Estimativa de clorofila-a utilizando simulação de bandas do Satélite Sentinel 3 em um Sistema Estuarino-Lagunar Tropical

Abstract

One of the main factors affecting the integrity of water bodies is the excessive discharge of organic matter, combined with the natural load from the watershed. These factors contribute to the increase in nutrient concentrations in the system, which can intensify the eutrophication process and increase the frequency of microalgae blooms. The assessment of the trophic state can be performed through continuous monitoring of the concentration of chlorophyll-a, a green pigment present in microalgae. A technique that has been gaining ground as a replacement for traditional monitoring is the use of in situ sensors and satellites to obtain radiometric properties and estimate the concentration of chlorophyll-a in water bodies. In this study, the effectiveness of the NDCI model was evaluated, which uses two satellite bands to estimate the concentration of chlorophyll-a using reflectance data measured in situ and simulating the bands of the Sentinel-3 satellite in the Mundaú-Manguaba Estuarine Lagoon Complex (CELMM). This system has suffered major negative impacts due to the occupation of its surrounding areas. Comparisons were made between the reflectance values measured in situ and those simulated based on the Sentinel-3 bands. Additionally, the chlorophyll-a values obtained in the field were compared with those estimated from the NDCI, using linear and polynomial fits. Both methods presented good results, with coefficients of determination (r2) higher than 0.75. These results indicate that the proposed models are promising for accurate chlorophyll-a estimates, offering significant advantages over other models.