Parameterization of bio-optical models for estimating chlorophyll-a concentration in a tropical eutrophic reservoir

• Autor(a) principal: Watanabe, Fernanda Sayuri Yoshino [UNESP]
• Data de Publicação: 2016
• Tipo de documento: Tese
• Idioma: eng
• Título da fonte: Repositório Institucional da UNESP
• Texto Completo: http://hdl.handle.net/11449/138176
• topic: Quasi-analytical algorithms; Bio-optical status; Remote sensing; Inland waters; Phytoplankton; Algoritmos quase-analíticos; Caracterização bio-óptica; Sensoriamento remoto; Águas continentais; Fitoplâncton

The aim of this research was to parameterize and calibrate models based on remote sensing data in order to estimate accurately the chlorophyll-a concentration, [Chl-a], in a tropical eutrophic reservoir. Firstly, a bio-optical characterization was conducted to identify particularities in the study area. Thus, existing empirical models and quasi-analytical algorithms (QAA) were tested and, after, parameterized and calibrated for the investigated environment. Such models derive [Chl-a] and inherent optical properties (IOPs), respectively, from remote sensing reflectance (Rrs). This research was developed in the Barra Bonita hydroelectric reservoir (BBHR), lies in Tietê River (Brazil). Reservoirs are artificial environments which change severely the hydrodynamic of rivers and the biogeochemical balance of aquatic systems. Such alterations can lead to unique bio-optical status and, consequently, models developed for rivers and lakes are not suitable to explain the processes which happen in reservoirs. The trophic state is an important water quality parameter and can be determined based on Chl-a concentration, photosynthetically active pigment present in all the phytoplankton species and detected by remote sensors. Therefore, the use of orbital and aerial images is a viable alternative to monitoring of trophic state in these environments. Results showed that bio-optical status in BBHR is remarkable different compared to other aquatic systems found in literature, corroborated by inaccurate performance of models proposed to other areas. The parameterization and calibration proposed in this research estimated accurately Chl-a concentration, mainly, adopting absorption coefficients derived by QAA. The fitted models can be used in mapping trophic state and frequent monitoring of water quality in BBHR by environmental agency and hydroelectric plant managers. In addition, it is likely that the parameters proposed in this research are suitable for other inland waters.