Application of SfM photogrammetry for morphological changes on gravel beaches: Dugi Rat case study (Croatia)

Abstract

Glavica (natural) and Dugi Rat (artificial) gravel beaches in Croatia were monitored using ground-based photography and structure-from-motion (SfM) photogrammetry, in order to assess morphological changes after storm events. In contrast to stormy waves caused by Bora winds (NE), Sirocco winds (SE) induced waves which initiated morphological changes on both beaches. Beach orientation with respect to the prevailing wind directions is the governing factor determining direction and quantity of sediment transport. We demonstrate that the SfM approach using Agisoft PhotoScan Pro and high accuracy dGPS measurement can give DEMs with error on control points generally <2cm and thus are suitable for assessing morphological changes that exceed ~5 cm.