Space-Time Variations In Macrobenthic Fauna Of A Sandy Beach, Related To Changes In The Beach Profile And Sediment Grain Size, At El Pelícano Beach, Baja California

We have investigated beach stability against storm waves. The studies are done in relation to eroded beaches. We are testing a cobble-sand-gravel mixture as a means of using a soft method for coastal protection on nourished beaches. A physical model of an existing beach was built at scale 1:3. The cobble/sand grain size is in 1:3 scale while the gravel is 1:1.5 scale. The large scale experimental flume tests have been set-up in the new outdoor 120 m long flume in Québec city, Canada. The tests were conducted over two test seasons (2013–14). While we in the first test season studied impact on the beach due to incoming regular plunging breakers, the last season contained tests with incoming irregular plunging breakers on the beach with/without tidal variation. Herein, we primarily report on the wave impact due to irregular plunging breakers on constant and tidal varying water depths. The wave-tide interactions were conducted with a tidal range of 1 m in relation to beaches with steep beach slopes (1:10, 1:5, 1:1). The model inlet significant wave height was 1.1–1.5 m corresponding to equivalent prototype waves in the range of max. wave heights of 6–8.5 m with dominant periods of 12 s in water depth of about 15 m and tidal range of 3 m. In general, the Equilibrium Beach Profile (EBP) was reached after exposure to about 10,000 plunging breakers or the equivalent of five storms assuming each lasting 3 hours. A cobble berm was formed rapidly on the top of the beach, protecting the backshore against wave action and flooding while finer sediment was transported “offshore”. Beach width reduction was observed when the initial slope of the beach fill material exceeded the equilibrium beach slope. Sediment grain size sorting along the beach profile is discussed and compared to existing beach models, and EBP was compared to several EBP equations. From a coastal management perspective, in terms of durability, the mixed cobble-sand-gravel material is showing promise as a material to use for coastal protection. It is highly absorbent and the beach tends to maintain its shape over long time when exposed to several storms. However, storm surges in the combination with high tides can results in excessive run-up and potential flood risks. The stabilized beach typically had slopes of 1:7–1:9 independent of the initial slope. We found that irregular seas result in a less pronounced trough in the beach profile in the swash zone than incoming regular plunging breakers. The tidal interaction was further advantageous, naturally shifting the material back and forth. However, other materials and other sensitivity studies are necessary in order to provide firm conclusions about the usage of the cobble-gravel-sand mixture for coastal protection.

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Cross-shore profile and coastline changes of a sandy beach in Pieria, Greece, based on measurements and numerical simulation

Mediterranean Marine Science ◽

10.12681/mms.214 ◽

2004 ◽

Vol 5 (1) ◽

pp. 91 ◽

Cited By ~ 2

Author(s):

A.M. PROSPATHOPOULOS ◽

A. SOTIROPOULOS ◽

E. CHATZIOPOULOS ◽

CH. ANAGNOSTOU

Keyword(s):

Numerical Simulation ◽

Grain Size ◽

Simulation Model ◽

Field Data ◽

Sandy Beach ◽

Field Work ◽

Sediment Grain Size ◽

Sediment Analysis ◽

Coastline Evolution ◽

Coastal Changes

In the present work, the changes of cross-shore profile and the coastline of a sandy beach in Pieria, Greece, are studied by using topographic profiles, sediment analysis and a numerical simulation model. The work is motivated by the considerable erosion problems caused to an extended portion of the coast north of the studied area due to the construction of a craft shelter, and its scope is two-fold: to help in understanding the dynamics of the beach based on results of the field work and to proceed a step further, studying the responses of this beach by numerical simulation, utilizing the topographic and sediment field data and measured wave data. The study of the cross-shore profiles, as well as the sediment analysis of the samples obtained along the profiles, revealed the morphological features of the coast under study and provided information concerning the dynamic zones in each profile. The sediment grain size reduces from south to north, following the direction of the longshore currents generated in the area. The results of the numerical simulation concerning the coastline evolution are found to be in agreement with the qualitative estimations and visual observations of existing coastal changes to the broader area.

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Temporal and spatial relationship between sediment grain size and beach profile

Marine Geology ◽

10.1016/0025-3227(94)90083-3 ◽

1994 ◽

Vol 118 (3-4) ◽

pp. 195-206 ◽

Cited By ~ 34

Author(s):

R Medina ◽

M.A Losada ◽

I.J Losada ◽

C Vidal

Keyword(s):

Grain Size ◽

Spatial Relationship ◽

Beach Profile ◽

Sediment Grain Size ◽

Temporal And Spatial

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RECENT VARIATION IN SEDIMENT GRAIN SIZE IN THE MUD AREA OF CHANGJIANG SUBAQUEOUS DELTA AND ITS INFLUENCE FACTORS

Marine Geology & Quaternary Geology ◽

10.3724/sp.j.1140.2011.05009 ◽

2011 ◽

Vol 31 (5) ◽

pp. 9-16

Author(s):

Rui ZHANG ◽

Yaping WANG ◽

Jianhua GAO ◽

Shaoming PAN

Keyword(s):

Grain Size ◽

Influence Factors ◽

Sediment Grain Size ◽

Recent Variation ◽

Mud Area

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NUMERICAL PREDICTION OF SEDIMENT GRAIN SIZE DISTRIBUTION SUPPLIED FROM A SIMPLE DRAINAGE: DEATH VALLEY QUATERNARY FAN CASE STUDY

10.1130/abs/2020am-357377 ◽

2020 ◽

Author(s):

Todd Engelder ◽

Keyword(s):

