The application of Sentinel-2 satellite imagery to construct a model to estimate the concentration of Chlorophyll-a in surface water in the Hinh River basin, Vietnam

Developing a water quality monitoring model aids in managing water resources and offers a thorough understanding of the water system under investigation. The choice of a water quality monitoring model depends on many factors, including the source of the data and the purpose of the study. In this study, a model for determining the concentration of chlorophyll-a in the dry season over a 6-year period (from 2019 to 2024) was built based on 6 spectral bands of Sentinel-2 satellite images and the results of an analysis of 22 water environment samples according to 4 regression models: Log-Log, Log-Lin, Lin-Log and Lin-Lin. The model results revealed that the chlorophyll-a concentration exhibited the strongest linear correlation in the blue and green spectral bands. As a result, we constructed a map of the chlorophyll-a concentration for the dry season Hinh River basin from 2019 to 2024 using the log-lin model, which has the highest accuracy (R² = 0.86, RMSE = 1.2). According to the log-lin model, the chlorophyll-a concentration reached an average of 3–5 µg/L. During the dry season, the concentration of chlorophyll-a fluctuated primarily in rivers and streams, whereas it remained highly stable in reservoirs. In summary, this study constructed a model for estimating chlorophyll-a concentrations in surface water environments in river basins based on satellite images. The findings of the present study serve as an essential dataset for surface water quality monitoring programs in river basins.