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

2010 ◽  
Vol 7 (2) ◽  
pp. 1621-1654
Author(s):  
D. C. Shaha ◽  
Y.-K. Cho ◽  
G.-H. Seo ◽  
C.-S. Kim ◽  
K.-T. Jung
Keyword(s):  
River Flow ◽  
Spring Tide ◽  
Vertical Mixing ◽  
River Estuary ◽  
Spatial Variations ◽  
Tidal Exchange ◽  
Tidal Amplitude ◽  
Gravitational Circulation ◽  
Flushing Rate ◽  
Rate Method

Abstract. Spring-neap and spatial variations of gravitational circulation and tidal exchanges in the Sumjin River Estuary (SRE) were investigated using the flushing rate method. This method was applied to multiple estuarine segments to estimate both the 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. Strong gravitational circulation developed during neap tide along the SRE due to the significant reduction in vertical mixing that accompanied strong stratification. The tidal exchanges dominated over gravitational circulation 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 which induced gravitational circulation and weakened the tidal exchange. Only the gravitational circulation dominated at the upstream end during spring and neap tides which was governed by the river flow.

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 Dynamics of the Estuarine Turbidity Maximum Zone from Landsat-8 Data: The Case of the Maroni River Estuary, French Guiana

2020 ◽  
Vol 12 (13) ◽  
pp. 2173 ◽  
Author(s):  
Noelia Abascal-Zorrilla ◽  
Vincent Vantrepotte ◽  
Nicolas Huybrechts ◽  
Dat Dinh Ngoc ◽  
Edward J. Anthony ◽  
...  
Keyword(s):  
River Flow ◽  
Temporal Dynamics ◽  
Spring Tide ◽  
River Estuary ◽  
Turbidity Maximum ◽  
Sediment Supply ◽  
Estuarine Turbidity Maximum ◽  
Landsat 8 ◽  
Residual Circulation ◽  
Spatio Temporal

The estuarine turbidity maximum (ETM) zone occurs in river estuaries due to the effects of tidal dynamics, density-driven residual circulation and deposition/erosion of fine sediments. Even though tropical river estuaries contribute proportionally more to the sediment supply of coastal areas, the ETM in them has been hardly studied. In this study, surface suspended particulate matter (SPM) determined from OLI (Operational Land Imager)-Landsat 8images was used to gain a better understanding of the spatio-temporal dynamics of the ETM of the tropical Maroni estuary (located on the Guianas coast, South America). A method to estimate the remotely-sensed ETM location and its spatiotemporal evolution between 2013 and 2019 was developed. Each ETM was defined from an envelope of normalized SPM values > 0.6 calculated from images of the estuary. The results show the influence of the well-marked seasonal river discharge and of tides, especially during the dry season. The ETM is located in the middle estuary during low river-flow conditions, whereas it shifts towards the mouth during high river flow. Neap–spring tidal cycles result in a push of the ETM closer to the mouth under spring-tide conditions or even outside the mouth during the rainy season. An increase in SPM, especially since 2017, coincident with an extension of the ETM, is shown to reflect the periodic influence of mud banks originating from the mouth of the Amazon and migrating along the coast towards the Orinoco (Venezuela). These results demonstrate the advantages of ocean color data in an exploratory study of the spatio-temporal dynamics of the ETM of a tropical estuary, such as that of the Maroni.

scholarly journals Determination of spatially varying Van der Burgh's coefficient from estuarine parameter to describe salt transport in an estuary

2010 ◽  
Vol 7 (6) ◽  
pp. 8781-8808
Author(s):  
D. C. Shaha ◽  
Y.-K. Cho
Keyword(s):  
Spatial Variation ◽  
Salinity Gradient ◽  
Spring Tide ◽  
Vertical Mixing ◽  
River Estuary ◽  
Relative Strength ◽  
Salt Transport ◽  
K Value ◽  
Relative Contribution ◽  
Spatially Varying

