基于当量距离算法的山洪灾害避灾路线研究

Research on Route of Mountain Flood Disaster Avoidance based on Equivalent Distance Algorithm

山区乡村防灾减灾能力薄弱,山洪灾害突发性强,避灾响应时间短,容易造成人员伤亡,合理设计避灾路线,有助于降低灾害损失。本文基于GIS技术,以河北省邢台市田白芷村所在山区避灾路线规划为例,通过高分辨率无人机摄影测量获得研究区DEM数字高程模型和正射影像。以坡度作为避灾阻力值,利用成本距离和成本路径函数计算山区初始避灾路线,以山洪沟所在区域、坡度较大区域作为避灾路线阻隔,同时充分考虑现有山路,优化形成最终避灾路线,基于避灾路线的距离和平均坡度2个指标将研究得到的避灾路线与原有的避灾路线进行定量对比分析。研究结果表明:①在设计形成的20条远距离避灾路线中,该方法能够缩短18条避灾路线的长度,同时有10条线路的平均坡度得到降低,其余8条线路平均坡度的增加控制在2°以内;②生成的路线较原始路线单条最长可缩短329.74 m,且平均坡度仅增加0.68°,实现增加少量的平均坡度来缩短避灾距离,从而提高避灾效率;③剩余2条路线分别增加了15.21 m和9.57 m行程使得平均坡度降低了8.43°和1.43°,实现增加少量的距离来降低线路的平均坡度,从而提高避灾的安全性;④田白芷村南部临近避灾点,避灾难度较低,而田白芷村北部到达避灾点的行程较长,最远长达1210.02 m,避灾难度较大。优化后的避灾路径与大坡度阻隔区域分离,与山洪沟的贴合度也大大降低,可为相关决策人员提供科学依据。

The ability of disaster prevention and mitigation in mountainous and rural areas is weak.Mountain flood disasters have strong suddenness,and the response time of disaster avoidance is short,which are likely to cause casualties.Reasonable design of avoidance routes can help reduce losses caused by disasters.Based on GIS,this paper designs disaster avoidance routes in Tianbaizhi Village,Xingtai City,in the Hebei Province.The Digital Elevation Model(DEM)and orthophoto of the research area are obtained through Unmanned Aerial Vehicle(UAV)photogrammetry.Factors that influence disaster avoidance route planning including slope,cost distance,and function of cost path are used to calculate the initial avoidance route in the mountainous areas.The area where the mountain flood ditch is located and the area with a large slope are used as the interrupted area of the disaster avoidance route.The existing mountain roads are fully considered and rationally used to optimize the final disaster avoidance route.Based on the distance and average slope of the disaster avoidance route,the disaster avoidance route obtained by this method is quantitatively compared with the original disaster avoidance route.The result shows that(1)Among the 20 long-distance disaster avoidance routes designed,this method shortens the length of 18 routes,reduces the average slope of 10 routes,and controls the increase of the average slope of the other 8 routes within 2°;(2)Compared with the original route,the maximum length of each route can be shortened by 329.74 m,and the average slope only increases by 0.68°.The disaster avoidance distance is shortened by adding a small amount of average slope,which improves the disaster avoidance efficiency;(3)The length of remaining two routes increases by 15.21 m and 9.57 m,respectively,resulting in an average slope reduction of 8.43°and 1.43°.The average slope of the routes is reduced by adding a small amount of distance,which improves the safety of disaster avoidance routes;(4)The southern part of Tianbaizhi Village is close to the disaster avoidance point,and the avoidance of disasters is relatively difficult.In contrast,the northern part of Tianbaizhi Village has a longer route to the disaster avoidance point.The longest distance is 1210.02 m,and the difficulty of disaster avoidance is greater.The optimized disaster avoidance path has been separated from the barrier area with large slope,and the degree of overlap between disaster avoidance path and the mountain flood ditch is greatly reduced.The method proposed in this study provides a sufficient scientific basis for relevant decision-makers.