极端洪水灾害损失评估方法及应用

极端洪水灾害具有频率低、影响范围大、损失高等特点,一般常遇洪水的灾害损失评估方法难以适用。分析了极端洪水灾害的自然属性与社会属性,认为极端洪水灾害损失具有时空分布的特性,因此借鉴空间信息格网技术,分别形成了极端洪水水文特性格网与社会经济特性格网,并将其叠加得到具有空间拓扑关系和属性信息的基于GIS的极端洪水损失空间信息格网模型,从而有效地反映了极端洪水灾害的时空特性。结合极端洪水损失率数据库,可评估极端洪水灾害损失。利用该方法评估了1998年特大洪水造成哈尔滨市江南主城区的直接经济损失,实证说明该方法可用于极端洪水灾害损失的评估。     

北江大堤洪水风险信息管理系统研究

以北江大堤保护范围作为研究区域，将洪水风险分析技术与GIS技术相结合，应用洪水仿真模型描述洪水的泛滥过程及水情风险特征，勾画出不同洪水频率下最大可能淹没范围，表述淹没水深、流速、历时、到达时间等风险指标的空间分布，刻划风险区内部风险程度的空间差异；应用GIS技术，叠加必要的社会经济与基础工程信息，采用GIS电子地图多层叠加方式，制作和表述洪水风险圈；进而应用洪水风险图。完成风险信息查询、灾害评估以及抢险与避难方案的设计等，并形成一套完整的风险管理与决策支持应用系统。     

洪水管理经济评价研究进展

洪水管理经济评价是践行洪水管理治水方略必不可少的环节。从洪水管理经济评价理论、洪灾损失评估以及洪水管理成本效益评估等方面综述了洪水管理经济评价的主要研究进展,分析了目前研究存在的不足,指出现有的防洪经济理论与方法已难以满足洪水管理决策对经济评价的要求。强调建立完善的洪水管理经济评价理论体系,扩展评价内容和范围,深入开展非工程措施效益、生态环境影响和社会公平等评价方法的研究是中国今后洪水管理经济评价研究的重点。     

浅析历史特大洪水在设计洪水中的作用

运用统计分析方法,研究了实测系列中加入４种不同情况的历史洪水对设计洪水的影响。结果表明：加入的历史洪水重现期越长,则设计洪水成果的稳定性越好;在同一历史洪水考证期内,加入１－２个历史洪水对提高设计洪水成果的稳定性和精订作用很明显。     

岩相古地理方法在古洪水研究中的应用

用古洪水外延洪水频率曲线是水文学中常见的问题,古洪水沉积研究法是最常用的方法,但该方法面临洪积物识别的问题。从岩相古地理学的研究思路出发,通过选取典型区进行古沟谷洪水沉积采样,用筛分法进行颗粒分析,并对其粒度级配特征值进行统计计算,同时参照岩相古地理沉积物粒度参数计算公式和分析原理,分析了古沟谷洪水的颗粒构成特性,证实了沉积物属于古洪水沉积。为古洪水研究提供一条新的思路与方法。     

洪水递减指数及其在洪水过程设计中的应用研究

基于暴雨公式的思想,定义了指数型时段平均洪水流量公式,经公式推导提出洪水递减指数的概念,研究总结了洪水递减指数的分析计算方法,可将其移用至无实测流量资料小流域设计洪水过程线的推求,并选取窟野河上游的乌兰木伦河流域进行了应用示例。结果表明该方法合理可行,为无资料地区设计洪水过程线的推求提供了新思路。     

BP神经网络洪水预报模型在洪水预报系统中的应用

采用相关分析法,在区域降水、观测断面流量(或水位)因子中识别出影响预报断面径流过程的主要变量,在多个观测断面的数据均为流量情况下,采用基于时延组合的合成流量为影响预报断面径流过程的变量,采用自相关分析法,识别出影响预报断面径流过程的前期流量(或水位),以这些变量为BP神经网络模型的输入,以预报断面的流量(或水位)为模型的输出,在BP神经网络隐层节点数自动优选的基础上,构建了基于BP神经网络的洪水预报模型。将模型载入中国洪水预报系统中,应用结果表明:模型在历史洪水训练样本具有一定代表性的情况下,可获得较高的预报精度。     

