FLOW VELOCITY AND DISCHARGE MEASUREMENTS USING DRONE IN RIVER ENVIRONMENTAL SURVEYS

Abstract

To measure flow velocity and discharge with less effort and time by using drones in river environmental survey, flow velocity was compared between the field direct measurements and the analysis of airborne videos. Flow velocity analyzed from video by a STIV (Space Time Image Velocimetry) method was quite similar with the direct measurements for flows with >0.5 m/s and a rough water surface. For flows with <0.5 m/s or smooth water surface, flow velocity from video did not always coincide well with the direct measurements or was hardly evaluated. Despite some shortcomings, flow videos by drones seem to be useful for a rough estimate and understanding spatial heterogeneity of flow velocity and discharge in river environmental surveys especially in large rivers or when time and number of people are limited in field surveys.