Assessing the morphological evolution of a breakwater-protected sandy beach by means of UAV surveys at Mar del Plata, Argentina

GUIDO BACINO; GUADALUPE ALONSO; CAROLINA BILLET; WALTER DRAGANI; JOSE BEDMAR; MARCELO FARENGA

JOURNAL OF SOUTH AMERICAN EARTH SCIENCES

PERGAMON-ELSEVIER SCIENCE LTD

Año: 2023

0895-9811

This paper aims to study the morphological evolution of a breakwaterprotected sandy beach and its response to coastal storms at Mar del Plata,Argentina. The Unmanned Aerial Vehicles (UAV) and Structure from Motion (SfM)monitoring technique, was used to reconstruct the high-resolution beachmorphology. Coastal storms characterization was done through the analysis of thesignificant wave height and sea level series. Two different indexes were applied toquantify storm severity and relate it to the magnitude of beach response, one basedon the significant wave height (SPI) and the other on the surge level (SEPI). Accuratemorphological changes were mapped and volume was computed by comparing fourconsecutive UAV monthly surveys between July and November (2019) and one lastsurvey in September 2020. The beach suffered erosion between July andSeptember 2019, and then, partially recovered because occurred only one stormwith appreciable waves without the occurrence of storm surges, between Septemberand October. The period elapsing between October and November wascharacterized by a prolongate calm because there were no significant storms. Inaddition, significant wave heights decreased from July to November, and the wavepropagating direction turned from SSE to E. A significant erosive process was foundin the whole period, July 2019 and September 2020. Finally, an apparent linearrelationship between the morphological changes and the oceanographic variableswas inferred. These results indicate that the SEPI and SPI indexes could beconsidered reliable indicators of sediment-mobilizing storms on this beach.