一种地形指数计算方法在Topmodel洪水模拟计算中的应用

介绍了Topmodel的基本理论，提出一种简单的地形指数ln(α/tanβ)计算方法，该方法分别提取数字高程模型(DEM)网格单元的α和tanβ，对坡度为0的网格单元进行专门处理，然后计算每一个网格单元的ln(α/tanβ)。以沿渡河流域为例，将计算的地形指数用于Topmodel进行洪水模拟计算，得到了比较满意的结果。     

新疆河流洪水与洪灾的变化趋势

在西北气候由暖干转向暖湿的过程中,新疆河流的洪水和洪灾反映明显.对新疆29条河流选取年最大洪水,统计出超标准洪水、20a一遇、50a一遇洪水的出现频次进行分析,结果显示1987年后洪水量级、洪水频次呈增加的变化趋势.通过20世纪90年代以来灾害性洪水出现的频次、灾害损失的变化比较分析,90年代以来灾害性洪水尤其是灾害性暴雨洪水和突发性洪水呈现增加的态势,1987—2000年的灾害损失与1950—1986年相比增加了30倍.     

Probabilistic stability evaluation for wildlife-damaged earth dams: a Bayesian approach

ABSTRACT

There is a growing body of evidence confirming the detrimental effects of invasive wildlife activities on the performance and – ultimately – the safety of earth dams and levee systems. Modelling cavities and burrows dug by animals in earth structures is rather cumbersome due to their geometrical complexity and randomness. This study proposes the use of the probabilistic approach to estimate the risk associated with the presence of wildlife chambers in an arbitrary dam section. Two dimensional limit equilibrium slope stability analyses were conducted for a homogeneous silty sand dam. The animal chambers were modelled as idealised highly permeable circles with a near-zero strength. Uncertainty in the dam material was introduced using the Monte-Carlo technique to randomise the input parameters. The conditional probability of failure, P(F|C), was spatially evaluated by manual perturbations of chamber locations within the dam section. Using the Bayesian approach, the section was accordingly mapped into three stability zones: “safe”, “marginally safe” and “likely to fail” based on P(F|C) values associated with the chamber location. For this very complex problem, the probabilistic handling seems to provide a mathematically normalised basis for risk assessment in lieu of the classical belief-based single-value factor of safety (FoS).     

Characterising soil property in an area with limited measurement: a Bayesian approach

The Bayesian approach has been proved useful to geotechnical engineering especially when project-specific data/measurements are very limited. In this paper, we introduced a new Bayesian algorithm to estimate soil properties at each location of a study area, with very limited project-specific data. In addition to the proposed methodology and algorithms, we also conducted a model application to estimate soil permeability for each of the 64 locations within a 4-by-4 m² area, based on very limited project-specific data, that is, one measurement from each location.     

Bayesian approach to daily rainfall modelling to estimate monthly net infiltration using the Thornthwaite water budget and Curve Number methods

The Thornthwaite and Mather water budget is a simple and frequently applicable tool to estimate surpluses of water, which are not stored in the soil profile. Combining it with the empiric CN-method of the US Soil Conservation Service (US-SCS), which is applied to daily rainfall records, it is possible to estimate the runoff, and this way, from the difference between surpluses and runoff, to estimate the net infiltration that would recharge a phreatic aquifer. In order to apply both methods during a sequence of years, it is necessary to predict the number of rain events per month, and the rainfall depth for each event. In this work, the author proposes a methodology based on the theorem of Bayes to estimate the number of occurrences of rainy events in a considered month conditioning the forecast to the monthly rainfall. In addition, an exponential distribution to generate rainfall depth knowing the monthly rainfall was done. Both algorithms were applied in four stations of the southern region of Santa Fe province (Argentina). More than 7,600 forecasts of rain occurrences and rainfall depths were compared with the observed records. Moreover, the runoff values estimated by means of the US-SCS method, using the observed rainfall and using rainfalls predicted with the algorithms were also compared. In both cases, the obtained results were also very satisfactory. The proposed methodologies allow the correct application of the balance of Thornthwaite and Mather together with the US-SCS method and a good forecast of monthly runoff and net infiltration.     

滞洪区安全滞洪GIS管理剖析

通过对滞洪区安全滞洪的系统分析,提出了应用GIS进行滞洪区安全管理的总体思路,对安全滞洪涉及到的关键性技术进行了探讨,给出了包括数据库建设、安全撤离及财产损失分析等问题的具体解决方案,为滞洪区的安全管理和指挥决策提供了新的思路.     

