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Titre : Parametrização de algoritmos semi‐analíticos para estimativa do coeficiente de atenuação difusa da água (Kd) do reservatório de Três Marias/MG por sensoriamento remoto

Auteur : Curtarelli Victor Pedroso

Université de soutenance : Instituto Nacional de Pesquisas Espaciais – INPE

Grade : Mestrado do Curso de Pós-Graduação em Sensoriamento Remoto 2020

Résumé
Water reservoirs are important manmade aquatic environment that ceases the river flux, flooding the watershed upstream, retaining most of the sediments carried by superficial runoffs. One way to assess the impact of anthropization in the drainage basin over water resources is to measure the diffuse attenuation of downwelling irradiance coefficient Kd on the water column, once sediments, wastewaters and solid waste inputs changes the concentrations of the so-called optically active constituents (COAs), modifying the optical properties of water. The radiometric measurements to calculate Kd can be acquired in-situ over high cost, becoming an undesirable method for water monitoring. However, alternatively one can estimate Kd using remote sensing reflectance satellite measurements and a parametrized semi analytical algorithm. As results, this study presents a bio optical characterization for Três Marias reservoir for drought periods in 2013 and 2019, assisting the implementation of Kd algorithm. The results shows that the light penetration on the water column is higher for green ( 560 nm) wavelengths, and lower for blue ( 443 nm) and red ( 665 nm) wavelengths, where the downwelling irradiance Ed of subsurface was average reduced to 1% in 8, 14 and 10 m for 443, 560 and 665 nm respectively. The proposed algorithm follows two steps : i) algorithm parametrization and application to estimate the backscattering (Bb) and absorption (a) coefficients ; and, ii) bb and a data application as input for a parametrized Kd algorithm using field data and then applied over MSI image.

Mots Clés  : Water reservoir. Inherent optical properties. Apparent optical properties. Remote sensing of water transparency. Quasi Analytical Algorithm.

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