scholarly journals Determination of Net Sediment Transport Patterns in Lirquén Harbor, Chile, Through Grain-size Trend Analysis: A Test Of Methods

2003 ◽  
Vol 30 (1) ◽  
pp. 65 ◽  
Author(s):  
FELIPE RÍOS ◽  
RAÚL ULLOA ◽  
IRAN CARLOS STALLIVIERE CORRÊA
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Transport Processes ◽  
Geographical Information ◽  
Aerial Photographs ◽  
Poor Correlation ◽  
Dispersal Patterns ◽  
Transport Pathways ◽  
South Central ◽  
Transport Patterns

During June 1997, bottom sediment samples were collected at 76 stations on a rectangular grid in a small port (Lirquén Harbor, south-central Chile) facing siltation problems. The spatial changes in grain-size parameters, analyzed by using three different methodologies to infer net sediment transport paths, are compared with the measured water circulation of the study area and sediment dispersal patterns on aerial photographs. A Geographical Information System (GIS) is used to determine the degree of similarity between the results of the three grain-size trend methodologies. The results of this study confirm that because of its formulation and underlying assumptions, the McLaren-Bowles methodology tends to confuse the space-scale of sediment transport processes. In this way, the obtained transport patterns are in poor correlation with the observed hydrodynamics and aerial photographs and they seem to represent a combination of the spatial macroscale and mesoscale sediment transport processes existing in Concepcion Bay and in Lirquén Harbor, respectively. On the contrary, because the results yielded by the Gao-Collins and Le Roux methodologies correlate well with these studies, it is suggested that both methodologies be applied in combination to allow a better representation of local net sediment transport patterns, especially in estuarine environments where multiple sediment sources exist. Spatial analysis suggests that transport pathways obtained through these two methodologies represent the mesoscale sediment circulation existing in Lirquén Harbor. This study also emphasizes the importance of applying a statistical test to the transport trend vectors obtained using the GSTA program of Gao (1996), as these may erroneously reflect sediment transport direction. Lastly, the analyzed data and the results of the models are combined to determine the sediment transport regime existing in Lirquén Harbor.

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

scholarly journals Sediment transport processes across the Tibetan Plateau inferred from robust grain-size end members in lake sediments

2014 ◽  
Vol 10 (1) ◽  
pp. 91-106 ◽  
Author(s):  
E. Dietze ◽  
F. Maussion ◽  
M. Ahlborn ◽  
B. Diekmann ◽  
K. Hartmann ◽  
...  
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Tibetan Plateau ◽  
Transport Processes ◽  
The Tibetan Plateau ◽  
Dust Deposition ◽  
Northerly Wind ◽  
Near Surface ◽  
Depositional Processes ◽  
End Members

Abstract. Grain-size distributions offer powerful proxies of past environmental conditions that are related to sediment sorting processes. However, they are often of multimodal character because sediments can get mixed during deposition. To facilitate the use of grain size as palaeoenvironmental proxy, this study aims to distinguish the main detrital processes that contribute to lacustrine sedimentation across the Tibetan Plateau using grain-size end-member modelling analysis. Between three and five robust grain-size end-member subpopulations were distinguished at different sites from similarly–likely end-member model runs. Their main modes were grouped and linked to common sediment transport and depositional processes that can be associated with contemporary Tibetan climate (precipitation patterns and lake ice phenology, gridded wind and shear stress data from the High Asia Reanalysis) and local catchment configurations. The coarse sands and clays with grain-size modes >250 μm and <2 μm were probably transported by fluvial processes. Aeolian sands (~200 μm) and coarse local dust (~60 μm), transported by saltation and in near-surface suspension clouds, are probably related to occasional westerly storms in winter and spring. Coarse regional dust with modes ~25 μm may derive from near-by sources that keep in longer term suspension. The continuous background dust is differentiated into two robust end members (modes: 5–10 and 2–5 μm) that may represent different sources, wind directions and/or sediment trapping dynamics from long-range, upper-level westerly and episodic northerly wind transport. According to this study grain-size end members of only fluvial origin contribute small amounts to mean Tibetan lake sedimentation (19± 5%), whereas local to regional aeolian transport and background dust deposition dominate the clastic sedimentation in Tibetan lakes (contributions: 42 ± 14% and 51 ± 11%). However, fluvial and alluvial reworking of aeolian material from nearby slopes during summer seems to limit end-member interpretation and should be crosschecked with other proxy information. If not considered as a stand-alone proxy, a high transferability to other regions and sediment archives allows helpful reconstructions of past sedimentation history.

