Eutrophication vulnerability analysis: A case study

River Cavado water quality variability was studied for eutrophication vulnerability assessment at a new surface water supply intake. Since the river flow regime is artificially controlled by upstream multipurpose reservoirs, mathematical modelling was applied in evaluating alternative management scenarios. Due to the fact that surface water quality at intake location is mainly affected by a wastewater treatment plant effluent discharge 5 km upstream, algae and nutrients concentration simulations have been worked out in order to identify critical situations. Different algal concentration profiles along the river were obtained for local conditions of light energy, water temperature and estimated nutrient loads, showing high probability of eutrophication occurrence for some of the simulated scenarios. The discussion of results of this study appears to be very useful for river basin wide water management policies evaluation.     

回归分析框架下洪涝灾害脆弱性曲线构建方法综合比较研究

脆弱性曲线定量揭示灾害危险性强度与承灾体损失程度的关系，链接灾害的自然属性与社会属性，是灾害经济影响评估和风险管理的重要支撑。当前研究提出了多种洪涝灾害脆弱性曲线，多为基于案例的实证性研究，缺少系统性的理论整理。本文在回归分析理论框架下，对脆弱性曲线模型进行一致性的考证。明晰了损失率脆弱性曲线与损失状态脆弱性曲线的区别与联系，分析两种脆弱性曲线10种不同构建形式的基本假设、优缺点、适用性、拟合方法及选取标准。同时，利用湖北省恩施市“7.17”洪灾调研数据，构建商业停滞损失脆弱性曲线模型，对理论进行了验证分析。研究建议：损失率脆弱性曲线可以更好地链接损失评估与资产计算，在有准确的损失率数据情况下选用。其中，简单线性模型和双对数模型具有更好的参数可解释性，可优先考虑。损失状态脆弱性曲线更容易对应风险分级与对策分类，在损失率数据存在较大不确定性时选用。其中，Lognormal模型具有更好的理论适用性，建议优先考虑。     

Determinants of livelihood vulnerability in farming communities in two sites in the Asian Highlands

ABSTRACT

To identify the indicators of adaptive capacity that determine vulnerability of households, an intensive investigation was conducted in farming communities at two locations in the Asian highlands. Livelihood vulnerability was assessed, classified to four categories and regressed against current adaptive capacity using logistic regression. Household head’s education, irrigated land, non-agricultural income, and technologies used were associated with adaptive capacity. The strengthening of human, natural and financial capital is identified as the best means of managing risk in farming communities in this mountainous region.     

盲数理论在湖泊水环境容量计算中的应用

借鉴已有确定性模型成果,首先建立了一个参量为灰区间数的湖泊水环境容量计算模型。然后从湖泊水环境系统多种不确定性共存的角度,运用盲数理论定义了水环境系统参量盲数。在此基础上,通过对上述包含灰区间数的水环境容量模型参数盲数化,得到了盲信息下湖泊水环境容量计算模型,并给出了大型浅水湖泊水体纳污能力计算方法。实例研究表明,以盲数理论研究湖泊水环境容量,理论上是可行的,计算结果是可信的     

Schistosomiasis in the Weija Lake: A case study of the public health importance of man-made lakes

The Weija lake, located 17 km west of Accra, capital of Ghana, has a shoreline of 48 km. The creation of the Weija lake in 1979 by the Government of Ghana to supply piped water and to support irrigation and fisheries programmes has provided ideal conditions for disease transmission. A survey on schistosomiasis conducted in and around the lake from 1991 to 1992 showed prevalence rates ranging between 25 and 89.4%. Migration of disease-infected fishermen and peasant farmers, flaws in resettlement programmes, changes in the flow rate of water, proliferation of water weeds and conditions favouring the growth and development of host snails were found to be responsible for the increasing incidence of schistosomiasis in the lake basin.     

