Low-cost coastal monitoring using citizen scientist data:

an overview of the CoastSnap program in Brazil

Resumo

Understanding the dynamics of coastal environments is challenging, as it requires reliable, high-frequency data that reflect environmental reality. In situ data collection demands high financial resources and specialized teams, while remote sensing may be limited by spatial and temporal resolution. Low-cost monitoring with citizen participation has therefore become essential for qualitative management strategies in coastal municipalities. This study provides an overview of the CoastSnap project worldwide, highlighting its implementation and dissemination in Brazil, and presenting two applications distinct from traditional shoreline analysis. The methodology employed images from the CoastSnap NE and RS networks to monitor cliff mass movements at Pacheco Beach and user density at Cal Beach. Cliff monitoring identified and mapped 91 mass movement events between April 2021 and June 2024, mostly during the rainy season, emphasizing the hazards and geomorphological evolution of cliffs, and reinforcing the importance of continuous monitoring that integrates citizen participation. User density analysis showed an area of ​​approximately 10.0 hectares, peak occupancy reached 77.9% and 40.9% at 12 a.m. and 3 p.m., while the lowest occurred at 9 a.m. and 6 p.m., with 4.3% and 31.7%. These case studies demonstrate CoastSnap’s potential to support coastal management at low cost, effectively involving citizens in environmental monitoring.