Floodplain Management in Urban Developing Areas. Part II. GIS-Based Flood Analysis and Urban Growth Modelling

In Part I of this article the very dynamic nature of floodplain management was discussed and the need for modelling the urban growth processes and formulating scenarios of urban development was emphasised. In this second part, the use of Geographic Information Systems (GIS) for addressing those problems is presented. GIS have been recognised as a powerful means to integrate and analyse data from various sources in the context of comprehensive floodplain management. Adequate information and prediction capability is vital to evaluate alternative scenarios for flood mitigation policies and to improve decision making processes associated with flood management. A framework for the comprehensive evaluation of flood hazard management policies is also addressed in this article. This comprehensive approach to flood problems is more than an attitude or a philosophical starting point. It makes use of specific technological tools conceived to be used by different actors, some of them being nonexperts in flood analysis. These tools, based on GIS, are very appropriate for a participatory approach to flood policy formulation and floodplain management because they help communicating with the public in a scientifically correct and yet rather simple manner.     

基于GIS的避洪转移分析技术研究

为减少洪水溃堤造成的洪灾生命损失,快速高效组织人员撤离避险,详细介绍了避洪转移分析流程,探讨了GIS网络分析技术在避洪转移分析中的应用方法。该方法包括路网数据的拓扑检查与处理、路网数据集的建立、转移单元与安置点的合理配置、避险最优路径计算分析等。并以浑河右岸某段堤防溃堤为例,实现了避洪转移最短路径搜索,绘制避洪转移路线图。结果表明应用GIS技术可方便得出避险转移最优路径、提高转移效率、节约转移成本,绘制的避险转移图及方法等能为防洪应急预案的制定提供科学参考。     

Design Flood Estimation Using GIS Supported GIUHApproach

Quantitative understanding and prediction of theprocesses of runoff generation and its transmission to theoutlet represent one of the most basic and challenging areasof hydrology. Traditional techniques for design floodestimation use historical rainfall-runoff data for unithydrograph derivation. Such techniques have been widelyapplied for the estimation of design flood hydrograph at thesites of gauged catchment. For ungauged catchments, unithydrograph may be derived using either regional unithydrograph approach or alternatively GeomorhologicalInstantaneous Unit Hydrograph (GIUH) approach. The unithydrograph thus derived may be used for the simulation offlood events for the ungauged catchments. In this study Gambhiri dam catchment located inRajasthan, India is selected for applying this approach. Gambhiri river is a small tributary of the Berach/Banasriver of the Chambal basin in Rajasthan, India. Theobjective of the present study is to apply GeographicalInformation System (GIS) supported GIUH approach for theestimation of design flood. A mathematical model has beendeveloped at the National Institute of Hydrology, whichenables the evaluation of the Clark Model parameters usinggeomorphological characteristics of the basin. This modelhas been applied for the present study.From this study it is observed that the peakcharacteristics of the design flood are more sensitive tothe various storm pattern as well as method of criticalsequencing followed for the computation of design stormpatterns. Earlier estimates for the peak and time to peakhydrograph was 9143.74 cumec and 18 hrs. respectively.However, the estimates for the peak characteristics ofdesign flood hydrograph obtained from the GIUH basedapproach are 11870.6 cumec and 19 hrs. respectivelyconsidering the same design storm pattern.     

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.     

瀑布沟工程的水文分析计算

本文简要的介绍了瀑布沟工程水文分析计算主要依据站的选定和基本资料的插补延长,以及径流、洪水的分析计算方法.在可行性研究阶段水文成果(通过审查)和新设立的毛头码水文站所取得的数年水文资料的基础上,将初设阶段对可行性研究阶段的水文分析计算方法和成果进行验证和补充的情况重点予以介绍.     

面向GIS的汛情信息时空展现

结合GIS的空间设计方法和防汛防台的工作需求,详细阐述如何在GIS平台上展现具有时空特征的降雨、水情、台风等汛情信息的设计理念,介绍适合建立汛情信息发布平台的最新GIS技术,并开发防汛二维和三维GIS平台,在此基础上进行汛情信息发布的具体实现。为提高汛情信息发布系统的浏览和响应速度,研究通过建立空间数据服务实现汛情信息发布的方法,实现汛情信息与GIS平台的高度融合和快速发布,为建立类似的防汛GIS系统提供了良好的思路和有益参考。     

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.     

结合GIS技术的洪水调度及风险分析

利用地理信息系统（GIS）技术中的空间数据管理功能对流域栅格数据、矢量数据和属性数据等信息进行管理;利用遥感图像和数字高程模型（DEM）形成流域二维、三维虚拟实现;利用二次开发组件对流域雨水情数据进行多方式的浏览;利用GIS二维、三维技术对洪水调度结果及风险分析结果进行演示（二维平面淹没演示、三维库水位动态演示）。逼真的模拟过程有助于洪水调度会商决策，从而提高洪水调度水平和最大程度减免风险。     

GIS在洪水预警报系统中的应用

通过研究GIS在洪水预警报系统中的应用,分析了系统的结构和功能,提出系统的工作原理和应用前景,为提高洪水预警报工作效率,为决策者提供更为科学的决策,探索新的思路。     

面向GIS的城市防洪图制作

介绍了以Mapinfo,Coreldraw为基本制图，制版平台，设计与制作城防工程电子地图的过程，探讨了面向GIS的城防图概括制作技术，并应用于城市防洪图集的制作中，取得了较好的效果。