HIGH-FREQUENCY BEACH MONITORING WITH UAV PHOTOGRAMMETRY

Abstract

Recently, due to the development of 3D photogrammetry and UAVs, the UAV photogrammetry has been widely applied to various fields of study including coastal engineering field. The UAV photogrammetry has some important advantages for beach monitoring to enable us to frequently and easily observe morphology of beaches and also nearshore wave propagation. In this study, morphological changes on the beach around the Nanakita River mouth were observed with one week frequency of UAV flights. A conventional method of shoreline analysis was firstly applied to see the short-term recovery of shoreline positions after a big typhoon event in 2016. And also the effect of a tsunami event in November 2016 on beach morphological changes around the river mouth was discussed through the shoreline change analysis and 3D shape analysis. More than ten meters of shoreline change often occurred during this period. The surface of the right sand spit was eroded by the tsunami and the jetty had an effect of interrupting sediment movement.