Use of Low-Cost Technologies for Monitoring User Density on Beaches: A Case Study of Guarita Beach, Southern Brazil

Albuquerque, M.G.; Pereira da Silva, C.; Paula, D.P.; Espinoza, J.M.A.; Moreira, J.; Façanha, M.C.; Leisner, M.M.; Gandra, L.C., and Bendô, A.R.R., 2024. Use of low-cost technologies for monitoring user density on beaches: A case study of Guarita Beach, southern Brazil. In: Phillips, M.R.; Al-Naemi, S., and Duarte, C.M. (eds.), Coastlines under Global Change: Proceedings from the International Coastal Symposium (ICS) 2024 (Doha, Qatar). Journal of Coastal Research, Special Issue No. 113, pp. 125-129. Charlotte (North Carolina), ISSN 0749-0208. Coastal management is centered around the regulation of resources and conflicts resolution to the use and occupation of coastal environments. In this context, developing tools capable of analyzing and addressing issues related to high user density on beaches has become increasingly needed among coastal managers. Coastal monitoring with a focus on low cost and citizen participation has become essential to formulate more qualitative management strategies with coastal municipalities, especially during peak tourist seasons. This study used orthorectified images collected by the CoastSnap network and UAV images to characterize user density on Guarita Beach in Torres, southern Brazil. Images from January 15, 2024, were used, collected between 9 a.m. and 6 p.m., with samples taken every 3 hours. Superpixel segmentation was employed for user counting, involving the partitioning of the image into various pixel groupings. These images were segmented into two classes: free and occupied beach area. Subsequently, binary images (masks) for both classes were generated. Densities were then calculated using a spatial density algorithm (kernel), assigning a density distribution for each date to represent the occupancy level on the beach. Across 84 hectares of beach, the results showed that the highest levels of beach occupancy were 59.47% and 21.95% at 3 p.m. and 6 p.m., respectively. The lowest peaks of occupancy occurred at 9 a.m. and 12 p.m., with 26.63% and 19.76% of users present, respectively. These occupancy values are considered moderate compared to other beaches in the region. The lower percentages of beachgoers in this area can be attributed to its location within a State Park, leading to more restricted access compared to other locations. Finally, the obtained results validate the use of CoastSnap for monitoring the number of users on beaches, demonstrating this tool's potential in management of coastal environments.