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1.
Toward a ground-motion logic tree for probabilistic seismic hazard assessment in Europe 总被引：9，自引：2，他引：7
Elise Delavaud Fabrice Cotton Sinan Akkar Frank Scherbaum Laurentiu Danciu Céline Beauval Stéphane Drouet John Douglas Roberto Basili M. Abdullah Sandikkaya Margaret Segou Ezio Faccioli Nikos Theodoulidis 《Journal of Seismology》2012,16(3):451-473
The Seismic Hazard Harmonization in Europe (SHARE) project, which began in June 2009, aims at establishing new standards for probabilistic seismic hazard assessment in the Euro-Mediterranean region. In this context, a logic tree for ground-motion prediction in Europe has been constructed. Ground-motion prediction equations (GMPEs) and weights have been determined so that the logic tree captures epistemic uncertainty in ground-motion prediction for six different tectonic regimes in Europe. Here we present the strategy that we adopted to build such a logic tree. This strategy has the particularity of combining two complementary and independent approaches: expert judgment and data testing. A set of six experts was asked to weight pre-selected GMPEs while the ability of these GMPEs to predict available data was evaluated with the method of Scherbaum et al. (Bull Seismol Soc Am 99:3234?C3247, 2009). Results of both approaches were taken into account to commonly select the smallest set of GMPEs to capture the uncertainty in ground-motion prediction in Europe. For stable continental regions, two models, both from eastern North America, have been selected for shields, and three GMPEs from active shallow crustal regions have been added for continental crust. For subduction zones, four models, all non-European, have been chosen. Finally, for active shallow crustal regions, we selected four models, each of them from a different host region but only two of them were kept for long periods. In most cases, a common agreement has been also reached for the weights. In case of divergence, a sensitivity analysis of the weights on the seismic hazard has been conducted, showing that once the GMPEs have been selected, the associated set of weights has a smaller influence on the hazard. 相似文献
2.
《中国科学:地球科学(英文版)》2021,(7)
Flash floods present significant heterogeneity over both space and time due to diverse topographic, geomorphologic,and hydro-meteorological conditions of catchments. Accurate identification and simulation of typical flash flood types are of great significance for the mitigation of flash flood disasters at the national scale. Three flood peak indices and dynamic indices were adopted to characterize the behavioral variability of flash floods. The typical flash flood types and corresponding behavior indices were identified and simulated using statistical analysis(i.e., principal component analysis, dynamic K-means clustering,and analysis of similarity) and hydrological modelling(i.e., HEC and XAJ models). There were 177 flash flood events at the hourly scale being selected for case study from eight catchments with various climatic and geographic characteristics. Results showed that all the flash flood events were clustered into three types(named Types 1, 2, and 3). Type 1 was characterized by low peak flow intensity, early flood peak occurrence time, and thin flood process with short duration. Type 2 was characterized by low peak flow intensity, late flood peak occurrence time, and flat flood process with long duration. Type 3 was characterized by high peak flow intensity and late flood peak occurrence time. Flash flood types showed high consistency with their influencing factors(e.g., catchment forest ratio and drainage area, occurrence time and magnitude of maximum storm intensity, and concentration of a storm event). The simulation performances were basically the same for HEC and XAJ models. As for flash flood event simulations, the average relative error varied from 23.25% to 27.98%, from 11.95% to 18.19%, and from 8.30% to18.25% for Types 1, 2 and 3, respectively. The average Nash-Sutcliffe efficiency coefficient varied from 0.39 to 0.54, from 0.76 to 0.85, and from 0.86 to 0.91, respectively. As for the six flash flood behavior indices simulations, the average relative rootmean-square error(RMSEr) varied from 0.37 to 0.69, from 0.37 to 0.41, and from 0.18 to 0.25 for Types 1, 2, and 3, respectively.The average correlation coefficient(r) varied from 0.52 to 0.68, from 0.78 to 0.85, and from 0.88 to 0.94, respectively. The flood peak indices were the best simulated for Types 2 and 3 with RMSEr varying from 0.18 to 0.28 and r varying from 0.86 to 0.91.The flood dynamic indices were the best simulated for Type 3 with RMSEr varying from 0.19 to 0.21 and r varying from 0.91 to0.97. The study provided detailed flood information supports for flood management at catchment scale, and also provided new insights into flash flood simulations in small and medium-sized catchments from perspective of flood behavioral processes. 相似文献
3.
