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目的:明确汶川地震所引发的滑坡对震区小流域水文响应过程的影响,推进震区洪水过程的准确预报。创新:评估汶川地震对碱坪沟流域的下垫面条件的破坏,并在此基础上利用先进的分布式水文模型定量评估地震事件对小流域产汇流过程的影响。方法:1.选取四川省龙溪河地区的碱坪沟小流域作为研究区域,利用遥感影像数据以及数字高程数据获得滑坡区的分布以及高程变化情况;2.运用基于物理概念的综合水文模型(In HM)对该流域水文过程进行模拟精度验证;3.对滑坡发生前后的降雨产流过程分别进行数值模拟,探讨在同样降雨条件下,由于滑坡所引起的下垫面特性变化对产流过程的影响。结论:1.震后滑坡灾害所带来的下垫面变化导致了流域内的山洪特性变化,且在流域内局部地区的表现更为明显,局部山洪危害增加;2.与震前相比,随着暴雨规模的增强,震后下垫面变化所致的流量峰值增量也随之增加,峰值的增加比例在6小时雨量达到235 mm时急剧增大,但降雨持续增强后趋近于稳定值(约87%)。
Objective: To clarify the impact of landslide caused by the Wenchuan earthquake on the hydrological response process in the small watershed of the earthquake area and to promote the accurate prediction of the flood process in the earthquake area. Innovation: The Wenchuan earthquake was evaluated for the destruction of the underlying surface conditions in the Jiping River Drainage Basin. Based on this, an advanced distributed hydrological model was used to quantitatively assess the impact of the earthquake events on the convergence process in the small watershed. Methods: 1.Selecting the small watershed of Jiping Pinggou in Longxihe area of Sichuan Province as the research area, using the remote sensing image data and digital elevation data to get the distribution of the landslide area and the elevation change; 2. Using the integrated hydrological model based on the physical concept In HM) to simulate the accuracy of the hydrological process in the basin; (3) Numerical simulation of the rainfall runoff process before and after the landslide, respectively, to explore the same rainfall conditions, due to landslide caused by the underlying surface characteristics of the runoff process Impact. The change of underlying surface caused by the landslide disaster caused the change of the flash flood characteristics in the basin, and the performance in some parts of the basin is more obvious, and the damage of local flood damage increases.2. Compared with the pre-earthquake, With the increase of rainstorm, the peak increment of flow rate caused by the change of underlying surface after the earthquake also increased. The peak increase rate increased sharply when the rainfall reached 235 mm in 6 hours, but the rainfall continued to increase and became stable Value (about 87%).