Assessing coastal morphodynamics for climate-change related risk analysis

Abstract

Coastal zones are highly dynamic land-ocean interfaces, exposed to numerous natural and man-made risks. In the scope of the MarRISK project (0262_MARRISK_1_E) a multi-disciplinary consortium (joining MeteoGalicia, APA, CETMAR, CIIMAR, IEO, IH, IIM-CSIC, INTECMAR, IPMA, LMAG, UAveiro, UMinho and UVigo) addresses several types of coastal risks, including erosion, overwash/overtopping and flood risks, aiming to support coastal management in the mitigation of climate-change related impacts in the Northern Portuguese and Galician regions. The present work focusses on coastal morphodynamics assessment using airborne platforms. It demonstrates how survey systems can complement each other to provide a comprehensive picture of coastal morphology and dynamics. Regional surveys were done from a small airplane, equipped with a digital high-resolution photogrammetric camera. This overall assessment was complemented with local surveys of highly dynamic beaches that showed particular vulnerability to coastal erosion. For these surveys unmanned aerial vehicles (UAVs), drones, with high-resolution mass-market cameras were used. The plane-based survey provided images and topography with 15 cm ground sampling distance (GSD). UAV-based surveys resulted in 2 cm to 4 cm GSDs, for flying heights of 60 m to 120 m. Photographs were processed using automatic photogrammetric methods to obtain Digital Elevation Models (DEMs) for the study region. Using historical surveys and the data obtained within the project, coastal dynamics was evaluated and related to coastal features (e.g. shoreline orientation, exposure/protection, beach type and slope) and to local wind and wave conditions, to evaluate vulnerabilities and infer possible climate-change effects on coastal morphology.