Louise Crochemore Charles Perrin Vazken Andréassian Uwe Ehret Simon P. Seibert Salvatore Grimaldi 《水文科学杂志》2013,58(3):402-423
AbstractThis paper investigates the relationship between expert judgement and numerical criteria when evaluating hydrological model performance by comparing simulated and observed hydrographs. Using a web-based survey, we collected the visual evaluations of 150 experts on a set of high- and low-flow hydrographs. We then compared these answers with results from 60 numerical criteria. Agreement between experts was found to be more frequent in absolute terms (when rating models) than in relative terms (when comparing models), and better for high flows than for low flows. When comparing the set of 150 expert judgements with numerical criteria, we found that most expert judgements were loosely correlated with a numerical criterion, and that the criterion that best reflects expert judgement varies from expert to expert. Overall, we identified two groups of 10 criteria yielding an equivalent match with the expertise of the 150 participants in low and high flows, respectively. A single criterion common to both groups (the Hydrograph Matching Algorithm with mean absolute error) may represent a good indicator for the overall evaluation of models based on hydrographs. We conclude that none of the numerical criteria examined here can fully replace expert judgement when rating hydrographs, and that both relative and absolute evaluations should be based on the judgement of multiple experts.
Editor D. Koutsoyiannis 相似文献
4.
The present study focused on the use of benthic invertebrate communities to assess the ecological quality of a Portuguese estuary characterized by strong seasonal changes and with eutrophication problems. Seasonal benthic samples were collected during a flood year and the methodology proposed by the WFD Portuguese group was used to classify benthic assemblages into five different quality classes. Factor analysis was applied to classify stations based on their physical-chemical status. Different classifications were obtained with different indices and among seasons and there was low agreement between indices and index-season interactions. Diversity indices were better correlated to eutrophication related variables than AMBI and ABC method. Predictable responses of benthic indices to anthropogenic stress symptoms were stronger during the dry period. 相似文献
5.
Schulze-Makuch D 《Ground water》2005,43(3):443-456
Longitudinal dispersivity (alpha) data were compiled from 109 different authors for different types of geological media. The data were subdivided into different subsets. Dispersivity values for consolidated media were subdivided as basalts, granites, sandstones, and carbonate rocks, while unconsolidated sediments were subdivided into three reliability classes. The data sets provided here may provide ground water practitioners a preliminary guide to estimate dispersivity values at various scales and to guide and verify theories on scaling behavior. Based on the data set presented here, the relationship that empirically best described the dispersivity data in regard to scale of measurement was in the form of a power law. The scaling exponent for consolidated and unconsolidated geological media varied between 0.40 and 0.92, and 0.44 and 0.94, respectively. Higher reliability subsets of data for the unconsolidated sediments and more frequently tested rock formations indicate that the scaling exponent is at the lower end of the observed range, close to 0.5. No significant difference in scaling exponent was found among different media, and no clear evidence exists for the presence of an upper bound or asymptotic behavior on the relationship for any of the analyzed media. 相似文献
6.
Wang Xiaoqing Gao MengtanCenter for Analysis Prediction SSB Beijing China Institute of Geophysics SSB Beijing China 《中国地震研究》1996,(2)
This paper offers an approach to the relative confidence level of medium- and long-term earthquake prediction methods by use of the analytical hierarchy process (AHP). We construct the criterion judgment matrices according to the results of an expert questionnaire known as the Delphi scheme. From the matrices we can obtain a scale for the relative preference or priority weight of each factor. The quantitative weights might be applied to make synthetic prediction of earthquake risk areas in the northern part of the North China seismic region. 相似文献
7.
