Aplicação das imagens do Sentinel-2 para o monitoramento multi temporal do uso e cobertura da terra e processos costeiros em Marromeu

Abstract

Coastal zones are ecosystems of high ecological and socioeconomic importance, yet they are highly vulnerable to erosion, climate change, and anthropogenic pressures. In Mozambique, these pressures are particularly evident in the Marromeu district, located in the Zambezi River delta and recognized as a Ramsar site of high biodiversity. This study analyzed the multitemporal dynamics of land use and land cover, coastline evolution, and fire severity between 2016 and 2025 using Sentinel-2 imagery. Spectral indices (NDVI, NDWI, MNDWI, and dNBR) and supervised classification (Maximum Likelihood) were applied, complemented by coastline analysis in a GIS environment. The results showed high accuracy 93%, Kappa = 0.90 and revealed significant transformations: reduction of bare soil and sparse vegetation, associated with the expansion of moderate and dense/mangrove vegetation. The dNBR analysis indicated that between 2016 and 2020, fires of low to moderate severity predominated, with localized occurrences of high-severity events. Between 2020 and 2025, a more spatially homogeneous pattern was observed, with prevalence of low-to-moderate severity fires and a reduction of extreme events, although accompanied by lower active vegetation regeneration. Coastline analysis indicated strong spatial variability among the studied sectors, with alternating erosion and accretion. Sector A showed coexistence of deposition and retreat; Sector B revealed instability dominated by erosion; and Sector C displayed continuous erosion with localized deposition. These findings highlight both the natural resilience of the ecosystem and the limitations of ecological succession due to recurrent fires.