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Applied flood risk analyses, especially in urban areas, very often pose the question how detailed the analysis needs to be
in order to give a realistic figure of the expected risk. The methods used in research and practical applications range from
very basic approaches with numerous simplifying assumptions up to very sophisticated, data and calculation time demanding
applications both on the hazard and on the vulnerability part of the risk. In order to shed some light on the question of
required model complexity in flood risk analyses and outputs sufficiently fulfilling the task at hand, a number of combinations
of models of different complexity both on the hazard and on the vulnerability side were tested in a case study. The different
models can be organized in a model matrix of different complexity levels: On the hazard side, the approaches/models selected
were (A) linear interpolation of gauge water levels and intersection with a digital elevation model (DEM), (B) a mixed 1D/2D
hydraulic model with simplifying assumptions (LISFLOOD-FP) and (C) a Saint-Venant 2D zero-inertia hyperbolic hydraulic model
considering the built environment and infrastructure. On the vulnerability side, the models used for the estimation of direct
damage to residential buildings are in order of increasing complexity: (I) meso-scale stage-damage functions applied to CORINE
land cover data, (II) the rule-based meso-scale model FLEMOps+ using census data on the municipal building stock and CORINE
land cover data and (III) a rule-based micro-scale model applied to a detailed building inventory. Besides the inundation
depths, the latter two models consider different building types and qualities as well as the level of private precaution and
contamination of the floodwater. The models were applied in a municipality in east Germany, Eilenburg. It suffered extraordinary
damage during the flood of August 2002, which was well documented as were the inundation extent and depths. These data provide
an almost unique data set for the validation of flood risk analyses. The analysis shows that the combination of the 1D/2D
model and the meso-scale damage model FLEMOps+ performed best and provide the best compromise between data requirements, simulation
effort, and an acceptable accuracy of the results. The more detailed approaches suffered from complex model set-up, high data
requirements, and long computation times. 相似文献
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华北南缘古元古代末岩墙群侵位的磁组构证据 总被引：7，自引：3，他引：4
华北克拉通南缘的中条山及邻区广泛发育元古宙放射状基性岩墙群,与五台山-恒山和大同地区的北北西向基性岩墙群以及熊耳中条拗拉谷的火山岩在时空分布和地球化学方面均具有密切的相关性。中条山及邻区放射状基性岩墙群的宏观和微观流动构造(包括捕虏体、冲痕构造、矿物线理和定向斑晶)指示岩墙群以一定的仰角向北西侵位。通过该区岩墙群磁化率各向异性(AMS)测量得到磁组构的最大磁化率长轴优势方位分布图和磁组构各向异性特征分析进一步指示华北南缘古元古代末岩墙群从熊耳中条拗拉谷的底部向北西侵位。岩墙群的流动构造和磁组构的统计成果夯实了华北克拉通古元古代末基性岩墙群与熊耳中条拗拉谷的成生联系。 相似文献
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In urban drainage systems, knowledge of short-duration rainfall events can be considered as one of the most critical elements when their hydrological behaviour wants to be investigated. The temporal resolution of rainfall data usually available for practical applications is often lower than the data requested for the design procedures or mathematical models application, greatly affecting their reliability. Moreover, when high resolution rain gauges are available in the catchment, the registration period cannot be sufficiently long for obtaining practically usable statistical analyses. The present study proposes a method for estimating the distribution of sub-hourly extreme rainfalls at sites where data for time interval of interest do not exist, but rainfall data for longer duration are available. The proposed method is based on the “scale-invariance” (or “scaling”) theory whose concepts imply that statistical properties of the extreme rainfall processes for different temporal scales are self-related by a scale-changing operator involving only the scale ratio. The methodology is applied to extreme rainfall data from a rain gauge network within the metropolitan area of Palermo (Italy). Following the application, it is shown that the statistical properties of the rainfall series have a simple scaling property over the range of duration 10 min–24 h. A simple parsimonious analytical formulation for the DDF curves, which embodies the scaling behaviour, is presented. 相似文献
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In this paper we extend the generalized likelihood uncertainty estimation (GLUE) technique to estimate spatially distributed uncertainty in models conditioned against binary pattern data contained in flood inundation maps. Untransformed binary pattern data already have been used within GLUE to estimate domain‐averaged (zero‐dimensional) likelihoods, yet the pattern information embedded within such sources has not been used to estimate distributed uncertainty. Where pattern information has been used to map distributed uncertainty it has been transformed into a continuous function prior to use, which may introduce additional errors. To solve this problem we use here ‘raw’ binary pattern data to define a zero‐dimensional global performance measure for each simulation in a Monte Carlo ensemble. Thereafter, for each pixel of the distributed model we evaluate the probability that this pixel was inundated. This probability is then weighted by the measure of global model performance, thus taking into account how well a given parameter set performs overall. The result is a distributed uncertainty measure mapped over real space. The advantage of the approach is that it both captures distributed uncertainty and contains information on global likelihood that can be used to condition predictions of further events for which observed data are not available. The technique is applied to the problem of flood inundation prediction at two test sites representing different hydrodynamic conditions. In both cases, the method reveals the spatial structure in simulation uncertainty and simultaneously enables mapping of flood probability predicted by the model. Spatially distributed uncertainty analysis is shown to contain information over and above that available from global performance measures. Overall, the paper highlights the different types of information that may be obtained from mappings of model uncertainty over real and n‐dimensional parameter spaces. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献
