CoastSnap Valparaíso Region: An experience of citizen science in Chile

In recent decades, Chile's coastal areas have undergone significant transformations due to extreme events, intensification of tidal waves, and anthropogenic actions that have deepened coastal erosion. Currently, erosion rates in the Valparaíso region are irrefutable, with some beaches reaching -1.5 m/year and others, such as the Algarrobo Bay, up to -4.5 m/year. Given this scenario, beach monitoring poses excellent challenges for quantifying and projecting changes in sandy coastlines. Therefore, rigorous monitoring is required, based on low-cost, high-quality, and accurate data, involving the participation of coastal communities as fundamental axes in data capture. To achieve effective local monitoring, we have joined the Coastal Citizen Science (CoastSnap) program, developed by scientists at the Water Research Laboratory, University of New South Wales (UNSW) Sydney. This program has become a benchmark in coastal monitoring and a novel alternative for quantifying changes in marine-coastal environments. The implementation of the CoastSnap program in Chile has been carried out in the following phases: (i) Selection of the installation sites and taking of angles that will define the direction (yaw) and inclination (pitch) of the cell phone to achieve the expected visual; (ii) request for permits to install the platforms to the municipalities; (iii) design, signaling and, construction of the platforms; (iv) taking of control points (v) installation of the platforms; (vi) inauguration and start-up and (vii) extraction of the coastlines from the open repository GitHub, in the user profile Coastal Imaging Research Network (CIRN): https://github.com/Coastal-Imaging-Research-Network/CoastSnap-Toolbox. Eight CoastSnap platforms have been installed in the Valparaíso region on beaches (Papudo, Maitencillo, Reñaca, Viña del Mar, Caleta Portales, Algarrobo, Punta de Tralca and Santo Domingo). Since the installation of the first platform in August 2022, the community has shared approximately 350 photographs. The results show significant changes in the short term with beach widths averaging -20 m in San Alfonso del Mar beach.