Editorial

3 pages, 146 KiB

Open AccessEditorial

Recent Advances in Marine Environmental Research

by Chih-Chieh Young

Water 2023, 15(3), 462; https://0-doi-org.brum.beds.ac.uk/10.3390/w15030462 - 23 Jan 2023

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The marine environment includes the waters of seas and estuaries, the seabed and its subsoils, and all marine wildlife and its sea and coastal habitats [...] Full article

(This article belongs to the Special Issue Marine Environmental Research)

Research

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31 pages, 12020 KiB

Open AccessArticle

Effects of Environmental Factors on Suspended Sediment Plumes in the Continental Shelf Out of Danshuei River Estuary

by Wen-Cheng Liu, Hong-Ming Liu and Chih-Chieh Young

Water 2022, 14(17), 2755; https://0-doi-org.brum.beds.ac.uk/10.3390/w14172755 - 04 Sep 2022

Cited by 3 | Viewed by 2239

Abstract

The effects of environmental factors on suspended sediment plumes in the continental shelf out of the Danshuei River estuary were numerically investigated using an unstructured-grid three-dimensional hydrodynamic model (SCHISM) together with a suspended sediment (SS) module. The coupled model (SCHISM-SS) was calibrated and [...] Read more.

The effects of environmental factors on suspended sediment plumes in the continental shelf out of the Danshuei River estuary were numerically investigated using an unstructured-grid three-dimensional hydrodynamic model (SCHISM) together with a suspended sediment (SS) module. The coupled model (SCHISM-SS) was calibrated and validated against the in situ measurement data in 2016. Consistent with the observation results, the model simulations satisfactorily reproduced the water levels, velocities, salinities, and suspended sediment concentrations. The model was then applied to explore the role of various environmental factors in the dynamics of suspended sediment plumes from the estuary to the adjacent coastal seas. These factors include tidal forcing, salinity, river discharge, and wind stress. Analysis and comparisons of different scenario results indicated that the suspended sediment plume was greatly affected by tides, e.g., a longer plume distance resulted from a larger flux under tidal motions. A higher sediment concentration in the plume in the offshore area was also found during the neap tide, relative to that observed during the spring tide. In addition, salinity affects the movement of density currents and the spread of the sediment plume, i.e., the plume distance is longer due to the residual circulation when a salinity difference is present. Further, an extreme river flow could occur during typhoon periods and would discharge a greater water volume into the coastal region, causing the suspended sediment plume to expand from the near shore. Finally, the directions of prevailing winds can slightly influence the sediment plumes. Full article

(This article belongs to the Special Issue Marine Environmental Research)

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18 pages, 1040 KiB

Open AccessFeature PaperArticle

Effects of Slide Shape on Impulse Waves Generated by a Subaerial Solid Slide

by Chiung-Shu Huang and I-Chi Chan

Water 2022, 14(17), 2643; https://0-doi-org.brum.beds.ac.uk/10.3390/w14172643 - 27 Aug 2022

Cited by 2 | Viewed by 1276

Abstract

We review several historical landslide tsunami events and perform a set of numerical experiments to investigate the particular effects of slide shape on impulsive waves generated by a subaerial solid slide. The computational model is based on OpenFOAM, which solves 2D RANS formulations [...] Read more.

We review several historical landslide tsunami events and perform a set of numerical experiments to investigate the particular effects of slide shape on impulsive waves generated by a subaerial solid slide. The computational model is based on OpenFOAM, which solves 2D RANS formulations with a volume of fluid method used to capture the air–water interface. We consider triangular prism shaped solid slides in our numerical experiments and introduce a slide shape parameter

σ

to describe the front face steepness of the slide. Observations from the experiments reveal that slide shape can have significant impacts on the characteristics of impulsive waves, such as maximum wave amplitude and its location, impact energy conversion rate, and the amplitude ratio between the first wave crest and the second crest in the leading wave group. In particular, the maximum wave amplitude is inversely proportional to

σ

; the impact energy conversion ratio decays exponentially with

σ

; and the wave period is almost independent of

σ

. Full article

(This article belongs to the Special Issue Marine Environmental Research)

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14 pages, 3787 KiB

Open AccessArticle

Surface Seawater pCO₂ Variation after a Typhoon Passage in the Kuroshio off Eastern Taiwan

by Lan-Feng Fan, Chun Hoe Chow, Gwo-Ching Gong and Wen-Chen Chou

Water 2022, 14(9), 1326; https://0-doi-org.brum.beds.ac.uk/10.3390/w14091326 - 19 Apr 2022

Cited by 4 | Viewed by 1630

Abstract

In this study, two cruises were conducted across the mainstream of the Kuroshio off eastern Taiwan before and after the passage of Typhoon Saola in summer 2012. The continuous underway pCO₂ (i.e., partial pressure of CO₂) measurements revealed that [...] Read more.

