scholarly journals Characteristics of Tidal Discharge and Phase Difference at a Tidal Channel Junction Investigated Using the Fluvial Acoustic Tomography System

Water ◽  
2019 ◽  
Vol 11 (4) ◽  
pp. 857 ◽  
Author(s):  
Mochammad Meddy Danial ◽  
Kiyosi Kawanisi ◽  
Mohamad Basel Al Sawaf
Keyword(s):  
Phase Difference ◽  
Neap Tide ◽  
Spring Tide ◽  
Asymmetry Index ◽  
Acoustic Tomography ◽  
Tomography System ◽  
Tide Period ◽  
Flow Division ◽  
Cross Wavelet ◽  
Northern Branch

This study investigates the tidal discharge division and phase difference at branches connected to a channel junction. The tidal discharge at three branches (eastern, western, and northern branches) was continuously collected using the fluvial acoustic tomography system (FATS). The discharge asymmetry index was used to quantify the flow division between two seaward branches (eastern and western branches). The cross-wavelet method was applied to calculate the phase difference between the tidal discharge and water level. The discharge asymmetry index shows that the inequality of flow division is obviously prominent during the spring tide duration, where the eastern branch has the capability to deliver greater amounts of subtidal discharge, approximately 55–63%, compared with the western branch. However, the equality of flow division between the eastern and western channels can be observed clearly during the neap tide period. The wavelet analysis shows that the phase difference at the western branch is higher than at the eastern branch, because the geometry of the western branch is more convergent than that of the eastern branch. Accordingly, the amplitude of the tidal wave at the western branch is more magnified compared with that at the eastern branch. Moreover, the phase difference at the northern branch is greater than at the two seaward branches, implying that the phase difference is slightly increased after passing through the junction into the northern branch.

scholarly journals Tidal variability of nutrients in a coastal coral reef system influenced by groundwater

2018 ◽  
Vol 15 (4) ◽  
pp. 997-1009 ◽  
Author(s):  
Guizhi Wang ◽  
Shuling Wang ◽  
Zhangyong Wang ◽  
Wenping Jing ◽  
Yi Xu ◽  
...  
Keyword(s):  
Coral Reef ◽  
Water Column ◽  
Water Depth ◽  
Neap Tide ◽  
Groundwater Discharge ◽  
Spring Tide ◽  
Biological Processes ◽  
Reef System ◽  
Nitrite Nitrate ◽  
Coral Reef System

Abstract. To investigate variation in nitrite, nitrate, phosphate, and silicate in a spring–neap tide in a coral reef system influenced by groundwater discharge, we carried out a time-series observation of these nutrients and 228Ra, a tracer of groundwater discharge, in the Luhuitou fringing reef at Sanya Bay in the South China Sea. The maximum 228Ra, 45.3 dpm 100 L−1, appeared at low tide and the minimum, 14.0 dpm 100 L−1, appeared during a flood tide in the spring tide. The activity of 228Ra was significantly correlated with water depth and salinity in the spring–neap tide, reflecting the tidal-pumping feature of groundwater discharge. Concentrations of all nutrients exhibited strong diurnal variation, with a maximum in the amplitude of the diel change for nitrite, nitrate, phosphate, and silicate in the spring tide of 0.46, 1.54, 0.12, and 2.68 µM, respectively. Nitrate and phosphate were negatively correlated with water depth during the spring tide but showed no correlation during the neap tide. Nitrite was positively correlated with water depth in the spring and neap tide due to mixing of nitrite-depleted groundwater and nitrite-rich offshore seawater. They were also significantly correlated with salinity (R2  ≥  0.9 and P < 0.05) at the ebb flow of the spring tide, negative for nitrate and phosphate and positive for nitrite, indicating the mixing of nitrite-depleted, nitrate- and phosphate-rich less saline groundwater and nitrite-rich, nitrate- and phosphate-depleted saline offshore seawater. We quantified variation in oxidized nitrogen (NOx) and phosphate contributed by biological processes based on deviations from mixing lines of these nutrients. During both the spring and neap tide biologically contributed NOx and phosphate were significantly correlated with regression slopes of 4.60 (R2  =  0.16) in the spring tide and 13.4 (R2  =  0.75) in the neap tide, similar to the composition of these nutrients in the water column, 5.43 (R2  =  0.27) and 14.2 (R2  =  0.76), respectively. This similarity indicates that the composition of nutrients in the water column of the reef system was closely related with biological processes during both tidal periods, but the biological influence appeared to be less dominant, as inferred from the less significant correlations (R2  =  0.16) during the spring tide when groundwater discharge was more prominent. Thus, the variability of nutrients in the coral reef system was regulated mainly by biological uptake and release in a spring–neap tide and impacted by mixing of tidally driven groundwater and offshore seawater during spring tide.

