%0 Journal Article
%9 ACL : Articles dans des revues avec comité de lecture répertoriées par l'AERES
%A Aranha, T. R. B. T.
%A Martinez, Jean-Michel
%A Souza, E. P.
%A Barros, M. U. G.
%A Martins, E. S. P. R.
%T Remote analysis of the chlorophyll-a concentration using Sentinel-2 MSI images in a semiarid environment in Northeastern Brazil
%D 2022
%L fdi:010084301
%G ENG
%J Water
%K remote sensing ; water quality ; chlorophyll-a ; reservoirs ; semiarid
%K BRESIL ; ZONE SEMIARIDE ; CEARA ETAT
%M ISI:000755253400001
%N 3
%P 451 [22 ]
%R 10.3390/w14030451
%U https://www.documentation.ird.fr/hor/fdi:010084301
%> https://horizon.documentation.ird.fr/exl-doc/pleins_textes/2022-04/010084301.pdf
%V 14
%W Horizon (IRD)
%X In this paper, the authors use remote-sensing images to monitor the water quality of reservoirs located in the semiarid region of Northeast Brazil. Sentinel-2 MSI TOA Level 1C reflectance images were used to remotely estimate the concentration of chlorophyll-a (chl-a), the main indicator of the trophic state of aquatic environments, in five reservoirs in the state of Ceara, Brazil. A three-spectral band retrieval model was calibrated using 171 water samples, collected from November 2015 through July 2018 in 5 reservoirs. For validation, 71 additional samples, collected from August 2018 through December 2019, were used to ensure a robust accuracy assessment. The TOA Level 1C products performed very well, achieving a relative RMSE of 28% and R-2 = 0.80. Data on wind direction and speed, solar radiation and reservoir volume were used to generate a conceptual model to analyze the behavior of chl-a in the surface waters of the Castanhao reservoir. During 2019, the reservoir water quality showed strong variation, with concentration fluctuating from 30 to 95 mu g/L We showed that the end of the dry season is marked by strong eutrophic conditions corresponding to very low water inflows into the reservoir. During the rainy season there is a large decrease in the chl-a concentration following the increase of the lake water storage. During the following dry season, satellite data show a progressive improvement of the trophic state controlled by wind intensity that promotes a better mixing of the reservoir waters and inhibiting the development of most phytoplankton.
%$ 062 ; 126 ; 036