Single-variable method for predicting trends in chlorophyll a concentration based on the similarity of time series

Ding, Han; Li, Zeli; Ren, Qiuru; Chen, Haitao; Song, Menglai; Wang, Yuqiu

doi:10.1016/j.ecolind.2022.109027

Cited by 3 publications

(2 citation statements)

References 32 publications

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“…It is the first large-scale inter-watershed water transfer project in China, with a normal storage area of 86.8 km 2 . The total area of the reservoir watershed is 2060 km 2 , of which 424 km 2 is in Tianjin [ 43 ]. The altitude of the watershed is high in the northeast and low in the southwest.…”

Section: Methodsmentioning

confidence: 99%

The Effect of Rainfall on Aquatic Nitrogen and Phosphorus in a Semi-Humid Area Catchment, Northern China

Shou

Tian

Zeng

et al. 2022

IJERPH

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The impact of rainfall on water quality may be more important in semi-arid regions, where rainfall is concentrated over a couple of months. To explore the impact of rainfall changes on water quality, e.g., nitrogen (TN) and phosphorous (TP), the diversion from Luan River to Tianjin Watershed in the northern semi-humid area was selected as the study area. TN and TP concentrations in rivers and the Yuqiao Reservoir during the three-year high-flow season (2019–2021) were analyzed. The response relationship and influencing factors among the watershed’s biogeochemical process, rainfall, and water quality were clarified. The results showed that rainfall in the high flow season mainly controlled the river flow. The concentration of TN and TP in the inflow rivers is regulated by rainfall/flow, while the concentration of TN and TP in the water diversion river has different variation characteristics in the water diversion period and other periods. The lowest annual concentrations of TN and TP were observed in the normal year, while the highest annual concentration was observed in the wet year, indicating that the hydrological process drove the nutrient transport in the watershed. For the tributaries, the Li River catchment contributed a large amount of N and P to the aquatic environment. For the reservoir, the extreme TN concentrations were the same as the tributaries, while the extremes of TP concentrations decreased from the dry year to wet year, which was in contrast to the tributaries. The spatial variation of TN and TP concentrations in the reservoir showed that the concentration decreased following the flow direction from the river estuary to the reservoir outlet. Considering climate change, with the increase of rainfall in North China in the future, the TN and TP transport fluxes in the watershed may continue to increase, leading to the nitrogen and phosphorus load of the downstream reservoir. To ensure the impact of the increase of potential N and P output fluxes in the watershed on the water quality of the reservoir area, it is necessary to strengthen the effective prevention and control of non-point source pollution in the watershed.

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Section: Methodsmentioning

confidence: 99%

The Effect of Rainfall on Aquatic Nitrogen and Phosphorus in a Semi-Humid Area Catchment, Northern China

Shou

Tian

Zeng

et al. 2022

IJERPH

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“…По этой причине исследователей интересует компонента долгосрочного тренда, т.е. характеристики изменения исследуемой величины в течение длительного периода времени [5][6][7][8]. Также встречается способ выделения тренда в функциональном виде, что является анализом процесса на более глубоком уровне, где используется та же терминология.…”

Section: Introductionunclassified

Analysis of approaches to identification of trend in the structure of the time series

Mokhnatkina,

Parfenov,

Petrusevich

2024

Rossijskij tehnologičeskij žurnal

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Objectives. The study set out to compare the forecasting quality of time series models that describe the trend in different ways and to form a conclusion about the applicability of each approach in describing the trend depending on the properties of the time series.Methods. A trend can be thought of as the tendency of a given quantity to increase or decrease over the long term. There is also an approach in which a trend is viewed as some function, reflecting patterns in the behavior of the time series. In this case, we discuss the patterns that characterize the behavior of the series for the entire period under consideration, rather than short-term features. The experimental part involves STL decomposition, construction of ARIMA models (one of the stages of preparation for which includes differentiation, i.e., removal of the trend and transition to a weakly stationary series), construction of ACD models (average conditional displacement) and other approaches. Time-series models based on various trend models are compared with respect to the value of the maximum likelihood function. Many of the combinations have not been constructed before (Fourier series as a trend model, combination of ACD model for trend with seasonal models). Example forecasts of macroeconomic statistics of the Russian Federation and stock prices of Sberbank on the Moscow Exchange in the time range of 2000–2021 are presented.Results. In the experiments, The LOESS method obtained the best results. A combination of polynomial model for trend description and ARIMA for seasonally description and combination of ACD algorithm for trend and ETS for seasonal model obtained good forecasts in case of seasonal time series, while Fourier time series as a trend model also achieved close quality of prediction.Conclusions. Since the LOESS method for groups of seasonal and non-seasonal series gives the best results for all indicators, this method can be recommended for obtaining the most accurate results for series of different nature. Trend modeling using Fourier series decomposition leads to quite accurate results for time series of different natures. For seasonal series, one of the best results is given by the combination of modeling a trend on the basis of a polynomial and seasonality in the form of the ARIMA model.

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Rain Pattern Deeply Reshaped Total Phosphorus Load Pattern in Watershed: A Case Study from Northern China

Ding

Ren

Wang

et al. 2023

Water

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Excessive phosphorus in aquatic systems poses a threat to ecosystem stability and human health. Precipitation has a profound influence on the phosphorus biogeochemical process; however, it has been inadequately considered at the watershed scale. In this study, the Bayesian latent variable regression model was utilized to quantify the impact of rainfall on the concentration of total phosphorus using daily monitoring data from 2019 to 2021. The results revealed a piecewise linear relationship between total phosphorus concentration and precipitation. It was further inferred that the breakpoint (The total rainfall during a single rainfall event equal to 39.4 ± 0.45 mm) represented the tipping point for the transformation of the primary river runoff generation mechanism. Subsequently, the excess phosphorus load caused by rainfall events was estimated in the Shahe basin by combining the regional nutrient management approach with the results of the Bayesian latent variable regression model. The results indicated that rainfall events were one of the most significant sources of TP loads from 2006 to 2017, accounting for 28.2% of the total. Non-artificial land, including farmland, forests, and grasslands, serves as the primary source of the excess phosphorus load resulting from rainfall events. This study provides insights into how to quantify the phosphorus load resulting from rainfall events at the basin scale, which is valuable for phosphorus management. Environmental managers should prioritize the regulation of phosphorus in non-artificial land moving forward. Implementing hierarchical management based on calibrated curve numbers and soil phosphorus content could prove to be an efficient approach for regulating phosphorus in the watershed.

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Single-variable method for predicting trends in chlorophyll a concentration based on the similarity of time series

Cited by 3 publications

References 32 publications

The Effect of Rainfall on Aquatic Nitrogen and Phosphorus in a Semi-Humid Area Catchment, Northern China

The Effect of Rainfall on Aquatic Nitrogen and Phosphorus in a Semi-Humid Area Catchment, Northern China

Analysis of approaches to identification of trend in the structure of the time series

Rain Pattern Deeply Reshaped Total Phosphorus Load Pattern in Watershed: A Case Study from Northern China

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