The use of the normalized relative algoindex for the assessment of algae blooms in the reservoirs of the Vyatka-Kama cis-Urals
Т.I. Kutyavina, V.V. Rutman, Т.Ya. Аshikhmina
Section: Monitoring of natural and anthropogenically disturbed areas
The article presents the results of monitoring of two plain reservoirs located in the Vyatka-Kama Pre-Urals, according to remote sensing data and field observations. The reservoirs are located in the Kirov region, have similar morphological parameters, the same origin, but differ in the level of anthropogenic load. According to the satellite images taken from the Sentinel-2 satellite (A, B) in the period from May to September 2015–2020, the normalized relative algoindex (NDAI) was calculated. This index allows you to detect accumulations of phytoplankton in reservoirs. The NDAI values do not depend on atmospheric interference and the influence of the reflection spectrum of the water itself. The index images are built in the QGIS software product, version 3.20. The results obtained are compared with the data of field observations on reservoirs. The NDAI values in the water area of the Omutninsky reservoir during the observation period varied from 0.36 to 0.80, in the water area of the Chernokholunitsky reservoir from 0.32 to 0.84. Intensive algae bloom in the studied reservoirs was observed in August 2016 and July 2020. In the areas of water areas where intense algae blooming was noted, the following species prevailed in the phytoplankton samples: Anabaena lemmermannii P.G. Richter, A. spiroides Klebahn, A. planctonica Brunnthaler, Aphanizomenon flos-aquae Ralfs ex Bornet & Flahault. The optical density of water in this case was from 0.150 and higher (the length of the optical path of the cuvette is 10 mm, λ = 615 nm), and the NDAI values were more than 0.55.
Keywords: reservoir, eutrophication, phytoplankton, remote sensing of the Earth, spectral indices, monitoring
Article published in number 3 for 2021 DOI: 10.25750/1995-4301-2021-3-060-065
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