Abstract. The estuarine parameter ν is widely accepted as describing the relative contribution of the tide-driven and density-driven mixing mechanism of salt transport in estuaries. Van der Burgh's coefficient K is another parameter that also determines the relative strength of two mechanisms. However, a single value of K, which has been considered in previous studies, can not represent the spatial variation of these mechanisms in an estuary. In this study, the spatially varying K has been determined from the ν value calculated using intensively observed longitudinal salinity transects of the Sumjin River Estuary with exponential shape. The spatially varying K describes the spatial variation of these mechanisms reasonably well and is independent of the river discharge downstream of the estuary during spring tide where the strong tides cause well mixed conditions. However, K values increase upstream and are found to depend on the freshwater discharge, with suppressing vertical mixing. The K value has been scaled on the basis of the ν value and ranges between 0 and 1. If K is <0.4, the up-estuary salt transport is entirely dominated by tide-driven mixing during spring tide near the mouth. If 0.4 < K < 0.8, both tide-driven and density-driven mixing contribute to transporting salt in the central regimes. If K > 0.8, the salt transport is almost entirely by density-driven circulation in the upper most regimes during both spring and neap tides. In addition, another K-based dispersion equation has been solved by using this spatially varying K. The spatially varying K demonstrates density-driven circulation more prominently at the strong salinity gradient location compared with a single K value.

scholarly journals Subtidal Salinity and Velocity in the Hudson River Estuary: Observations and Modeling

2008 ◽  
Vol 38 (4) ◽  
pp. 753-770 ◽  
Author(s):  
David K. Ralston ◽  
W. Rockwell Geyer ◽  
James A. Lerczak
Keyword(s):  
Boundary Layer ◽  
River Discharge ◽  
Vertical Mixing ◽  
River Estuary ◽  
Hudson River ◽  
Hudson River Estuary ◽  
Velocity Variation ◽  
Open Boundary ◽  
Tidal Amplitude ◽  
Residual Velocity

Abstract A tidally and cross-sectionally averaged model based on the temporal evolution of the quasi-steady Hansen and Rattray equations is applied to simulate the salinity distribution and vertical exchange flow along the Hudson River estuary. The model achieves high skill at hindcasting salinity and residual velocity variation during a 110-day period in 2004 covering a wide range of river discharges and tidal forcing. The approach is based on an existing model framework that has been modified to improve model skill relative to observations. The external forcing has been modified to capture meteorological time-scale variability in salinity, stratification, and residual velocity due to sea level fluctuations at the open boundary and along-estuary wind stress. To reflect changes in vertical mixing due to stratification, the vertical mixing coefficients have been modified to use the bottom boundary layer height rather than the water depth as an effective mixing length scale. The boundary layer parameterization depends on the tidal amplitude and the local baroclinic pressure gradient through the longitudinal Richardson number, and improves the model response to spring–neap variability in tidal amplitude during periods of high river discharge. Finally, steady-state model solutions are evaluated for both the Hudson River and northern San Francisco Bay over a range of forcing conditions. Agreement between the model and scaling of equilibrium salinity intrusions lends confidence that the approach is transferable to other estuaries, despite significant differences in bathymetry. Discrepancies between the model results and observations at high river discharge are indicative of limits at which the formulation begins to fail, and where an alternative approach that captures two-layer dynamics would be more appropriate.

Sources of Chlorophenolic Compounds to the Fraser River Estuary

1988 ◽  
Vol 23 (1) ◽  
pp. 55-68 ◽  
Author(s):  
J. H. Carey ◽  
J. H. Hart
Keyword(s):  
River Flow ◽  
River Estuary ◽  
Low Flow ◽  
Fraser River ◽  
Pulp Mills ◽  
Flow Conditions ◽  
Downstream Site ◽  
Upstream Site ◽  
The North ◽  
Main River

