scholarly journals Relating Hydrodynamic Forcing and Topographic Response for Tide-Dominated Sandy Beaches

2020 ◽  
Vol 8 (3) ◽  
pp. 151 ◽  
Author(s):  
Evelien Brand ◽  
Anne-Lise Montreuil ◽  
Rik Houthuys ◽  
Margaret Chen
Keyword(s):  
Intertidal Zone ◽  
Spring Tide ◽  
Field Measurements ◽  
Sandy Beaches ◽  
Tidal Currents ◽  
Sediment Supply ◽  
Wave Steepness ◽  
Natural Sediment ◽  
Order Of Magnitude ◽  
Study Sites

To relate hydrodynamic forcing and topographic response for a tide-dominated sandy beach, extensive field measurements were carried out in the intertidal zone. Hydrodynamics and beach topography were monitored during a total of 12 weeks at two different study sites: one with a featureless intertidal zone and one with intertidal bars. The results of both study sites indicate that the intertidal beach grows when wave steepness is small, whereas it erodes when wave steepness is large. Spring-neap variations in tidal current direction heavily distort this trend: strong spring tidal currents transport sediment away from the beach, resulting in enhanced erosion. Tide-induced beach volume changes are on the same order of magnitude as wave-induced changes. Besides waves and tides, the effect of variations in the amount of sediment supply is substantial, with enhanced accretion when the sediment supply is large. The effect of variations in sediment supply on the intertidal beach topography is subordinate to the effect of waves and tide, though. From this study, it is concluded that larger waves are primarily erosive, but they can also enhance the natural sediment supply. Furthermore, it is found that tidal currents can be equally important as waves in shaping the beach topography, especially during spring tide on macrotidal beaches.

scholarly journals Zonation in a cryptic Antarctic intertidal macrofaunal community

2012 ◽  
Vol 25 (1) ◽  
pp. 62-68 ◽  
Author(s):  
Catherine L. Waller
Keyword(s):  
Outer Surface ◽  
Intertidal Zone ◽  
General View ◽  
Annual Cycles ◽  
West Antarctic ◽  
Order Of Magnitude ◽  
Size Of Animals ◽  
Study Sites ◽  
Macrofaunal Community ◽  
The Antarctic

AbstractDespite the general view that the Antarctic intertidal conditions are too extreme to support obvious signs of macrofaunal life, recent studies have shown that intertidal communities can survive over annual cycles. The current study investigates distribution of taxa within a boulder cobble matrix, beneath the outer, scoured surface of the intertidal zone at Adelaide Island, west Antarctic Peninsula. The intertidal zone at the study sites comprised compacted, flattened cobble pavements, which have been shown to be highly stable over time. Community structure was investigated using univariate and multivariate approaches. Virtually no macrofauna were present on the outer surface, but richness, diversity, abundance and size of animals increased with depth into the rock matrix. Abundance of taxa increased by an order of magnitude between the outer surface and the lowest level sampled. These findings show that the Antarctic intertidal is not always the uninhabitable environment currently perceived, and that under these highly variable environmental conditions at least some species have the capacity to survive.

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.

Assessment of Moisture Content in Sandy Beach Environments from Multispectral Satellite Imagery

2021 ◽  
Author(s):  
Julie Paprocki ◽  
Nina Stark ◽  
Hans C Graber ◽  
Heidi Wadman ◽  
Jesse E McNinch
Keyword(s):  
Moisture Content ◽  
Laboratory Data ◽  
Field Measurements ◽  
Weather Conditions ◽  
Sandy Beaches ◽  
Percent Error ◽  
Moisture Contents ◽  
Multispectral Satellite Imagery ◽  
Factor C

A framework for estimating moisture content from satellite-based multispectral imagery of sandy beaches was tested under various site conditions and sensors. It utilizes the reflectance of dry soil and an empirical factor c relating reflectance and moisture content for specific sediment. Here, c was derived two ways: first, from in-situ measurements of moisture content and average NIR image reflectance; and second, from laboratory-based measurements of moisture content and spectrometer reflectance. The proposed method was tested at four sandy beaches: Duck, North Carolina, and Cannon Beach, Ocean Cape, and Point Carrew, Yakutat, Alaska. Both measured and estimated moisture content profiles were impacted by site geomorphology. For profiles with uniform slopes, moisture contents ranged from 3.0%-8.0% (Zone 1) and from 8.0%-23.0% (Zone 2). Compared to field measurements, the moisture contents estimated using c calibrated from in-situ and laboratory data resulted in percent error of 3.6%-44.7% and 2.7%-58.6%, respectively. The highest percent error occurred at the transition from Zone 1 to Zone 2. Generally, moisture contents were overestimated in Zone 1 and underestimated in Zone 2, but followed the expected trends based on field measurements. When estimated moisture contents in Zone 1 exceeded 10%, surface roughness, debris, geomorphology, and weather conditions were considered.

