Pragmatic Approaches for Water Management Under Climate Change Uncertainty1

Stakhiv, Eugene Z., 2011. Pragmatic Approaches for Water Management Under Climate Change Uncertainty. Journal of the American Water Resources Association (JAWRA) 47(6):1183–1196. DOI: 10.1111/j.1752‐1688.2011.00589.x Abstract: Water resources management is in a difficult transition phase, trying to accommodate large uncertainties associated with climate change while struggling to implement a difficult set of principles and institutional changes associated with integrated water resources management. Water management is the principal medium through which projected impacts of global warming will be felt and ameliorated. Many standard hydrological practices, based on assumptions of a stationary climate, can be extended to accommodate numerous aspects of climate uncertainty. Classical engineering risk and reliability strategies developed by the water management profession to cope with contemporary climate uncertainties can also be effectively employed during this transition period, while a new family of hydrological tools and better climate change models are developed. An expansion of the concept of “robust decision making,” coupled with existing analytical tools and techniques, is the basis for a new approach advocated for planning and designing water resources infrastructure under climate uncertainty. Ultimately, it is not the tools and methods that need to be revamped as much as the suite of decision rules and evaluation principles used for project justification. They need to be aligned to be more compatible with the implications of a highly uncertain future climate trajectory, so that the hydrologic effects of that uncertainty are correctly reflected in the design of water infrastructure.     

A multi-approach strategy in climate attribution studies: Is it possible to apply a robustness framework?

Attribution studies investigate the causes of recent global warming. For a few decades the scientific community generally adopted dynamical models – the so-called Global Climate Models (GCMs) – for such an investigation. These models show the essential role of anthropogenic forcings in driving the temperature behaviour of the last half century. In the last period even other (data-driven) methodological approaches were adopted for attribution studies. This allows the scientific community to compare the results coming from these different approaches and to possibly increase their robustness. For such a purpose, the paper explores the possibility of applying a robustness framework, so far used only in the case of multi-model GCM ensembles, to a strategy including models from different methodological orientations, assessing such an application especially in the light of the independence issue.     

工业总排放水中Cr~(6+)含量测量不确定度的评定

采用分光光度法对工业总排放水中Cr6+进行不确定度评定,充分考虑测量重复性、标准溶液的配制、标准曲线的制备等因素对测量的影响,测得Cr6+的合成标准不确定度为0.023mg/L。     

气候试验箱内部条件不确定度计算(上)

提供了对温度和湿度气候试验箱内部环境条件进行不确定度分析的方法。首先介绍了测量的不确定度概念,然后讨论容差的意义。考虑到湿度和温度测量是采用确定和合成不确定度。结合校准空载试验箱和有负载试验箱的条件测量的案例。最后,逐条整理成为范本用于分析结果以给出规范的不确定度评估依据。     

Climatic Implications of Revised IPCC Emissions Scenarios, the Kyoto Protocol and Quantification of Uncertainties

In December 1997, the United Nations Framework Convention on Climate Change (FCCC) adopted the Kyoto Protocol. This paper describes a framework that models the climatic implications of this international agreement, using Monte Carlo simulations and the preliminary Intergovernmental Panel on Climate Change emissions scenarios (SRES). Emissions scenarios (including intervention scenarios), climate sensitivity, and terrestrial carbon sink are the key sampled model parameters. This framework gives prior probability distributions to these parameters and, using a simple climate model, posterior distributions of global temperature change are determined for the future. Our exercise showed that the Kyoto Protocol's effectiveness will be mostly dependent upon which SRES world evolves. In some worlds the Protocol decreases the warming considerably but in others it is almost irrelevant. We exemplified this approach with a current FCCC issue, namely “hot air”. This modelling framework provides a probabilistic assessment of climate policies, which can be useful for decision-makers involved in global climate change management. This revised version was published online in July 2006 with corrections to the Cover Date.     

X射线荧光光谱法测定土壤样品中铅的不确定度评定

用实例对X射线荧光光谱法测定土壤样品中铅的不确定度进行了评定.测量结果的不确定度由仪器综合稳定性、制样、标准物质、回归工作曲线、重复测量等所引入的不确定度分量组成.在对各个不确定度分量进行量化的基础上,通过合成得到测量结果的标准不确定度,再乘以95%置信概率下的扩展因子2,得到测量结果的扩展不确定度.     