In this study, two cruises were conducted across the mainstream of the Kuroshio off eastern Taiwan before and after the passage of Typhoon Saola in summer 2012. The continuous underway pCO₂ (i.e., partial pressure of CO₂) measurements revealed that surface seawater pCO₂ (SS pCO₂) displayed spatial variations in response to typhoon passage. The simulated results showed that the mixed-layer deepening after typhoon passage had a minor effect on SS pCO₂ variation because pCO₂ decrease driven by temperature dropdown and enhanced biological production fueled by nutrients input was largely compensated by pCO₂ increase caused by salinity increase and dissolved inorganic carbon input from the subsurface layer. By contrast, the advection pattern showed significant change before and after the typhoon, which could play a major role in controlling the variation of SS pCO₂. In the exit area of the cyclonic eddy, SS pCO₂ decreased, while in the area of its arrival, SS pCO₂ increased. Besides, the discharge of freshwater and the intrusion of the South China Sea subsurface could result in SS pCO₂ increase in the nearshore area. The present study highlights that more advection changes need to be considered to better understand the impact of the typhoon on SS pCO₂, especially in the strong current area, such as the Kuroshio. Full article

(This article belongs to the Special Issue Marine Environmental Research)

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18 pages, 5075 KiB

Open AccessFeature PaperArticle

Numerical Simulation of the Trajectory of Garbage Falling into the Sea at the Coastal Landfill in Northeast Taiwan

by Yu-Hsuan Lai, Ching-Yuan Lu, Zhe-Wen Zheng, Li-Chun Chiang and Chung-Ru Ho

Water 2022, 14(8), 1251; https://0-doi-org.brum.beds.ac.uk/10.3390/w14081251 - 13 Apr 2022

Cited by 2 | Viewed by 1811

Abstract

This study used a numerical model to simulate the floating trajectory of garbage falling into the sea from the landfill near the coast of Wanghaixiang Bay in northeast Taiwan to understand its impact on the local environment. The Regional Ocean Model System was [...] Read more.

This study used a numerical model to simulate the floating trajectory of garbage falling into the sea from the landfill near the coast of Wanghaixiang Bay in northeast Taiwan to understand its impact on the local environment. The Regional Ocean Model System was used to simulate the probability densities of the distribution of garbage drifting trajectories under scenarios of no-wind, northeast monsoon, and typhoons. The results show that, in the no-wind scenario, garbage was mainly affected by tidal currents. It moved in the northwest–southeast direction outside the bay. In the northeast monsoon scenario, garbage was forced toward the shore due to the windage effect. In typhoon scenarios, strong winds forced the garbage to the shore, as typhoons continued to advance and the wind direction kept changing, the garbage trajectory was also changed. After typhoons moved away, the drifting trajectory of the garbage was again affected by tidal currents. When the garbage falling into the sea was located in the bay or the mouth of the bay, the garbage had a higher probability of being forced into the bay by typhoons. Full article

(This article belongs to the Special Issue Marine Environmental Research)

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16 pages, 6723 KiB

Open AccessArticle

The Wave Climate of the Sea of Azov

by Natalia Yaitskaya

Water 2022, 14(4), 555; https://0-doi-org.brum.beds.ac.uk/10.3390/w14040555 - 12 Feb 2022

Cited by 5 | Viewed by 1802

Abstract

This article describes the results of the retrospective numerical simulation of wind waves in the Sea of Azov using the SWAN spectral wave model and the ERA-Interim global reanalysis for 1979–2019. A digital model of the sea-floor relief of the Sea of Azov [...] Read more.

