Assessment of Sentinel-2 to monitor highly dynamic small water bodies: The case of Louro lagoon (Galicia, NW Spain)

Coastal lagoons have been providing ecological, economic and cultural benefits for many centuries. Despite their importance, the monitoring of coastal lagoons poses numerous challenges related to their complex environmental processes, their large variability in size and their remote location, inhibiting effective management programmes. This study demonstrates the effectiveness of Sentinel-2 satellites to map highly dynamic morphological and hydrological changes in the Louro lagoon, a small choked lagoon located on the Galician coast (NW Spain). For this purpose, a simple methodology using the Normalised Difference Water Index (NDWI) has been evaluated, which allows to monitor the sand barrier changes and the inlet formation. The results show that the sand barrier's opening and closing might take only a very short period, and the recovery of the lagoon to its full water level can happen in less than a month. Sentinel-2 images also reveal drastic changes in the water level once the sand barrier is broken. A water surface area of 0.24 km(2) was estimated on 04/11/2019, while this surface was reduced to 0.10 km(2) on 04/12/2019. Monitoring these changes is critical to understand the different processes ongoing in these valuable environments and making informed decisions for their management and protection. (c) 2021 Institute of Oceanology of the Polish Academy of Sciences. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license ( http://creativecommons.org/licenses/by-nc-nd/4.0/ ).