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Previously we have detailed an application of the generalized likelihood uncertainty estimation (GLUE) procedure to estimate spatially distributed uncertainty in models conditioned against binary pattern data contained in flood inundation maps. This method was applied to two sites where a single consistent synoptic image of inundation extent was available to test the simulation performance of the method. In this paper, we extend this to examine the predictive performance of the method for a reach of the River Severn, west‐central England. Uniquely for this reach, consistent inundation images of two major floods have been acquired from spaceborne synthetic aperture radars, as well as a high‐resolution digital elevation model derived using laser altimetry. These data thus allow rigorous split sample testing of the previous GLUE application. To achieve this, Monte Carlo analyses of parameter uncertainty within the GLUE framework are conducted for a typical hydraulic model applied to each flood event. The best 10% of parameter sets identified in each analysis are then used to map uncertainty in flood extent predictions using the method previously proposed for both an independent validation data set and a design flood. Finally, methods for combining the likelihood information derived from each Monte Carlo ensemble are examined to determine whether this has the potential to reduce uncertainty in spatially distributed measures of flood risk for a design flood. The results show that for this reach and these events, the method previously established is able to produce sharply defined flood risk maps that compare well with observed inundation extent. More generally, we show that even single, poor‐quality inundation extent images are useful in constraining hydraulic model calibrations and that values of effective friction parameters are broadly stationary between the two events simulated, most probably reflecting their similar hydraulics. Copyright © 2004 John Wiley & Sons, Ltd. 相似文献
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晋北地区中元古代岩墙群的地球化学特征和大地构造背景 总被引：18，自引：7，他引：18
晋北地区发育大规模的中元古代北北西向岩墙群，未变形和未变质，是华北克拉通前寒武纪构造演化研究的最显著标志，根据本区岩墙群的岩石学和地球化学研究，这些岩墙群的岩石属于板内大陆裂谷玄武岩系列，形成于大陆裂谷拉张的构造环境，与东侧的燕辽－中条拗拉槽内的火山岩岩石化学对比分析，本区岩墙群的基性岩浆可能来自拗拉槽深部，这些基性岩浆从拗拉槽的深部向北西方向侵位于晋北地区先存的构造裂隙中形成了基性岩墙群。 相似文献
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An innovative approach in the investigation of complex landscapes for hydraulic modelling applications is the use of terrestrial laser scanner (TLS) that can lead to a high-resolution digital elevation model (DEM). Another notable factor in flood modelling is the selection of the hydrodynamic model (1D, 2D and 1D/2D), especially in complex riverine topographies, that can influence the accuracy of flood inundation area and mapping. This paper uses different types of hydraulic–hydrodynamic modelling approaches and several types of river and riparian area spatial resolution for the implementation of a sensitivity analysis for floodplain mapping and flood inundation modelling process at ungauged watersheds. Four data sets have been used for the construction of the river and riparian areas: processed and unprocessed TLS data, topographic land survey data and typical digitized contours from 1:5000-scale topographic maps. Modelling approaches combinations consist of: one-dimensional hydraulic models (HEC-RAS, MIKE 11), two-dimensional hydraulic models (MIKE 21, MIKE 21 FM) and combinations of coupled hydraulic models (MIKE 11/MIKE 21) within the MIKE FLOOD platform. Historical flood records and estimated flooded area derived from an observed extreme flash-flood event have been used in the validation process using 2 × 2 contingency tables. Flood inundation maps have been generated for each modelling approach and landscape configuration at the lower part of Xerias River reach at Volos, Greece, and compared for assessing the sensitivity of input data and model structure uncertainty. Results provided from contingency table analysis indicate the sensitivity of floodplain modelling on the DEM spatial resolution and the hydraulic modelling approach. 相似文献
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准噶尔盆地新生代构造应力对石炭纪火山岩构造裂缝发育的控制 总被引：2，自引：1，他引：1
构造裂缝的发育对改善储层的储渗条件有着重要的作用,特别是火山岩这种非传统储层,构造裂缝的发育是其成为有效储层的必要条件。本文主要借助构造应力场有限元数值模拟这一成熟的方法对准噶尔盆地石炭纪火山岩构造裂缝的发育状况进行预测。其两个主要的步骤是首先对区域构造应力场进行模拟计算,然后结合岩石的强度指标判断构造裂缝的发育状况。通过对准噶尔盆地地质背景和构造演化的分析,明确了新生代构造应力场的的决定性作用和石炭纪火山岩的分布区域(划分出六个区域),建立了数值模拟的计算模型、确定了边界条件与载荷。通过二维有限元数值模拟(应用Ansys软件)得到了新生代盆地应力场的分布特征和应力值。结合岩石强度指标,对火山岩构造裂缝(张裂缝和剪裂缝)的发育进行了预测并圈出相应的区域,主要为盆地西北缘、中央坳陷中部、滴西1东部,彩参2周缘、大井-将军庙等地区,对石炭纪火山岩的油气勘探战略选区, 优化勘探部署具有重要指导意义。 相似文献
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G. Aronica E. Athanassoula M. Bureau A. Bosma R.-J. Dettmar D. Vergani M. Pohlen 《Astrophysics and Space Science》2003,284(2):753-756
We present a near-infrared K
n-band photometric study of edge-on galaxies with a box/ peanut-shaped `bulge'. The morphology of the galaxies is analysed
using unsharp masking and fits to the vertical surface brightness profiles, and the results are compared to N-body simulations
and orbital calculations of barred galaxies. Both theoretical approaches reproduce the main structures observed.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献