Abstract The identity and concentrations of chlorophenolic compounds in the Fraser River estuary were determined under conditions of high and low river flow at three sites: a site upstream from the trifurcation and at downstream sites for each main river arm. Major chlorophenolics present under both flow regimes were 2,4,6-trichlorophenol (2,4,6-TCP), 2,3,4,6-tetrachlorophenol (2,3,4,6-TeCP), pentachlorophenol (PCP), tetrachloroguaiacol (TeCG) and a compound tentatively identified as 3,4,5-trichloroguaiacol (3,4,5-TCG). Under high flow conditions, concentrations of the guaiacols were higher than any of the Chlorophenols and concentrations of all five chlorophenolics appeared to correlate. Under low flow conditions, concentrations of chloroguaiacols were higher than Chlorophenols at the upstream site and at the downstream site on the Main Arm, whereas at the downstream site on the North Arm, concentrations of 2,3,4,6-TeCP and PCP were higher than the chloroguaiacols in some samples. Overall, the results indicate that pulp mills upstream from the estuary are important sources of chlorophenolics to the estuary under all flow conditions. Additional episodic inputs of 2,3,4,6-TeCP and PCP from lumber mills occur along the North Arm. When these inputs occur, they can cause the concentrations of Chlorophenols in the North Arm to exceed provisional objectives. If chloroguaiacols are included as part of the objective, concentrations of total chlorophenolics in water entering the estuary can approach and exceed these objectives, especially under low flow conditions.

scholarly journals The Response of Turbidity Maximum to Peak River Discharge in a Macrotidal Estuary

Water ◽  
2021 ◽  
Vol 13 (1) ◽  
pp. 106
Author(s):  
Yuhan Yan ◽  
Dehai Song ◽  
Xianwen Bao ◽  
Nan Wang
Keyword(s):  
River Discharge ◽  
Recovery Time ◽  
Morphological Evolution ◽  
Spring Tide ◽  
River Estuary ◽  
Sediment Concentration ◽  
Ocean Model ◽  
Turbidity Maximum ◽  
Sediment Supply ◽  
Three Dimensional Model

The Ou River, a medium-sized river in the southeastern China, is examined to study the estuarine turbidity maximum (ETM) response to rapidly varied river discharge, i.e., peak river discharge (PRD). This study analyzes the difference in ETM and sediment transport mechanisms between low-discharge and PRD during neap and spring tides by using the Finite-Volume Community Ocean Model. The three-dimensional model is validated by in-situ measurements from 23 April to 22 May 2007. In the Ou River Estuary (ORE), ETM is generally induced by the convergence between river runoff and density-driven flow. The position of ETM for neap and spring tides is similar, but the suspended sediment concentration during spring tide is stronger than that during neap tide. The sediment source of ETM is mainly derived from the resuspension of the seabed. PRD, compared with low-discharge, can dilute the ETM, but cause more sediment to be resuspended from the seabed. The ETM is more seaward during PRD. After PRD, the larger the peak discharge, the longer the recovery time will be. Moreover, the river sediment supply helps shorten ETM recovery time. Mechanisms for this ETM during a PRD can contribute to studies of morphological evolution and pollutant flushing.

scholarly journals Size and Ambundance of glass eel Anguilla spp in mouth of Poigar River

2019 ◽  
Vol 7 (1) ◽  
pp. 212
Author(s):  
Kristanto R. Lumi ◽  
Victor N. R. Watung ◽  
Nego E. Bataragoa
Keyword(s):  
River Flow ◽  
Average Length ◽  
Sampling Site ◽  
River Estuary ◽  
Average Density ◽  
Fishing Gear ◽  
Sampling Area ◽  
Glass Eel ◽  
Phase Sampling ◽  
New Moon

