A satellite-based investigation into the algae bloom variability in large water supply urban reservoirs during COVID-19 lockdown

Autor(es)

Alcantara, Enner ^[1] ; Coimbra, Keyla ^[2] ; Ogashawara, Igor ^[3] ; Rodrigues, Thanan ^[4] ; Mantovani, Jose ^[1] ; Rotta, Luiz Henrique ^[5] ; Park, Edward ^[6] ; Cunha, Davi Gasparini Fernandes ^[7]

Afiliação do(s) autor(es)

^[1] Sao Paulo State Univ, Inst Sci & Technol, Sao Jose Dos Campos, SP - Brazil

^[2] Univ Estadual Campinas, Inst Geosci, Campinas, SP - Brazil

^[3] Leibniz Inst Freshwater Ecol & Inland Fisheries, D-16775 Neuglobsow - Germany

^[4] Fed Inst Educ Sci & Technol Para State, Castanhal, PA - Brazil

^[5] Sao Paulo State Univ, Fac Sci & Technol, Presidente Prudente, SP - Brazil

^[6] Nanyang Technol Univ, Natl Inst Educ, Singapore - Singapore

^[7] Univ Sao Paulo, Sao Carlos Sch Engn, Sao Carlos, SP - Brazil

• Tipo de documento: Artigo Científico
• Fonte: REMOTE SENSING APPLICATIONS-SOCIETY AND ENVIRONMENT; v. 23, AUG 2021.
• Citações Web of Science: 0

Resumo

Here we report the first case study of the significant algae blooming in large reservoirs in relation to the COVID-19 lockdown in Sao Paulo, Brazil. Chlorophyll-a (Chl-a) and phycocyanin (PC) concentrations were estimated for the Guarapiranga and Billings reservoirs, which supply daily water use for over 20 million people and receives treated wastewater. We employed field-calibrated Sentinel 2 MSI and Landsat 8 OLI images to map the spatial patterns of Chl-a and PC over the two periods: before the lockdown (April, August and October 2019) and after the lockdown in Sao Paulo (April 2020). We found a significant increase in algae pigments (Chl-a and PC) in both reservoirs in April 2020, compared to the same month of 2019. We show that the episodic algae blooming is strongly related to the increased inflows of the residential wastewater from the surrounding watersheds, because the household water use has increased similar to 3.2% in April 2020, while the runoff into the reservoirs driven by the rainfall was much lower in 2020 compared to the previous year for the same month. In the case of Guarapiranga Reservoir, PC increased nearly 500% in April 2020 compared to April 2019. Given the importance of Billings and Guarapiranga reservoirs for the water supply of the Metropolitan Region of Sao Paulo (MRSP), the abrupt occurrence of cyanobacteria blooms related to the state's lockdown should be considered a major concern for public and environmental health of the region. Although several environmental consequences have been reported due to the COVID-19 worldwide, this study is the first to report the impact of COVID-19 on the trophic state in the tropical reservoirs. (AU)

• Processo FAPESP: 19/00259-0 - Desenvolvimento de algoritmos para estimativa de parâmetros de qualidade de água via espaço
• Beneficiário: Enner Herenio de Alcântara
• Modalidade de apoio: Auxílio à Pesquisa - Regular