This work evaluates four indices that have been used for benthic macroinvertebrate ecological quality classification in the Mediterranean Sea. Our study was based on the data obtained from the participation of Greece and Cyprus in the Mediterranean Geographical Intercalibration group. The indices AMBI, M-AMBI, MEDOCC and BENTIX were applied to the available benthic species data, and the succession of the ecological groups along the graded values of each index was plotted. The level of agreement among methods was calculated, and the performance of each method in estimating ecological quality status was evaluated. AMBI, based on the Atlantic model, and its derivative M-AMBI overestimated the statuses, while MEDOCC showed the best level of agreement with BENTIX. BENTIX gives equal weight to tolerant and opportunistic species groups, which correlates them more closely than the other indices and makes BENTIX the most sensitive in detecting ecological disturbances in the Eastern Mediterranean basin, where tolerant and opportunistic groups seem to play an equally important role in the response of benthic communities to stressors. 相似文献
8.
《Advances in water resources》2001,24(6):677-688
Using simultaneous scaling, soil spatial variability of hydraulic functions can be described from a single set of scaling factors. The conventional scaling approach is based on empirical curve fitting, without paying much attention to the physical significance of the scaling factors. In this study, the concept of simultaneous scaling of the soil water retention and unsaturated hydraulic conductivity functions is applied to a physically based scaling theory. In this approach, it is assumed that soils are characterized by a lognormal pore-size distribution, which leads directly to lognormally distributed scaling factors. To test this concept, a total of 143 undisturbed soil samples were collected from two soil depths (25 and 50 cm), with each depth divided into two subsets based on the median soil capillary pressure head value, as determined from the lognormal pore-size distribution assumption. Moreover, the theory was compared with the conventional simultaneous scaling method. Both the conventional and physically based simultaneous scaling method performed equally well for all four subsets, as determined from the reduction in weighted root mean squared residual (WRMSR) values after scaling. We showed that the theoretical interpretation of the lognormal scaling factor distribution was applicable to simultaneous scaling of soil hydraulic functions. 相似文献
9.
Low streamflow statistic estimators at ungauged river sites generally have large errors and uncertainties. This can be due to many reasons, including lack of data, complex hydrologic processes, and the inadequate or improper characterization of watershed hydrogeology. One potential solution is to take a small number of streamflow measurements at an ungauged site to either estimate hydrogeologic indices or transfer information from a nearby site using concurrent streamflow measurements. An analysis of four low streamflow estimation techniques, regional regression, regional plus hydrogeologic indices, baseflow correlation, and scaling, was performed within the Apalachicola–Chattahoochee–Flint watershed, a U.S. Geological Survey WaterSMART region in the south‐eastern United States. The latter three methods employ a nominal number of spot measurements at the ungauged site to improve low streamflow estimation. Results indicate that baseflow correlation and scaling methods, which transfer information from a donor site, can produce improved low streamflow estimators when spot measurements are available. Estimation of hydrogeologic indices from spot measurements improves regional regression models, with the baseflow recession constant having more explanatory power than the aquifer time constant, but these models are generally outperformed by baseflow correlation and scaling. 相似文献
10.
