UNCERTAINTY AND SENSITIVITY ANALYSES OF SEDIMENT TRANSPORT FORMULAS     

Keh Chia YEH  Sen Long DENG 《国际泥沙研究》1998,(1)

ＵＮＣＥＲＴＡＩＮＴＹＡＮＤＳＥＮＳＩＴＩＶＩＴＹＡＮＡＬＹＳＥＳＯＦＳＥＤＩＭＥＮＴＴＲＡＮＳＰＯＲＴＦＯＲＭＵＬＡＳＫｅｈＣｈｉａＹＥＨ１ａｎｄＳｅｎＬｏｎｇＤＥＮＧ２ＡＢＳＴＲＡＣＴＩｎｖｉｅｗｏｆｔｈｅｒａｎｄｏｍｃｈａｒａｃｔｅｒｉｓｔ...  相似文献   

基于各国NDC/INDC目标的全球减排不确定性研究     

陈楠  林炫辰 《气候变化研究进展》2021,17(2):223-235

基于各国提交的165份国家自主贡献文件,以其中提出的减排目标为基准,尽可能充分地考虑了减排目标的范围不确定性、不同经济情景带来的碳强度减排目标不确定性、减排气体种类边界差异、碳排放达峰约束等因素,并通过蒙特卡洛模拟的方法对全球、各区域和主要经济体的温室气体排放总量、不确定度及其来源进行了定量分析。结果表明,到2030年全球温室气体排放总量将达到62.69 Gt CO₂当量,其90%信度的置信区间为53.17~74.26 Gt CO₂当量;由于未来经济总量预期不确定对排放量的影响最显著,因此,不同地区之间不确定性来源差异较大。同时,基于到2050年排放总量比2010年下降40%~70%的2℃目标排放情景,2030—2050年全球温室气体排放年均需要下降5.0% %。为了尽可能减小全球温室气体排放预期目标的不确定性和继续实现2℃目标,各国在进行自主贡献文件更新时进一步提出统计边界更为明确和统一且更有雄心的减排目标将是第一次全球盘点继续解决的重点问题。  相似文献   

Quantification of uncertainty in design water levels due to uncertain bed form roughness in the Dutch river Waal     

J. J. Warmink  M. J. Booij  H. Van der Klis  S. J. M. H. Hulscher 《水文研究》2013,27(11):1646-1663

Hydrodynamic river models are applied to design and evaluate measures for purposes such as safety against flooding. The modelling of river processes involves numerous uncertainties, resulting in uncertain model results. Knowledge of the type and magnitude of these uncertainties is crucial for a meaningful interpretation of the model results. Uncertainty in the hydraulic roughness due to bed forms is one of the main contributors to the uncertainty in the modelled water levels. The aim of this study was to quantify the uncertainty in the bed form roughness under design conditions and quantify the effect on the design water levels in the Dutch river Waal. Five roughness models that predict bed form roughness based on measured bed form and flow characteristics were extrapolated to design conditions. The results show that the 95% confidence interval of the predicted Nikuradse roughness values under design conditions ranges from 0.32 to 1.03 m. This uncertainty was propagated through the two‐dimensional hydrodynamic model, WAQUA, by means of a Monte Carlo simulation for an idealized schematization of the Dutch river Waal. The uncertain bed form roughness results in an uncertainty in the design water levels, with a 95% confidence interval of 0.53 m, which is significant for Dutch river management practice. The uncertainty in the bed form roughness was mainly caused by a lack of knowledge about the physical process of bed form evolution that causes roughness. An improved estimation of bed form roughness can significantly reduce the uncertainty in the design water levels. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   

The tower of Babel: Different perceptions and controversies on change and status of North Sea fish stocks in multi-stakeholder settings     

M.C. Verweij  W.L.T. van Densen  A.J.P. Mol 《Marine Policy》2010

Fishermen, scientists, national policy makers, and staff of environmental NGOs (ENGOs) hold different perceptions about temporal patterns in fish stocks. Perception differences are problematic in multi-stakeholder settings, because they elicit controversies and unbalanced disputes. These hinder effective participation, a prerequisite for ‘good governance’ and effective management of sustainable fisheries. This study shows that perceptions of change (‘does the stock increase or decrease?’) and of current status of a fish stock (‘is it doing well or not?’) are influenced by the capturing and processing of information, rather than by interests alone. We focused on the Dutch North Sea fishery on plaice and sole and examined (1) availability and accessibility of information on temporal patterns of these stocks and (2) perception differences between all parties. A first explanation for these differences is the use of different parameters as a measure for stock size. Fishermen focus on catch rates or catch-per-unit-effort (relative stock size), whereas scientists, policy makers, and ENGO-staff mainly use scientific assessments of spawning stock biomass (absolute stock size). Between-group perception differences are further explained by spatial aggregation levels of information, lengths of time series evaluated, and by modes of comparison to qualify the current status of fish stocks. Awareness of information differences and the development of shared information use and processing may release some of the tensions in multi-stakeholder settings debating fisheries management. However, comprehension problems amongst all parties on how spawning stock biomass is reconstructed and how it relates to catch rates in the fishery may pose an enduring barrier.  相似文献   

An index to represent lateral variation of the confidence of experts in a 3-D geological model     

