隐潭溪流域山洪预警模型构建与应急避险分析OA

The frequent occurrence of extreme rainstorms triggered by global climate change,combined with the complex flow dynamics of mountainous river channels,makes flash flood early warning a persistent scientific challenge.Although various hydrological and hydrodynamic models widely adopted for flood forecasting each have their own strengths,they are generally difficult to apply to small-scale flash flood early warning,which demands high-resolution topographic datasets.Taking the Yintanxi Watershed as a case study,this research constructs a coupled hydrological-hydrodynamic model based on high-precision topographic datasets to improve flash flood early warning and risk assessment capabilities,establishes a flash flood early warning indicator system for the Yintanxi Watershed,and investigates the distribution of flash flood hazard zones,evacuation routes,and shelter locations.The results show that,in the simulation of four typhoon flood events from 2015 to 2021 using the Xin'anjiang model,the relative errors of runoff depth and peak discharge are all below 20%,with determination coefficients exceeding 0.70,indicating high applicability,and the model also performs well in individual flood event simulations.Using the HEC-RAS Model,this study carries out coupled one-dimensional and two-dimensional unsteady flow simulations for the 20210721 flood event.Based on grid cell division,the primary inundated areas are identified as low-lying river channels and floodplains.A flash flood early warning indicator system for the Yintanxi Watershed is constructed using the water level(discharge)back-calculation method.It is found that the critical rainfall threshold rises with extended warning periods but decreases with the increase of antecedent soil moisture content.The flash flood risk gradually decreases from the river channel outward to the surrounding areas.Due to variations in terrain,hydrological conditions,and other factors among different villages,there are regional differences in flood hazard zones,evacuation routes,and shelter locations.To tackle the technical bottlenecks restricting flash flood early warning in small watersheds,this study optimizes the technical approach from three dimensions including model coupling,dynamic early warning and closed-loop disaster prevention,and establishes a full-process technical system for flash flood management in small watersheds in southern hilly regions.This can provide technical support for disaster prevention and mitigation in similar watersheds.