Flood Hazard Mapping in Lower Reach of Kelani River
Flood Hazard Mapping in Lower Reach of Kelani River
复制标题
凯拉尼河下游洪水灾害测绘
DOI：
10.4038/engineer.v41i5.7115
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发表时间：
2008
期刊：
影响因子：
--
通讯作者：
I. Gunasekara
中科院分区：
文献类型：
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作者：
I. Gunasekara
海啸之后，灾害管理策略发生了迅速变化。特别是，洪水灾害测绘已成为支持灾害管理和可持续发展需要完成的首要任务之一。作为一项开创性的努力，凯拉尼河下游覆盖了岛屿首都科伦坡和该国两个人口稠密的地区。科伦坡和加姆珀哈地区经常受到洪水事件的严重影响，我们选择与邻近凯格勒地区受影响较小的部分地区一起进行洪水灾害测绘。该研究涵盖了克拉尼河几乎所有潜在洪水区域。该研究的目标是：1) 准备不同重现期的洪水深度和洪水延伸图，2) 确定洪水管理和洪水减灾策略。本练习包括四个基本步骤，1）生成研究区域的地形模型以在 Arc View 中工作，2）确定不同重现期的洪水流量，3）使用水动力模型生成流量剖面； HEC RAS 和 4) 通过将水动力模型结果导出到 ArcView 来生成洪水区域和深度图。利用HEC-RAS软件的一维稳流模块进行水面剖面、洪水面积和洪水深度计算。通过在 ArcView 环境中使用不规则三角网 (TIN) 模型实施 HEC-GeoRAS 模块，可以方便地对洪泛区进行必要的地理空间建模。通过频率分析获得与选定重现期相关的峰值流量，并模拟 50 年重现期洪水事件执行校准运行。与上述1989年事件对应的现场记录的比较表明，流量和地形条件的建模是非常成功的。因此，一组与 10 年、20 年和 50 年重现期事件相关的洪水灾害地图。结果表明，10年一遇、20年一遇、50年一遇的洪水淹没研究区的面积分别为60平方公里、77平方公里和94平方公里。除了现场验证之外，模型结果还与灌溉部门现有的记录进行了比较和验证。
After the Tsunami, disaster management strategies have undergone rapid changes. Flood hazard mapping has, particularly, been realized as one of foremost tasks to be accomplished in support of disaster management and sustainable development. As a pioneering effort, the lower reach of Kelani River which covers the islandis capital, Colombo, and two densely populated districts of the country. Colombo and Gampaha districts which are frequently and considerably affected by flood events, were chosen for flood hazard mapping together with the part of the slightly affected adjoining Kegalle district. The study covers all most all the potential flood area in Kelani river. The objective of the study were, 1) Prepare flood depth and flood extend maps for different return periods, 2) Identify flood management and flood-disaster mitigation strategies. This exercise comprises four basic steps,1) Generation of Terrain model in the study area to work in Arc View, 2) Determination of flood discharges for different return periods, 3) Flow profile generation using Hydrodynamic model; HEC RAS and 4) Generation of flood area and depth maps by exporting the hydrodynamic model results to ArcView. The one dimensional steady flow module of HEC-RAS Software was utilized for water surface profile, flood area, and flood depth calculations. The requisite geo-spatial modeling of the flood plain was carried out conveniently by implementing HEC-GeoRAS module in the ArcView environment using a triangular irregular network (TIN) model. Peak flows associated with selected return periods were obtained from a frequency analysis and the calibration run was executed simulating the 50 year return period flood event. Comparison of field records corresponding to the above event of 1989 indicates that the modeling of flow and terrain conditions is very successful. Accordingly, a set of flood hazard maps associated with 10 year, 20 year, and 50 year return period events. Results show that the study area would be subjected to flood encroachments of 60, 77, and 94 square kilometers for events with return periods of 10 years, 20 years, and 50 years respectively. Model results were compared and verified against the records available in the Irrigation Department in addition to the field verification.