scholarly journals Calculated Potential Bedload Versus Real Transported Sands along the Guadiana River Estuary (Spain–Portugal)

2019 ◽  
Vol 7 (11) ◽  
pp. 393
Author(s):  
Juan A. Morales ◽  
Claudio Lozano ◽  
Mouncef Sedrati
Keyword(s):  
Bottom Water ◽  
River Estuary ◽  
Acoustic Doppler Current Profiler ◽  
Bedload Transport ◽  
Cohesive Sediments ◽  
Coastal System ◽  
Deep Channel ◽  
Current Profiler ◽  
Comparison Of The Results ◽  
Guadiana Estuary

The Guadiana estuary is a coastal system located in the southwest of the Iberian Peninsula and is the natural border between Portugal and Spain. It is a rock-bounded estuary which extends along more than 40 km and is characterized by a semidiurnal mesotidal regime. This paper represents an approach to the bedload transport across two flow sections located in the fluvial and marine domains. In the fluvial profile, the most frequent bedform is the plane bed. In the marine area the bed of the deep channel is composed of well-sorted sand, while a lateral bar displays partially cohesive sediments with dominant fine sands in a matrix of clayey silts. Data were acquired during spring and neap tides. Near-bottom water velocities were registered by an acoustic Doppler current profiler (ADCP). Density and bed rugosity were determined in sediment samples. These data were employed using Bagnold’s equation (1963) to quantify the potential bedload (Qb). Further, real bedload values (Sb) were obtained by using Poliakoff traps. The comparison of the results of Qb under both ebb and flood conditions demonstrated a clear river-to-sea net transport in both sectors. The values of Sb were lower than those of Qb in every condition. The sand input across the fluvial estuary cannot supply the potential bedload in the lower domain of the channel, thereby causing a deficit that explains this lack of agreement between potential and real transport.

Flow and Stratification in a Bedrock Confined Estuary

2021 ◽  
Author(s):  
Amanda Wild ◽  
Eva Kwoll
Keyword(s):  
River Estuary ◽  
Acoustic Doppler Current Profiler ◽  
Limited Information ◽  
Cross Sectional ◽  
Current Profiler ◽  
Hydrodynamic Processes ◽  
Ongoing Development ◽  
Skeena River ◽  
The Impact ◽  
Temperature Depth

<p>This research describes the impact of the bedrock island structure on the circulation and stratification of a macrotidal, partially mixed estuary in northwestern Canada (the Skeena River Estuary). Due to ongoing development in this formerly remote region, pressures have increased within the Skeena River Estuary over the past decade. However, there is still limited understanding of the estuary's morphodynamics due to its deviation from a 'typical' estuarine morphology. Located along an emergent, fjordal coastline, the Skeena Estuary River drains into a basin confined by bedrock and interrupted by multiple, irregular bedrock islands. Observations suggest that a subaqueous delta, associated facies, and the surface plume are split between several bedrock passages with limited information on the governing hydrodynamic processes. To overcome this, Acoustic Doppler current profiler cross-sectional transects and conductivity, temperature, depth, and turbidity profiles were taken in the nearshore (under 40 m) at locations across the estuary over two different (by ~1000 m<sup>3</sup>s<sup>-1</sup>) river stages. Over multiple dates with various river inflows, the tidal ratio to river inflow produces varied stratification patterns at a given site. During one point in time and river stage, bedrock passages are disproportionally exposed to marine and fluvial inflows, creating spatially diverse stratification patterns across the estuary. Stratification and passage morphology interactions determine the characteristics of tidal slack transitions, with horizontal and vertical separation occurring during well-mixed conditions and stratified conditions, respectively.</p>

scholarly journals Multiyear high-frequency physical and environmental observations at the Guadiana Estuary

2015 ◽  
Vol 8 (2) ◽  
pp. 567-586
Author(s):  
E. Garel ◽  
Ó. Ferreira
Keyword(s):  
High Frequency ◽  
Acoustic Doppler Current Profiler ◽  
Time Frame ◽  
Discharge Data ◽  
The Status ◽  
Current Profiler ◽  
Hydrodynamic Processes ◽  
Southern Portugal ◽  
Machine Readable ◽  
Guadiana Estuary