This paper investigates the specific contributions of river network geomorphology, hillslope flow dynamics and channel routing to the scaling behavior of the hydrologic response as function of drainage area. Scaling relationships emerged from the observations of geomorphological and hydrological data and were reproduced in previous works through mathematical models, for both idealized self-similar networks and natural basins. Recent literature highlighted that scale invariance of hydrological quantities depends not only on the metrics of the drainage catchment but also on effective flow routing. In this study we employ a geomorphological width function scheme to test the simple scaling hypothesis adopting more realistic dynamic conditions than in previous approaches, specifically taking into account the role of hillslopes. The analysis is based on the derivation of the characteristic distributions of path lengths and travel times, inferred from DEM processing and measurements of rainfall and runoff data. The study area is located in the Tiber River region (central Italy).Results indicate that, while scaling properties clearly emerge when the hydrologic response is defined on the basis of the sole geomorphology, scale invariance is broken when less idealized flow dynamics are taken into account. Lack of scaling appears in particular as a consequence of the catchment to catchment variability of hillslope velocities. 相似文献
11.
M. Van Den Eeckhaut J. Poesen G. Verstraeten V. Vanacker J. Nyssen J. Moeyersons L. P. H. van Beek L. Vandekerckhove 《地球表面变化过程与地形》2007,32(5):754-769
Large, deep‐seated landslides are common features in the Flemish Ardennes (Belgium). As most of these old (>100 years) landslides are located under forest in this hilly region, aerial photograph interpretation is not an appropriate landslide mapping method. This study tested the potential of LIDAR (Light Detection and Ranging) images for mapping old landslides under forest. Landslide inventory maps were created for a 125 km2 area by applying the expert knowledge of seven geomorphologists to LIDAR‐derived hillshade, slope and contour line maps in a GIS environment. Each of the seven LIDAR‐based landslide inventories was compared (i) with the other six, (ii) with a detailed field survey‐based inventory, and (iii) with a comparable study in which topographic data were extracted from a topographical map. The combination of the percentage of field landslides indicated by an expert and the percentage of positional discrepancies (expressed in terms of positional mismatch) were used to evaluate the quality of the LIDAR‐based inventory maps. High‐quality LIDAR‐derived landslide inventory maps contain more than 70 per cent of the landslides mapped during the field survey, and have positional discrepancies smaller than 70 per cent when compared with the field survey‐based inventory map. Four experts and the combination map of all experts satisfied these criteria. Together the seven experts indicated all landslides mapped in the field. Importantly, LIDAR enabled the experts to find ten new landslides and to correct the boundaries of eleven (of the 77) landslides mapped during the field survey. Hence, this study showed that large‐scale LIDAR‐derived maps analysed by experienced geomorphologists can significantly improve field survey‐based inventories of landslides with a subdued morphology in hilly regions. Copyright © 2006 John Wiley & Sons, Ltd. 相似文献
12.
2012年夏季三江平原湿地抚远地区浮游植物群落结构及多样性 总被引：2，自引：0，他引：2
2012年6月(夏季)对三江平原湿地抚远地区水域的浮游植物进行调查,设置了10个采样点,经鉴定共有浮游植物262个分类单元,包括239种19变种4变型,隶属于7门9纲22目32科73属.通过对浮游植物群落结构的初步分析,得出三江平原湿地抚远地区水域浮游植物群落结构组成以绿藻门、硅藻门、裸藻门为主,种类数为绿藻门(42.6％)＞硅藻门(22.8％)＞裸藻门(20.9％),细胞密度在3.88×104～278.07×104cells/L之间.聚类分析结果显示,可以将10个采样点分为两组,即农场区5个样点为一组,非农场区5个样点为另一组,两大区域的浮游植物群落结构差异明显,水体类型及生态环境的不同是其存在差异的主要原因.浮游植物多样性指数相对较为一致,Shannon-Wiener多样性指数均在2左右,Margalef丰富度指数均大于3,Pielou均匀度指数在0.3 ～0.5之间.综合群落结构以及多样性分析表明,三江平原湿地抚远地区水域浮游植物物种丰富度较高,多样性良好. 相似文献
13.
