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河流洪水风险分析及省级洪水风险图研究

River Flood Risk Analysis and Research on Provincial Flood Risk Maps

【作者】 丁勇

【导师】 许士国;

【作者基本信息】 大连理工大学 , 水文学及水资源, 2010, 博士

【摘要】 我国是世界上洪水灾害频发的国家之一,洪水灾害严重威胁着国民的生命安全并制约着社会经济的可持续发展。近年来,人们在与洪水灾害斗争的实践中,提出了由“控制洪水”向“洪水管理”转变的新的防洪理念。洪水管理的核心就是洪水风险管理,然而人们洪水风险意识的缺乏阻碍了新的洪水管理战略实施与推进,加之目前洪泛区连续、完整和准确的洪水风险信息相对比较匮乏,不能满足应急管理和决策制定的需要。因此,对防洪区进行风险分析,绘制洪水风险图,将各种风险信息直观展示给决策者和公众,提高决策的科学性和增强公众的风险意识,对于洪水管理战略目标的实现具有重要意义。本文以辽河中下游段及左岸保护区为研究背景,以洪水数值模拟为技术支撑,对石佛寺水库下游堤防及其保护区的洪水风险、洪水风险图编制体系及防御超标准洪水对策进行了研究。主要内容概括如下:(1)外界因素的变化对于堤防防洪能力具有显著的影响作用。建立了河道洪水演进模型,以堤防运行的特征水位、堤防高程、模拟水位三者关系比较来分析校核堤防的防洪能力。在河流堤防防洪能力复核分析过程中,采用历史洪水率定了洪水演进模型中的主河槽和滩地糙率,模拟了设计洪水和超标准洪水的演进过程,最后应用堤防设计时推求的水面线对模拟结果进行了校核验证。对石佛寺水库下游堤防防洪能力校核的应用结果表明,现状堤防可防御设计标准洪水,该方法具有良好的实用性和便利性。(2)分析了堤防失事类型和堤防溃口的特性,对不同溃口水流计算方法进行比较,并分析溃口参数取值对溃堤洪水的影响。研究表明,受到堤防内外水位差的显著影响,堰流方程和管涌方程计算的结果明显优于能量方程计算的结果。其中,堰流方程适于堤防发生漫溢破坏引起溃堤:管涌方程适于堤防是发生渗透破坏引起溃堤。两种方法都能较好地模拟溃堤洪水出流过程。溃堤的发生时间和溃口的最大宽度是溃堤出流的主要影响因素。建立一维、二维耦合洪水泛滥模型,模拟了溃堤洪水在有无道路阻隔情况下的洪水淹没过程。结果表明,道路有很好的阻隔和延缓洪水演进过程的作用。(3)针对我国人口和经济发达地区主要集中在江河中下游地区的特点,探讨了河流洪水风险图编制方法,并绘制了辽河左岸典型河段洪水风险图。最后对省级洪水风险图系统建设进行了研究,该系统更利于洪水风险图的编制及运用。(4)洪泛区洪灾损失评估是决策者制定方案的重要参考。将现有的统计资料进行分类整理成基础资料数据库;对不同工况下的洪水模拟结果分析处理转化,采用ArcGIS软件进行空间分析,将洪灾信息展布到受灾区域。建立洪灾损失评估模型,对可能发生的超标准洪水淹没造成的损失评估,计算洪水的淹没面积、受灾村庄、人口和其它的各项损失。通过不同淹没方案之间损失大小的比较,优选出最佳的防洪减灾对策。(5)辽河中下游地区是经济发展较快地区,也是防洪的重点地区。利用堤防、道路等线状阻水物将保护区分区后,提出了“分区防御、分区管理、联合调度”的防洪策略;利用辽河和浑河之间的地理关系及洪水过程差异,通过工程措施将辽河洪水引到浑河,从而减轻辽河的防洪压力;漫堤造成的损失远小于溃堤带来的损失,有控制地允许洪水泛滥既可减轻防洪压力,又能产生生态效益。然而仍有溃堤发生的可能性,制定了溃口应急对策和人员撤离路线。最后对全文进行了总结,并对有待进一步研究的问题进行了展望。

【Abstract】 China is one of the most frequent flooding countries. Flood disasters seriously threaten the civil lives and restrict the sustainable development of social economy. In recent years, people have come up with practical experience in flood fighting, and put forward the new flood control concepts which transform’flood control’into’flood management’. Flood risk management is the core of flood management. But the lack of awareness of flood risk hampered the development of new flood management strategies. And the lack of continuous, complete and accurate flood risk information of flood plain will delay the emergency management and rational decision-making. Therefore, the risk analysis of flood zone is in an emergency. Flood risk map will display the risk information to decision makers and the public. And it will improve scientific decision-making and enhance public awareness of flood risk.In the paper, the middle and lower reaches of Liao River and its protected zone are taken as the case studies. Based on the numerical simulation of flood, downstream embankment and protected area’s flood risk, the provincial flood risk mapping system are studied, respectively. The main research results are summeried as follows:(1) Changes of external factors have significant influence on flood control capacity. In this research, river flood routing model was established. Flood control capacity of embankment is checked through comparing characteristic level of the dike with the embankment elevation and simulated water level. The model roughness of river main channel and flood land is calibrated by means of historical floods. Then, the design flood routing is simulated. At last, the simulation results are validated by water surface profile which is calculated during dike design. The results that flood control capacity of downstream embankment of Shifosi reservior is validated show that this method has better practicality and convenience and present levee can defense the design standard flood.(2) Crash types and breach characteristics of embankment are analyzed. Different calculation methods of breach flow were compared and analyzed the impact of breach parameters on floods. The results show that by the significant effects of the water level difference inside and outside the dike, the results of weir flow equation and piping equation are better than the results of the energy equation. Among them, the weir flow equation adapts to damage caused by overflow; the piping equation adapts to infiltration and sabotage. Both methods can simulate the flow process of the dike-breaking flood. The occurrence time and the maximum width of dike-break are the main factors on outflow. A flooding model coupled one-dimension with two-dimension is established, and flood inundation is simulated under the circumstance that wheter the roads delay the flood procession. Simulation results show that roads play an important role in delaying the flood evolution.(3) In view of the population and developed areas mainly localized in the middle and lower reaches of rivers, discussed the river flood risk mapping methods and draw the flood hazard mapping in left bank of the Liao River. Finally, the construction of the provincial flood risk mapping system has been studied, the system is more conducive to the establishment and use of flood risk maps.(4) Flood damage assessment of flood plain is an important reference for policy makers. Existing statistical data are sorted and putted into database. And the flood information which is got from flood simulation results analysis and convertion of different conditions is distributed to the affected area using ArcGIS software. The flood damage assessment model is constructed and exceeding standard flood damages are evaluated using former model. Flood inundation area, affected villages, the loss of population and others are calculated. As a result, the optimized flood control measures are chose through the comparison of various programs of flood damage assessment.(5) Liao River regions are the rapid economic development regions, but also key areas for flood control. A strategy of "regional defense, district management, joint scheduling" is adopted based on zoning by dikes, roads and other linear water-blocking material. As the flood differences and geographical relationship between Liaohe River and Hun River, by engineering measures leading flood from Liao river to the Hun River, the the flood pressure of Liao river can be reduced. A controlled flooding can ease the flood pressure, but also bring ecological benefits. However, there is always the likelihood of a breach occurred,developing emergency response and evacuation routes.At last, the paper has given some conclusions, as well as the questions which still need a fruther study.

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