山区跨河桥梁阻水溃决对山洪灾害的复合影响分析

Combined Effects Analysis of Water Blocking Failure of Bridges Across Riverson Mountain Flood Disaster in Mountainous Areas

针对现有山洪灾害沿河村落影响分析中对极端降雨情况下跨沟桥涵阻水等山洪灾害风险隐患考虑较少的问题,选取黎川县资福水厚村乡以上流域9座阻水严重桥梁,采用水位-面积法按最不利情况分析完全阻水时上游洪水位和淹没范围,采用近似瞬间全溃模式分析溃决洪水的影响。结果表明:在山洪发生过程中,因沟道内桥梁阻水作用,强烈改变了山洪水流的汇流、演进等运动状态,山洪过程中出现壅水、溃决等灾害放大效应,受桥梁雍水或溃决影响的人口、户数及淹没水深大大提高,进一步加重灾害后果。研究结果有助于完善山洪灾害危险区清单,并为山洪灾害危险区预警转移工作提供科学参考。

In view of the problem that the existing analysis of the impact of mountain flood disaster on villages along rivers does not take into account the hidden risks of mountain flood disaster such as water obstruction by Bridges and culverts in extreme rainfall conditions,9 Bridges with severe water obstruction in the drainage basin above Shuihou village in Zifu County of Lichuan County were selected,and the water level-area method was adopted to analyze the upstream flood level and inundation range in the case of complete water obstruction.An approximate instantaneous total collapse model is used to analyze the impact of outburst flood.The results show that,during the occurrence of mountain flood,the movement state of mountain flood is strongly changed due to the blocking effect of Bridges in the channel,and the disaster amplifying effect such as backwater and collapse occurs in the course of mountain flood,and the affected population,number of households and inundation depth will be greatly increased,further aggravating the disaster consequences.The research results are helpful to improve the list of mountain flood hazard areas and provide scientific reference for flood control decision-makers to work on the early warning and transfer of mountain flood hazard areas.