太湖流域洪水风险模拟研究

【作者】 胡昌伟；

【导师】 程晓陶；

【作者基本信息】 中国水利水电科学研究院 ， 水灾害与水安全， 2013， 博士

【摘要】 太湖流域是我国经济最为发达的区域,由于降雨丰沛且时空分布不均,加上流域碟形地貌与外江外海的影响,导致洪灾频繁且损失巨大。在太湖流域治理骨干工程基本完成后,防洪格局发生了较大的变化,如何在现有基础上更好地加强能力建设,以应对未来气候变化、流域城镇化等因素引起的洪水风险变化,是一个具有重大意义的研究课题。为了使研究更加具备科学性,结果更有参考价值与指导意义,需要在现有定性结论的基础上进一步开展量化研究,从而较准确地把握降雨量变化、海平面上升、外排能力变化、下垫面改变等因素对于太湖流域洪水的具体影响幅度。流域尺度的数值模拟模型是进行此类研究的前沿技术手段,具有广阔的发展前景,在国内外也开展了广泛的研究,其目前面临的主要问题有3个：①大范围的研究区域涉及众多计算对象,需要分别采用水文学、水力学、气象预报等技术手段予以解决,但当前缺乏有效的技术手段将多个学科领域的模型联合起来协同完成计算,笔者自主开发了多模型联合技术予以解决；②大范围的数值模型与微观尺度上的数模有着很多重大差异,例如目标抽象概化、参数获取、运用目标等,这些对于流域模型的实用性、扩展性有着重要影响,本论文中对这些问题作了详细分析与设计；③太湖流域洪水风险有着诸多影响因素,如果逐一进行模拟分析,计算任务量之大将是不可想象的,也是没有必要的,本论文中通过分析太湖流域防洪形势的成因与格局,提炼出较为重要的影响因素,研究其最可能的变化趋势并予以量化反映到数值模型中,设计几种代表性的场景予以计算,并通过结果分析进一步总结得出对太湖流域防洪策略的认识与建议。本论文的研究技术路线可以概括为：在最大程度利用现有资源的前提下,寻找或开发适宜的数值模型来分别模拟太湖流域气候、产汇流、河网、区域排涝等关键因素的影响,使用合适的联合计算技术将各个数模连接到一起以建立流域模型,在此基础上对太湖流域洪水进行模拟计算与结果分析,针对目标洪水影响因素的可能变化而设定不同场景,从而实现量化评估影响的具体幅度,并总结得出相应的思考与结论。本论文的主要研究内容及结论如下：1.研究太湖流域防洪的现状,探究其原因与格局；分析现有的数值模型,寻找适合太湖流域具体情况与本论文研究目标的数模；调查国内外的联合计算技术,分析其特点与适用范围。2.自行开发了河道水力学模型,基于太湖流域河网的特点,选择基于拉克斯显格式的有限体积法,采用基于邻接链表法表达的“图”数据结构以描述太湖河网的复杂拓扑连接关系。所开发的河网模型能够计算任意复杂的河道拓扑结构,很好地处理横断闸门与干床情况,具备较高的容错能力、可维护性与扩展性,数值计算稳定且速度较快,对于平原感潮河道的往复流动现象能很好模拟。经过比较验证,本河网模型对太湖流域河道洪水运动的模拟具有较好的精度与效果。3.自主开发了多模型联合计算技术,这是涉及到数值模拟与计算机技术的跨学科课题,本论文研究基于“各学科人员在其各自领域内自由发挥专业特长”的原则,采用COM、AUTOMATION、管道通信与多程序间同步技术开发了全新的联合计算平台。其具有架构开发、包容性强、附加限制少、易于实现、使用灵活、执行高效、调用便捷的特点,大大降低对各领域技术人员的专业外要求,最大程度地实现了对现有数模资源的利用,使得真正意义上的模型库与计算中心成为了可能。实际应用表明,新开发的联合计算技术完全达到预期目标,很好地实现了各个数模之间的同步与数据传输,协同搭建起了太湖流域数值模型。4.基于搭建的流域数值模型,对太湖流域洪水风险进行模拟计算。在思考现有防洪形势与格局的基础上,分析洪水影响因素的最可能变化趋势,并相应设定了降雨量增加、海平面上升、沿江沿海外排能力加强、下垫面变化、防洪排涝关系变化、抽排能力提高等6个场景进行模拟分析,量化评估其对于流域洪水的影响幅度,并总结得出对太湖流域洪水应对措施与策略的认识与建议。本项研究所建立的技术方法与成果对于其它地区的流域模型建设、大尺度洪水模拟与洪水风险变化分析等具有较好的借鉴意义与推广价值。更多还原

