scholarly journals Hydrodynamic and Sediment Transport Patterns in the Minho and Douro Estuaries (NW Portugal) Based on ADCP Monitoring Data: Part 2—Statistical Interpretation of Bottom Moored Datasets

Coasts ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 56-72
Author(s):  
Ana Isabel Santos ◽  
Anabela Oliveira ◽  
Dora Carinhas ◽  
José Paulo Pinto ◽  
M. Conceição Freitas
Keyword(s):  
Sediment Transport ◽  
Clustering Analysis ◽  
River Discharge ◽  
Sandy Sediment ◽  
Statistical Interpretation ◽  
Nw Portugal ◽  
Transport Patterns ◽  
Sediment Export ◽  
Acoustic Responses ◽  
Effective Contribution

Exploratory statistical partitioning methods (K-means Clustering analysis) were applied to ADCP monitoring datasets collected inside the Douro and Minho estuaries. This analysis is aimed to discriminate ADCP acoustic responses according to the variations of the suspended particles within the ensonified medium. Based on the interpretation of the results, this work establishes general sediment transport patterns at both estuaries’ exits under continuously varying river flows and tidal amplitudes recorded during a summer dry seasonal scenario (September 2005) and winter high river discharge (January/February 2007) conditions. Results confirm the already known present scarcity of (sandy) sediment export from the Douro and Minho estuaries into the inner shelf and the consequent sediment depletion of the adjacent littoral, with no effective contribution of the Douro and some evidence of sand export observed at the Minho outlet during the winter of 2007.

scholarly journals Hydrodynamic and Sediment Transport Patterns in the Minho and Douro Estuaries (NW Portugal) Based on ADCP Monitoring Data: Part 1-Tidal Sediment Exchanges

Coasts ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 31-55 ◽  
Author(s):  
Ana Isabel Santos ◽  
Anabela Oliveira ◽  
José Paulo Pinto ◽  
M. Conceição Freitas
Keyword(s):  
River Flow ◽  
Acoustic Backscatter ◽  
Inner Shelf ◽  
Sediment Fluxes ◽  
Nw Portugal ◽  
Column Structure ◽  
Shelf Sediment ◽  
Tidal Variability ◽  
Transport Patterns ◽  
Sediment Export

The tidal variability of the Minho and Douro lower estuaries (NW Portugal) water column structure was assessed at the semi-diurnal and fortnightly time scales under two contrasting seasonal river flow scenarios during the summer of 2005 and winter of 2006. Sediment fluxes inferred from calibrated ADCP acoustic backscatter revealed that, during spring tides and low runoff conditions, both estuaries act as sinks instead of sources of sediments into the inner shelf. Sediment export occurred during neaps, in both estuaries, when the river flow values were high enough to counteract the effect of the entering flood. No evidence of coarse sediment export into the inner shelf that would eventually nourish the littoral system could be inferred from these datasets.

Satellite Observations of Sediment Transport Patterns in the Lac Saint-Pierre Region of the St. Lawrence River

1988 ◽  
Vol 23 (2) ◽  
pp. 243-252 ◽  
Author(s):  
J.E. Bruton ◽  
J.H. Jerome ◽  
R.P. Bukata
Keyword(s):  
Sediment Transport ◽  
Close Relationships ◽  
Satellite Observations ◽  
Near Surface ◽  
Thermal Data ◽  
Digital Formats ◽  
Transport Patterns ◽  
Mutually Independent ◽  
River Corridor ◽  
St Lawrence River

Abstract Satellite data from Landsats 4 and 5 were utilized to delineate the seasonal variations of sediment transport zones in the Lac Saint-Pierre region of the St. Lawrence River corridor. A seasonally cyclic succession of patterns displaying persistent, mutually independent, and extensive (in both space and time) turbidity zones was clearly in evidence. Visible and thermal data in both imagery and digital formats were used to show the close relationships existing among the distinct zonal synoptic patterns, the bathymetry of lake and river, and the near surface aquatic temperatures.

Monitoring sediment transport patterns on an energetic ebb-tidal delta using dual-signature tracers

2018 ◽  
Author(s):  
Stuart Pearson ◽  
Bram van Prooijen ◽  
Jack Poleykett ◽  
Matthew Wright ◽  
Kevin Black ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Ebb Tidal Delta ◽  
Transport Patterns

Sediment transport patterns on the Estremadura Spur continental shelf: Insights from grain-size trend analysis

2014 ◽  
Vol 93 ◽  
pp. 28-32 ◽  
Author(s):  
Maria Balsinha ◽  
Carlos Fernandes ◽  
Anabela Oliveira ◽  
Aurora Rodrigues ◽  
Rui Taborda
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Continental Shelf ◽  
Trend Analysis ◽  
Transport Patterns ◽  
Grain Size Trend Analysis

Mass balance controls on sediment scour and bedrock erosion in waterfall plunge pools

Geology ◽  
2021 ◽  
Author(s):  
Joel S. Scheingross ◽  
Michael P. Lamb
Keyword(s):  
Sediment Transport ◽  
Mass Balance ◽  
River Discharge ◽  
Sediment Load ◽  
Sediment Flux ◽  
Habitat Availability ◽  
Flux Divergence ◽  
Plunge Pool ◽  
Bedrock Erosion ◽  
Recurrence Intervals

