Coupling GIS with Hydrologic and Hydraulic Flood Modelling

Geographic Information Systems (GIS) have been recognised as a powerful means to integrate and analyse data from various sources in the context of comprehensive floodplain management. As part of this comprehensive approach to floodplain management, it is very important to be able to predict the consequences of different scenarios in terms of flooded areas and associated risk. Hydrologic and hydraulic modelling plays a crucial role and there is much to gain in incorporating these modelling capabilities in GIS. This is still a rather complex task and research is being done on the full integration of these models. Interfacing between these models and GIS may be a very efficient way of overcoming the difficulties and getting very good results in terms of engineering practice. This paper presents results based on the use of Intergraph GIS coupled with Idrisi GIS. Using these two systems substantially increased the flexibility of using GIS as a tool for flood studies. A lumped (XSRAIN) and a distributed (OMEGA) hydrologic models were used to simulate flood hydrographs. The well known HEC-2 Hydraulic model was used to compute flooded areas. These models were applied in the Livramento catchment with very good results. The computation of flooded areas for different flood scenarios, and its representation in GIS, can be used in the assessment of affected property and associated damages. This is a very useful GIS-based approach to floodplain management.     

Floodplain Management in Urban Developing Areas. Part I. Urban Growth Scenarios and Land-Use Controls

Some of the most critical flood problems occur in urban areas where values at risk are higher and damages tend to be heavier. Fast urban developing regions raise very specific problems because of the unsteady situation of these regions in terms of catchment land-use and urban encroachment. A realistic approach to flood management in these situations requires the consideration of urban growth scenarios and the simulation of the corresponding flood conditions. Coastal towns are frequently located in floodplains and are subject to flood hazard. This is the case for many coastal areas in Southern Europe that are still developing fast due to migration of the population to these areas. In such cases, flood management cannot be dissociated from land-use management, and non-structural measures for flood control can play a crucial role. It is important to make an ex-post evaluation of these types of measures in areas where they have been adopted. These issues are addressed in two Portuguese catchments, representative of urban growth and related to flood problems in Portugal and other Southern European regions. The Laje catchment is used for the ex-post evaluation of nonstructural measures, and the Livramento catchment is used for the modelling of urban growth scenarios. Quantitative results and policy recommendations are presented based on these two case-studies. Floodplain management is better done with GIS, especially if it is linked to hydrologic and hydraulic modelling capabilities. The use of GIS for conducting these studies is presented in Part II of this article.     

Flood Hazard Assessment and Management: Interface with the Public

The understanding of how people evaluate and respond to natural hazards in an urban area, and how this knowledge can be integrated in the planning and management process, are becoming very important elements of a comprehensive and participatory approach to flood hazard management. Such an approach demands a clear comprehension of the processes of the risks perception, causal attribution, possible solutions for the problem and patterns of behaviour developed during hazard situations. The willingness of the public to participate in flood management, and the attitudes to previous initiatives also need to be addressed. The provision of structural flood defences can have a major impact on the environment and there has been an expression of concern by many members of the public for the degradation of river corridors. In this context, it is becoming a commonly accepted practice by central or local governments to submit flood management plans to public discussion. Appropriate techniques for interfacing with the public are necessary to support this upsurge of public involvement. This paper presents results from research on public perception of floods, flood management and participatory initiatives in Setúbal, Portugal. An extensive interview programme was undertaken with residents and shopkeepers – with and without flood experience, professionals responsible for dealing with flood control problems and local authorities responsible for decision-making on flood management. The paper concludes with a number of recommendations for flood hazard management policy making and processes.     

Evaluating Flood Hazard for Land-Use Planning in Greater Dhaka of Bangladesh Using Remote Sensing and GIS Techniques

Floods are a common feature in rapidly urbanizing Dhaka and its adjoining areas. Though Greater Dhaka experiences flood almost in every year, flood management policies are mostly based on structural options including flood walls, dykes, embankments etc. Many shortcomings of the existing flood management systems are reported in numerous literatures. The objective of this paper is to assess flood hazard in Greater Dhaka for the historical flood event of 1998 using Synthetic Aperture Radar (SAR) data with GIS data. Flood-affected frequency and flood depth calculated from the multi-date SAR imageries were used as hydrologic parameters. Elevation heights, land cover classification, geomorphic division and drainage network data generated from optical remote sensing and analogue maps were used through GIS approach. Using a ranking matrix in three dimensional multiplication mode, flood hazard was assessed. All possible combination of flood hazard maps was prepared using land-cover, geomorphology and elevation heights for flood-affected frequency and floodwater depth. Using two hazard maps which produced the highest congruence for flood frequency and flood depth, a new flood hazard map was developed by considering the interactive effect of flood-affected frequency and floodwater depth, simultaneously. This new hazard map can provide more safety for flood countermeasures because pixels belonging to higher hazard degrees were increased due to the consideration of higher degrees of ranks. The estimation of flood hazard areas revealed that a major portion of Greater Dhaka comprised moderate to very high hazard zone. Only a little portion (8.04%) was found to be the least vulnerable to potential flood hazard. Conversely, 28.70% of Greater Dhaka was found within very high hazard zone. Based on this study, comprehensive flood hazard management strategies for land use planning decision were proposed for the efficient management of future flood disasters.     

