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Article

Experimental Study on the Effects of a Vertical Jet Impinging on Soft Bottom Sediments

1
Ocean College, Zhejiang University, Zhoushan 316000, China
2
Ocean Research Center of Zhoushan, Zhejiang University, Zhoushan 316000, China
3
The State Key Lab of Fluid Power and Mechatronic System, Zhejiang University, Hangzhou 310027, China
4
Ocean Academy, Zhejiang University, Zhoushan 316000, China
*
Author to whom correspondence should be addressed.
Sustainability 2020, 12(9), 3775; https://doi.org/10.3390/su12093775
Received: 25 February 2020 / Revised: 18 April 2020 / Accepted: 22 April 2020 / Published: 6 May 2020
(This article belongs to the Section Sustainable Engineering and Science)
Artificial downwelling, which is an ecological engineering method, potentially alleviates bottom hypoxia by bringing oxygen-rich surface water down below the pycnocline. However, the downward flow is likely to disturb sediments (or induce sediment resuspension) when reaching the bottom and then have unwanted side effects on the local ecosystem. To evaluate this, our paper presents a theoretical model and experimental data for the sediment resuspension caused by artificial downwelling. The theoretical model considers the critical conditions for sediment resuspension and the scour volume with the downwelling flow disturbing sediment. Experiments with altered downwelling flow speeds, discharge positions relative to the bottom, and particle sizes of sediment were conducted in a water tank, and the results were consistent with our theoretical model. The results show that the critical Froude number (hereinafter Fr) for sediment resuspension is 0.5. The prevention of sediment resuspension requires the downwelling flow speed and the discharge position to be adjusted so that Fr < 0.5; otherwise a portion of sediment is released into the water and its volume can be predicted by the derived formulation based on the Shields theory. Furthermore, sediment resuspension has side effects, such as a water turbidity increase and phosphorus release, the magnitudes of which are discussed with respect to engineering parameters. Further study will focus on field experiments of artificial downwelling and its environmental impacts. View Full-Text
Keywords: sediment resuspension; artificial downwelling; experiments; turbidity; phosphorus release sediment resuspension; artificial downwelling; experiments; turbidity; phosphorus release
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MDPI and ACS Style

Fan, W.; Bao, W.; Cai, Y.; Xiao, C.; Zhang, Z.; Pan, Y.; Chen, Y.; Liu, S. Experimental Study on the Effects of a Vertical Jet Impinging on Soft Bottom Sediments. Sustainability 2020, 12, 3775. https://doi.org/10.3390/su12093775

AMA Style

Fan W, Bao W, Cai Y, Xiao C, Zhang Z, Pan Y, Chen Y, Liu S. Experimental Study on the Effects of a Vertical Jet Impinging on Soft Bottom Sediments. Sustainability. 2020; 12(9):3775. https://doi.org/10.3390/su12093775

Chicago/Turabian Style

Fan, Wei, Weicheng Bao, Yong Cai, Canbo Xiao, Zhujun Zhang, Yiwen Pan, Ying Chen, and Shuo Liu. 2020. "Experimental Study on the Effects of a Vertical Jet Impinging on Soft Bottom Sediments" Sustainability 12, no. 9: 3775. https://doi.org/10.3390/su12093775

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