Abstract. High-frequency data collected continuously over a multiyear time frame are required for investigating the various agents that drive ecological and hydrodynamic processes in estuaries. Here, we present water quality and current in-situ observations from a fixed monitoring station operating from 2008 to 2014 in the lower Guadiana Estuary, southern Portugal (37°11.30' N, 7°24.67' W). The data were recorded by: a multi-parametric probe providing hourly records of temperature, chlorophyll, dissolved oxygen, turbidity, and pH at a water depth of ~ 1 m; and, a bottom-mounted acoustic Doppler current profiler measuring the pressure, near-bottom temperature, and flow velocity through the water column every 15 min. The time-series, in particular the probe one, present substantial data gaps arising from equipment failure and maintenance, which are ineluctable with this type of observations in harsh environments. However, prolonged (months-long) periods of observations during contrasted external forcing conditions are available. The raw data are reported together with quality flags indicating the status (valid/non-valid) of each record. Hourly river discharge data from two hydrographic stations located near the estuary head are also provided to support data analysis and interpretation. The dataset is publicly available at PANGAEA (doi:10.1594/PANGAEA.845750) in machine-readable format.

scholarly journals Relevance of acoustic methods to quantify bedload transport and bedform dynamics in large sandy-gravel bed river

2020 ◽  
Author(s):  
Jules Le Guern ◽  
Stéphane Rodrigues ◽  
Thomas Geay ◽  
Sébastien Zanker ◽  
Alexandre Hauet ◽  
...  
Keyword(s):  
Measurement Techniques ◽  
Reference Method ◽  
Acoustic Doppler Current Profiler ◽  
Accurate Method ◽  
Bedload Transport ◽  
Fluvial Systems ◽  
Sandy Gravel ◽  
Gravel Bed ◽  
Current Profiler ◽  
Gravel Bed River

Abstract. Despite the inherent difficulties to quantify its value, bedload transport is essential to understand fluvial systems. In this study, we assessed different indirect bedload measurement techniques with a reference direct bedload measurement in a section of a large sandy-gravel bed river. Acoustic Doppler Current Profiler (aDcp), Dune Tracking Method (DTM) and hydrophone measurement techniques were used to determine bedload transport rates using calibration with the reference method or using empirical formula. Results show that the hydrophone is the most efficient and accurate method to determine bedload flux in the Loire River. Even though parameters controlling self-generated noise of sediments still need to better understood, the calibration determined in this study allows a good approximation of bedload transport rates. Moreover, aDcp and hydrophone measurement techniques are both able to continuously measure bedload transport associated to bedform migration.

scholarly journals Calibration of Acoustic Doppler Current Profiler Apparent Bedload Velocity to Bedload Transport Rate

2017 ◽  
pp. 209-233 ◽  
Author(s):  
Colin D. Rennie ◽  
Damià Vericat ◽  
Richard D. Williams ◽  
James Brasington ◽  
Murray Hicks
Keyword(s):  
Acoustic Doppler Current Profiler ◽  
Bedload Transport ◽  
Transport Rate ◽  
Current Profiler

scholarly journals Transport of Antarctic bottom water through the Kane Gap, tropical NE Atlantic Ocean

Ocean Science ◽  
2013 ◽  
Vol 9 (5) ◽  
pp. 825-835 ◽  
Author(s):  
E. G. Morozov ◽  
R. Y. Tarakanov ◽  
H. van Haren
Keyword(s):  
Atlantic Ocean ◽  
Bottom Water ◽  
Low Frequency ◽  
Acoustic Doppler Current Profiler ◽  
Antarctic Bottom Water ◽  
Current Profiler ◽  
Ne Atlantic Ocean ◽  
Flow Through ◽  
Seasonal Signal ◽  
Frequency Properties

Abstract. We study low-frequency properties of the Antarctic Bottom Water (AABW) flow through the Kane Gap (9° N) in the Atlantic Ocean. The measurements in the Kane Gap include five visits with CTD (Conductivity-Temperature-Depth) sections in 2009–2012 and a year-long record of currents on a mooring using three AquaDopp current meters. We found an alternating regime of flow, which changes direction several times during a year. The seasonal signal seems to dominate. The maximum daily average values of southerly velocities reach 0.20 m s−1, while the greatest north-northwesterly velocity is as high as 0.15 m s−1. The velocity and transport at the bottom are aligned along the slope of a local hill near the southwestern side of the gap. The distribution of velocity directions at the upper boundary of AABW is wider. The transport of AABW (Θ < 1.9 °C) based on the mooring and LADCP (Lowered Acoustic Doppler Current Profiler) data varies approximately within ±0.35 Sv in the northern and southern directions. The annual mean AABW transport through the Kane Gap is almost zero.

scholarly journals Multi-year high-frequency physical and environmental observations at the Guadiana Estuary