水流移床力及河道运动力学的初步探讨

本文首次提出了水流移床力和河道运动力学的概念，并建立了水流移床力与流量脉动强度的关系。水流挟沙力是水流挟带泥沙通过河道的能力，而移床力则是水流改造河道的能力。非恒定流输沙使水流具有移床力，因而造成河道运动。研究发现，流量脉动强度愈大，移床力也愈大。不同频率的脉动对移床力有不同的贡献。在缺少河道实测运动资料的情况下，可以利用流量脉动能谱算出修正系数k推算实际水流移床力。由移床力与流量脉动的关系可以推论，水流脉动强度愈大，河道愈不稳定。利用水流移床力公式，可以计算和预测河道运动的速度和距离。     

Large lakes in climate models: A Great Lakes case study on the usability of CMIP5

Large lakes have an impact on regional weather. In addition, they can be both sensitive to and influence regional climate changes. In the climate models that are used to investigate future climate changes, lakes are greatly simplified and sometimes absent. At the regional scale, this can have strong implications for the quality of the model information about the future. Through our work with climate information users in the Laurentian Great Lakes region, we have found that basic credibility of the information requires the underlying climate models simulate lake-atmosphere-land interactions. We are not aware of efforts within the scientific community to make known how individual large lakes are represented in models and how those representations translate to the quality of the data for particular regions. We share our framework for identifying how the Laurentian Great Lakes are represented in the Coupled Model Intercomparison Project (CMIP) version 5 climate models. We found that most CMIP5 models do not simulate the Great Lakes in a way that captures their impact on the regional climate, which is a credibility issue for their projections. We provide a perspective on the usability of CMIP5 for practitioners in the Great Lakes region and offer recommendations for alternative options.     

浮泥水域水流挟沙力公式初探

浮泥发育水域水体的含沙量通常变幅较大,无法与水流流速建立良好关系.在分析浮泥水域含沙量时空变化特征及常用挟沙力公式的基础上,提出了以浮泥重度为参数的挟沙力公式.该公式建立了浮泥水域水体含沙量与浮泥床面泥沙条件的关系,使泥沙数学模型中泥沙输运过程的数值模拟结果更加符合实际情况,有助于提高泥沙数值模拟精度.     

四湖流域水生态环境保护与修复探讨

对湖北省四湖流域水污染源进行了分析,并根据四湖流域水生态环境、水污染现状和各水体的水环境功能类别要求,在总结流域水生态修复和水环境保护现状的基础上,提出了流域水生态环境保护与修复的对策与建议。     

考虑大气沉降的湖库分区动态水环境容量精细解析

针对面源污染为主的湖库型流域,为建立水质目标管理与污染总量控制之间更精准的响应关系,借鉴日最大负荷总量模式,基于物质量平衡原理提出考虑径流丰枯变化、不均匀混合、大气沉降等影响因素的湖库分区动态水环境容量精细解析方法,包括污染混合区设置、代表水文系列确定、逐日分区水量水质计算。以沙河水库为例,分别以全湖Ⅱ类、主湖Ⅱ类作为水质管理目标,采用2010—2015年代表水文系列对总氮动态水环境容量进行精细解析。结果表明：全湖Ⅱ类、主湖Ⅱ类水质管理目标下沙河水库总氮水环境容量的多年均值分别为36.7 t和99.43 t,若不考虑湖滨混合区,全湖Ⅱ类水质目标下总氮的年水环境容量计算值偏大66.43%;实施水质目标管理的水域面积越大,大气沉降对水环境容量的影响越大;径流年际及年内丰枯变化对水环境容量的影响显著;各分区总氮控制总量占全流域总量的比例与面积比基本一致。湖库分区动态水环境容量精细解析可量化不同因素对水环境容量计算结果的影响,科学解析面源输入型湖库水环境容量的时空结构特征,实现水质目标管理与污染总量分区管控的有机联动,更好地支撑流域水环境的精细化管理。     

