Abstract
The grain size distribution from aerial photos taken using an unmanned aerial vehicle (UAV) at the Shichiri-mihama coast, Mie Prefecture, Japan was estimated using an automatic object detection software tool for granulometric analysis for fluvial gravel beds, BASEGRAIN, and its accuracy was examined from comparison with sieve analysis. Furthermore, the spatio-temporal distribution of the medium grain size estimated from orthomosaic images generated using a structure-from-motion (SfM) technique was examined and discussed. Results indicated the characteristics of the spatio-temporal distribution of the medium grain size at the Shichiri-mihama coast. This suggested that BASEGRAIN can be applied to gravel beaches to assess their grain size distribution.
