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 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 The Response of Lateral Flow to Peak River Discharge in a Macrotidal Estuary

Water ◽  
2020 ◽  
Vol 12 (12) ◽  
pp. 3571 ◽  
Author(s):  
Yuhan Yan ◽  
Dehai Song ◽  
Xianwen Bao ◽  
Yang Ding
Keyword(s):  
River Discharge ◽  
Recovery Time ◽  
Three Dimensional ◽  
Ocean Model ◽  
Lateral Flow ◽  
Longitudinal Momentum ◽  
Longitudinal Flow ◽  
Three Dimensional Model ◽  
Flooding Duration ◽  
The Impact

The Ou River, a medium-sized river in southeastern China, is selected to study the lateral flow response to rapidly varied river discharge, i.e., peak river discharge (PRD). A three-dimensional model based on the Finite-Volume Community Ocean Model is validated by in situ measurements from 15 June to 16 July 2005. PRD, which considers the extra buoyancy and longitudinal momentum in a short time, rebuilds the stratification and lateral flow. PRD, compared with low-discharge, generally makes stratification stronger and lateral flow weaker. PRD mainly rebuilds lateral flow by changing lateral advection, lateral Coriolis, and lateral-barotropic pressure gradient terms. After PRD, the salinity recovery time is longer than that of the flow because the impact on buoyancy lasts longer than that on longitudinal flow. Longitudinal flow is mostly affected by the momentum transferred during PRD; therefore, the recovery time is close to the flooding duration. However, the lateral flow is affected by the buoyancy, and its recovery time is generally longer than the flooding duration. The lateral flow recovery time depends on transect width, flow velocity and the variation caused by PRD. PRD occurs widely in global small-/medium-sized river estuaries, and the result of this work can be extended to other estuaries.

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.

Numerical Simulation of the Residual Current during the Dry Season in the Lingdingyang Bay, China

2014 ◽  
Vol 955-959 ◽  
pp. 2996-3000
Author(s):  
Biao Wang ◽  
Jian Rong Zhu
Keyword(s):  
Spring Tide ◽  
River Estuary ◽  
Circulation Pattern ◽  
Pearl River Estuary ◽  
Ocean Model ◽  
Dry Season ◽  
Residual Current ◽  
Lateral Circulation ◽  
Coastal Ocean Model ◽  
The Pearl River

The hydrodynamics in the Lingdingyang Bay of the Pearl River Estuary is complicated due to the combined effect of river runoff, tide and bathymetry. In this paper, the residual current patterns were investigated in the Lingdingyang Bay during the dry season based on Finite-Volume Coastal Ocean Model (FVCOM). The horizontal distributions of the residual current suggest that during both neap and spring tide the residual current is relatively strong at the surface while it weakens quite a lot at the bottom. Due to the northeasterly wind, a lateral circulation westward at the surface and eastward at the bottom is also found, which is more evident during neap tide than spring tide. The vertical profiles of residual current along deep channels show an obvious spring-neap variation, with the strongest estuarine circulation pattern during the moderate tide after neap.

Distribution Characteristics and Environmental Impacts of Nutrients in the Dry Season of the Pearl River Estuary in 2016

2020 ◽  
Author(s):  
Danna Zeng ◽  
Lixia Niu ◽  
Qingshu Yang
Keyword(s):  
Chlorophyll A ◽  
River Discharge ◽  
Spring Tide ◽  
River Estuary ◽  
Pearl River Estuary ◽  
Dry Season ◽  
Pearl River ◽  
The Pearl River Estuary ◽  
Significant Difference ◽  
The Pearl River

<p>Based on the field efforts in 2016 during a dry season (30 Nov-6 Dec) in the Pearl River Estuary (PRE)，south China, this study aimed to investigate the tidal changes of phytoplankton variability (in terms of chlorophyll a) and their responses to multiple environmental factors.Time series analysis，principal component analysis (PCA)，Pearson correlation analysis, and Delft3D model were carried out. A significant difference was found in the tidal variations of dissolved nutrients, covering both a spring tide and neap tide . Moderate differences in salinity and suspended sediment played different roles in the nitrogen and phosphate. The negative correlations of salinity and nitrogen ecologically implied a stronger diluting-mixing effect than that of phosphate, which has a large impact on the water quality. The adsorption of phosphorus by sediment particles was stronger than that of nitrogen. Nitrogen was mainly contributed by river discharge. DIN was constrained by tide-river dynamics and their mutual increase-decline trend, and a new source was supplemented along the transport from river to sea. The weak correlation between PO<sub>4</sub> and salinity suggested a different source contribution of the terrestrial emission from coastal cities; the contribution of river discharge was less compared with nitrogen. Over site, P-limitation was detected and was more frequently resulted in eutrophication and even bloom events. Characterizing the relationships among chlorophyll a, nutrients, and hydrological factors enables us to develop effective ecosystem management strategies, and to design studies more focused on ecological health and function.</p>

scholarly journals Circulation and salt balance in the São Francisco river Estuary (NE/Brazil)

RBRH ◽  
2017 ◽  
Vol 22 (0) ◽  
Author(s):  
Geórgenes Cavalcante ◽  
Luiz Bruner de Miranda ◽  
Paulo Ricardo Petter Medeiros
Keyword(s):  
River Discharge ◽  
Neap Tide ◽  
Spring Tide ◽  
River Estuary ◽  
Salt Transport ◽  
Salt Flux ◽  
Sao Francisco River ◽  
Tidal Cycles ◽  
São Francisco River ◽  
And Diffusion