R.M. Lark  S.J. MathersA. Marchant  A. Hulbert 《Proceedings of the Geologists' Association. Geologists' Association》2014

A Confidence Index is proposed that expresses the confidence of experts in the quality of a 3-D model as a representation of the subsurface at particular locations. The Confidence Index is based on the notion that the variation of the height of a particular geological surface represents general geological variability and local variability. The general variability comprises simple trends which allow the modeller to project surface structure at locations remote from direct observations. The local variability limits the extent to which borehole observations constrain inferences which the modeller can make concerning local fluctuations around the broad trends. The general and local geological variability of particular contacts are modelled in terms of simple trend surfaces and variogram models. These are then used to extend measures of confidence that reflect expert opinion so as to assign a confidence value to any location where a particular contact is represented in a model. The index is illustrated with an example from the East Midlands region of the United Kingdom.  相似文献   

地震灾害损失预测中的不确定性研究回顾     

王晓青  何钧  丁香  王岩 《震灾防御技术》2007,2(1):75-82

本文概述了对象研究的不确定性类型、研究方法,着重描述了震害预测过程中存在的不确定性及其研究进展,目前应用于震害预测不确定性研究的主要方法,并对当前震害预测中存在的主要问题进行了初步总结与讨论。  相似文献   

时空数据质量与模型     

童小华 《测绘软科学研究》2009,(2):28-33

时空数据不确定性与数据质量是地理信息科学的基础理论之一，也是GIS应用发展的重要问题。本文作为ISPRS2008大会专题“时空数据质量与模型”导读，从空间实体的位置不确定性、数字高程模型的位置不确定性、遥感数据的不确定性、属性数据的不确定性与质量控制、空间分析与操作的不确定性传播和空间数据采集的不确定性与处理等方面，分析了时空数据不确定性与数据质量的最近发展。  相似文献   

An uncertainty model for deep ocean single beam and multibeam echo sounder data     

K. M. Marks  W. H. F. Smith 《Marine Geophysical Researches》2008,29(4):239-250

Comparing single beam and multibeam echo sounder data where surveys overlap we find that: 95% of multibeam measurements are repeatable to within 0.47% of depth; older single beam data can be at least as accurate as multibeam; single beam and multibeam profiles show excellent agreement at full-wavelengths longer than 4 km; archival sounding errors are not Gaussian; 95% of archival soundings in the northwest Atlantic are accurate to within 1.6% of depth; the 95th percentile error is about five times greater in pre-1969 data than in post-1968 data; many of the largest errors are located over large seafloor slopes, where small navigation errors can lead to large depth errors. Our uncertainty model has the form σ ² = a ² + (bz)² + (cs)², where 2σ is approximately the 95th percentile error, z is the depth, s is the slope, and a, b, c are constants we determine separately for pre-1969 and post-1968 data.  相似文献   

全球升温1.5℃和2.0℃情景下澜沧江流域极端降水的变化特征     

丁凯熙  张利平  佘敦先  张琴  向竣文 《气候变化研究进展》2020,16(4):466-479

澜沧江是我国为数不多的跨境河流,流域内多发暴雨、洪水灾害,因此定量、科学地评估澜沧江流域未来全球升温情景下极端降水的变化特征,能够为澜沧江-湄公河沿线国家共同管理流域水资源和抵御自然灾害提供一定的科学指导。文中基于部门间影响模式比较计划（ISI-MIP）下5个全球气候模式降水数据,通过偏差校正增强其在澜沧江流域极端降水的模拟能力,使用降水强度、日最大降水量和强降水量等9个指标评价未来全球升温1.5℃和2.0℃下澜沧江流域极端降水的变化情况,并对结果的不确定性和可信度进行研究,得出以下主要结论：随着全球温度的升高,澜沧江流域年降水和极端降水均呈现增大趋势,其中极强降水量（R99p）升幅最大,升温1.5℃和2.0℃下升幅分别为37%和75%;相对于基准期,全球升温2.0℃下各极端降水指数增幅明显大于升温1.5℃,前者升幅甚至超出后者一倍;未来全球升温情景下,澜沧江流域湿季会变得更湿润,而干季则会更干燥;澜沧江流域降水集中程度会增大,使得流域内洪涝灾害发生的风险增大;ISI-MIP气候模式对澜沧江流域未来极端降水模拟存在较大不确定性,升温2.0℃较升温1.5℃情景下不确定性更大,但相对于基准期,前者极端降水增大的可信度更高。  相似文献   

Navigating a complex policy system—Explaining local divergences in Swedish fish stocking policy     

Annica Sandström 《Marine Policy》2011

Swedish fish stocking policy constitutes an example of the disparate challenges associated with adaptive management theory and the realization thereof. The vast substantial and institutional uncertainties of the policy subsystem have previously been identified as variables that complicate the realization of adaptive policy making. The aim of this paper is to address and tentatively explain differences in regards to how these uncertainties are handled. What regional variances in Swedish fish stocking policy can be distinguished and how can these variations be explained? The empirical analysis shows that Swedish fish stocking policy consists of a wide array of different regional policies. These regional variations are explained by differences in existing implementation resources, policy beliefs and readings of formal regulations. Policy makers can decrease these divergences in two ways; they can either change formal regulations or influence available implementation resources. Both management approaches might have positive as well as negative effects on the subsystem's adaptability.  相似文献