An expert system is proposed for the assessment of characteristic and the trophic status of lakes for which little or no direct observational data are available. The system is based on the mathematical apparatus of fuzzy logic and applied to the best studied in Russia Karelian lake region. The created database on the morphometry, hydrology, hydrochemistry, and hydrobiology for 100 best studied lakes is described. The lakes are classified by methods of multidimensional statistics, factor, cluster, and logical-information analysis with the use of multidimensional scaling technique. Serious drawbacks of different classifications are demonstrated, in particular, because of the lack of a constructive algorithm for the recovery of unknown characteristics of a lake once it is referred to a certain class. In such cases, the mathematical apparatus of fuzzy sets and fussy logic should be used. 相似文献
14.
致密砂岩流体识别难度大,智能算法能够较好地建立其流体识别模型.相较于单一智能算法,分类委员会机器通过联合多个专家(智能算法)有助于提升智能模型整体性能.而针对分类委员会机器中单个专家性能难以提升的问题,添加门网络构建动态分类委员会机器是一种更有效的模块化学习方式.本研究首先采用门网络将输入数据划分为多个子数据集,然后联合决策树、概率神经网络、贝叶斯分类、BP神经网络、最近邻算法分别训练子数据集得到多个子模型,最后利用组合器最优化子模型组合得到最佳的流体识别模型.针对塔里木盆地库车坳陷大北、克深、博孜地区致密砂岩地层测井数据和测试数据,采用平均影响值法优选敏感测井系列作为输入,构建了动态的测井流体识别模型,其训练、验证准确率分别为96.29%和91.39%.利用此模型以BZ9井为例进行流体类型判别,预测结果与测试结果一致.该方法将无监督与有监督学习相结合,引入门网络提高了数据集利用效率,避免了数据集分布不均衡对模型构建的影响;采用投票机制集成多种专家,建立了子模型与专家的适应关系,流体识别模型预测精度和泛化能力大大提高. 相似文献
15.
Classifying the flow regimes of Mediterranean streams using multivariate analysis 总被引：1，自引：0，他引：1 
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下载免费PDF全文 Ons Oueslati Anna Maria De Girolamo Aziz Abouabdillah Thomas R. Kjeldsen Antonio Lo Porto 《水文研究》2015,29(22):4666-4682
Rivers in the Mediterranean region often exhibit an intermittent character. An understanding and classification of the flow regimes of these rivers is needed, as flow patterns control both physicochemical and biological processes. This paper reports an attempt to classify flow regimes in Mediterranean rivers based on hydrological variables extracted from discharge time series. Long‐term discharge records from 60 rivers within the Mediterranean region were analysed in order to classify the streams into different flow regime groups. Hydrological indices (HIs) were derived for each stream and principal component analysis (PCA) and then applied to these indices to identify subsets of HIs describing the major sources of variations, while simultaneously minimizing redundancy. PCA was performed for two groups of streams (perennial and temporary) and for all streams combined. The results show that whereas perennial streams are mainly described by high‐flow indices, temporary streams are described by duration, variability and predictability indices. Agglomerative cluster analysis based on HIs identified six groups of rivers classified according to differences in intermittency and variability. A methodology allowing such a classification for ungauged catchments was also tested. Broad‐scale catchment characteristics based on digital elevation, climate, soil and land use data were derived for each long‐term station where these data were available. By using stepwise multiple regression analysis, statistically significant relationships were fitted, linking the three selected hydrological variables (mean annual number of zero‐flow days, predictability and flashiness) to the catchment characteristics. The method provides a means of simplifying the complexity of river systems and is thus useful for river basin management. Copyright © 2015 John Wiley & Sons, Ltd. 相似文献
16.