Assessing Parameter Uncertainty of a Semi‐Distributed Hydrology Model for a Shallow Aquifer Dominated Environmental System

This paper examines the performance of a semi‐distributed hydrology model (i.e., Soil and Water Assessment Tool [SWAT]) using Sequential Uncertainty FItting (SUFI‐2), generalized likelihood uncertainty estimation (GLUE), parameter solution (ParaSol), and particle swarm optimization (PSO). We applied SWAT to the Waccamaw watershed, a shallow aquifer dominated Coastal Plain watershed in the Southeastern United States (U.S.). The model was calibrated (2003‐2005) and validated (2006‐2007) at two U.S. Geological Survey gaging stations, using significant parameters related to surface hydrology, hydrogeology, hydraulics, and physical properties. SWAT performed best during intervals with wet and normal antecedent conditions with varying sensitivity to effluent channel shape and characteristics. In addition, the calibration of all algorithms depended mostly on Manning's n‐value for the tributary channels as the surface friction resistance factor to generate runoff. SUFI‐2 and PSO simulated the same relative probability distribution tails to those observed at an upstream outlet, while all methods (except ParaSol) exhibited longer tails at a downstream outlet. The ParaSol model exhibited large skewness suggesting a global search algorithm was less capable of characterizing parameter uncertainty. Our findings provide insights regarding parameter sensitivity and uncertainty as well as modeling diagnostic analysis that can improve hydrologic theory and prediction in complex watersheds. Editor's note : This paper is part of the featured series on SWAT Applications for Emerging Hydrologic and Water Quality Challenges. See the February 2017 issue for the introduction and background to the series.     

Uncertainty of exposure assessment of consumers to pesticide residues derived from food consumed

The sources of quantitative and qualitative uncertainties of the exposure of a consumer to a pesticide residue are identified. The contribution of quantifiable uncertainties of input parameters of deterministic model to the combined uncertainty of the estimated exposure is shown with detailed calculation using the pesticide residue content of food consumed during two days. The daily intakes of bifenthrin residues calculated for the 60 kg bodyweight of the reporting person are 0.00257 mg/kgbw and 0.00281 mg/kgbw for day 1 and day 2, respectively with 27-28% combined uncertainty. The major contributors were fruits and whole meal bread. The contribution of the individual steps to the combined uncertainty depends on the particular food item. In general, the variability of recipes, estimation of the mass of consumed food, sampling, processing of raw commodities and analysis of pesticide residues influenced most, in decreasing order, the combined uncertainty of the estimated daily exposure.     

环境监测用正己烷气体标准样品的研制

采用称量法通过两步稀释制备了含量水平为1μmol/mol的氮气中正己烷气体标准样品,考察了气瓶内壁吸附作用、制备重现性、瓶内均匀性、时间稳定性等相关因素的影响,并将该正己烷气体标准样品与同类气体标准样品进行了比较。结果表明:该正己烷气体标准样品的最低使用压力为1 MPa,有效期为12个月(0~38℃),相对扩展不确定度(k=2)为2%;该正己烷气体标准样品的量值与同类标准样品具有可比性,可为相关环境监测工作提供技术支持。     

Do remediation experts have what it takes to explain empirical uncertainty?

Words matter in risk communication, and experts’ choice of words is critical when remediation risks are being explained to nonexperts. In risk communication studies, communication gaps between experts and nonexperts are investigated but there is lack of primary research. An Australian project addresses this shortcoming through research into communication about the risks of contaminated land remediation, and this paper provides some of its findings. Seventeen experts completed a questionnaire about the meaning of some scientific terms, and analysis found that they have capacity to improve communication through their selection and use of language. When experts undertake risk communication, the language they use may increase or reduce communication gaps. When the topic is uncertainty about health risks, communication gaps about the extent of uncertainty may reduce the effectiveness of social engagement, leading to unintended consequences such as cost overruns. This situation makes for a good case study since remediation is about benefit as well as risk, and communication about benefit, while desirable, may not always be achievable. The study suggests how to improve risk communication by exploring the accuracy, clarity, and depth of expert language. It identifies attributes of language that can bridge gaps in knowledge and understanding and characterizes them as integration mechanisms. These are defined as knowledge forms and mental processes that support cooperation between different epistemic communities to achieve mutually agreed outcomes. Two integration mechanisms are suggested. Bridging content addresses communication gaps through the selection of content (what knowledge is selected). Bridging process addresses communication gaps through the use of language (how knowledge is explained). Bridging content and bridging process can be expressed through cognitive and experiential platforms, or a blending of both, so whether words are positioned in the science‐based or mental model of risk communication, a utility value can be found in their quality, whether reflected by accuracy or the power to communicate meaning.