Integrated modelling under uncertainty in watershed-level assessment and management.

Uncertainty in water quality model predictions is inevitably high due to natural stochasticity, model uncertainty, and parameter uncertainty. An integrated modelling system (modified-BASINS) under uncertainty is described and demonstrated for use in receiving-water quality prediction and watershed management. A Monte Carlo simulation was used to investigate the effect of various uncertainty types on output prediction. Without pollution control measures in the watershed, the concentrations of total nitrogen (T-N) and total phosphorus (T-P) in the Hwaong Reservoir, considering three uncertainty types, would be less than about 4.4 and 0.23 mg L(-1), respectively, in 2012, with 90% confidence. The effects of two watershed management practices, wastewater treatment plants (WWTP) and constructed wetlands (WETLAND), were evaluated. The combined scenario (WWTP + WETLAND) was the most effective at improving reservoir water quality, bringing concentrations of T-N and T-P in the Hwaong Reservoir to less than 3.4 and 0.14 mg L(-1), 24 and 41% improvements, respectively, with 90% confidence. Overall, the Monte Carlo simulation in the integrated modelling system was practical for estimating uncertainty and reliable in water quality prediction. The approach described here may allow decisions to be made based on the probability and level of risk, and its application is recommended.     

GLUE框架下似然函数对水文模型不确定性的影响

似然函数的选取对模型参数不确定性结果存在较大影响。本文以淮河上游大坡岭水文站控制流域为例,采用GLUE不确定性分析方法、SCE-UA优化算法与流域水循环系统模型(HEQM)耦合,探索Nash-Sutcliffe系数与水量平衡系数这两个似然函数对模型参数敏感性、取值分布特征以及不确定性的影响。结果表明:从敏感性分析结果来看,Nash-Sutcliffe系数作为似然函数时,所选择的9个参数均为敏感性参数,而水量平衡系数作似然函数时,仅有1个敏感性参数,Nash-Sutcliffe系数更适合作似然函数;从不确定性区间评价结果来看,水量平衡系数作为似然函数时,模拟结果的覆盖率和对称性均优于Nash-Sutcliffe系数。以上研究可为GLUE方法似然函数的选取提供参考,也为多目标GLUE方法中权重的分配提供理论依据。     

Using the W&H integrated uncertainty analysis framework with non-initiated experts.

The W&H (Walker and Harremo?s) integrated uncertainty analysis framework was put forward with the aim of providing a conceptual basis for the systematic treatment of uncertainty in model-based decision support activities such as policy analysis, integrated assessment and risk assessment. It provides a heuristic tool that can be applied in decision support exercises to classify and report the various dimensions of uncertainty. The intention is to stimulate better communication among analysts as well as between them and policymakers and stakeholders. The framework successfully articulates diverse scholarly understandings of 'uncertainty', 'ignorance', and 'quality' in science for policy, Nevertheless, experience with the W&H framework has revealed that many of the concepts put forward are relatively unfamiliar--and perhaps somewhat controversial--to experts practising decision support. Thus, efforts are required to communicate the W&H framework to experts in such a way that their knowledge of uncertainty is elicited adequately, without them being overly intimidated or confused by the novelty of the concepts presented to them. After introducing the W&H conceptual framework, this paper presents the methodology that was used in applying the W&H framework in expert elicitations on uncertainty in the risk assessment of genetically modified crops. Experiences with the use of this methodology are discussed and recommendations for further improvement are given.     

城市排水行业管理体制不同模式的比较和分析

当前，全国范围内掀起一股排水管理体制改革的浪潮。如何理顺体制，以适应加入WTO后的新形式和日益迫切的环境保护的要求，各地做法并不相同。选取4个具有代表性的城市进行比较和分析，期望能对其他各地正在进行的改革提供借鉴和思路。     

Sediment management in sustainable urban drainage system ponds.

Since removal and disposal of sustainable urban drainage system (SUDS) sediment can incur high maintenance costs, assessments of sediment volumes, quality and frequency of removal are required. Sediment depth and quality were surveyed annually from 1999-2003 in three ponds and one wetland in Dunfermline, Scotland, UK. Highest sediment accumulation occurred in Halbeath Pond, in the most developed watershed and with no surface water management train. From comparison of measured potentially toxic metal concentrations (Cd, Cr, Cu, Fe, Ni, Pb, Zn) with standards, the average sediment quality should not impair aquatic ecosystems. 72-84% of the metal flux into the SUDS was estimated to be associated with coarse sediment (> 500 microm diameter) suggesting that management of coarse sediment is particularly important at this site. The timing of sediment removal for these SUDS is expected to be determined by loss of storage volume, rather than by accumulation of contaminants. If sediment removal occurs when 25% of the SUDS storage volume has infilled, it would be required after 17 years in Halbeath Pond, but only after 98 years in Linburn Pond (which has upstream detention basins). From the quality measurements, sediment disposal should be acceptable on adjacent land within the boundaries of the SUDS studied.     

