西南山区暴雨诱发泥沙补给突变下的山洪灾害研究

The mountain region is frequently affected by the extreme disaster weather, resulting in frequent occurrences of heavy rainfall processes that lead to serious casualty and property losses. The study of flash flood disaster is still the focus and difficulty of the work of flood control and disaster prevention in China. For a long time, the critical rainfall condition is considered to be the criteria for the forecast and warning of storm flood. The mechanism of disaster relative to the mutation of sediment supply is rarely considered. However, large numbers of disaster scenes demonstrate that the disaster is mainly from the coupling of sediment supply and flood. .This project will be based on the investigation of disaster scenes in the southwest mountain region and series of experiments. Through the theoretical analysis of hydrology, soil mechanics, hydraulics and river dynamics, and the numerical simulation, the applicants will investigate the coupling disaster process of storm flood in typical small watersheds, sediment from landslip, gravel and pebble transport with a large range of size grading, and the excess sand supply in a gully. The characteristics of storm flood and sediment in mountain regions, the complex transport power of the channel bed, the water and sediment motion and channel bed response patterns with excessive sediment supply will be systematically investigated..The response disaster mechanism of rainstorm flood process in the mountain region and the mutation of sediment supply will be clarified. The forgoing research contents will provide theoretical and technical support for the warning and prevention of flood disaster in the mountain region, and will enrich and perfect the hydrological sediment motion and the disaster prevention method during the flood disaster.

山地区域受极端灾害天气频发影响，强降雨过程频繁，人员伤亡和财产损失极为严重，暴雨山洪灾害研究仍是我国当前防洪减灾工作的重点和难点。长期以来的暴雨山洪预报预警与灾害治理多以临界降雨条件为判据，较少涉及泥沙补给突变致灾机制，而大量的暴雨山洪灾害现场表明泥沙补给与洪水的耦合作用是灾害的关键源动力。本课题以西南山区暴雨山洪灾害现场调查与系列试验为基础，利用水文学、土力学、水力学及河流动力学等理论方法和水沙运动数值模拟技术，突出研究山区小流域暴雨洪水、坡地破坏产沙、宽级配卵砾石输沙以及沟床来沙超量补给的耦合致灾过程。系统研究山地区域暴雨洪水及其产沙特征、复杂沟床输沙动力，以及超量泥沙补给下的水沙运动及其沟床响应规律，揭示山地区域暴雨山洪过程与泥沙补给突变的沟床响应致灾机理，为山区流域山洪预警及灾害防治提供理论与技术支撑，并及时丰富和完善暴雨山洪灾害过程所涉及的水文泥沙运动规律与沟床响应致灾防治方法。

暴雨山洪灾害已成为全球非常严重的自然灾害之一。中国西南山区受暴雨洪水泥沙耦合作用诱发的重大山洪灾害事件频发，严重威胁国民经济发展和人民生命财产安全。本项目以典型山洪灾害为研究对象，采用野外调查、室内试验、数值模拟及理论分析相结合的方法，重点研究暴雨作用下泥沙补给突变诱发的山洪致灾机理及防御方法，揭示了西南山区暴雨诱发的泥沙超量补给突变致灾机理，突出表现为“暴雨—洪水—泥沙—沟床响应”突变的山洪成灾特征，进一步发现山洪灾害主要存在干支流交汇区、宽窄相间、陡缓相接及弯曲河段等易发区；采用滑坡失稳分析、斜坡单元法、离散单元法（DEM）和计算流体力学（CFD）相结合的数值模拟方法，开发了一套水沙输移流固耦合模型（DEM-CFD），建立了山区小流域泥沙补给过程及山洪水沙输移致灾模拟方法，构建了山洪水沙输移平面二维水沙模拟模型，阐明了山洪水沙耦合演进的水位陡增及洪峰放大致灾效应；针对暴雨山洪在陡缓相接河段、宽窄相间河段、干支流交汇及弯曲河段水沙耦合致灾难题，提出了沟道桩林、条槛、漂石等滞沙减淤技术，研发了识别重大山洪泥沙灾害易发区及山洪灾害分区预警防御方法，并建立了融合DEM、ArcGIS、天地图和基于降雨预测与实时校正的山洪过程模拟的重大山洪泥沙易发区实时动态预测预警平台。该成果为指导西南山区暴雨山洪灾害防御工作和丰富我国山洪灾害防治研究提供了坚实的理论依据和技术支撑，项目组成员多次被四川省水利厅水旱灾害防御处邀请参与暴雨山洪灾害现场调研及应急抢险处置工作。项目研究期间共发表学术论文58篇（其中SCI收录论文34篇（含2022春季发表2篇）；EI收录论文19篇；核心期刊论文2篇；其他论文3篇），获国家发明专利授权11项，软著授权4项，著作出版1部及待出版1部，获中国大坝工程学会特等奖1项，重庆市科技进步一等奖1项和四川省科技进步二等奖1项，培养国家级青年学术人才2名，培养硕博士研究生22名，开展国内外学术交流38次，项目组织学术交流会议5次。