Relationships explaining streamflow behaviour in terms of drainage basin physiography greatly assist efforts to extrapolate streamflow metrics from gauged to ungauged basins in the same landscape. The Dorset Environmental Science Centre (DESC) has monitored streamflow from 22 small basins (3.4–190.5 ha) on the Precambrian Shield in south-central Ontario, in some cases since 1976. The basins exhibit regional coherence in their interannual response to precipitation; however, there is often a poor correlation between streamflow metrics from basins separated by as little as 1 km. This study assesses whether inter-basin variations in such metrics can be explained in terms of basin scale and physiography. Several characteristics (annual maximum, minimum and average flow) exhibited simple scaling with basin area, while magnitude, range and timing of annual maximum daily runoff showed scaling behaviour consistent with the Representative Elementary Area (REA) concept. This REA behaviour is partly attributed to convergence of fractional coverage of the two dominant and hydrologically-contrasting land cover types in the DESC region with increasing basin size. Three Principal Components (PCs) explained 82.4% of the variation among basin physiographic properties, and several runoff metrics (magnitude and timing of annual minimum daily runoff, mean number of days per year with 0 streamflow) exhibited significant relationships with one or more PC. Significant relationships were obtained between basin quickflow (QF) production and the PCs on a seasonal and annual basis, almost all of which were superior to simple area-based relationships. Basin physiography influenced QF generation via its control on slope runoff, water storage and hydrologic connectivity; however, this role was minimized during Spring when QF production in response to large rain-on-snow events was relatively uniform across the DESC basins. The PC-based relationships and inter-seasonal changes in their form were consistent with previous research conducted at point, slope and basin scales in the DESC region, and perceptions of key hydrological processes in these small basins may not have been as readily obtained from scaling studies using streamflow from larger basins. This process understanding provides insights into scaling behaviour beyond those derived from simple scaling and REA analyses. The physiography of the study area is representative of large portions of the Precambrian Shield, such that basin streamflow behaviour could potentially be extended across much of south-central Ontario. This would assist predictions of streamflow conditions at ungauged locations, development and testing of hydrological models for this landscape, and interpretation of inter-basin and intra-annual differences in hydrochemical behaviour on the southern Precambrian Shield. 相似文献
17.
A broader consensus on the number of ground motions to be used and the method of scaling to be adopted for nonlinear response history analysis (RHA) of structures is yet to be reached. Therefore, in this study, the effects of selection and scaling of ground motions on the response of seismically isolated structures, which are routinely designed using nonlinear RHA, are investigated. For this purpose, isolation systems with a range of properties subjected to bidirectional excitation are considered. Benchmark response of the isolation systems is established using large sets of unscaled ground motions systematically categorized into pulse-like, non-pulse-like, and mixed set of motions. Different subsets of seven to 14 ground motions are selected from these large sets using (a) random selection and (b) selection based on the best match of the shape of the response spectrum of ground motions to the target spectrum. Consequences of weighted scaling (also commonly referred to as amplitude scaling or linear scaling) as well as spectral matching are investigated. The ground motion selection and scaling procedures are evaluated from the viewpoint of their accuracy, efficiency, and consistency in predicting the benchmark response. It is confirmed that seven time histories are sufficient for a reliable prediction of isolation system displacement demands, for all ground motion subsets, selection and scaling procedures, and isolation systems considered. If ground motions are selected based on their best match to the shape of the target response spectrum (which should be preferred over randomly selected motions), weighted scaling should be used if pulse-like motions are considered, either of weighted scaling or spectral matching can be used if non-pulse-like motions are considered, and an average of responses from weighted-scaled and spectrum-matched ground motions should be used for a mixed set of motions. On the other hand, the importance of randomly selected motions in representing inherent variability of response is recognized and it is found that weighted scaling is more appropriate for such motions. 相似文献
18.