scholarly journals Preliminary Study on Fish Larvae at Selected Coastal Waters of Sarawak

1970 ◽  
Vol 4 (2) ◽  
pp. 1-8
Author(s):  
Norhakimi Muhamad ◽  
Siti Akmar Khadijah Ab Rahim
Keyword(s):  
Coastal Waters ◽  
Intertidal Zone ◽  
Larval Dispersal ◽  
Sampling Methods ◽  
Fish Larvae ◽  
Mesh Size ◽  
Subtidal Zone ◽  
Preliminary Study ◽  
Study Sites

A survey were carried out from April to November 2012 at five study sites namely Teluk Pandan beach, Rambungan beach, Puteri beach, Sampadi Island and Satang Besar Island, Sarawak. This survey was carried out in order to obtain early documentation of fish larvae at selected coastal waters of Sarawak. Seine net (1 mm mesh size) which was pulled by two persons at intertidal zone; and bridle net (0.5 mm mesh size) that was towed by boat at subtidal zone (Sampadi Island only) were used to collect the samples. A total of 2,562 fish larvae which comprise 25 families were obtained from both sampling methods. A total of 16 families of fish larvae were caught by seine net from the intertidal zone. The same number of families was collected at the subtidal zone of Sampadi Island by bridle net. Ambassidae, Clupeidae, Engraulidae and Gerreidae found to be dominant families in the study sites. Clupeidae and Gerreidae shown a wide larval dispersal area because they were collected at all study sites. These findings seem to indicate that the subtidal zone of Sampadi support more species of fish larvae.

scholarly journals MORPHODYNAMICS OF SANDY BEACHES IN LOW ENERGY, NON-TIDAL ENVIRONMENTS

2020 ◽  
pp. 47
Author(s):  
Anne Ton ◽  
Vincent Vuik ◽  
Rinse Wilmink ◽  
Stefan Aarninkhof
Keyword(s):  
Risk Reduction ◽  
Flood Risk ◽  
Sandy Beaches ◽  
Low Energy ◽  
Flood Risk Reduction ◽  
Study Sites ◽  
Over Time

Sandy foreshores play an important role in flood risk reduction in areas near seacoasts, estuaries and lakes. The morphodynamics of sandy foreshores or beaches in lakes, known as low-energy, non-tidal environments, have not been studied as extensively as open coasts. The goal of this research is to understand the relation between hydrodynamics and morphology on sandy lake beaches. At our four study sites, a sub aqueous horizontal platform evolved of which the elevation stabilizes over time. We conclude that the eventual elevation of these platforms is located at the depth of closure. Recorded Presentation from the vICCE (YouTube Link): https://youtu.be/7TbmH3hXnDE

scholarly journals Bedforms in a tidally modulated ridge and runnel shoreface (Berck-Plage; North France): implications for the geological record

2018 ◽  
Vol 189 (1) ◽  
pp. 5 ◽  
Author(s):  
Romain Vaucher ◽  
Bernard Pittet ◽  
Sophie Passot ◽  
Philippe Grandjean ◽  
Thomas Humbert ◽  
...  
Keyword(s):  
Intertidal Zone ◽  
Spring Tide ◽  
Experimental Studies ◽  
Weather Condition ◽  
Weather Conditions ◽  
Field Investigation ◽  
Fair Weather ◽  
Coastal System ◽  
The North ◽  
Current Ripples

