基于DEM的三峡区间洪水淹没范围模拟

基于栅格型数字高程模型，采用VC 6．0和MapObjects进行三峡区间的洪水淹没模拟，包括数字高程模型数据的预处理、矢量与栅格数据的一体化管理、无源淹没和有源淹没分析模拟。应用结果表明：洪水淹没区范围可以准确计算，洪水淹没过程的动态可以清楚地图示，这为灾情评估和防洪决策提供了科学依据。     

GIS支持下的洪水淹没范围模拟

洪水淹没范围的确定是洪灾损失评估的核心环节。采用地理信息系统 (GIS)与水力演进模型,结合三维模拟技术和对象关系模型数据库,对浙江奉化江流域洪水淹没范围进行模拟。该方法能够准确地模拟洪水淹没范围,为快速评估洪灾损失和防洪决策服务提供了科学的依据。     

溃坝洪水分析及影响研究——以陕北地区瑶镇水库为例

为研究溃坝洪水带来的影响,以陕北地区的瑶镇水库为例,采用洪水演进模拟和GIS技术等先进的溃坝分析技术,对水库遭遇五十年一遇洪水下右岸与非溢流坝连接的副坝段溃坝洪水演进过程、水深及淹没范围、流速分布及流速矢量分布展开评估,重点对溃坝洪水对水库下游产生的影响进行分析,从而得出相应结论。研究结果认为:受溃坝洪水影响最大的是瑶镇地区,水流最大流速均发生在主河道区域,五百年一遇洪水淹没范围与五十年一遇洪水淹没面积相比增加明显。瑶镇水库溃坝不会对下游的采兔沟水库安全产生很大影响。研究结果对本区域溃坝洪水及未来研究提供了参考依据。     

基于ArcGIS的洪水淹没分析与三维模拟

洪水淹没范围的确定是洪灾损失评估和防洪决策的核心环节。基于TIN数据,运用ArcMap,采用＂无源淹没分析＂方法对区域天然防洪能力进行划分;实现了在给定水位条件下,对洪水淹没范围提取与统计计算,建立了洪水水位高程和淹没面积关系公式,并用于洪水淹没快速预测;运用ArcScene,对水位抬升的＂无源渐进淹没＂情况进行了三维模拟。     

黄河下游花园口-夹河滩河段二维洪水模拟

黄河下游花园口至夹河滩河段系典型的游荡型河段.在该河段,黄河大堤内范围宽广,一般洪水频率年份,水流主要限制在主槽内,因此大堤内分布有不少居民点以及纵横交错的保护居民点的生产堤和不少高于地面的灌溉渠堤和公路,使洪水行洪范围受到了很大的限制.当洪峰流量很大时,洪水将造成生产堤溃决,极大地危害滩区居民的生活.因此,设计模拟模型计算网格时需要考虑大堤、生产堤、明显高于地面的道路等阻水建筑物的影响,使这些堤及公路成为计算格网的边.不规则四边形网格能够很好地拟合黄河这种复杂的计算域.数值模拟时采用有限体积法,为确保通量的单向性,文中使用Osher格式计算通量.通过对1982年洪水的模拟,模拟结果表明了模型的合理性.     

基于水文水动力耦合模型的山区小流域洪水预报

开展无资料地区洪水模拟研究具有重要意义。针对于无资料地区洪水预报的挑战性,以我国东南沿海典型山区小流域—梅溪流域为例,构建了山区水文-城区水动力耦合模型。山区水文模型经河道计算流量率定后,模拟了2016年"莫兰蒂"台风场景下的城区洪水淹没过程。结果表明,模拟最大淹没水深结果与城区17处洪水淹没痕迹吻合较好,验证了耦合模型的适用性。分析了"莫兰蒂"台风场景下重点区域的淹没水深与历时。此外,根据不同重现期的设计降雨,分析了城区淹没水深与淹没范围。同时,重现期越大,城中心区域洪水滞后时间越短。     