Optimum design of the ocean acoustic tomography system for the Sea of Japan

1994 ◽  
Vol 50 (3) ◽  
pp. 281-293 ◽  
Author(s):  
Arata Kaneko ◽  
Gang Yuan ◽  
Noriaki Gohda ◽  
Iwao Nakano
Keyword(s):  
Optimum Design ◽  
Sea Of Japan ◽  
Acoustic Tomography ◽  
The Sea Of Japan ◽  
Tomography System ◽  
Ocean Acoustic Tomography

scholarly journals Using flushing rate to investigate spring-neap and spatial variations of gravitational circulation and tidal exchanges in an estuary

2010 ◽  
Vol 14 (8) ◽  
pp. 1465-1476 ◽  
Author(s):  
D. C. Shaha ◽  
Y.-K. Cho ◽  
G.-H. Seo ◽  
C.-S. Kim ◽  
K. T. Jung
Keyword(s):  
Neap Tide ◽  
Spring Tide ◽  
Vertical Mixing ◽  
River Estuary ◽  
Spatial Variations ◽  
Tidal Amplitude ◽  
Gravitational Circulation ◽  
Flushing Rate ◽  
Rapid Exchange ◽  
Dispersive Flux

Abstract. Spring-neap and spatial variations of gravitational circulation and tidal exchanges in the Sumjin River Estuary (SRE) were investigated using the flushing rate. The flushing rate was calculated between multiple estuarine segments and the adjacent bay to examine the spatial variation of two exchanges. The strength of gravitational circulation and tidal exchanges modulated significantly between spring and neap tides, where stratification alternated between well-mixed and highly-stratified conditions over the spring-neap cycle. Tide-driven dispersive flux of salt dominated over gravitational circulation exchange near the mouth during spring tide due to the larger tidal amplitude that caused well-mixed conditions and rapid exchange. In contrast, the central and inner regimes were found to be partially stratified during spring tide due to the reduction in tidal amplitude where both gravitational circulation and tidal exchanges were important in transporting salt. The combined contributions of two fluxes were also found during neap tide along the SRE due to the significant reduction in vertical mixing that accompanied strong stratification. Gravitational circulation exchange almost entirely dominated in transporting salt at the upstream end during spring and neap tides.

scholarly journals Comparison of empirical models with intensively observed data for prediction salt intrusion in the Sumjin River estuary, Korea

2009 ◽  
Vol 6 (2) ◽  
pp. 1879-1905 ◽  
Author(s):  
D. C. Shaha ◽  
Y.-K. Cho
Keyword(s):  
River Discharge ◽  
Neap Tide ◽  
Spring Tide ◽  
River Estuary ◽  
High Water ◽  
Empirical Models ◽  
Length Scale ◽  
Salt Intrusion ◽  
Salinity Data ◽  
Comparative Results

Abstract. Intensive measurements of salt intrusion in the Sumjin River estuary were taken at high and low waters during both spring and neap tides in each season from August 2004 to April 2007. The estuary demonstrated partially- and well-mixed characteristics during the spring tide and stratified condition during the neap tide. The salt intrusion at high water varied from about 13.39 km in summer 2005 to 25.62 km in autumn 2006. The salt intrusion depended primarily on the freshwater discharges rather than those of spring-neap tidal oscillations. Analysis of three years of observed salinity data indicated that the salt intrusion length scale in the Sumjin River estuary was proportional to the river discharge to the −1/5 power. Five empirical models were applied to the Sumjin River estuary to explore the most suitable as an easy-to-use tool for prediction of the salt intrusion length as functions of the geometry, river discharge and tide. Comparative results showed that the Nguyen and Savenije (2006) model developed under both partially- and well-mixed estuaries yielded the most satisfactory results of all the models studied for computing the salt intrusion length in the Sumjin River estuary. Our study suggests that the model can generate reasonable results for stratified conditions also.

