Thermal stratification responses of a monomictic reservoir under different seasons and operation schemes

Duka, Maurice A.; Shintani, Tetsuya; Yokoyama, Katsuhide

doi:10.1016/j.scitotenv.2020.144423

Cited by 33 publications

(15 citation statements)

References 29 publications

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“…This study points out three distinct periods of operation, namely, (1) Period A for DPW operation for 1959-1991, (2) Period B for a purely SW operation for 1992-2001, and, lastly, (3) Period C for the combined operation of SW and VC for 2002-2016. More comprehensive details of the study site and the reservoir's operation history can be referred to in the paper of Duka et al [23].…”

Section: Site Backgroundmentioning

confidence: 99%

“…Weekly monitoring records of reservoir temperatures are available from 1959 until 2001, while daily records can be accessed from 2003 until 2016 (Table 1) from the Bureau of Waterworks of the Tokyo Metropolitan Government [23]. Raw temperature values from depths of 0, 10, 20, 30, and 70 m were examined.…”

Section: Reservoir Temperaturesmentioning

confidence: 99%

“…Furthermore, reservoirs are predicted from a conceptual model to have a robust capacity in mediating the effects of climate, especially when some water management practices are implemented [20]. One type of these management filters involves the use of variable withdrawal techniques and the installation of hydraulic facilities that can modify the thermal structure of the reservoir [23]. Nowadays, selective withdrawal (SW) systems can be retrofitted in reservoirs that allow warm water releases from the epilimnion, while vertical curtains (VCs) can be installed in the upstream reaches to control the direct inflow of river water into the main reservoir body.…”

Section: Introductionmentioning

confidence: 99%

“…In terms of the thermal structure of the reservoir, several studies that have employed numerical simulations point out that surface releases through the SW system would increase the thermal stability of the reservoir while bottom releases would induce the warming of the entire water column [27][28][29]. One example of an SW facility is a retrofit to an existing water supply and hydropower dam in the Ogouchi Reservoir in Japan, allowing epilimnetic releases only [23]. The function of this facility is not limited to regulating outflow temperatures; it also releases highly turbid water in the reservoir during times of flood [30].…”

Section: Introductionmentioning

confidence: 99%

“…In this study, the influence of climate on the temperature and thermal structure of a reservoir that has undergone varying operation schemes is investigated. The Ogouchi Reservoir in Japan was chosen as the study site as it had apparently experienced climate warming between 1959 and 2016, and its operation had transitioned through three distinct periods within this duration with the use of deep penstock withdrawal (DPW), purely SW, and a combination of SW and VC [23]. This paper attempts to answer how these different facilities affect the thermal condition of the reservoir and what roles they play as climate warming happens in the reservoir.…”

Section: Introductionmentioning

confidence: 99%

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Mediating the Effects of Climate on the Temperature and Thermal Structure of a Monomictic Reservoir through Use of Hydraulic Facilities

Duka

Shintani

Yokoyama

2021

Water

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Climate warming can alter the thermal conditions of reservoirs. However, some hydraulic interventions can be explored to mitigate this impact. This study investigates the long-term effects of climate on the temperature and thermal structure of a monomictic reservoir that has had varying operations from 1959 to 2016. Reservoir progressively operated through three distinct periods, namely, (A) deep penstock withdrawal (DPW; 1959–1991), (B) purely selective withdrawal (SW; 1992–2001), and (C) combination of SW and vertical curtain (VC; 2002–2016). Although annual air temperatures are increasing (+0.15 °C decade−1) in the long term, the reservoir’s surface water temperatures have been found to be decreasing (−0.06 °C decade−1). Periods B and C produced colder profiles and exhibited lower heat content and higher potential energy anomaly than Period A. Furthermore, stronger thermoclines, as indicated by Brunt–Vaisala frequency, were observed in the two latter periods. The results of this study show that varying operations bear a stronger influence on the reservoir’s temperature and thermal structure than climate change itself. Mitigating the thermal impacts of climate warming in reservoirs appears promising with the use of SW and VC.

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Section: Site Backgroundmentioning

confidence: 99%

Section: Reservoir Temperaturesmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Mediating the Effects of Climate on the Temperature and Thermal Structure of a Monomictic Reservoir through Use of Hydraulic Facilities

Duka

Shintani

Yokoyama

2021

Water

Self Cite

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Mitigating thermal stratification in lakes/reservoirs through wind‐powered air diffusers

Hazar,

Elçi

2024

Water Environment Research

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Thermal stratification can cause various water quality issues in large water bodies. To address this, a new wind‐powered artificial mixing system is designed and experimentally tested for various Savonius rotor combinations (three‐stage and four‐stage rotors). These turbines directly utilize wind energy to draw air into the water column for aeration, bypassing the need for electrical conversion. The rotor performances were tested in terms of power and torque coefficients. Additionally, these rotors were tested for artificial mixing efficiencies in a specially designed water tank that can mimic thermal stratification typically observed in an actual water supply reservoir. Among the rotors, the three‐stage rotor with a 60° phase shift was found to exhibit superior power and torque coefficients, achieving a power efficiency value of 0.14. As for the mixing efficiency, the four‐stage rotor with a 45° phase shift excelled in mixing efficiency, reaching 95%.Practitioner Points A new wind‐powered artificial mixing system is designed and tested for various Savonius rotor combinations. While keeping the total rotor height constant, the three‐stage Savonius rotor class shows superior performance against the four‐stage Savonius rotor class in terms of power and torque efficiency. Apart from the rotor performance results, the four‐stage Savonius rotors show greater artificial mixing efficiency than the three‐stage Savonius rotors. Single‐pump/diffuser artificial destratification system exhibits better mixing efficiency than multiple‐pump/diffuser systems.

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Combined effects of climatic change and hydrological conditions on thermal regimes in a deep channel-type reservoir

Shi

Morovati

Sun

et al. 2023

Environ Monit Assess

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Thermal stratification responses of a monomictic reservoir under different seasons and operation schemes

Cited by 33 publications

References 29 publications

Mediating the Effects of Climate on the Temperature and Thermal Structure of a Monomictic Reservoir through Use of Hydraulic Facilities

Mediating the Effects of Climate on the Temperature and Thermal Structure of a Monomictic Reservoir through Use of Hydraulic Facilities

Mitigating thermal stratification in lakes/reservoirs through wind‐powered air diffusers

Combined effects of climatic change and hydrological conditions on thermal regimes in a deep channel-type reservoir

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