山洪灾害关键致灾因素对临界雨量与成灾风险的响应机制研究

For different force directions and intensity of many influencing factors in the process for triggering flash floods, applying “aggregation-decomposition–coordination”idea and disaster environment, disaster-bearing body and disaster-causing factor disaster mechanism analysis method in disaster system, and grouping the influencing factors that have the same force direction, to construct flood disaster mechanism; The key factors such as river channel storage and regional meteorological characteristics under the influence of early rainfall are scientifically and rationally expressed on the basis of decoupling analysis. Utilizing the improved Nash instantaneous unit line, the estimation of disaster time, the construction of criterion of rationality of critical rainfall and coordination of river channel storage capacity to establishe the critical rainfall determination model of mountain flood disaster, and then to calculate and check the critical rainfall. Combined with the current situation of disaster prevention and based on the forecast of heavy rainfall and rain in the future, applying the fuzzy membership function and information entropy method to establish the risk warning model of flash floods and assess the risk of disaster. The research of this project is of great significance to reveal the mechanism of the flash floods influencing factors in the process of disaster, which provides theoretical basis and technical support for perfecting the theoretical system of the rainfall thresholds for triggering flash floods and achieving the organic fusion of rigid rainfall thresholds and flexible early warning decision.

针对众多影响因素在山洪成灾过程中不同的作用力方向和力度，应用“聚合-分解-协调”理念和灾害系统中“孕灾环境、承灾体、致灾因子”的成灾机制分析方法，聚合具有相同作用力方向的影响因素，构建山洪灾害成灾机制；对前期降雨影响下的河道槽蓄水量、区域气象特征等关键因素在解耦分析的基础上进行科学合理表达。采用改进的Nash瞬时单位线、推求成灾时间、构建临界雨量双层合理性判别标准，协调河道槽蓄水量建立山洪灾害临界雨量复核计算模型，对临界雨量进行计算和检验复核。结合防灾现状，基于对未来时段强降雨量级与雨型的预判，利用模糊隶属度函数和信息熵等方法建立山洪灾害风险预警模式，对成灾风险进行评估。本项目研究对于揭示山洪影响因素在成灾过程中的作用机理具有重要的意义，对完善山洪灾害临界雨量计算体系，实现刚性临界雨量与柔性预警决策的有机融合提供了理论基础与技术支撑。

针对降雨随机性所导致山洪灾害预警预报“空报”、“漏报”问题，本项目开展了小流域山洪灾害成灾机制分析、降雨时程分配不确定性研究、山洪灾害雨量预警指标计算及检验复核、山洪灾害预警模式建立四部分研究。通过解耦分析致灾因子，定量分析了降雨雨型、前期影响雨量对山洪灾害临界雨量的影响程度，计算结果表明，降雨雨型的影响程度远大于前期影响雨量。因此，基于多种理论方法，研究降雨时间分配的不确定性，提出了特征雨型、概率雨型、随机雨型、聚类雨型，将单一的设计雨型、单一的雨量预警指标转化为多种代表性雨型、雨量预警指标阈值等作为山洪灾害预警预报的参考依据。提出了前期影响雨量下河道槽蓄水量的估算方法，并建立了耦合河道槽蓄水量和雨型的山洪灾害临界雨量计算模型。基于成灾洪水调查，提出了采用时段特征雨量检验法对理论临界雨量进行合理性检验，依托多场次实际成灾降雨资料验证所确定临界雨量的合理性。并基于多情景模式下提出基于概率雨型的O-G-P预警模式、信息熵预警模式等多种预警模式。以河南省新县小流域为例计算分析，结果表明：雨型和前期影响雨量对临界雨量的影响程度分别位于19%-47.2%和9%-20%之间，雨型较前期影响雨量对临界雨量影响幅度更大；考虑基于多样性雨型下临界雨量计算结果合理可行，本项目提出的多种预警模式具有合理性和可操作性。本项目研究成果对于揭示山洪影响因素在成灾过程中的作用机理具有重要的意义，对完善山洪灾害临界雨量计算体系，实现刚性临界雨量与柔性预警决策的有机融合提供了理论基础与技术支撑。