Corrections to "coastal acoustic tomography system and its field application"

2002 ◽  
Vol 27 (3) ◽  
pp. 768-768
Author(s):  
H. Yamoaka ◽  
A. Kaneko ◽  
Jae-Hun Park ◽  
Hong Zheng ◽  
N. Gohda ◽  
...  
Keyword(s):  
Field Application ◽  
Acoustic Tomography ◽  
Tomography System

scholarly journals Effects of Water Quality Parameters on Abundance and Biomass of Zooplankton in Merbok Estuary Malaysia

2016 ◽  
Vol 9 (1) ◽  
pp. 117-122 ◽  
Author(s):  
K Fatema ◽  
WMW Omar ◽  
MM Isa ◽  
A Omar
Keyword(s):  
Water Quality ◽  
Light Intensity ◽  
Neap Tide ◽  
Spring Tide ◽  
Quality Parameters ◽  
Zooplankton Biomass ◽  
Water Quality Parameters ◽  
Zooplankton Abundance ◽  
Chl A ◽  
Merbok Estuary

Influence of water quality parameters on zooplankton abundance and biomass in the Merbok estuary Malaysia were investigated. Twenty four hours sampling were conducted at station 1, 3 and 5 from 12th November (spring tide) to 3rd December (neap tide) 2011 on weekly interval. Results showed that water quality parameters varied with the following ranges: conductivity (10.00-315.00?S-1cm), transparency (25.50-154.00 cm), light intensity (53.5-1959.00 lux), TSS (20-70 mg-1L), BOD (0.25-3.46 mg-1L) and chl a (0.1-1.46 ?g-1L). The highest zooplankton abundance was found at Station 5 (176×103) and (230×103) ind-3m and the lowest was at station 1(5.3×103) and (3.4 ×103) ind-3m during spring and neap tide. Zooplankton biomass varied from 0.04 to 0.096 gm-3m. Spearman’s rank correlation analysis results showed that there was a correlation among zooplankton abundance and conductivity, transparency, TSS, BOD, and biomass except chl and light intensity. Mann-Whitney U test result showed that water quality parameters, zooplankton abundance and zooplankton biomass were significantly different between spring and neap tides.J. Environ. Sci. & Natural Resources, 9(1): 117-122 2016

scholarly journals Modelling Study of Transport Time Scales for a Hyper-Tidal Estuary

Water ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 2434
Author(s):  
Guanghai Gao ◽  
Junqiang Xia ◽  
Roger A. Falconer ◽  
Yingying Wang
Keyword(s):  
Numerical Model ◽  
Water Level ◽  
Residence Time ◽  
Exposure Time ◽  
Neap Tide ◽  
Spring Tide ◽  
High Water ◽  
Residence Times ◽  
Severn Estuary ◽  
Release Times

This paper presents a study of two transport timescales (TTS), i.e., the residence time and exposure time, of a hyper-tidal estuary using a widely used numerical model. The numerical model was calibrated against field measured data for various tidal conditions. The model simulated current speeds and directions generally agreed well with the field data. The model was then further developed and applied to study the two transport timescales, namely the exposure time and residence time for the hyper-tidal Severn Estuary. The numerical model predictions showed that the inflow from the River Severn under high flow conditions reduced the residence and exposure times by 1.5 to 3.5% for different tidal ranges and tracer release times. For spring tide conditions, releasing a tracer at high water reduced the residence time and exposure time by 49.0% and 11.9%, respectively, compared to releasing the tracer at low water. For neap tide conditions, releasing at high water reduced the residence time and exposure time by 31.6% and 8.0%, respectively, compared to releasing the tracer at low water level. The return coefficient was found to be vary between 0.75 and 0.88 for the different tidal conditions, which indicates that the returning water effects for different tidal ranges and release times are all relatively high. For all flow and tide conditions, the exposure times were significantly greater than the residence times, which demonstrated that there was a high possibility for water and/or pollutants to re-enter the Severn Estuary after leaving it on an ebb tide. The fractions of water and/or pollutants re-entering the estuary for spring and neap tide conditions were found to be very high, giving 0.75–0.81 for neap tides, and 0.79–0.88 for spring tides. For both the spring and neap tides, the residence and exposure times were lower for high water level release. Spring tide conditions gave significantly lower residence and exposure times. The spatial distribution of exposure and residence times showed that the flow from the River Severn only had a local effect on the upstream part of the estuary, for both the residence and exposure time.