Waterfall plunge pools experience cycles of sediment aggradation and scour that modulate bedrock erosion, habitat availability, and hazard potential. We calculate sediment flux divergence to evaluate the conditions under which pools deposit and scour sediment by comparing the sediment transport capacities of waterfall plunge pools (Qsc_pool) and their adjacent river reaches (Qsc_river). Results show that pools fill with sediment at low river discharge because the waterfall jet is not strong enough to transport the supplied sediment load out of the pool. As discharge increases, the waterfall jet strengthens, allowing pools to transport sediment at greater rates than in adjacent river reaches. This causes sediment scour from pools and bar building at the downstream pool boundary. While pools may be partially emptied of sediment at modest discharge, floods with recurrence intervals >10 yr are typically required for pools to scour to bedrock. These results allow new constraints on paleodischarge estimates made from sediment deposited in plunge pool bars and suggest that bedrock erosion at waterfalls with plunge pools occurs during larger floods than in river reaches lacking waterfalls.

scholarly journals Effects of Cascade Reservoir Systems on the Longitudinal Distribution of Sediment Characteristics: A Case Study of the Heihe River Basin

2021 ◽  
Author(s):  
Yu Wang ◽  
Bao-long Li ◽  
Juan-juan Liu ◽  
Qi Feng ◽  
Wei Liu ◽  
...  
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Longitudinal Distribution ◽  
Heihe River ◽  
Hydrodynamic Conditions ◽  
Sediment Grain Size ◽  
Cascade Reservoirs ◽  
Grain Size Distributions ◽  
Transport Patterns ◽  
The Impact

Abstract Spatial variations in grain-size parameters can reflect river sediment transport patterns and depositional dynamics. Therefore, 22 surficial sediment samples taken from the Heihe River and its cascade reservoirs were analyzed to better understand the impact of cascade reservoir construction on sediment transport patterns in inland rivers in China. The results showed that the longitudinal distribution of sediment grain size in the Heihe River was significantly affected by the influence of the cascade reservoirs. The grain size of the reservoir sediments within the cascade reservoir system was much lower than that of sediments in the natural river section, and the sediments in the natural river were well sorted, exhibiting leptokurtosis and positive or very positive skew. The lower reaches of the dammed river experienced strong erosion, and the grains of the bed sediments were coarse and poorly sorted; the grain-size distributions were more positively skewed and exhibited leptokurtosis. The backwater zone of the reservoir was influenced by both backwater and released water, and the sediment grain size was between the grain size of the natural river and that of the lower reaches of the dam; these sediments were moderately well sorted and had a positively skewed, leptokurtic grain-size distribution. Sedimentary environmental analysis revealed that the characteristics of the sediment grain size in an upstream tributary of the Heihe River were more influenced by source material than by hydrodynamic conditions, while the grain-size characteristics of the mainstream sediments were controlled mainly by hydrodynamic conditions.

Rapid morphological evolution during beach breaching and closure at a bar-built estuary

2021 ◽  
Author(s):  
Mara Orescanin ◽  
Tyonna McPherson ◽  
Paul Jessen
Keyword(s):  
Sediment Transport ◽  
River Discharge ◽  
Morphological Evolution ◽  
Water Levels ◽  
Low Flow ◽  
Long Term Stability ◽  
Erosion Rates ◽  
Discharge Rates ◽  
Elevation Changes ◽  
Elevated Water

<p>The Carmel River runs 58 km from the Santa Lucia Mountains through the Carmel Valley eventually entering a lagoon at Carmel River State Beach near Carmel, California, USA. During the dry summer months, the lagoon is closed, with no connection to the coastal ocean.  However, during the wet winter months, the river often breaches through the lagoon allowing water to freely flow between the river and Carmel Bay. Sediment transport, in part owing to river discharge and in part owing to ocean forcing (tides and waves), contributes heavily to whether the lagoon is open or closed: when there are low flow conditions, waves and tides can decrease flow rates in the breach, allowing sediment to settle. The sediment budget is expected to be a closed system, owing to the rocky headlands and long-term stability (no yearly regression or transgression) of the shoreline, despite managed attempts to control breach and closure timing. However, it is currently unknown 1) how velocity profiles evolve during breaching, and 2) how much sediment moves during such an event. The hypothesis is that the breach mouth can completely disappear and re-emerge over a single breach-closure cycle, leading to meter-scale daily accretion and erosion rates of berm height if berm elevation is significantly lower than the expected steady-state berm height. Furthermore, it is hypothesized that during active breaching, discharge rates through the breach channel are larger than upstream river discharge rates owing to elevated water levels within the back lagoon. This study uses a RiverSurveyor M9 Acoustic Doppler Profiler to measure outflow discharge and GPS topographic surveys to quantify elevation changes. A velocity profile can be built which will estimate the sediment transport potential within the breach. The information obtained will help identify and better understand the river discharge thresholds which contribute to frequent breaching as well as estimates of morphological evolution during breaching, which are currently unknown, and can assist in determining likelihood of successful managed breaching and closure events. </p>

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