Gully volume estimates using UAV Photometry in the Salagou area

Abstract

The Area around lake Salagou in the south of France has been experiencing significant fluvial erosion in the form of gullying since the last glacial maximum. With the aim of creating a better understanding of long-term erosion rates the volumes of some of these gullies have been calculated. Using aerial images acquired from a UAV platform and DGPS measurements DEMs of four gullies were made in Agisoft Photoscan. From these DEMs the vegetation was removed and the gully volumes were calculated using several GIS algorithms. Accuracy analysis revealed a lot of variability of accuracy with respect to internal gully relief. Overall the accuracy were on par with those of other studies which utilized UAV photometry. The gully volumes range from 10.95 × 104 cubic meters for the largest gully and 1.17 × 104 cubic meters for the smallest gully, that were measured.