四川省北川县正河流域山洪泥石流危险性分析OA

Flood and debris flow occur frequently in mountain streams-due to multiple factor such as landslides,loose solids,and heavy rainfall.Their carrying of sediment,rocks,driftwood,and other debris obstructs road embankment and bridge culverts,amplifying the magnitude of flood disasters and seriously troubling flood prevention efforts.Based on the investigation of flash flood and debris flow disasters in the Zhenghe River basin of Beichuan County in Sichuan Province and by combing the types of floods and the debris jam characteristics of culverts,the pro-cess of floods and debris flow,as well as the maximum flow depth and flow velocity characteristics under six disaster scenarios,are investigated using numerical simulation approach.The dynamic factor v2d(where v is the flow velocity and d the flow depth),is introduced as an index of the intensity of the external load acting on buildings or disaster-bearing bodies to divide floods and debris flow risk zones and determine the level of hazard.The findings demonstrate that there are significant differences in the spatial distribution of the maximum depth and flow velocity under the six simulation scenarios of flood and debris flow.The scenario of culvert blockage has the smallest difference between simulated and measured flood marks in mud depth.The hazard grades can well represent the actual degree of damage to buildings the amplification effect of flow and the diversion of the main flow caused by the blockage of road embank-ment and bridge culverts are the main reasons for the amplification of disaster-affected areas.The research results can provide an important reference for disaster prevention and reduction planning in mountainous areas,the assessment of building location and structural type,the selection of temporary safe evacuation sites,and potential risk investiga-tion,etc.