二元驱动的河湖历史演变及其启示

以河湖历史演变过程为研究对象,分析了演变的驱动力及其作用特征、影响因素,提出河湖演变呈现出由自然-人工二元平行驱动向二元交错驱动发展的趋势。针对在人为改变河湖水系的历史过程中曾出现过的问题和风险,重点讨论了当前水系布局规划需要思考的问题,包括自然地理分异、气候变化、成本效益、生态环境等。建议拓展研究的维度和尺度,合理利用自然情势并关注人类活动潜在而深远的影响,多途径削减不利影响,以构建满足水资源合理配置、兴利除害、生态环境保护等社会需求的江河湖库水系格局。     

供水管网优化模型比较研究

以寻找工程实践中最可行的管网优化模型为目的,通过理论分析和实例计算对工程中常用的单目标线性规划模型、多目标线性规划模型和单目标非线性规划模型进行对比研究。结果表明,单目标非线性规划模型具备较强实用价值。三类模型的比较研究也为进一步改进管网优化设计方法提供了新的思路。     

考虑湖泊调蓄的引江济淮工程旬水量调度方案

为挖掘引江济淮工程沿线湖泊调蓄能力在保障供水、降低泵站输水能耗方面的潜力,开展考虑湖泊调蓄的 跨流域调水工程旬水量调度研究,构建考虑湖泊调蓄的泵站-湖泊多目标旬水量优化调度模型,并采用遗传算法进 行求解,以制定满足用水单元缺水量最少、泵站能耗最小和湖泊不平衡量最小的泵站-湖泊联合调度方案。分析 引江济淮工程调度运行的不同典型运行工况,以自流引江工况为例讨论考虑湖泊调蓄的旬水量调度方案的优势。 结果表明,考虑湖泊调蓄的调度方案能有效提高供水保证率、降低泵站总输水能耗,可为引江济淮工程运行调度 提供决策支撑。     

基于GIS加权叠加的南四湖流域地质环境质量评价

南四湖是中国南水北调东线工程的重要输水储蓄枢纽,做好该流域地质环境质量评价工作对合理规划人类工程活动和保护生态环境具有重要意义.以南四湖上游流域为研究区,从地形地貌、构造活动性、地下水质量、土壤质量、地面沉降、崩塌滑坡、地面塌陷、人类工程活动强度8个方面,采用综合指数法并基于MapGIS软件进行分层加权叠加,然后根据分...     

我国与世界水电工程环境保护比较研究

通过对我国与世界主要国家水电工程环境保护情况进行比较分析,表明了我国水电开发的环境保护理念处于先进水平,环境管理制度日臻完善,环境保护措施体系发展较快,今后应继续加大对水电环保基础科研工作的投入,促进水电开发与环境保护的和谐发展。     

The relevance of species-based indicators as a tool for evaluating the structure of exploited fish assemblages: a comparative study of two tropical lakes in Mali, West Africa

A comparative study of the fish communities in two lake ecosystems in Mali (Lakes Manantali and Selingue) was based on monitoring small‐scale fishery landings for a 13‐month period. The main difference between the two lakes is the fishing pressure, being higher in Lake Selingue and lower in Lake Manantali. The effects of fishing on the structure of the fish communities in the two lakes were analysed with the use of diversity indices, rank species abundance (RSA) and abundance–biomass comparative curve (ABC) methods. The diversity differed significantly between the lakes, being higher for Lake Selingue. Analysis of the community structure, using RSA curves, indicated a more regular distribution of the weights between fish species for Lake Selingue than for Lake Manantali. The two lakes exhibited different exploited fish community structures. For Lake Selingue, the fishery was based on smaller‐sized species, compared to that for Lake Manantali. The indicators based on the species composition of exploited fish communities, in terms of abundance and life‐history traits, seemed to be more relevant in this study. Indicators such as diversity indices and RSA curves depend strongly on the exploitation strategy, being unreliable for evaluating exploited fish communities from catch data.     