The time-varying characteristics in tidal duration asymmetry

2020 ◽  
Author(s):  
Guo Wenyun ◽  
Song Dehai ◽  
Guo Leicheng ◽  
Ge Jianzhong ◽  
Ding Pingxing ◽  
...  
Keyword(s):  
Neap Tide ◽  
Spring Tide ◽  
Time Variability ◽  
Tidal Asymmetry ◽  
Water Effect ◽  
The Changjiang Estuary ◽  
Tidal Constituents ◽  
Sea Area ◽  
Tide Interaction ◽  
Shallow Water Effect

&lt;p&gt;Tides always behaves different rising and falling durations, which can mostly attribute to the shallow-water effect and interactions among tidal constituents. The duration asymmetry may lead to an inequality in flood/ebb tidal current magnitudes, affecting the net sediment transport. Tidal duration asymmetry has time-dependent characteristics. We deducted a general framework for identifying the time-variability in tidal duration asymmetry. The application to the global tides showed that the fortnightly variability in tidal asymmetry is universal and that duration asymmetry can be stronger during neap tide than during spring tide. Then the framework is applied to the tides in the Changjiang Estuary. Prominent seasonal variation in tidal asymmetry is revealed, mainly relate to the river-tide interaction. Application to the tides in the Yangshan Harbor sea area revealed that the local-scale tidal asymmetry can be changed strongly by a large coastal engineering.&lt;/p&gt;

Daytime surface swarming by Meganyctiphanes norvegica (M. Sars) (Crustacea, Euphausiacea) off Brier Island, Bay of Fundy

1979 ◽  
Vol 57 (12) ◽  
pp. 2285-2291 ◽  
Author(s):  
R. G.B. Brown ◽  
S. P. Barker ◽  
D. E. Gaskin
Keyword(s):  
Spring Tide ◽  
Solar Irradiation ◽  
Food Sources ◽  
Subsurface Water ◽  
Gonad Maturation ◽  
Marine Predators ◽  
Vertical Turbulence ◽  
Meganyctiphanes Norvegica ◽  
Tidal Streams ◽  
Tide Period

In July–September the euphausiid Meganyctiphanes norvegica (M. Sars) swarms at the surface in daytime off Brier Island, Nova Scotia (ca. 44°15′ N 66°23′ W). Systematic observations of swarming were made, mainly in late August 1974, 1975, 1976, and 1978, supplemented in 1974 and 1975 by the frequency of occurrence of the euphatisiids in the proventriculi of collected greater shearwaters, Puffinus gravis (O'Reilly). Swarms, consisting mostly of immature animals, occurred near an area of turbulence where strong tidal streams ran up against steep underwater ledges, bringing cool subsurface water and also copepods to the surface. Swarming was apparently not an attempt to avoid underwater predators or unfavourable oceanographic conditions, nor was it a means of advancing gonad maturation through exposure to solar irradiation. Swarming was most common in spring tide periods when tidal streams were strongest, and did not occur at all during a neap tide period in late August 1975. It is suggested that M. norvegica swarms were transported passively to the surface by strong vertical turbulence. However, the possibility that they swam actively to the surface in search of copepods and other food passively transported in that way could not be ruled out. It is suggested that the surface swarming of Euphausia pacifica Hansen, the other well-documented survey of the phenomenon, by Y. Komaki in 1967, be reexamined in the light of these conclusions. The significance of surface swarms as food sources for a variety of marine predators is discussed.

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