CHLOROPHYLL-A MONITORING IN RESERVOIRS OF SÃO PAULO METROPOLITAN REGION: APPLICATION OF MODELS WITH SENTINEL-2 IMAGES

Abstract

Global water scarcity is exacerbated by urbanization in Brazil, especially in the Metropolitan Region of Sao Paulo (MRSP), where eutrophication demands continuous monitoring. Remote Sensing allows for detailed monitoring of Chlorophyll-A in extensive reservoirs. In this study, Sentinel-2 images estimated Chlorophyll-A in three MRSP reservoirs: Billings, Guarapiranga, and Rio Grande. Several models were tested to identify the most suitable one. The exponential model of Dall'Olmo et al. (2003) showed the best fit to Chlorophyll-A data (R2 = 0.92), followed by the model of Gitelson et al. (2003) (R2 = 0.90). The single band model (705 nm) obtained R2 = 0.71. The results reinforce the potential of Remote Sensing in monitoring water quality in reservoirs with precision and consistency. However, it is essential to highlight that Chlorophyll-A estimates from different models exhibit wide variability. Therefore, a preliminary evaluation is necessary to identify the most suitable model for the reservoirs where they will be employed.