Tidally modulated shoreface (TMS) corresponds to peculiar costal environments. The general morphology and the expressed bedforms are provided by the interplay of both waves and tides. The recognition of TMS in the fossil record still remains a difficult task. The study of one mega-tidal modern TMS in the north of France (Berck-Plage) provides new key criteria to identify this kind of coastal system in the rock record. Field investigation and digital mapping were realized at lowest tide during spring tide under fair-weather condition. The intertidal zone is characterized by a succession of several sand banks shore parallel separated by topographic lows that are defined as ridges and runnels. Seven distinct dominant bedforms are recognized: 3D current ripples, 3D asymmetrical ripples, 2D symmetrical ripples, 2D small symmetrical dunes, 2D large symmetrical dunes, 3D symmetrical dunes and plane beds. The upper stage plane bedding mainly composed the ridges while the six other bedforms are commonly found within the runnels or on the flanks of the ridges. Comparison of the bedforms of Berck-Plage with previous experimental studies on bedforms genesis proves that the necessary flow parameters for generating these bedforms belong to an oscillatory flow except for the 3D current ripples, which are formed by a unidirectional flow. This study confirms the dominance of oscillatory structures through the intertidal zone in a mega-tidal context and show that wave processes are more powerful than tide processes for bedform generation although during fair weather conditions. Based on the timing of genesis, the description and the repeated pattern of distribution of bedforms between two ridges is highlighted thus helping to propose a theoretical facies sequence for an intertidal zone characterized by ridges and runnels applicable to ancient sedimentary successions.

Recovery Assessment of Two Nearby Sandy Beaches with Contrasting Anthropogenic and Sediment Supply Settings

2016 ◽  
Vol 75 (sp1) ◽  
pp. 462-466 ◽  
Author(s):  
Nadia Senechal ◽  
Jonathan Pavon ◽  
Remy Asselot ◽  
Mohammed Taaouati ◽  
Sophie Ferreira ◽  
...  
Keyword(s):  
Sandy Beaches ◽  
Sediment Supply ◽  
Recovery Assessment

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.

Experimental Investigation of Swirl and Flow Structure Inside a Rotor-Stator Cavity

2015 ◽  
Author(s):  
Bruno Facchini ◽  
Daniele Massini ◽  
Alessio Picchi ◽  
Mirko Micio ◽  
Francesco Bavassano ◽  
...  
Keyword(s):  
Working Conditions ◽  
Field Measurements ◽  
Flow Behaviour ◽  
Turbine Engines ◽  
Test Case ◽  
Rotating Disc ◽  
Inlet Geometry ◽  
Order Of Magnitude ◽  
Secondary Air ◽  
Computational Resources

In order to ensure safety, predictable and acceptable life of gas turbine engines an important task is the design of the secondary air system (SAS). To avoid hot gas path ingestion, one of the most critical concerns in a well-performing SAS is the understanding of the air motion within of the stator-rotor cavity systems. The state of the art of the fluid solver tools used to predict the flow behaviour inside cavities is generally based on codes with correlative approaches, in order to reduce calculation times and computational resources. In order to improve the precision of correlations, by means of data with reduced associated uncertainty, experimentalists performed an experimental campaign selecting a simple test case composed by a rotating disc facing a flat stator. Imposing several working conditions, the rotational speed was varied in order to gain a rotational Reynolds number up to 1.2 × 106 which is one order of magnitude less than real seals working conditions. The analysis of the swirl rate as well as the frictional moment exerted by the rotor on the fluid was carried out based on different sealing mass flows. Pressure probes were used to obtain radial distribution of static and total pressure on the stator side. In order to deepen the analysis on the flow behaviour inside cavity, flow field measurements using a 2D PIV system was performed on two different planes: velocity contours were used to help the detection of the core region. Finally, the wide database of the experimental results were used to improve a simple model able to predict the behaviour of rotor-stator cavities including the effect of the inlet geometry of the cavity.

Numbers of naked amoebae inhabiting the intertidal zone of two geographically separate sandy beaches

2000 ◽  
Vol 80 (4) ◽  
pp. 731-732 ◽  
Author(s):  
Andrew Rogerson ◽  
Fiona Hannah ◽  
Gwen Hauer ◽  
Phillip Cowie
Keyword(s):  
Intertidal Zone ◽  
Sandy Beach ◽  
Sandy Beaches ◽  
Beach Sand ◽  
Cultivation Method ◽  
Future Studies ◽  
Beach Communities ◽  
Shallow Subtidal ◽  
Lower Intertidal Zone ◽  
Naked Amoebae

Numbers of naked amoebae (Gymnamoebae) inhabiting the lower intertidal zone of two sandy beaches were estimated using a novel enrichment cultivation method. Samples were collected between June and September, 1999. Beach sand at Kames Bay, Isle of Cumbrae, Scotland contained on average 2604 amoebae cm−3 while at Dania Beach, Florida, USA, sand harboured 4236 amoebae cm−3. This is the first study to focus on the abundance of naked amoebae inhabiting a sandy beach. These numbers are higher than densities generally reported for shallow subtidal sands and show that amoebae must be considered in future studies on the dynamics of sandy beach communities.

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