ABSTRACT In order to evaluate how river discharge and tidal currents forcing influence the circulation and salt transport within the São Francisco River-Estuary, a two 25 hour surveys campaigns and along-channel profiles were performed in the estuary main channel (18/19 and 25/26 February 2014). The current intensity showed higher asymmetry between flood (v<0) and ebb (v>0) currents in spring tide (-0.6 and 1.1 m/s), as compared to neap tide (-0.4 and 1.0 m/s), which was attributed to the intense buoyancy energy enhanced by the stronger discharge in spring. Overall, salinity presented high stratified conditions and varied between 0.0<S<36.6, and 0.5<S<36.1 from surface to bottom, during spring and neap, respectively. Although river discharge reduced from spring to neap tide partially mixed-highly stratified conditions (type 2b) remained in both periods, with advection and diffusion contributing with 34% and 66% to the net upstream salt flux in spring, respectively, and 56% and 44% in neap tide, respectively, which was attributed to the balance of tidal and baroclinic forcing and river discharge. The dominant downstream advective salt transport in both spring (12.5 kg.m-1s-1) and neap (15.2 kg.m-1s-1) tidal cycles suggests that there is little salt accumulation inside the São Francisco estuary.

scholarly journals BEACH RESPONSE TO EXPOSED RIVERINE SEDIMENT AND BEACH NOURISHMENT

2018 ◽  
pp. 92
Author(s):  
Yu-Qi Huang ◽  
Jing-Hua Lin ◽  
Ray-Yeng Yang ◽  
Yang-Yih Chen ◽  
Jia-Lin Julie Chen
Keyword(s):  
Tropical Cyclones ◽  
Morphological Evolution ◽  
Beach Nourishment ◽  
Sediment Concentration ◽  
Sediment Supply ◽  
Coastal Habitat ◽  
Sediment Deposits ◽  
Continental Shelves ◽  
Riverine Sediment ◽  
Offshore Industry

Studying the process of riverine sediment at mouths and continental shelves is a critical subject for many engineering applications, such as dredging, navigation, dispersal and remobilization of contaminants. Sediment deposits also determine seabed properties, coastal geomorphology, and the health of coastal habitat/ecology. During extreme conditions, episodic river discharge triggered by large rainfall due to tropical cyclones may contribute significant amount of riverine sediment into the ocean. In the past decade, evidence of severe seabed erosion (up to 1m/year) along the sandy coast of Yunlin County has raised concerns regarding the sustainability of coastal structures. The exposed riverine sediment from the Jhuoshuei River is considered as one of major sources for sediment supply in this region. Bottle samples collected from bridge station in the Jhuoshuei River during the passage of tropical cyclones suggest sediment concentration can exceed 40 g/l for the major duration of the storm (Milliman et al. 2007). To mitigate the damage caused by shoreline retreat, 600,000 cubic meters per month of sand has been placed in two specific locations near the offshore industry park. The overarching goal of this study is to clarify the contribution of exposed riverine sediment and beach nourishment to enhance our understanding on the observed sediment transport and morphological evolution.

scholarly journals Fluvial modulation of hydrodynamics and salt transport in a highly stratified estuary

2010 ◽  
Vol 58 (2) ◽  
pp. 165-175 ◽  
Author(s):  
Carla de Abreu D'Aquino ◽  
Jurandir Pereira Filho ◽  
Carlos Augusto França Schettini
Keyword(s):  
Time Series ◽  
Water Level ◽  
River Discharge ◽  
Spring Tide ◽  
River Estuary ◽  
Salt Transport ◽  
Salt Flux ◽  
Rain Event ◽  
Stratified Estuary ◽  
A Site

An oceanographic campaign was conducted in the Araranguá river estuary during the period from May 11th to 13th of 2006 in order to produce a first hydrographic characterization of this system. The campaign was carried out during the spring tide period, and coincidentally after an intense rain event in the region which produced a peak in river discharge. Water level, currents and salinity time series were recorded hourly during a 50-hour period, at a site nearly 7 km upstream from the estuarine mouth. Two longitudinal distributions of salinity along the estuary were also recorded. The hydrographic data time-series were used to compute the advective salt flux in order to investigate the changes in the transport terms as a function of the change in discharge. The results showed that the estuarine structure was strongly modulated by the river discharge. The drop in water level of about 0.5 m during the first 24 hours was directly related to the ebb phase of the river flood. The water column was highly stratified throughout the period, therefore the stratification increased during the last 24 hours. The currents were stronger, ebbing and uni-directional at the beginning and became weaker and bidirectional as the water level went down, assuming a tidal pattern. The total salt transport in the first 25 hours was of -13.6 kg.m-1.s-1 (seawards), decreasing to 3 Kg.m-1.s-1 during the last 25 hours (landwards). It was also noticeable that the pH in the estuary, recorded together with the salinity, was around 5, showing that the water quality in the estuary is affected by the coal mining activity in the hydrographic basin.

Accumulation of muds and metals in the Hudson River estuary turbidity maximum

1998 ◽  
Vol 34 (2-3) ◽  
pp. 214-222 ◽  
Author(s):  
M. G. Menon ◽  
R. J. Gibbs ◽  
A. Phillips
Keyword(s):  
River Estuary ◽  
Hudson River ◽  
Turbidity Maximum ◽  
Hudson River Estuary
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