;湖泊群中隔堤的存在会给湖泊污染治理带来困难,而在湖泊群中适当区域设置生态小岛对水质变化过程影响微弱.     

Development of a system‐based water balance model to assess interrelated physical and anthropogenic constraints in lake and reservoir watersheds,applied to Coeur d'Alene Lake,Idaho, USA

This study presents a methodology for the development of a water balance model that uses publicly available data in a manner useful to water scientists and managers who manage complex lake and reservoir watersheds. The approach was applied to Coeur d'Alene Lake, a naturally occurring lake that is controlled by a dam located on its outlet (Spokane River) in North Idaho, USA. As in many other areas, the region surrounding Coeur d'Alene Lake has experienced high rates of population growth in recent years, and there is concern that, as consumptive water use increases, the lake will eventually not be able to be managed to simultaneously maintain the federally mandated minimum flow requirements in the Spokane River and also maintain the target summertime elevation of 2128 feet (648.6 m) for recreation and hydropower purposes. The complexity caused by the competing uses at Coeur d'Alene Lake makes it an excellent case study for similarly characterized watersheds. Both a natural flow model and regulated elevation model were developed, and sensitivity analysis was conducted on both models to evaluate which lake processes have the greatest effects on lake elevation, thereby requiring the most attention. A ‘low‐flow’ scenario was modelled to demonstrate the usefulness of the model and to inform Coeur d'Alene Lake regional stakeholders regarding the interrelationship between current water policy and the lake's physical behaviour under stressed conditions that could result from climate change. Model result indicates that, while lake elevation may be maintained at the summertime elevation of 2128 feet (648.6 m) under a low‐flow scenario, the outflows in the Spokane River start to approach the minimum flow requirements in the month of August. The developed approach is useful where publicly available data exist and allows for economic, yet rigorous, water resources systems evaluation without requiring significant field data collection.     

基于数值模拟的南湖流场优化与水质改善研究

针对城市景观水体流动性差,往往处于封闭或半封闭状态,容易造成富营养化的问题,以典型城市景观水体山东郓城南湖为研究对象,基于MIKE21软件构建了湖区水动力-水质耦合模型,对湖区流场与水质情况进行了模拟计算。为改善湖区流场和水质状况,提出增设水源热泵回水口的优化方案,并根据模型模拟结果,对不同方案流场改善效果进行了分析比较。结果表明:增设水源热泵回水口能有效改善南湖流场分布与湖区水质;以氨氮为评价指标,沿湖岸设置4个回水口的方案与原方案相比较,观测点的氨氮质量浓度平均降低了59.7%,对水质的改善效果最好。     

城市景观湖泊水体交换的数值模拟研究

通过水流数学模型模拟城市湖泊流场分布是评估水体交换能力的重要依据。利用二维水动力数学模型研究了惠州西湖的水动力优化调控方案,探明了惠州西湖各状条件下水动力较差的区域,评估了引水对于惠州西湖湖水动力的改善程度,并对比了不同方案的的引水效果,进而提出了较好的引水方案。其成果可为惠州西湖和其他城市湖泊水质改善工程提供参考和借鉴。