2015 ◽  
Vol 7 (2) ◽  
pp. 299-309 ◽  
Author(s):  
E. Garel ◽  
Ó. Ferreira
Keyword(s):  
High Frequency ◽  
Time Series Data ◽  
Acoustic Doppler Current Profiler ◽  
Time Frame ◽  
Series Data ◽  
Data Set ◽  
Discharge Data ◽  
Current Profiler ◽  
Machine Readable ◽  
Guadiana Estuary

Abstract. High-frequency data collected continuously over a multi-year time frame are required for investigating the various agents that drive ecological and hydrodynamic processes in estuaries. Here, we present water quality and current in situ observations from a fixed monitoring station operating from 2008 to 2014 in the lower Guadiana Estuary, southern Portugal (37°11.30' N, 7°24.67' W). The data were recorded by a multi-parametric probe providing hourly records (temperature, salinity, chlorophyll, dissolved oxygen, turbidity, and pH) at a water depth of ~ 1 m, and by a bottom-mounted acoustic Doppler current profiler measuring the pressure, near-bottom temperature, and flow velocity through the water column every 15 min. The time series data, in particular the probe ones, present substantial gaps arising from equipment failure and maintenance, which are ineluctable with this type of observation in harsh environments. However, prolonged (months-long) periods of multi-parametric observations during contrasted external forcing conditions are available. The raw data are reported together with flags indicating the quality status of each record. River discharge data from two hydrographic stations located near the estuary head are also provided to support data analysis and interpretation. The data set is publicly available in machine-readable format at PANGAEA (doi:10.1594/PANGAEA.845750).

scholarly journals OBSERVATION OF COASTAL FRONT AND CIRCULATION IN THE NORTHEASTERN JAVA SEA, INDONESIA

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Agus S. Atmadipoera ◽  
Edi Kusmanto ◽  
Adi Purwandana ◽  
I Wayan Nurjaya
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
River Estuary ◽  
Acoustic Doppler Current Profiler ◽  
Water Source ◽  
Observation Time ◽  
Joint Research ◽  
Current Profiler ◽  
Java Sea ◽  
Coastal Front

<p><em>The structure and spatial extent of a coastal front and circulation in the shallow (&lt;55 m depth) northeastern Java Sea in Indonesia was investigated with a new dataset of high-resolution conductivity-temperature-depth (CTD) and along-track shipboard acoustic Doppler current profiler (SADCP) during a DIKTI-LIPI 2010 joint research cruise on R.V. Baruna Jaya 8.  The coastal front separates fresh warm coastal water derived mainly from Barito River discharge and the saline, cool Java Sea water.  The surface fresh water plume extends approximately 760 km from the Barito River estuary to the south, and its thickness varies from the surface to 10 m and 20 m depth, depending on its proximity to the fresh water source.  The front is aligned a northeast and east direction, probably related to a meandering of strong northeastward monsoon current in the eastern part of the Java Sea during the observation time.</em></p> <p><em> </em></p> <p><strong><em>Keywords:</em></strong><em> hydrographic measurement, coastal front, Matasiri Islands, Barito River, the northwest</em><em> monsoon current</em></p>

scholarly journals OBSERVATION OF COASTAL FRONT AND CIRCULATION IN THE NORTHEASTERN JAVA SEA, INDONESIA

2015 ◽  
Vol 7 (1) ◽  
Author(s):  
Agus S. Atmadipoera ◽  
Edi Kusmanto ◽  
Adi Purwandana ◽  
I Wayan Nurjaya
Keyword(s):  
Fresh Water ◽  
Sea Water ◽  
River Estuary ◽  
Acoustic Doppler Current Profiler ◽  
Water Source ◽  
Observation Time ◽  
Joint Research ◽  
Current Profiler ◽  
Java Sea ◽  
Coastal Front

The structure and spatial extent of a coastal front and circulation in the shallow (<55 m depth) northeastern Java Sea in Indonesia was investigated with a new dataset of high-resolution conductivity-temperature-depth (CTD) and along-track shipboard acoustic Doppler current profiler (SADCP) during a DIKTI-LIPI 2010 joint research cruise on R.V. Baruna Jaya 8.  The coastal front separates fresh warm coastal water derived mainly from Barito River discharge and the saline, cool Java Sea water.  The surface fresh water plume extends approximately 760 km from the Barito River estuary to the south, and its thickness varies from the surface to 10 m and 20 m depth, depending on its proximity to the fresh water source.  The front is aligned a northeast and east direction, probably related to a meandering of strong northeastward monsoon current in the eastern part of the Java Sea during the observation time. Keywords: hydrographic measurement, coastal front, Matasiri Islands, Barito River, the northwest monsoon current

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