Peak flow projection based on drone aerial survey results
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 cross-section 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.
drone aerial surveyDOMDSMratio-drop methodpeak flowtotal random uncertainty
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