一种基于DEM的洪水有源淹没算法的设计与实现

洪水淹没范围的确定是洪灾损失评估和防洪决策的核心环节,现已成为GIS在水利应用领域的研究前沿,洪水淹没模拟分为有源淹没和无源淹没两种情形,针对有源淹没的递归算法占用计算机资源较多,容易造成系统堆栈溢出,导致程序崩溃等缺陷,丈中提出了一种计算洪水有源淹没范围算法：堆栈节点遍历算法：其以．NET为编程基础平台,在GIS技术的基础上应用数字高程模型（DEM）的格网模型进行洪水淹没分析一通过与原有的递归算法对比,该算法在一定程度上提高了计算效率和稳定性,最后成功应用在“南昌洪水淹没分析系统”中,对促进防洪减灾的信息化建设有一定意义。     

基于改进填洼模型的城市洪涝灾害计算方法

城市水文模型广泛应用于城市雨洪管理研究中,但由于它无法直接给出流域的淹没情况,制约了其在城市洪涝灾害评价中的应用,因此,有必要对其进行改进。本研究开发了考虑下游影响的填洼模型,并将其与较为成熟的城市水文模型相耦合,使改进后的模型可以模拟流域的淹没状况,并在北京市天堂河流域进行了试验研究。结果表明:改进后的模型可以快速模拟流域的淹没水深及淹没范围,其淹没水深结果与相关水动力学方法模拟结果较为一致。天堂河流域河道行洪能力低于20年一遇设计标准,流域洪水风险较大的区域集中在天堂河下游区域和田营沟与永北干渠的交汇处。若在下游区域进行开发,洪水风险还可能会继续增加。     

基于二维浅水模拟的河道滩地洪水淹没研究

提出了一种河道滩地洪水淹没分析的多分辨率处理方法。该方法首先利用有限元数值求解二维浅水方程,模拟河道水流运动,并利用干湿判断处理河道动边界,获得不同流量情况下的河道水面线沿程变化;然后以水面线切割河道滩地高精度DEM(数字高程)地形,利用图像分割及区域生长法识别陆域和水域。该方法实际应用于南渡江下游河口段的滩地洪水淹没分析,有效将二维浅水模拟的低分辨率网格(10m精度)和局部滩地高分辨率地形(2m精度)结合,获得了高精度的淹没范围计算结果。     

动态实时洪水风险分析及管理系统

当前洪水风险分析按照典型设计标准洪水进行计算的模式难以满足实际防洪管理需要,为了提高洪水风险分析的实时性以及适应洪水演进的动态性,设计了动态实时洪水风险分析框架。在本框架中,先采用一维和二维动态耦合水动力学数值方法耦合溃堤模型,然后在樵桑联围防洪保护区建立洪水演进模拟模型,通过灵活处理模型计算边界条件以及动态设置溃堤功能,计算不同设计标准洪水发生时,堤防出现单一溃口或者组合溃口后保护区内洪水演进过程。按照上述框架开发了樵桑联围动态实时洪水风险图编制与管理应用系统,并利用历史洪水资料开展模型验证,验证结果表明,2008-06洪水马口站、三水站、大熬站、甘竹（一）站的实测最高水位和模型计算最高水位的绝对误差分别为-0.10、0.10、0.09、0.04 m,均满足洪水模拟精度要求。利用模型计算了西江发生200年一遇的洪水情况下,江根堤防出现溃口后的洪水流量及溃口内外洪水水位变化过程,模拟溃口宽度168 m,最大溃口洪水流量达到5 190 m³,分析了堤防溃决后3、6和24 h洪水漫延导致村落淹没情况,结果表明其满足合理性分析。     

Three-dimensional flood routing of a dam break based on a high-precision digital model of a dense urban area

