A novel method based on time series satellite data analysis to detect algal blooms

Assessing land use and land cover change in Los Molinos reservoir watershed and the effect on the reservoir water quality

“…Dates that present pixels with clouds over the reservoir were removed using the quality flag information in MOD09GQ. In order to avoid land effects, for each evaluated date an NDVI average value was calculated among pixels located further than 250 m from the shore of the reservoir (Germán et al, 2020).…”

“…NDVI ranges from -1 to +1. Negative values usually indicate pure water pixels and positive values are strongly correlated with the greenness of the water due to the presence of photosynthetic organisms such as algae (Germán et al, 2020). Values equal or greater than 0.1 can be interpreted as algal scums or blooms (Kiage and Douglas, 2020).…”

“…These indices are generally calculated from the combination of visible and infrared bands of remote sensing sensors (Qing et al, 2020). Among several satellites that have been successfully used for evaluating water quality from spectral indices, the MODIS (Moderate Resolution Imaging Spectroradiometer) sensor onboard NASA's Terra/Aqua satellites has proven useful for deriving assessment of inland and coastal waters due to its shorter revisit time and its ability to provide long-term and dense time-series data (Villar et al 2013Germán et al, 2020;Li et al, 2020).…”

“…Advances in remote sensing technology have considerably improved the assessment of a long time-series of LULC change (Huang et al, 2002;Fukushima et al, 2007;Huang et al, 2014;Loveland and Irons, 2016;Gómez et al, 2016;Wei et al, 2020), variations in water quality (Tebbs et al, 2013;Chen et al, 2014;Villa et al, 2014;González-Márquez et al, 2018;Zhou et al, 2018;Bonansea et al, 2019;Elhag et al, 2019;Germán et al, 2020;Kiage and Douglas, 2020;Li et al, 2020, Torregroza-Espinosa, et al 2020) and eutrophication causes (Smith and Schindler, 2009;Mendoza et al, 2015;Padedda et al, 2017;Bhagowati and Ahamad, 2019;Le Moal et al, 2019;Cai et al, 2020). However, to the best of our knowledge, studies that relate LULC change and reservoir water quality are scarce and dispersed, particularly in the Southern hemisphere.…”

Remote Detection of Cyanobacterial Blooms and Chlorophyll-a Analysis in a Eutrophic Reservoir Using Sentinel-2

“…This low value of the Chl-a determination coefficient is due to the fact that this band does not reflect the correct wavelength for this photosynthetic pigment. Despite this, numerous studies [62,63] Chl-a may not be the only photosynthetic pigment that indicates the presence of cyanobacteria in lakes and reservoirs, so in-depth analysis of other pigments that form these cells is needed. This will facilitate the analysis of satellite images and help discern aquatic phytoplankton.…”