An initial evaluation of drone-based monitoring of boulder beaches in Galicia, north-western Spain

Low altitude flights by a micro-drone were made in 2012 and 2013 over two boulder beaches in north-western Spain. Geographical information system software was used to map the data. Boulder outlines from the first flight were recorded on 4796 clasts at Laxe Brava and 2508 clasts at Oia. Changes in location were identified by overlaying these outlines on the 2013 images. About 17.5% of the boulders (mean surface area 0.32m(2)) moved at Laxe Brava and about 53% (mean surface area 0.23m(2)) at Oia. Most movement on both beaches was between the mid-tide to about 2m above the high tidal level. The location and elevation of the highest points were also recorded on the 2012 images on 4093 boulders at Laxe Brava and 3324 boulders at Oia. These elevations were compared with the elevations at the same locations in 2013. The occurrence and scale of the elevational changes were generally consistent with changes in the boulder outlines. The study confirmed that boulder beaches can be cheaply and effectively monitored using high resolution, micro-drone technology. Copyright (c) 2014 John Wiley & Sons, Ltd.