西部山区小流域震后山洪危害激增机制与估算方法

Based on the flood evolution theory in ordinary scale, traditional torrential flood disaster theory pays little consideration to both the influence of the earthquake over the floods and the change of the formation of the loose solid material composition after the earthquake. Due to the imperfection in research methods, it cannot explain the surging mechanism of flood hazards after earthquake reasonably. .On the basis of the dynamic process and the coupling mechanism of the rainfall-infiltration-runoff under heavy rain conditions in small watershed after earthquake, this project is intended to analyze the surface hydrological process and the formation mechanism of overland flow, the dynamics mechanism of overland flow convergence and evolution in the conditions complex terrain and vegetation, the scale amplification mechanism of the torrential rain and the landslide hazard in the slope-channel system, and to reveal the surge mechanism of flood disasters in the case of the change of the channel and the loose debris accumulation body triggered by the earthquake. Having examined the application scope of the traditional torrential flood disaster theory, the project plans to present the problems and improved ways, to erect the risk assessment method and system of flood disaster in Meizoseismal area. The research results of this project will develop the theory of the formation mechanism, the evolution course, movement mechanism of the flood disasters. It is believed to put forward some new insights and solutions to the forecasts of flood disasters and the implementation of prevention projects after the earthquake.

传统的暴雨型山洪灾害理论是基于普通规模上山洪演进过程理论，考虑强震对山洪形成的影响及震后松散固体物质构成的变化较少，研究方法上存在一些不完善的地方，难以合理解释震后山洪灾害激增机制。.本项目基于震后灾区小流域特大暴雨条件下降雨-入渗-产流的动态过程和耦合机制，分析地表水文过程和坡面流形成机理、复杂地形及植被条件下坡面流汇流、演进的动力学机制和坡面-沟道系统中暴雨山洪及滑坡灾害的规模放大机制，揭示地震引发的沟道和松散土石堆积体变化下的山洪灾害激增机制。考察传统的暴雨条件下山洪致灾理论的适用范围，提出存在问题和改进方法，建立强震区山洪灾害风险评价方法与体系。本项目的研究成果将会对山洪灾害的形成机制、演进过程、运动机理理论进行补充，也将为震后山洪灾害的预测和防治工程的实施提出一些新的见解和解决途径。

一般洪水致灾理论是基于普遍规模的洪水形成和演进理论，很少考虑地震引发的松散堆积体对洪水过程的影响。地震诱发的大量次生地质灾害, 使地表富集了大规模的松散堆积体，滑坡堵江、堰塞湖存在坝体的渗透变形、稳定性、不均匀沉降和砂土液化等工程地质问题的同时，还存在水力学与河床演变等科学问题。.该项目基于震后灾区小流域暴雨条件下降雨-入渗-产流的动力过程，分析地表水文过程和坡面流形成机理、复杂地形及植被条件下坡面流汇流、演进的动力学机制和坡面-沟道系统中暴雨山洪及滑坡灾害的规模放大机制，揭示地震引发的沟道和松散土石堆积体变化下的山洪灾害激增机制。对传统暴雨条件下山洪致灾理论进行研究，提出存在问题和改进方法，建立强震区山洪灾害风险评价方法与体系。.以汶川地震重灾区龙溪河流域为主要观测点，进行原型实验,获得了地震重灾区小流域降雨、水文、地形、河床等野外现场实测数据。揭示了龙溪河流域地震引发的地质灾害的分布规律，及地质灾害引起的河床、沟谷形态变化情况。通过野外原型观测实验，分析了龙溪河流域引发山洪形成的降雨和水文机制。.传统理论在很大程度上不能满足地震灾区山洪泥石流防治设计规范和实际需求。本项目对山区小流域震后山洪危害机制研究，描述震后山洪灾害的形成与演进机制、探讨传统理论存在的问题和改进方法，具有重要的科学意义和工程意义。