Title: Determining the most suitable Sentinel-2 indices for turbidity and chlorophyll-a concentration for an oligotrophic to mesotrophic reservoir in Brazil

Authors: Fernanda Mara Coelho Pizani; Camila Costa de Amorim; Philippe Maillard

Addresses: Department of Geography, Universidade Federal de Minas Gerais, 6627 Av. Antônio Carlos, Belo Horizonte, 31270-901, Brazil ' Department of Environmental Engineering, Universidade Federal de Minas Gerais, 6627 Av. Antônio Carlos, Belo Horizonte, 31270-901, Brazil ' Department of Geography, Universidade Federal de Minas Gerais, 6627 Av. Antônio Carlos, Belo Horizonte, 31270-901, Brazil

Abstract: Water quality is a major issue for agencies responsible for the management and maintenance of reservoirs. In this article, Sentinel-2 (S-2) data is tested to produce reliable estimates of turbidity and chlorophyll-a concentrations in an oligotrophic to mesotrophic reservoir in Brazil. The spectral bands were all tested individually and jointly to determine the best and most stable features. Many indices are also tested. In situ data was acquired over a period of three years with synchronous S-2 data. The models were evaluated on their robustness and stability using a bundle of in situ dataset (all field campaigns). The results show that no model can be directly applied to other reservoirs or different dates without calibration. Conversely, calibrating the S-2 indices with two in situ measurements greatly reduces the errors. Average root mean square errors of 0.518 FNU and 1.1 μg/l were obtained for turbidity and chlorophyll-a concentrations respectively.

Keywords: chlorophyll-a; turbidity; empirical models; Sentinel-2; reservoir.

DOI: 10.1504/IJHST.2024.140850

International Journal of Hydrology Science and Technology, 2024 Vol.18 No.3, pp.237 - 266

Received: 22 Dec 2022
Accepted: 24 Apr 2023
Published online: 03 Sep 2024 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article