Experiences with the NUSAP system for multidimensional uncertainty assessment.

This paper discusses recent experiences with the NUSAP system for multidimensional uncertainty assessment, based on case studies that vary in complexity. We show that the NUSAP method, and especially the pedigree analysis part of it, is useful to assess not only parameter uncertainty but also to systematically reflect upon (model) assumptions and problem frames. A diagnostic diagram can be used to synthesize results of quantitative and qualitative analysis. It provides an analytic tool to prioritize uncertainties according to quantitative and qualitative insights in the limitations of available knowledge. We further show that extension of the pedigree scheme to include societal dimensions of uncertainty, such as problem framing and value-laden assumptions, further promotes reflexivity and collective learning. When used in a deliberative setting, NUSAP pedigree assessment has the potential to foster a deeper social debate and a negotiated management of complex environmental problems.     

Performance indicators for the efficiency analysis of urban drainage systems.

Performance indicators implemented in a decision support system (DSS) for the technical, managerial and economic evaluation of urban drainage systems (UDS), called MOMA FD, are presented. Several kinds of information are collected and processed by MOMA FD to evaluate both present situation and future scenarios of development and enhancement. Particular interest is focused on the evaluation of the environmental impact, which is considered a very relevant factor in the decision making process to identify the priorities for UDS improvements.     

A framework for evaluating the persistence of urban drainage risk management systems

Despite remarkable advances in urban flood management techniques, pluvial flood damages still occur throughout the world. This may be attributed to uncertainties in the rainfall events which may disrupt the normal performance of an urban drainage system and eventually lead to inundations and damages. Therefore, the conventional urban drainage management approach focusing on system security should be modified. As a new approach to urban drainage management, this paper defines the persistence of a system as the ability of a disturbed system to resist, buffer the effects of variable disturbances and return to accepted level of performance after disturbances and introduces a framework to evaluate the concept of risk management persistence for urban drainage systems based on joint consideration of resilience and resistance standpoints. Based on this perspective, some of the required indicators were selected from the literature and adapted to the present study in order to quantify urban drainage risk management (UDRM) systems persistence against disturbances. Evaluation of urban drainage measures would indicate the level of persistence achieved. As a case study, part of the urban drainage system of city of Tehran–Iran was analyzed using the proposed scheme. Four urban drainage measures including three best management practices (BMPs) and a conventional system were added to the current urban drainage system to assess the performance of various measures in improvement of the persistence of UDRM systems. Results indicate that the analysis of the systems persistence can efficiently enable urban planners to select measures with an insight into the behavior of the UDRM systems faced with disturbances.     

基于不确定性的雄安新区城市水系统安全保障技术研究

为提升雄安新区应对气候变化和急性冲击灾害的适应能力,建设高韧性高弹性的城市水系统,实现新区水系统的安全运行与可持续发展,构建了基于不确定性的雄安新区城市水系统安全保障技术.该技术包括水系统的风险源识别、风险综合评价和风险管理策略3部分.在应对气候变化方面,提出了"气候变化模拟预估—气候变化增量分析—水系统影响风险分析"的技术框架、不同精度的气候变化增量分析方法,以及分层级的城市水系统气候变化影响与风险分析方法.在应对急性冲击方面,提出了有效识别城市水系统面临的急性冲击风险源识别方法,以及急性冲击灾害多情景多灾种风险分析方法.在安全保障机制方面,提出了建立雄安新区水系统应急预案体系的要求,以及区域协同、综合应对、专业负责和网格化管理的"城市-组团-社区"三级风险管控机制.     

城市排水系统集成模拟研究进展

在回顾城市排水系统集成模拟研究发展和现状的基础上,结合可持续性城市排水系统理论,分析了现阶段城市排水系统集成模拟研究的局限和面临的问题。为了适应城市排水系统结构和功能的演变,实现系统的可持续性,今后城市排水系统集成模拟的研究应当完善对系统结构的描述,在集成模拟的过程中考虑不确定性因素对系统的影响,并构建高效能计算平台,解决城市排水系统大规模计算问题。     

城市内湖综合治理及效果评价

双龙湖是重庆市内一座城市景观内湖,2002年监测双龙湖属Ⅴ类水体,水质严重恶化.2003年对双龙湖水环境进行了治理,采取生态措施、工程措施与管理措施相结合的综合治理方案,水体水质发生了很大变化,为科学评估双龙湖综合治理效果,引入模糊数学概念,应用模糊综合评判方法来客观地反映水环境质量状况.结果表明:双龙湖水体在治理前属Ⅴ类水质,隶属度达到90%,主要污染物为磷;治理后水体水质优于Ⅳ类标准,Ⅳ类及以上隶属度达到97%,年季水质动态稳定在Ⅲ类和Ⅳ类之间,敏感性因子为氮和磷.应用模糊数学方法,通过计算分析污染因子隶属度、权重系数和模糊综合指数来评价水体水质具有科学性和实用性.     

