基于无人机航测成果的洪峰流量推算

Peak flow projection based on drone aerial survey results

因山丘区小流域暴雨洪水洪峰流量实测困难,为及时掌握暴雨洪水特征参数,亟须完成洪峰流量推算工作。无人机航空摄影测量装备的发展为暴雨洪水应急调查工作提供新思路。研究利用无人机航测效率高、数据成果丰富等特点,在不依赖地面实测数据前提下,基于高精度航测成果DOM(Digital orthophoto map)和DSM(Digital surface model)提取河道高程、洪痕边界和糙率等计算参数,结合比降-面积法(曼宁公式)提出一种推算洪峰流量新方法。以东风沟“7·12”暴雨洪水为例,提取15组断面数据、按三种比降取值方案推算洪峰流量,以GNSS-RTK测量数据推算的洪峰流量为标准值检验该方法。均值检验结果显示,该方法成果样本均值与检验值差别不显著(P>0.05);流量测验精度评定显示该方法成果精度满足三类精度水文站标准(随机不确定度<15、系统误差<±2)。综合分析显示,该方法与GNSS-RTK测量数据推算洪峰流量在外业效率、环境适应性、数据种类和数量等方面具有优势,证明将无人机航测高精度成果与典型洪峰流量公式相结合的可行性。研究结果为山丘区小流域暴雨洪水洪峰流量推算、洪水调查等工作提供参考。

It was difficult to measure the peak flow of torrential floods in small watersheds in hilly areas,and in order to grasp the characteristic parameters of torrential floods in a timely manner,it was necessary to complete the work of projecting the peak flow of torrential floods as soon as possible.With the development of drone aerial photogrammetry equipment,it provided new ideas for storm flood emergency investigation work.The article utilized the features of high efficiency of UAV aerial survey and rich data results to extract the calculation parameters,such as river channel elevation,flood scar boundary and roughness,based on the high-precision aerial survey results of DOM(Digital Orthophoto Map)and DSM(Digital Surface Model),and put forward a new method of projecting the peak flow rate by combining with the ratio-drop-area method(Manning's formula),without relying on the ground actual measurement data.Taking Dongfenggou"7·12"rainstorm flood as an example,15 groups of crosssection data were extracted,and the method was applied to project the flood peak flow according to three kinds of ratio drop schemes,and the projected flood peak flow of GNSS-RTK measurement data was used as the standard value to test the method.The results of the test of means showed that the difference between the sample mean and the test value of the results of this method was not significant(P>0.05);the accuracy assessment of the flow test showed that the accuracy of the results of this method met the criteria for a ClassⅢaccuracy hydrological station(random uncertainty<15,Systematic error<±2);comprehensive analysis showed the advantages of this method over GNSS-RTK measurements in terms of amateur efficiency,environmental adaptability,data types and quantities for flood flow estimation.The feasibility and technical advantages of combining the high-precision results of UAV aerial surveys with typical flood flow formulas were demonstrated.The research results could provide references for flood peak flow projection and flood investigation in small watersheds in hilly areas with heavy rainfall.