The  aims of this study are determine the composition of the length and abundance of glass eel Anguilla spp that migrates at the mouth of the Poigar River. Sampling is done every month for four months in the new moon phase. Sampling site on one side of the Poigar River estuary, by making a 10 meter track in the direction of the river flow. The fishing gear used is a triangle-shaped handy scoop net with a length of 100 cm and a width of 75 cm. The catch of Glass eel eel for four months (from April to July 2018) as many as 3,551 individuals. Average length (± SD) in April was 44.4 ± 1.4 cm, May 48.7 ± 1.6 cm, June 51.1 ± 2.0 cm and July 51.1 ± 2.4 cm. The highest number of catches in May was 1,841 individuals, followed by June 785, July 860 individuals and April as many as 55 individuals. The average density of eels in April, Mai, June and July 2018 migrating in the sampling area of 10 x 0.7 meters is 1,160 individuals.Keywords: glass eel, size, abundance, Poigar River.ABSTRAKPenelitian ini bertujuan untuk mengetahui komposisi ukuran panjang dan kelimpahan  ‘‘glass eel’’ sidat Anguilla spp yang bermigrasi di muara Sungai Poigar.  Pengambilan sampel dilakukan setiap bulan selama empat bulan pada  fase  bulan baru. Tempat sampling  pada  satu sisi muara Sungai Poigar, dengan membuat lintasan sepanjang 10 meter searah aliran sungai. Alat tangkap yang digunakan adalah seser (handy scoop net) berbentuk segitiga dengan panjang 100 cm dan lebar 75 cm. Hasil tangkapan Glass eel sidat selama empat bulan (dari bulan April sampai Juli 2018) sebanyak 3.551 individu.  Rata-rata  panjang (± SD) pada bulan April 44,4±1,4 cm, Mei 48,7±1,6 cm, Juni 51,1±2,0 cm dan Juli 51,1±2,4 cm.  Jumlah tangkapan terbanyak pada bulan Mei 1.841 individu, diikuti bulan Juni 785, bulan Juli 860 individu dan bulan April sebanyak 55 individu.  Rata-rata kepadatan sidat pada bulan April, Mai, Juni dan Juli 2018 yang bermigrasi dalam wilayah sampling 10 x 0,7 meter adalah 1.160 individu.Kata kunci: glass eel, ukuran, kelimpahan, Sungai Poigar.

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.

scholarly journals Temporal and Spatial Variations of Hypoxic Water and Suspended Substances around Tama River Estuary in Tokyo Bay, Japan

2007 ◽  
Vol 54 ◽  
pp. 1036-1040 ◽  
Author(s):  
Hiroshi YAGI ◽  
Nobuaki EZURE ◽  
Hajime ISE ◽  
Kazuo NADAOKA ◽  
Kazunobu MOROHOSHI ◽  
...  
Keyword(s):  
River Estuary ◽  
Spatial Variations ◽  
Tokyo Bay ◽  
Temporal And Spatial Variations ◽  
Suspended Substances ◽  
Hypoxic Water ◽  
Temporal And Spatial

A new genus of frenulates (Annelida: Siboglinidae) from shallow waters of the Yenisey River estuary, Kara Sea

2021 ◽  
Author(s):  
N. P. Karaseva ◽  
N. N. Rimskaya-Korsakova ◽  
I. A. Ekimova ◽  
M. M. Gantsevich ◽  
V. N. Kokarev ◽  
...  
Keyword(s):  
New Genus ◽  
River Flow ◽  
Posterior Part ◽  
River Estuary ◽  
Molecular Study ◽  
Morphological Characters ◽  
Kara Sea ◽  
The Arctic ◽  
Permafrost Degradation ◽  
Bottom Water Temperature

Only seven frenulate species are currently known along the Eurasian coast of the Arctic Ocean. We describe a new genus and a new species of frenulates Crispabrachia yenisey, gen. nov. et sp. nov. The morphological analysis involved standard anatomical techniques, semithin sections and scanning electron microscopy (SEM). The molecular study included four markers (partial COI, 16S, 18S and 28S) and implemented Bayesian and Maximum likelihood phylogenetic approaches. The description of Crispabrachia gen. nov. is the first documented finding of frenulates in the Kara Sea at the estuary of the Yenisey River in rather shallow water (28 m). The establishment of a new genus is warranted based on the composition of morphological characters and several specific features including free, comparatively short curly tentacles, a triangular cephalic lobe with amplate base, the valvate extension of the posterior part of the forepart and prominent papillae on the nonmetameric region. The tube structure with prominent frills and the worm’s numerous tentacles, metameric papillae with cuticular plaques and segmental furrow on the forepart indicate that the new genus belongs to the polybrachiid group. Although the type locality in the Yenisey River estuary is unusual for siboglinids in general, the physical conditions here are common for other frenulates habitats, i.e. salinity ~30–33, bottom water temperature –1.5°C. This finding was made in the Yenisey Gulf in the region with the highest methane concentrations in the southern part of the Kara Sea that reflects permafrost degradation under the influence of river flow. Further study of the region would help to understand the factors influencing frenulate distributions and improve our knowledge of their biodiversity.

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