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.

scholarly journals Passive acoustic measurement of bedload grain size distribution using self-generated noise

2018 ◽  
Vol 22 (1) ◽  
pp. 767-787 ◽  
Author(s):  
Teodor Petrut ◽  
Thomas Geay ◽  
Cédric Gervaise ◽  
Philippe Belleudy ◽  
Sebastien Zanker
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Size Distribution ◽  
Grain Size Distribution ◽  
Measurement Techniques ◽  
Bedload Transport ◽  
Transport Processes ◽  
Signal Spectrum ◽  
Inversion Method ◽  
Passive Acoustic

Abstract. Monitoring sediment transport processes in rivers is of particular interest to engineers and scientists to assess the stability of rivers and hydraulic structures. Various methods for sediment transport process description were proposed using conventional or surrogate measurement techniques. This paper addresses the topic of the passive acoustic monitoring of bedload transport in rivers and especially the estimation of the bedload grain size distribution from self-generated noise. It discusses the feasibility of linking the acoustic signal spectrum shape to bedload grain sizes involved in elastic impacts with the river bed treated as a massive slab. Bedload grain size distribution is estimated by a regularized algebraic inversion scheme fed with the power spectrum density of river noise estimated from one hydrophone. The inversion methodology relies upon a physical model that predicts the acoustic field generated by the collision between rigid bodies. Here we proposed an analytic model of the acoustic energy spectrum generated by the impacts between a sphere and a slab. The proposed model computes the power spectral density of bedload noise using a linear system of analytic energy spectra weighted by the grain size distribution. The algebraic system of equations is then solved by least square optimization and solution regularization methods. The result of inversion leads directly to the estimation of the bedload grain size distribution. The inversion method was applied to real acoustic data from passive acoustics experiments realized on the Isère River, in France. The inversion of in situ measured spectra reveals good estimations of grain size distribution, fairly close to what was estimated by physical sampling instruments. These results illustrate the potential of the hydrophone technique to be used as a standalone method that could ensure high spatial and temporal resolution measurements for sediment transport in rivers.

Grain size trends associated with net sediment transport patterns: An example from the Belgian continental shelf

1994 ◽  
Vol 121 (3-4) ◽  
pp. 171-185 ◽  
Author(s):  
S. Gao ◽  
M.B. Collins ◽  
J. Lanckneus ◽  
G. De Moor ◽  
V. Van Lancker
Keyword(s):  
Grain Size ◽  
Sediment Transport ◽  
Continental Shelf ◽  
Belgian Continental Shelf ◽  
Transport Patterns

scholarly journals ANALYSIS OF A BEACH QUALITY PROBLEM

1986 ◽  
Vol 1 (20) ◽  
pp. 108
Author(s):  
Gordon K. Prestedge ◽  
Christopher A. Fleming
Keyword(s):  
Sediment Transport ◽  
Transport Processes ◽  
Aerial Photographs ◽  
Quality Improvements ◽  
Quality Problem ◽  
Recreational Beaches ◽  
Aeolian Sediment

A study was recently undertaken to investigate sediment transport on a section of coastline where recreational beaches have experienced periodic erosion. Alongshore, onshore/offshore and aeolian sediment transport processes were investigated and quantitative transports predicted with the aid of calibration using surveys and aerial photographs. This paper describes the study and the recommendations proposed for beach quality improvements.

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