Identificação de áreas salinas em zonas húmidas com recurso a índices espetrais e dados geoquímicos. O caso do Baixo Vouga Lagunar (Aveiro, Portugal)

ABSTRACT: The Baixo Vouga Lagoon (BVL) is an important wetland on the Portuguese coastal continent that has been suffering from the destruction of its agricultural fields due to saline intrusion processes. The aim of the research was to identify areas of salinity combining geochemical data and spectral indices obtained from Sentinel 2B satellite images. The methodology was developed using images from July 2023 and February 2024, with samples taken during the same seasonal period. Fourteen spectral indices were calculated: four vegetation indices and ten salinity indices. Pearson's method was used to assess the correlation between geochemical data and the spectral indices. The Canopy Response Salinity Index (CRSI) and Salinity Index 1 (SI 1) showed the highest correlation, at 0.428 and 0.516 respectively. Despite the limitations of using optical sensor in flooded areas, the spectral response of halophyte vegetation in areas of higher salinity was crucial for its differentiation and primary delimitation of the most affected areas.