Dense buildings are the major factor affecting urban flood routing. Currently, the study of urban dam-break flood routing primarily focuses on a simplified terrain model and 2D shallow water equations, which ignore the effects of dense urban buildings. Furthermore, the complex interactions between the dam-break wave and the wall surfaces of buildings are not reflected in the results. To tackle these problems, three-dimensional flood routing with a high-precision digital model of an urban area is studied in this paper. Firstly, the vector data of various land types is extracted from a remote sensing image, and the NURBS algorithm based on the TIN algorithm is introduced to construct a three-dimensional terrain model. Coupled with the vector data and the terrain model, a three-dimensional digital model of the urban area is established. Next, a three-dimensional \(k{-}\varepsilon\) turbulence model is proposed for the flood routing simulation. A polyhedral grid with a second-order accuracy and a discrete format is used to divide the digital model of the urban area, and the governing equations are solved using the PISO algorithm. Finally, the superiority of the 3D mathematical model and the computational efficiency of the polyhedral mesh model are validated according to the urban flood routing experiments of Testa and Soares-Frazão. An urban reservoir, located in SZ City, China, is modelled to show that a dam-break flood in an urban area exhibits significant three-dimensional characteristics. Moreover, due to the surrounding buildings, the flood exhibits complex three-dimensional turbulence phenomena, including collision, reflection and vortices.     

Assessment of flood mitigation through riparian detention in response to a changing climate – a case study

Considering that urban areas may suffer more substantial losses than riparian farmlands during floods, diverting floodwater into riparian areas for temporal detention is expected to mitigate flood damage in downstream urban areas. In this study, an assessment has been conducted to evaluate the effect of flood mitigation through riparian detention in response to a changing climate in the Tou-Chien River basin of Taiwan. An integrated 1D–2D flow model was used to simulate the movement of flood wave in the main stream and the overbank flow inundating into the nearby lowlands. Based on the numerical simulation results, the flooding extents in the basin corresponding to different return periods of flood using existing flood prevention infrastructures were investigated. A detention strategy by lowering the levee along the riparian farmlands was proposed to avoid severe flooding in the densely populated urban areas of the basin. Research findings showed that the proposed detention measure can completely protect the downstream areas from overbank flooding when a flood having 20-yr period occurs, and can effectively alleviate the downstream flooding area from 27.4 to \(7.6\,\hbox {km}^{2}\) for a flood possessing 200-yr period.     

Emerging grassroots resilience and flood responses in informal settlements in Accra,Ghana

In the last five decades, many informal communities in Accra, Ghana have suffered from annual flood hazards. Residents of these communities appear to have successfully resisted evictions by city authorities; survived flood hazards and poor environmental health conditions. These flood affected households continue to survive with increasing housing and population densities in the face of these annual floods. Are they becoming resilient? Have residents built adaptive capacities through learning experiences from previous flood occurrences and evictions attempts? What has produced and continued to shape their responses to flooding? What can be learned from this supposed grassroots resilience to inform flood management in urban Africa? Using case studies of three informal communities of Glefe, Agbogbloshie and Old Fadama, this paper explores the gradual and evolving adaptive capacities and social resilience to flood hazards among poor urban dwellers. The paper reveals the depth of understanding and embodied nature of flood experiences among affected slum dwellers and how these are gradually being transformed into adaptive capacities and shaping their responses. In the absence of efficient state flood interventions, there are emerging and enduring flood responses and adaptation practices shaped by residents’ social networks, political alliances and sense of place. These responses translates into continuous re-structuring of housing units, construction of communal drains, creation of local evacuation teams and safe havens. Urban policy contributions that can be learned from these emerging grassroots capacities for flood vulnerability management have been proposed.     

