Uncovering the influence of hydrological and climate variables in chlorophyll-A concentration in tropical reservoirs with machine learning

Carvalho, Taís Maria Nunes; Neto, Iran Eduardo Lima; Filho, Francisco de Assis de Souza

doi:10.1007/s11356-022-21168-z

Cited by 12 publications

(3 citation statements)

References 64 publications

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“…However, in the present study we found a significant moderate negative correlation between Chla and TP (r = -0.37; p<0.05). This is possibly because the drivers of Chla can vary according with the temporal resolution (Nunes Carvalho et al, 2022;Zhang et al, 2018). Since the present study evaluated the diel variation of nutrients, the consumption of nutrients by the phytoplankton community was possibly the process that predominated in the data.…”

Section: Phytoplankton Communitymentioning

confidence: 94%

Diel and seasonal mixing patterns and water quality dynamics in a multipurpose tropical semiarid reservoir

Rocha,

Barros,

Filho

et al. 2023

Preprint

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Eutrophication has become a recurrent concern in reservoirs worldwide. This problem is intensified in tropical semiarid regions, where the reservoirs have high seasonal and annual variability of water level and volume. Therefore, an extensive understanding of the diel variation of water quality key-parameters can help improve management of such reservoirs. This study focuses on Castanhão reservoir, the largest multipurpose dam in the Brazilian semiarid. Its main water uses are irrigation, fish farming, and human supply. The reservoir faced a decline in water quality due to a prolonged drought period. While previous research has predominantly emphasized the seasonal dynamics of thermal and chemical stratification, our investigation provides diel assessments of multiple water quality parameters, including nutrient concentrations and phytoplankton abundance. Our primary objective is to compare seasonal and diel variations in stratification and nutrient distribution within the reservoir. Key findings reveal a diel cycle of thermal stratification, primarily during dry season, driven by higher wind speeds. This is corroborated by a significant negative correlation between wind speed and the relative water column stability index. In contrast, during the rainy season, the reservoir experiences continuous thermal stratification due to inflowing water being warmer than the reservoir’s water temperature. Notably, a significant negative correlation between total phosphorus and chlorophyll-a, along with a two-fold increase of this nutrient throughout the day during the rainy season, underscores the influence of the phytoplankton community dynamics on the diel nutrient variation. Chemical stratification of dissolved oxygen occurred during dry and rainy seasons, indicating that even during the dry season, where there is no significant inflow, the internal nutrient loading can also significantly impact the water quality of a reservoir. This study advances the understanding of diel water quality dynamics in tropical semiarid reservoirs, shedding light on both climatic and anthropogenic influences on water resources.

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Section: Phytoplankton Communitymentioning

confidence: 94%

Diel and seasonal mixing patterns and water quality dynamics in a multipurpose tropical semiarid reservoir

Rocha,

Barros,

Filho

et al. 2023

Preprint

Self Cite

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“…The frequency of harmful algal blooms is increasing globally, mainly caused by the accelerated growth of large urban centers, posing severe risks not only to water quality but also to human health and economic development (Jargal et al, 2021;T Li et al, 2021). Reservoirs affected by the misuse of water and watershed inadequate occupation are more prone to eutrophication and algae proliferation, especially in regions with high climate variability and with frequent occurrence of extreme events such as droughts and oods, as is the case of Brazilian Northeast (Pontes Filho et al, 2020;Wiegand et al, 2021;Carvalho et al, 2022).…”

Section: Introductionmentioning

confidence: 99%

“…However, precipitation's in uence on concentration peaks is di cult to generalize. In addition to depending on the intensity and frequency of rainfall events(Ho and Michalak, 2020), it also depends on the initial conditions of the reservoir(Carvalho et al, 2022), the behavior between nutrient concentration and in ow(Rocha and Lima Neto, 2021a; Lima Neto et al, 2022) and other meteorological variables (wind speed, daily temperatures, evaporation rates, among others) (Woolway and Merchant, 2019; Woolway et al, 2020).…”

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confidence: 99%

Chlorophyll-a prediction in tropical reservoirs as a function of hydroclimatic variability and water quality

Guimarães

Neto

2023

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The study goal was to determine spatio-temporal variations in chlorophyll-a (Chl-a) concentration using models that combine hydroclimatic and nutrient variables in 150 tropical reservoirs in Brazil. The investigation of seasonal variability indicated that Chl-a varied in response to changes in total nitrogen (TN), total phosphorus (TP), volume (V), and daily precipitation (P). Simple linear regression models showed that nutrients yielded better predictability of Chl-a than hydroclimatic variables. Fitted relationships between Chl-a and the above-mentioned parameters resulted in equations capable of representing algal temporal dynamics and blooms, with an average coefficient of determination of R² = 0.70. Chl-a blooms presented seasonal and interannual variability, being more frequent in periods of high precipitation and low volume. The equations demonstrate different Chl-a responses to the parameters. In general, Chl-a was positively related to TN and/or TP. However, in some cases (22%), high nutrient concentrations reduced Chl-a, which was attributed to limited phytoplankton growth driven by light deficiency due to increased turbidity. In 49% of the models, precipitation intensified Chl-a levels, which was related to increases in the nutrient concentration from external sources in rural watersheds. Contrastingly, 51% of the reservoirs faced a decrease in Chl-a with precipitation, which can be explained by the opposite effect of dilution of nutrient concentration at the reservoir inlet in urban watersheds. In terms of volume, in 67% of the reservoirs, water level reduction promoted an increase in Chl-a as a response of higher nutrient concentration. In the other cases, Chl-a decreased with lower water levels due to wind-induced destratification of the water column, which potentially decreased the internal nutrient release from bottom sediment. Finally, an application of the model to the two largest studied reservoirs showed greater sensitivity of Chl-a to changes in water use classes regarding variations in TN, followed by TP, V, and P.

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Prediction of total phosphorus in reservoir cascade systems

Goes,

Barros,

Neto

2023

Environ Monit Assess

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Uncovering the influence of hydrological and climate variables in chlorophyll-A concentration in tropical reservoirs with machine learning

Cited by 12 publications

References 64 publications

Diel and seasonal mixing patterns and water quality dynamics in a multipurpose tropical semiarid reservoir

Diel and seasonal mixing patterns and water quality dynamics in a multipurpose tropical semiarid reservoir

Chlorophyll-a prediction in tropical reservoirs as a function of hydroclimatic variability and water quality

Prediction of total phosphorus in reservoir cascade systems

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