Defining and measuring braiding intensity 总被引：1，自引：0，他引：1
Geomorphological studies of braided rivers still lack a consistent measurement of the complexity of the braided pattern. Several simple indices have been proposed and two (channel count and total sinuosity) are the most commonly applied. For none of these indices has there been an assessment of the sampling requirements and there has been no systematic study of the equivalence of the indices to each other and their sensitivity to river stage. Resolution of these issues is essential for progress in studies of braided morphology and dynamics at the scale of the channel network. A series of experiments was run using small‐scale physical models of braided rivers in a 3 m ∞ 20 m flume. Sampling criteria for braid indices and their comparability were assessed using constant‐discharge experiments. Sample hydrographs were run to assess the effect of flow variability. Reach lengths of at least 10 times the average wetted width are needed to measure braid indices with precision of the order of 20% of the mean. Inherent variability in channel pattern makes it difficult to achieve greater precision. Channel count indices need a minimum of 10 cross‐sections spaced no further apart than the average wetted width of the river. Several of the braid indices, including total sinuosity, give very similar numerical values but they differ substantially from channel‐count index values. Consequently, functional relationships between channel pattern and, for example, discharge, are sensitive to the choice of braid index. Braid indices are sensitive to river stage and the highest values typically occur below peak flows of a diurnal (melt‐water) hydrograph in pro‐glacial rivers. There is no general relationship with stage that would allow data from rivers at different relative stage to be compared. At present, channel count indices give the best combination of rapid measurement, precision, and range of sources from which measurements can be reliably made. They can also be related directly to bar theory for braided pattern development. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
19.
Abhishek Singh Douglas D. Walker Barbara S. Minsker Albert J. Valocchi 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(6):881-898
The interactive multi-objective genetic algorithm (IMOGA) combines traditional optimization with an interactive framework that considers the subjective knowledge of hydro-geological experts in addition to quantitative calibration measures such as calibration errors and regularization to solve the groundwater inverse problem. The IMOGA is inherently a deterministic framework and identifies multiple large-scale parameter fields (typically head and transmissivity data are used to identify transmissivity fields). These large-scale parameter fields represent the optimal trade-offs between the different criteria (quantitative and qualitative) used in the IMOGA. This paper further extends the IMOGA to incorporate uncertainty both in the large-scale trends as well as the small-scale variability (which can not be resolved using the field data) in the parameter fields. The different parameter fields identified by the IMOGA represent the uncertainty in large-scale trends, and this uncertainty is modeled using a Bayesian approach where calibration error, regularization, and the expert’s subjective preference are combined to compute a likelihood metric for each parameter field. Small-scale (stochastic) variability is modeled using a geostatistical approach and added onto the large-scale trends identified by the IMOGA. This approach is applied to the Waste Isolation Pilot Plant (WIPP) case-study. Results, with and without expert interaction, are analyzed and the impact that expert judgment has on predictive uncertainty at the WIPP site is discussed. It is shown that for this case, expert interaction leads to more conservative solutions as the expert compensates for some of the lack of data and modeling approximations introduced in the formulation of the problem. 相似文献
20.
《Limnologica》2015
Morphometric differences were used to elucidate the stock geographic variations and phylogeography of Macrobrachium nipponense in Taiwan. Eight samples were collected from three estuaries (Tamsui River Estuary [TSE], Kaoping River Estuary [KPE], and Houlung River Estuary [HLE]) and five reservoirs (Shimen Reservoir [SMR], Mingde Reservoir [MDR], Deji Reservoir [DJR], Tsengwen Reservoir [TWR], and Chengqing Lake Reservoir [CLR]). Twelve morphometric measurements were size-standardized by the allometric method and via Cluster Analysis and Canonical Variate Analysis (CVA). Randomisation tests were used to verify the morphometric variation between groups. The results clustered the eight samples into a minimum of three groups. The first group included four reservoir samples (i.e. DJR, MDR, CLR, and TWR); the second included the SMR sample, and the third comprised the remaining estuarine samples (i.e. TSE, HLE, and KPE). Morphometric variation among the three groups was significant for each sex. Significant differences between these three groups may be derived from evolutionary origins, geographic events or environmental adaption which was discussed in the paper. The difference between multivariate allometric coefficients in both sexes and sites were also tested based on the eight group data sets, and the result showed that the difference between sexes was significant. 相似文献