Using the DPFT approach to improve flash flood forecasting models

DPFT is a lumped approach for operational flash flood forecasting, based on the unit hydrograph. Using a multi-event alternating iterative algorithm, it identifies a robust and stable average transfer function and a consistent set of effective rainfall series associated with each event at the same time. This key ingredient allows an objective calibration of different loss functions, relating gauged precipitation and effective rainfall. A case study based on an operational French basin (545 km²) is presented. Three lumped production functions have been calibrated and compared. The results show that more elaborate models of loss functions must be proposed, and some possible directions for this are pointed out.Presently at the Institut de Ciences de la Terra Jaume Almera, Apartat 30102, 08080 Barcelona, Spain.Presently at EDF-DTG. Service de Ressources en Eau, BP 4348, 31029 Toulouse Cedex, France.     

Web GIS在省级防汛指挥决策信息服务子系统中的应用研究

随着Web技术与GIS技术的迅猛发展,设计开发基于Web GIS的大型防汛指挥信息服务系统已变为可行与必须。结合黑龙江省防汛指挥信息服务子系统的设计开发实际,研究使用基于B/S体系的Arc IMS作为Web GIS的解决方案;研究解决应用Arc IMS中的几个关键技术问题:以正向与反向信息查询为例,研究设计信息查询的数据流程;为便于空间数据的管理与应用,研究图层的划分与组织方法;为达到经济与实用的目的,研究不同比例尺地图的无视觉差切换;为按用户要求表现地图,研究如何编写地图配置文件。还给出了这些关键技术在实际设计开发中的应用效果。     

Applying Bayesian approach to predict deformations during tunnel construction

In this paper a fully probabilistic approach based on the Bayesian statistical method is presented to predict ground settlements in both transverse and longitudinal directions during gradual excavation of a tunnel. To that end, the convergence confinement method is adopted to give estimates of ground deformation numerically. Together with in situ measurements of the evolution of vertical deflections at selected points along the tunnel line, it allows for the construction of a likelihood function and consequently in the framework of Bayesian inference to provide posterior improved knowledge of model parameters entering the numerical analysis. In this regard, the Bayesian updating is first exploited in the material identification step and next used to yield predictions of ground settlement in sections along the tunnel line ahead of the tunnel face. This methodology thus makes it possible to improve original designs by utilizing an increasing number of data (measurements) collected in the course of tunnel construction.     

基于贝叶斯理论的水文不确定性分析研究进展

水文过程受众多自然和人为因素影响,决定了其变化的极端复杂性,表现为确定性的动态规律与不确定性的统计规律共存。水文不确定性分析的理论和方法在认识水文规律中发挥着重要作用,其中贝叶斯作为一种主要理论方法在水文水资源相关问题的研究中得到了较广泛的应用。本文评述了贝叶斯理论在水文频率分析、水文预报、确定性和不确定性方法耦合等研究中的进展,对基于贝叶斯理论的水文不确定性重点研究内容进行了展望。     

On the use of Bayesian networks as a meta-modelling approach to analyse uncertainties in slope stability analysis

In this paper, we report on the use of Bayesian networks, BNs, learnt from data generated by physical and numerical models, to overcome to a certain degree a number of complications in traditional slope stability analyses that jointly consider the mechanical and hydraulic properties of soils. Discrete Bayesian networks resulted to be useful and efficient to acquire knowledge from simulated data and to identify significant factors by the combined use of backward inference and global sensitivity analysis. Further, BNs enable decision thresholds to be estimated quickly. Along with this, backward inference and global sensitivity analysis are performed in BNs at low computation costs. Moreover, under conditions in which knowledge is scarce, we show how a practitioner can be better informed using the proposed approach. All these previously under-reported modelling features in the specialised literature encourage the further application of the proposed approach to enhance slope stability analysis.     

黄浦江防汛墙沉降特征及其对防洪能力影响的分析

在黄浦江防汛墙沉降监测基础上,总结了防汛墙沉降特征与影响因素,部析各类沉降对黄浦江防汛墙防御能力的影响。同时,以外滩黄浦江防汛墙为例,分析了区域地面沉降、工程结构沉降和近墙施工等因素对防汛墙影响的权重,综合评价了防汛墙沉降对其防洪能力的影响,提出了相关的对策措施和建议。