洪涝灾害风险评估与分区研究进展

在全球气候变化和城市化进程不断加快的背景下,城市洪涝灾害频发,造成严重的经济损失和人员伤亡问题。对近年来中国典型城市洪涝灾害进行系统整理介绍,说明洪涝灾害带来的人员伤亡和经济损失巨大。风险评估作为一种非工程性防洪措施,是城市洪涝风险管理的首要工作,精确、高效的把握洪灾过程等特征可以为防灾减灾工作提供科学依据。对城市洪涝风险评估与分区的概念和内容进行系统梳理,常用的风险评估方法有数理统计法、不确定性分析法、遥感影像评估法、指标体系评估法、情景模拟评估法；风险分区常用方法有阈值法、经验公式法和物理机制法。论述了城市洪涝风险评估与分区常用方法的应用范围、优缺点及其发展前景。     

The definition of urban stormwater tolerance threshold and its conceptual estimation: an example from Taiwan

The combination of climate change and urbanization is worsening urban flooding problems. Estimating the amount of rainfall that a city can tolerate without flooding is a fundamental task that is difficult to perform, although large amounts of resources are invested in urban flood control. The purpose of this study is to determine the tolerance threshold for stormwater in a city. Based on hydrometeorological characteristics and existing flood control facilities, the urban adaptive water capacity is analyzed to determine the critical rainfall loading. Different critical levels are defined. The low critical point represents the beginning of the water accumulation, while the intermediate and high critical points are defined as flooding with heights of 300 and 600 cm, respectively, in low-lying areas. This study adopts a simple conceptual method to illustrate the critical levels instead of applying complex hydrologic and hydraulic modeling, which require high-resolution spatial data. Three cities and one township in Taiwan are used as urban case studies and to verify the conceptual method. As the capital, Taipei City utilizes the highest flood control engineering technology of our case studies; it is also the site in which the lowest rainfall thresholds cause the accumulation of water to reach the intermediate and high critical points because its small ‘internal water areas’ increase the height of floods rapidly. Conversely, Taichung City has a large internal water area that can disperse accumulating waters without increasing flood height. The estimations of urban storm tolerance thresholds increase the understanding of the limitations of water protection facilities. These estimations may be combined with rainfall forecasts to increase early warning functions and provide a reference point for subsequent planning related to urban flood adaptation strategies.     

Recent changes in flood risk in the Gran La Plata,Buenos Aires province,Argentina: causes and management strategy

The paper analyses the causes of flood occurrence in the Gran La Plata, Buenos Aires Province, Argentina, and the changes that have occurred since the 1970s. The area is characterized by serious deficiencies in the use and management of water resources. The main factors are: (1) flood risk information is not updated; (2) urban building organization does not consider the flood risk; (3) the topography and other physical features are not taken into account in urban development. This research considers some specific problems, especially in data availability, and suggests ways to solve them, including improved analytical methodology. One of the main objectives is to analyse flood risk in social terms, producing a map of flood risk from the “human social vulnerability” point of view. The results suggest that flood risk has increased since the 1980s and that this is associated with changes in precipitation patterns that have also been aggravated by lack of controls on urban development. The poorer areas with the lowest level of infrastructure and public services, many of them developed over the last quarter-century, are especially vulnerable.     

南华北石炭-二叠系陆表海层序古地理演化

通过对野外露头和钻孔的沉积相、古生物以及准层序堆叠方式的对比分析,将南华北石炭—二叠系陆表海沉积划分为三个三级层序:Sq1～Sq3。以层序和最大海泛面为绘图单元,分别对各层序进行了古地理重建。研究发现Sq1时期海侵范围小,时间短,来自东北方向;Sq2时期海侵范围达到最大,海侵方向由东北变为东南;Sq3时期延续了Sq2时期的古地理格局,但沉积中心向南迁移,盆地物源均主要来自北方。最后对古地理演化的成因进行了探讨,认为石炭—二叠系陆表海沉积主要受控于该时期全球海平面的变化,Sq1与Sq2之间的海侵转换面为稳定构造环境下的全球突发性海侵、南高北低的盆地基底与北缘稳定的物源共同造成的。     