This article describes the results of the retrospective numerical simulation of wind waves in the Sea of Azov using the SWAN spectral wave model and the ERA-Interim global reanalysis for 1979–2019. A digital model of the sea-floor relief of the Sea of Azov was used for the calculations. This model was built using a bathymetric map of the Sea of Azov, as well as nautical charts and remote sensing data. Verification of the model for the conditions that characterize the Sea of Azov was conducted using data from ship observations of wind waves. The features of the mean long-term wind wave patterns, as well as the seasonal, interannual, and interdecadal dynamics were presented. The main focus was on the following parameters: significant wave height, wave period, and wave direction. A description of storm conditions and a comparison with surge phenomena and ice conditions was also completed. The results indicated that, in contrast to Taganrog Bay, the wave patterns were heavily influenced according to the time of year (i.e., the seasons). The maximum wave heights were typical for the cold season of the year but not for the ice-free period. The interannual dynamics of wind waves were characterized by the alternation of three five-year periods of strengthening and weakening of wind waves. After 2002, the wave height increased in the summer and autumn seasons and slightly decreased in winter and spring. A shift of the storm season to a warmer period was also detected. Full article

(This article belongs to the Special Issue Marine Environmental Research)

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22 pages, 2463 KiB

Open AccessFeature PaperArticle

Scattering of Nonlinear Periodic (Cnoidal) Waves by a Partially Immersed Box-Type Breakwater

by Xing Lu, Chih-Hua Chang, Yu-Hsiang Chen and Keh-Han Wang

Water 2022, 14(3), 318; https://0-doi-org.brum.beds.ac.uk/10.3390/w14030318 - 21 Jan 2022

Cited by 1 | Viewed by 1959

Abstract

This paper presents a combined analytical and numerical (CAN) model to simulate the scattering of cnoidal waves by a fixed and partially immersed box-type breakwater. A set of Boussinesq equations are solved in the outer region using the finite-difference method to model the [...] Read more.

This paper presents a combined analytical and numerical (CAN) model to simulate the scattering of cnoidal waves by a fixed and partially immersed box-type breakwater. A set of Boussinesq equations are solved in the outer region using the finite-difference method to model the propagation of cnoidal waves and their subsequent reflection and transmission after encountering the breakwater. The two-dimensional (2D) velocity potential in the inner region beneath the body is derived analytically by solving the equations formulated from the orthogonality of eigenfunctions and the interfacial matching conditions. Experimental measurements on the wave profiles were carried out in a wave tank to verify the model solutions. Reflected and transmitted wave elevations obtained from the present CAN model match closely with the measured data. Additionally, the calculated horizontal and vertical forces on the body using the developed CAN model are in reasonable agreement with those from a potential 2D flow-based fully nonlinear wave model (FNWM). The method and proposed CAN model, if applied to a simple parametric investigation, can provide the expected trends in terms of applied forces, wave reflection, and transmission. Full article

(This article belongs to the Special Issue Marine Environmental Research)

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19 pages, 2448 KiB

Open AccessArticle

Abiotic Aggregation of Organic Matter in Coastal and Estuarine Waters: Cases in the Eastern Long Island Sound, USA

by Tzong-Yueh Chen and Annelie Skoog

Water 2021, 13(21), 3077; https://0-doi-org.brum.beds.ac.uk/10.3390/w13213077 - 02 Nov 2021

Cited by 4 | Viewed by 1454

Abstract

Organic aggregates, which formed from small particles and dissolved material, were chemically characterized in the Long Island Sound coastal waters. In this study, six aggregation experiments were conducted on low-salinity samples (the Thames River, CT, USA; salinity of 6.3–6.8) and high-salinity samples (the [...] Read more.

Organic aggregates, which formed from small particles and dissolved material, were chemically characterized in the Long Island Sound coastal waters. In this study, six aggregation experiments were conducted on low-salinity samples (the Thames River, CT, USA; salinity of 6.3–6.8) and high-salinity samples (the coast of Avery Point, CT, USA; salinity of 21.4–26.7). Water samples were incubated on a roller table for two days under dark conditions to generate laboratory-made aggregates. Particulate organic carbon (POC) concentrations increased 5–39% after two days of rolling. A higher POC increase occurred in low-salinity samples. The concentrations of neutral aldoses and amino acids, as well as their C- and N-yields, decreased during the experiments (except for particulate hydrolysable amino acid in low-salinity samples), while bacterial abundance increased 50–476%, indicating microbial degradation of biologically labile organic matter. Particulate hydrolysable amino acid was preferentially preserved in P-limited systems. An enrichment factor analysis showed the preferential microbial degradation of particulate hydrolysable neutral aldose and glucose appeared as the most labile aldose. The increase in bulk POC and the decrease in the fraction of labile organic carbon (neutral aldose and amino acid) in the particulate phase resulted in an accumulation of uncharacterized (presumably more refractory) particulate organic matter. Full article

(This article belongs to the Special Issue Marine Environmental Research)

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