FLOOD INUNDATION MAPPING FOR INTEGRATED FLOODPLAIN MANAGEMENT: UPPER MISSISSIPPI RIVER SYSTEM

Natural hydrogeomorphic characteristics and hydrologic alterations are important ecological drivers, and hydrology is also a common ecological, flood control and navigation system indicator. Hydrologic characteristics change dramatically from one end of the Upper Mississippi River System to the other, and hydraulic characteristics also differ spatially across the river channels and floodplain in response to dams, levees and diversions. Low flow surface water spatial change in response to navigation and flood control has been well known for many years, but little information was available on the spatial distribution of frequent floods. The flow frequency data presented here were developed to better estimate contemporary floods after historic flooding in 1993. Flood stage estimates are enhanced in GIS to help quantify and map potential floodplain inundation for more than 1000 river miles on the Upper Mississippi and Illinois Rivers. Potential flood inundation is mapped for the 50% to 0.2% annual exceedance probability flood stage (i.e. 2‐ to 500‐year expected recurrence interval flood) and also for alternative floodplain management scenarios within the existing flood protection infrastructure. Our analysis documents: (i) impoundment effects, (ii) a hydrologic gradient within the navigation pools that creates repeating patterns of riverine, backwater and impounded aquatic habitat conditions, (iii) potential floodplain inundation patterns for over 2 million acres and (iv) several integrated floodplain management scenarios. Extreme flood events are more common in recent decades, and they are expected to continue to occur at greater frequency in response to climate change. Floodplain managers can use the results presented here to help optimize land management and flood damage reduction on the Upper Mississippi River System. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.     

太湖流域城市防洪建设的进展、问题和对策

回顾太湖流域 2 0世纪 90年代城市防洪建设的进展 ,分析城市防洪存在的问题 .太湖流域的城市防洪正面临城市范围扩大和城市数量增加、流域防洪设计雨型变化、防洪标准较原规划标准提高等三大变化 .提出按照现代化水利的要求做好规划 ,继续加大资金投入 ,抓紧治理地面沉降 ,加强非工程措施等加强城市防洪建设的对策 .指出在传统水利向现代水利的转变中 ,城市防洪的重要性仍不容忽视     

用模糊综合评价法优选城市防洪标准

防洪标准与城市的政治、社会、经济与环境等多种因素有关，这些因素均具有一定程度的“不确定性”（或称“模糊性”）．本文以南方某大城市为例，介绍用模糊多因素、多层次综合评价法优选城市防洪标准的方法．先建立多目标多因素评价体系，再确定各指标的隶属函数与隶属度，用层次分析法确定各指标及效果的权重，最后定出城市防洪标准的决策向量．结果表明，本文举例城市的防洪标准提高到３００年一遇为最优方案     

基于GIS城市智能型防洪减灾决策支持系统研究

针对城市防洪减灾决策的特点,把专家系统和人工神经网络应用到防洪减灾决策支持系统中,并把其建立在GIS平台上,设计出基于GIS城市智能型防洪减灾决策支持系统的总体框架及主要功能。该系统的建立充分利用GIS强大的空间数据分析和处理能力,实现信息的可视化管理,为防洪减灾决策提供快捷的、形象直观的动态信息支持。     

汾河临汾市城区段综合治理工程对城市防洪的影响

汾河临汾市城区段综合治理工程,将完全改变该河段的水流状况,工程实施前必须分析它对于该段河流的防洪会产生什么影响。水文计算表明,工程兴建后,该河段的防洪标准将由不足50年一遇提高到100年一遇。     

城市洪涝灾情评估与风险管理初探

快速城市化背景下城市洪涝问题日趋严重,城市洪涝已成为制约经济社会可持续发展的重要瓶颈。聚焦城市洪涝灾情评估与风险管理,从城市洪涝灾情评估方法、城市洪涝风险分析与区划和城市洪涝风险管理与对策3个方面开展研究,预期成果可为城市洪涝灾害防治提供科学支撑和技术保障。     

