Landscape Dynamics of the Coastal Zone in the South of Santa Catarina State, Brazil: Environmental Reflexes from Anthropogenic Impacts

Predicting responses of ecological systems to anthropogenic modifications has been challenging in landscape management. This study aimed to analyze the socio-environmental dynamics and sustainability of coastal lagoons in the municipality of Balneário Gaivota, south of Santa Catarina state, Brazil. Based on geoprocessing techniques, we analyzed the evolution of post-colonial human occupation, and the spatiotemporal coastal lagoon hydrodynamics in the period 1980–2022, with the aim of predicting water use sustainability for the next three decades. The lagoons suffered a reduction of approximately 31.8% in surface area, from 19.3 km² in 1980 to 13.1 km² in 2021, with a projected reduction to 9.6 km² in 2050. However, the population showed geometric growth during the same period and in future projections. Currently, the total population in the study area is 15,600 inhabitants, and the water consumption is approximately 3,760 m³ day-1. By the year 2050, the estimated population will be 92,305 inhabitants, and the estimated water consumption will be 14,058 m³ day-1. The water balance, carried out with current availability and consumption data, points to the unsustainability of the public supply system, a trend that will worsen in the years 2030, 2040, and 2050, highlighting the need for better water consumption management.