Using combined AHP–genetic algorithm in artificial groundwater recharge site selection of Gareh Bygone Plain,Iran

Flood spreading is one of the suitable strategies to control and benefit from floods which in turn improve the groundwater recharge, makes soil more fertile, and increases nutrients in soil. It is also a method for reusing sediment, which is usually wasted. Thus, selection of suitable areas for flood spreading and directing the flood water into permeable formations are amongst the most effective strategies in flood spreading projects. Having combined analytic hierarchy process (AHP) of multi-criteria decision analysis and genetic algorithm (GA) of artificial intelligence approaches, this paper addresses the problem of finding the most suitable area location for flood spreading operation in the Gareh Bygone Plain of Iran. To this end, the nine effective geodata layers including slope, alluvium thickness, geology, morphology, electrical conductivity, land use, drainage density, aquifer transmissivity, and elevation were prepared in geographic information system environment. This stage was followed by elimination of the exclusionary areas for flood spreading while determining the potentially suitable ones. Having closely examined the potentially suitable areas using the proposed methodology, the land suitability map for flood spreading was produced. The AHP and GA were used for ranking all the alternatives and weighting the criteria involved, respectively. The results of the study showed that most suitable areas for the artificial groundwater recharge are located in Quaternary Qft ₂ and Qsf geologic units and in morphological units of pediment and Alluvial fans with slopes not exceeding 2 %. Finally, further evidence for the acceptable efficiency of the integrated AHP–GA method in locating most suitable flood spreading areas have been provided by such significant spatial coincidence between the produced map and the control areas located near Kowsar research station, where the earlier flood spreading projects were successfully performed.     

黄河中下游地区夏季旱涝年低频振荡特征分析

利用1971-2010年NCEP/NCAR逐日再分析资料和黄河流域67个测站逐日降水资料, 对黄河中下游地区旱涝年的低频振荡特征进行了分析.结果表明: 黄河流域30~60 d低频降水呈现区域性分布的特征, 大值区位于黄河中下游地区, 10~20 d低频降水呈现整体性分布.黄河中下游地区旱涝年夏季降水普遍存在10~20 d和30~60 d的低频振荡, 10~20 d振荡强度整体上均强于30~60 d振荡,10~20 d低频振荡在旱涝年差异不显著.涝年30~60 d低频振荡较旱年显著, 涝年和旱年30~60 d低频振荡的传播特征不相同, 同时涝年的30~60 d低频振荡的传播特征也存在差异.影响涝年30~60 d低频降水的主要原因是低纬的低频振荡强度增强向北传播到黄河流域, 以及青藏高原热源的低频振荡向东北传播与西太平洋热源的低频振荡向西传播在黄河中下游交汇.正常年份的低频降水主要受低纬低频振荡向北传播的影响.     

城市洪涝模拟应用场景及相应技术策略

城市洪涝模拟是当前国内外城市防洪减灾领域研究的热点。现有城市洪涝模拟方面的评述, 主要依据城市洪涝过程或模拟计算方法进行分类讨论, 缺乏基于应用需求的视角。随着应用需求日益深入, 城市洪涝模拟应用场景日趋多样化和复杂化, 不同模拟应用场景下, 所关注的洪涝过程不同, 采用的技术策略及其重点和难点也不同, 脱离模拟应用场景很难辨析这些不同。依据模拟对象和关注变量, 归纳总结出城市洪涝模拟的3种典型应用场景, 即城市外洪模拟、城市雨洪模拟、城市内涝模拟; 针对这3种典型模拟应用场景, 分析相应的城市洪水演进模型、城市雨洪模型、半分布式暴雨内涝模型、全分布式暴雨内涝模型等4类模拟技术策略; 辨析在不同模拟应用场景和技术策略下, 不同模拟技术的组合方式及其特点与难点, 以期从应用需求的角度对城市洪涝模拟技术进行全面的梳理, 为城市洪涝模拟应用和研究提供一个新的视角。