Assessment of flood regulation service based on source–sink landscape analysis in urbanized watershed

Facing climate change and rapid urbanization, urban flooding has exposed human and properties to increasing disaster risks. The attention from researchers and decision-makers to understand the key role of flood regulation service (FRS) in flood management has arisen. However, the mechanism of FRS supply–demand is little known from landscape scale. The FRS assessment methodology considering interacts between source, sink, and flow landscape was proposed in this study. The spatial distributions of surface runoff generation, runoff reduction capacity, and flood inundation were mapped using one-dimensional rainfall–runoff method SCS-CN and two-dimensional flood propagation model CADDIES. Four 3-hour designed rainfall scenarios ranging from nuisance to extreme events (3a, 11a, 56a, and 100a) were simulated. The Liuyang River Watershed in Changsha Municipality, China was selected for case study. The results showed that, the differences of runoff reduction coefficient and runoff generation volume between vegetation and built-up landscape have shortened. The peak flood depth, extent of flood inundation, and peak flood velocity have increased continuously with the growing rainfall intensity. The number of source–sink mismatch catchment was the highest under 56 and 100a, and the most of source-sink match catchments were observed under 3a. Under four rainfall scenarios, the changes of source–sink relationships were witnessed and the potentials of flow zone in source–sink mismatch catchments have increased. The FRS management framework concerning supply–demand connections has been proposed based on source–sink–flow analysis. These findings could provide a scientific basis for sustainable urban flood management and disaster risk mitigation.     

城市洪水模型在东莞城区洪水风险图编制中的应用

城市中密集的建筑和复杂的地下管网,给城市洪水模型构建及模拟带来了巨大困难,在很大程度上阻碍了城市洪水风险图技术的发展。为解决城市洪水模拟中密集的建筑和复杂的地下管网的问题,采用基于容积率系数二维浅水方程法模拟城市地表径流,并耦合动力波管网模拟方法,建立城市洪水模型。结果表明,该模型能够较好的模拟东莞城区城市洪水形势,同时,基于模型编制了东莞城区洪水风险图,为东莞城区防洪减灾提供了重要决策支持。     

基于MIKE FLOOD模型的西北城市河道橡胶坝群洪水风险分析研究

由于西北城市河道比降大,暴雨和山洪形成河道洪水突发性强,河道橡胶坝群的修建改善了城市生态环境,同时也客观上增大了城市洪水风险.基于MIKE FLOOD水动力学模型,对西北城市橡胶坝群河道典型案例进行了一二维耦合水动力学模型计算,研究了在河道遭遇大洪水时橡胶坝群未塌坝运行的洪水动态演进情况,定量计算了对城市可能造成的淹没情况以及洪灾损失,指明了橡胶坝群未按照防汛预案采取度汛措施而造成的潜在洪水风险,并且提出了降低城市河道橡胶坝群洪水风险的建设管理措施.     

安庆市城市防洪暨堤防管理系统的设计与实现

安徽省安庆市城市防洪暨堤防管理系统是应用GIS技术、数据仓库技术、网络技术、动态仿真模拟技术、动态规划自动寻优技术等，搭建起安庆市防汛指挥系统的基本框架，建设了包括实时水雨情数据库、工情数据库等为支撑，以堤防信息管理系统、堤防工程风险分析系统和城市洪水风险管理系统为主要内容的防汛信息系统，将为安庆市防洪与安广江堤堤防管理发挥重要作用。     

设计降雨特征对城市内涝模拟结果的影响分析

降雨是城市内涝的主要诱因之一,不同降雨特征对于城市内涝风险的影响也有所区别。为了进一步挖掘降雨特征对城市内涝风险的影响,采用综合流域排水模型（InfoWorks ICM）构建了我国南方某城市的内涝模型,系统分析了设计降雨的雨型和历时特征对城市内涝模拟结果的影响。在4个重现期的3种降雨雨型和3个降雨历时条件下,共计36个不同降雨情景对研究区的内涝情况进行模拟。通过对比不同模拟情景下的积水深度、积水面积以及积水量等结果发现：在相同降雨雨型和重现期条件下,降雨历时对积水深度的影响有一定的差别;在不同降雨雨型和降雨历时模拟情景中,积水点的位置基本保持一致,而积水面积受降雨雨型和降雨历时的双重影响;峰值积水量受降雨雨型影响较大,受降雨历时影响较小,而积水总量受降雨历时影响较大,受降雨雨型影响较小。研究中量化分析了不同设计降雨特征对城市内涝模拟结果的影响,旨在为合理地开展城市内涝预警以及应急管理等工作提供依据。     