坡面径流阻力计算模式对比研究

坡面流是污染物迁移、土壤侵蚀、泥沙输移的主要动力因素,阻力系数是影响坡面流模拟的重要参数。为比较三种阻力计算模式(阻力系数为常数、以淹没度为变量的Lawrence模型和阻力分割模型)在裸坡、砾石覆盖坡面、植被覆盖坡面三种常见坡面上的适用程度,本文建立了坡面降雨径流模型,对不同类型坡面的产流进行了模拟。坡面径流模型采用扩散波模型,坡面降雨入渗模型采用考虑坡度影响的Green-Ampt模型,当存在植被时,考虑冠层降雨截留损失。结果表明:在裸坡上,三种阻力计算模式均适用;而在有砾石覆盖和植被覆盖的坡面上,考虑阻力系数时空变化的阻力分割模型模拟精度最高。阻力系数对坡面径流流量的影响在坡面汇流的涨水与退水阶段较大,而在稳定阶段很小。对有植被覆盖坡面,降雨强度存在阈值,大于阈值时,不同阻力模式对坡面流模拟结果影响甚微;反之,需选择合适的阻力计算模式,且坡长越长,坡度越缓,降雨强度阈值越大。     

基于Vine Copula函数的河湖连通水环境多因子联合风险识别研究

河湖连通工程是水资源调配和水生态环境保护与修复的重要途经,同时作为一个包含着模糊性、随机性、灰色性以及未确知性信息的复杂系统工程,其不可避免地存在一定的风险。本文基于Vine Copula函数构建了南四湖在南水北调东线一期工程运行前后水环境多因子联合风险模型,通过对总磷(TP)、总氮(TN)、氨氮(NH₃-N)和叶绿素a(Chl-a)4种风险因子的敏感性分析,识别出运行后的关键风险因子;结合南四湖Ⅲ类水的供水水质要求,设置了运行后关键风险因子不同风险状态(即Ⅳ类和Ⅴ类)组合下的系列风险情景,识别出运行后潜在水环境多因子联合风险。结果表明:TN、NH₃-N、 Chl-a为关键风险因子;当TN和NH₃-N达到Ⅴ类水标准限值、Chl-a为35μg·L^-1时,工程运行后水环境联合风险变化速率增大,不确定性提高,需及时响应,建议重点关注TN和NH₃-N指标。     

阿克苏地区水资源承载力变化及驱动力生态脆弱性分析

以塔里木河源流区阿克苏地区为研究对象,分析区域水资源承载力变化及引起变化的驱动力因素。采用主成分分析法分析了2004-2014年水资源承载力水平,提取了社会经济和生态2个系统的主成分,并进一步选取生态脆弱性作为生态评估指标,采用模糊层次分析对驱动力生态环境的动态变化进行了分析。结果表明:自2004年到2014年,阿克苏地区的水资源承载力总体呈下降趋势,承载F值从-2.99增加到4.69,人口与GDP、生态用水率是承载力变化的主要驱动因素;生态系统的脆弱度整体呈上升态势,生态脆弱性由Ⅰ级的轻度脆弱区上升至Ⅲ级强度区,其中森林覆盖率和垦殖率影响因子为分别0.29和0.12,通过调整可降低生态破坏程度以增加水资源的可持续性。     

基于路径熵的长距离输水系统脆弱性研究

为定量分析长距离输水系统的脆弱性,综合运用图论和信息熵理论,建立长距离输水设施系统脆弱性计算模型。首先,根据输水系统拓扑结构网络图,分析长距离输水系统特征,阐明输水系统脆弱性产生机理;其次,依据水流不确定性,提出输水系统路径熵概念,定义最大路径熵,计算相对路径熵,表达输水系统脆弱度;最后,运用深度优先算法(DFS)对节点按离水源距离由近到远进行分层排序,借助序贯方法逐层逐点对模型进行求解。工程案例表明:该输水系统整体脆弱度为0.237 7,可靠性高;节点14脆弱性最小,脆弱度为0.047 0;脆弱度大于0.500 0的节点有6个,应重点监控并优化。本方法为长距离输水线路设计和确定重点监控对象提供决策支持。