【Abstract】 Taihu Basin is the most developed region in China, but it suffers from frequent flood and tremendous loss due to abundant rainfall (unevenly distributed in time and space), plate like topography and influence of high tide at boundary. After accomplishment of basin treatment framework projects, the flood control situation changed significantly. It is necessary to research how to enhance capacity building for coping with the changes of flood risk due to global warming and rapid urbanization on the base of current status. To make the research more scientific and the result more referable, quantitative analysis should be carried out based on current directive conclusions in order to get more accurate understanding about the influence of factors such as rainfall change, sea level rise, land use and etc.Basin scope numerical model is a new technology for research oriented to objectives above; it has large space for future development and is widely carried out in the world. However, currently there are some key problems in this field that need research:﹍arge calculation area involves thousands of targets, which needs hydrological, hydrodynamics and metrological to deal with respectively;﹍arge scale numerical model has significant difference with detailed model, such as objects abstraction, parameters figuring and calculation objectives;﹖here are many factors in Taihu Basin that affect flood risk distribution, if digital simulation is carried out one by one, the quantity of calculation task will be so tremendous that it is hard to accomplish and unnecessary also. The author refines the more important factors based on analysis of situation of flood control in the Taihu Basin, then figures out the most likely change of them and reflect it in the numerical model quantitatively, and therefore has got several representative scenarios and carried out simulation on them. Finally, some understanding and suggestions about strategy of flood control in Taihu Basin are proposed based on analysis of the simulation results of different scenarios.The technical routine of this paper can be summarized as:following the discipline of maximized utilization of available resources, search or develop adequate numerical model to reflect the influence of key factors such as climate, rainfall runoff, river network and pumping, use appropriate cooperative calculation technology to join models to build basin-scale model, which is used in further Taihu Basin flood analysis. Make research on the most likely change of various factors and set out several scenarios accordingly, then the conclusions can be drawn by comparing different scenario results. The task and conclusions of this paper can be divided into four parts:1. Study the current situation of flood control in Taihu Basin and make analysis on its layout; search available numerical models for target suitable for basin circumstance and this research; investigate world-wide joint calculation technologies and figure out their characteristics.2. The paper proposes a newly developed river hydrodynamic model. Considering the characteristics of river in Taihu Basin, the model uses finite volume method base on LAX explicit scheme and chooses "graph" data structure to describe the complicated connectivity of channels in basin. The model can reflect whatever topography and deal with cross gate and dry bed gracefully. It possesses good stability, maintenance and runtime efficiency. By comparing the calculated result with field data, it’s believed that the model can simulate the flood movement in channel of the Taihu Basin with enough precision.3. A new technology base on COM, AUTOMATION, named pipe communication and multiple processes synchronization has been developed to solve the problem of connect multiple numerical models and carry out joint calculation task. It possesses the advantages of open structure, high tolerance, little additional restriction, easy accomplishment, high efficiency and flexible application. It significantly decreases the requirement of technicians in other fields, achieves maximized utilization of current numerical model resources and make real model database and calculation center possible. Proved by practical usage, the technology developed in the paper fully achieved expected objectives and successfully built the Taihu Basin model.4. Based on the model built above, Taihu Basin flood risk simulation was carried out. Considering the current flood control situation, the most likely change of various factors was set out and quantitatively embedded into corresponding scenarios such as:rainfall increase, sea level rising, boundary pumping capacity increase, land use change, dispatching rule change and internal pumping capacity increase. Through the simulation results of different scenarios, the quantitative influence of factors was figured out and some understanding and suggestions were drawn out about the flood control strategy in Taihu Basin. The paper made some new progress in the basin-scale model building and flood scenarios simulation at large scale. The technical routine and results can be referred for research of large scale digital model construction and analysis of flood risk changes based on simulation results in other regions.更多还原