伦敦城市洪水风险管理的启示

伦敦作为世界最大城市之一,面临多重防洪压力。随着时代的发展,伦敦城市的防洪理念也逐渐从传统的以防洪工程为主导的抵御和控制洪水向注重预防和灾后恢复的综合性洪水风险管理转变,取得了良好的效果。从伦敦城市的洪水类型和特点入手,介绍英国现行的洪水风险管理组织体系,同时从预防型措施、抵御型措施、缓解型措施、应对型措施以及恢复型措施五方面对伦敦的城市洪水风险管理措施进行总结和分析。其中重视城市规划、能够抵御千年一遇风暴潮的泰晤士河口防洪工程体系、生态排水与地下排水相结合的排水排涝体系,准确的防洪预警预报体系以及较为完善的洪水保险及救援救灾系统等方面都有许多可取之处,可以为我国的城市防洪提供借鉴。     

Modelling floodplain inundation on a regulated river: integrating GIS,remote sensing and hydrological models

The lower River Murray in South Australia is highly regulated through weirs and water extraction for irrigation. Management of the river for environmental purposes requires an understanding of the extent of floodplain inundation from various flows and weir manipulations. This study aimed to produce a floodplain inundation model for the 600 km long and 1–5 km wide portion of the River Murray in South Australia from the New South Wales border to Lake Alexandrina. The model was developed using a Geographical Information System (GIS), remote sensing and hydrological modelling. Flood inundation extents were monitored from Landsat satellite imagery for a range of flows, interpolated to model flood growth patterns and linked to a hydrological model of the river. The resulting model can be analysed for flows ranging from minimum flow to a 1‐in‐13‐year flood event for any month and weir configuration and has been independently tested using aerial photography to an accuracy of approximately 15% underestimate. The results have proven the approach for determining flood inundation over a large area at approximately one‐tenth of the cost of detailed elevation and hydrodynamic modelling. The GIS model allows prediction of impacts on infrastructure, wetlands and floodplain vegetation, allowing quantitative analysis of flood extent to be used as an input into the management decision process. Copyright © 2005 John Wiley & Sons, Ltd.     

Floodplain Residents' Preferences for Non-Structural Flood Alleviation Measures in the Red River Basin,Manitoba, Canada

Abstract

Based on the assumption that there is a general gap in information about social aspects of flood/floodplain management, the authors undertook several surveys on rural and urban residents' preferences for selected non-structural flood alleviation measures in the Red River basin, following the 1997 flood of the century. In addition to regular multiple choice and preference scaling questions, each survey contained a discrete choice experiment (a stated preference approach) which allows explicit modeling of tradeoffs. For this purpose, respondents were shown a set of choice cards displaying varied profiles of hypothetical flood/floodplain management policies and each of the respondents was asked to select the most preferred profile from a set. The survey on emergency flood evacuation indicated that in their preferences for evacuation procedures, residents were sensitive to the level of risk present. The majority of the residents preferred voluntary evacuation at the 50 percent risk of hazardous flooding, but had no objection to mandatory evacuation at a 99 percent level of risk. The choice experiment was less successful in modeling preferences for floodproofing policies. In that case, the majority of respondents consistently preferred the option of floodproofing their homesteads, irrespective of the incentives that other policy options had provided. Some of the additional survey questions suggested that the absence of a typical tradeoff behavior might have been due to the fact that a government policy on floodproofing had already been announced. The latter might have unduly influenced the responses to the hypothetical scenarios. We conclude the paper by suggesting that social science research can make significant contributions to the management and policy design of non-structural flood alleviation measures, especially when investigating management options and outcomes in a tradeoff context.     

汾阳市城市防洪规划布局分析

介绍汾阳市概况,分析现状防洪能力,指出了现状防洪存在的问题,提出通过治理河道堤防岸线、布设蓄滞洪区、修建闸坝、对水库进行除险加固的城市防洪布局思路。     

黄河下游滩区实行分类管理的设想

随着小浪底水利工程的投入运用和黄河下游河道整治工程的逐步完善,以往笼统地将黄河下游滩区作为行洪河道管理的方式已不适应社会经济发展的要求。在全面调研分析的基础上,提出将黄河下游滩区按其功能分为3类进行建设与管理的新思路,即:Ⅰ类为行洪区、Ⅱ类为行滞洪区、Ⅲ类为集中居住区。为做好滩区的分类管理,现阶段应重点研究滩区的分类试点、滩区的补偿政策以及生产堤建设标准与管理政策等。