Eutrophication monitoring of lakes in Wuhan based on Sentinel-2 data

Analysis of water quality and trophic status of reservoirs in Chuzhou City, China

“…However, in 2020 and 2021, when China was experiencing the severity of COVID‐19, those areas ceased operations and population activity decreased dramatically, resulting in a downward trend in the nutrient indicators (TN and TP) in water bodies. Among the reservoirs, the TLI (TN) of Shahe Reservoir was abnormal in 2021, mainly because of the better management of the epidemic in the area around the reservoir and the return of population activities to the pre‐epidemic period (Liu et al, 2021); thus, the eutrophication of the reservoir was again aggravated.…”

“…From the CA results, it can be seen that there is a cluster corresponding to the winter low‐flow period in all three reservoirs (Figure S3), and the TLI ( j ) of the five parameters is higher during this period than the time corresponding to the other two clusters, which strongly suggests that low precipitation is an important reason for the high probability of eutrophication in the reservoirs. That's because low precipitation during this period can lead to slow flow and poor exchange in the reservoir, which is extremely likely to contribute to algal growth and thus increase the nutrient status of the water body (Liu et al, 2021).…”

“…This study used the TLI method for water quality eutrophication evaluation. It is widely used, and the evaluation results have high accuracy; most of the reservoirs in China have chosen this method to evaluate the nutrient status of water quality (Liu et al, 2021). According to the Technical Provisions on Eutrophication Evaluation Methods and Grading of Reservoirs developed by the China Environmental Monitoring General Station, taking Chl-a as the benchmark parameter; selecting TP, TN, SD, COD Mn and other parameters with significant correlation with Chl-a to be evaluation factors; and carrying out weighting analysis to get the water quality evaluation results.…”

“…The three reservoirs had higher TLI in water bodies. Among the reservoirs, the TLI (TN) of Shahe Reservoir was abnormal in 2021, mainly because of the better management of the epidemic in the area around the reservoir and the return of population activities to the pre-epidemic period (Liu et al, 2021); thus, the eutrophication of the reservoir was again aggravated.…”

“…Given the limitations of multivariate statistical analysis techniques for water quality assessment when used alone (Chen & Lu, 2014; Güler et al, 2002), in this study, multiple statistical analysis techniques were jointly applied to minimize their limitations and preserve their respective strengths (Chen et al, 2016; Zhou et al, 2007). At the same time, selected a higher scientific basis of the TLI method to analyse and evaluate the trophic state of three reservoirs in Chuzhou City (Liu et al, 2021). The aim of this study is (1) to research the drivers of water quality parameter changes over time in three reservoirs between 2019 and 2021; (2) to evaluate the trophic levels and causes of occurrence in reservoirs using the TLI method; and (3) to analyse the differences in nutrient levels in the water bodies of the three reservoirs.…”