Grain Size ◽

Size Distribution ◽

Grain Size Distribution ◽

Numerical Prediction ◽

Death Valley ◽

Sediment Grain Size ◽

Simple Drainage

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New Limit on Space-Time Variations in the Proton-to-Electron Mass Ratio from Analysis of Quasar J110325-264515 Spectra

Symmetry ◽

10.3390/sym12030344 ◽

2020 ◽

Vol 12 (3) ◽

pp. 344

Author(s):

T. D. Le

Keyword(s):

Fine Structure ◽

Structure Constant ◽

Space Time ◽

Fine Structure Constant ◽

Electron Mass ◽

Mass Ratio ◽

Quasar Spectra ◽

Time Variations ◽

Using Data ◽

The Universe

Astrophysical tests of current values for dimensionless constants known on Earth, such as the fine-structure constant, α , and proton-to-electron mass ratio, μ = m p / m e , are communicated using data from high-resolution quasar spectra in different regions or epochs of the universe. The symmetry wavelengths of [Fe II] lines from redshifted quasar spectra of J110325-264515 and their corresponding values in the laboratory were combined to find a new limit on space-time variations in the proton-to-electron mass ratio, ∆ μ / μ = ( 0.096 ± 0.182 ) × 10 − 7 . The results show how the indicated astrophysical observations can further improve the accuracy and space-time variations of physics constants.

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Centennial Impacts of the East Asian Summer Monsoon on Holocene Deltaic Evolution of the Huanghe River, China

Applied Sciences ◽

10.3390/app11062799 ◽

2021 ◽

Vol 11 (6) ◽

pp. 2799

Author(s):

Yanping Chen ◽

Wenzhe Lyu ◽

Tengfei Fu ◽

Yan Li ◽

Liang Yi

Keyword(s):

Grain Size ◽

Yellow River ◽

Asian Summer Monsoon ◽

River Delta ◽

Grain Size Analysis ◽

Size Analysis ◽

Sediment Grain Size ◽

Huanghe River ◽

Huanghe River Delta ◽

The Huanghe River

The Huanghe River (Yellow River) is the most sediment laden river system in the world, and many efforts have been conducted to understand modern deltaic evolution in response to anthropological impacts. However, the natural background and its linkage to climatic changes are less documented in previous studies. In this work, we studied the sediments of core YDZ–3 and marine surface samples by grain-size analysis to retrieve Holocene dynamics of the Huanghe River delta in detail. The main findings are as follows: The mean value of sediment grain size of the studied core is 5.5 ± 0.9 Φ, and silt and sand contents are 5.2 ± 2.3% and 8.2 ± 5.3%, respectively, while the variance of clay particles is relatively large with an average value of 86.4 ± 8.5%. All grain-size data can be mathematically partitioned by a Weibull-based function formula, and three subgroups were identified with modal sizes of 61.1 ± 28.9 μm, 30.0 ± 23.9 μm, and 2.8 ± 1.6 μm, respectively. There are eight intervals with abrupt changes in modal size of core YDZ–3, which can be correlated to paleo-superlobe migration of the Huanghe River in the Holocene. Based on these observations, the presence of seven superlobes in the history are confirmed for the first time and their ages are well constrained in this study, including Paleo-Superlobes Lijin (6400–5280 yr BP), Huanghua (4480–4190 yr BP), Jugezhuang (3880–3660 yr BP), Shajinzi (3070–2870 yr BP), Nigu (2780–2360 yr BP), Qikou (2140–2000 yr BP), and Kenli (1940–1780 and 1700–1650 yr BP). By tuning geomorphological events to a sedimentary proxy derived from core YDZ–3 and comparing to various paleoenvironmental changes, we proposed that winter climate dominated Holocene shifts of the Huanghe River delta on millennial timescales, while summer monsoons controlled deltaic evolution on centennial timescales.

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East Asian winter monsoon variation during the last 3000 years as recorded in a subtropical mountain lake, northeastern Taiwan

The Holocene ◽

10.1177/09596836211019094 ◽

2021 ◽

pp. 095968362110190

Author(s):

Tsai-Wen Lin ◽

Stefanie Kaboth-Bahr ◽

Kweku Afrifa Yamoah ◽

André Bahr ◽

George Burr ◽

...

Keyword(s):

Grain Size ◽

East Asian Winter Monsoon ◽

East Asian ◽

Winter Monsoon ◽

Mountain Lake ◽

Sediment Grain Size ◽

Global Monsoon ◽

Asian Winter Monsoon ◽

The Past ◽

Monsoon System

The East Asian Winter Monsoon (EAWM) is a fundamental part of the global monsoon system that affects nearly one-quarter of the world’s population. Robust paleoclimate reconstructions in East Asia are complicated by multiple sources of precipitation. These sources, such as the EAWM and typhoons, need to be disentangled in order to understand the dominant source of precipitation influencing the past and current climate. Taiwan, situated within the subtropical East Asian monsoon system, provides a unique opportunity to study monsoon and typhoon variability through time. Here we combine sediment trap data with down-core records from Cueifong Lake in northeastern Taiwan to reconstruct monsoonal rainfall fluctuations over the past 3000 years. The monthly collected grain-size data indicate that a decrease in sediment grain size reflects the strength of the EAWM. End member modelling analysis (EMMA) on sediment core and trap data reveals two dominant grain-size end-members (EMs), with the coarse EM 2 representing a robust indicator of EAWM strength. The downcore variations of EM 2 show a gradual decrease over the past 3000 years indicating a gradual strengthening of the EAWM, in agreement with other published EAWM records. This enhanced late-Holocene EAWM can be linked to the expansion of sea-ice cover in the western Arctic Ocean caused by decreased summer insolation.

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