县镇下水道建设与城市排水系统的变革

剖析了目前全国大规模建设县镇污水处理厂的形势和存在的问题,指出大中型城市的排水系统体制应用到县镇污水处理的弊端,提出了适合县镇实际情况的循环型排水系统体制。循环型县镇排水系统体制追求水资源、植物营养素的循环利用,为社会的可持续发展提供了基础保障。     

城市雨水排水系统提标改造与建设途径

城市雨水排水系统是城市重要的基础设施,直接关乎城市排水安全和内涝防治水平,也影响着城市水环境质量.国家对提高城市排水和内涝防治标准一直有明确的要求,"十四五"规划又提出了具体的发展目标."绿色、蓝色、灰色、管理"相统一、相协调的城市雨水排水提标改造与建设思路,体现了绿色发展、增强城市韧性的理念,也是提升城市排水标准,削...     

Impact of dimension uncertainty and model calibration on sewer system assessment.

Assessments of sewer performance are usually based on a single computation of CSO (combined sewer overflow) volumes using a time series of rainfall as system loads. A shortcoming of this method is that uncertainties in knowledge of sewer system dimensions are not taken into account. Moreover, sewer models are rarely calibrated. This paper presents the impacts of database errors and model calibration on return periods of calculated CSO volumes. The impact of uncertainties is illustrated with two examples. Variability of calculated CSO volumes is estimated using Monte Carlo simulations. The results show that calculated CSO volumes vary considerably due to database errors, especially uncertain dimensions of the catchment area. Furthermore, event-based calibration of a sewer model does not result in more reliable predictions because the calibrated parameters have low portability. However, it enables removal of database errors harmonising model predictions and 'reality'.     

SWMM模型在城市排水系统规划中的应用

对城市排水系统进行系统的模拟计算,可以为城市排水系统规划方案的调整与优化提供理论指导。以深圳河湾地区的排水系统规划为例,讨论了美国环保局开发的暴雨径流管理模型SWMM(StormWaterManagementModel)的应用情况。案例研究以典型降雨年的排污状况为参考,用SWMM分析和评价了深圳“布局规划方案”在近期(2010年)和远期(2020年)的环境影响。研究中所应用的方法和过程具有一定的通用性,可以用于其他地区排水系统的模拟。     

多态不确定条件下的城市供水调度模型研究

针对城市多水源供水调度系统中存在的不确定性和复杂性问题,将基于可信性理论的模糊规划与区间规划融入两阶段随机规划框架中,构建了基于可信性约束的区间两阶段随机规划的城市供水调度优化模型。该模型用区间数、随机变量和模糊参数等形式,有效表征了系统目标函数和约束中存在的多态不确定性,模拟了不确定条件下的城市供水调度过程,并对随机过程产生的风险进行了追索。通过模型运算,得到不同可信度水平下的稳定区间解,可为城市供水管理者提供不同情景下的决策方案,帮助其规避供水缺水风险。     

城镇雨排水与农田排涝流量计算方法对比分析

从暴雨统计、径流系数、汇流3个环节入手,对城镇雨排水及农田排涝流量的计算方法进行对比分析,得出径流系数和汇流环节是导致流量成果相差较大主要因素的结论。     

Integrated risk assessment and screening analysis of drinking water safety of a conventional water supply system.

Management of drinking water safety is changing towards an integrated risk assessment and risk management approach that includes all processes in a water supply system from catchment to consumers. However, given the large number of water supply systems in China and the cost of implementing such a risk assessment procedure, there is a necessity to first conduct a strategic screening analysis at a national level. An integrated methodology of risk assessment and screening analysis is thus proposed to evaluate drinking water safety of a conventional water supply system. The violation probability, indicating drinking water safety, is estimated at different locations of a water supply system in terms of permanganate index, ammonia nitrogen, turbidity, residual chlorine and trihalomethanes. Critical parameters with respect to drinking water safety are then identified, based on which an index system is developed to prioritize conventional water supply systems in implementing a detailed risk assessment procedure. The evaluation results are represented as graphic check matrices for the concerned hazards in drinking water, from which the vulnerability of a conventional water supply system is characterized.     

城市排水管网对排水系统安全运行的影响

北京市的排水基础设施陈旧、落后及管理存在严重缺陷.当务之急,是利用现代高科技手段掌握地下排水管网分布结构和排水变化规律,加强基础设施建设,完善城市排水应急管理措施,实现城市排水区域化、流域化和网络化科学管理,消除现存城市排水事故安全隐患,确保2008年奥运会的城市排水安全运行.通过对排水管网现状分析,强化计算机网络科学化管理,为保障2008年奥运会期间北京城市的排水安全运行提出建议.