Morphosedimentary and ecosystem evolution at Belharucas beach after a sand nourishment (Algarve, south Portugal)

2021 ◽  
Author(s):  
Teresa Drago ◽  
Sebastião Teixeira ◽  
Marcos Rosa ◽  
Miriam Tuaty-Guerra ◽  
Maria José Gaudêncio ◽  
...  
Keyword(s):  
Grain Size ◽  
Beach Nourishment ◽  
Control Area ◽  
Morphological Data ◽  
Beach Profile ◽  
Profile Data ◽  
Integrity Assessment ◽  
Emergency Situations ◽  
Sand Nourishment ◽  
South Portugal

<p>Beach nourishment is an increasingly recommended solution for reversing the erosion process that affects nowadays the coastal zone. Usually, it is used in emergency situations as a local and short-term solution or as a regional and long-term management strategy.</p><p>From April 2017 to November 2019, sediment samples and beach profile data were collected seasonally, before and after a sand nourishment (100.000m<sup>3</sup>) that increased 30m of width in Belharucas beach (south Portugal, Algarve).</p><p>The main objective of the work was to evaluate the nourishment impact in the beach ecosystem, aiming at contributing to seafloor integrity assessment, in the scope of Descriptor 6 of the Marine Strategy Framework Directive. </p><p>Methodology included grain size and macrobenthic fauna analyses in two profiles of the nourished area and another one further away, selected as a control area. Each profile was sampled at three intertidal zones: supralittoral (beach berm), mediolittoral (beach face) and infralittoral (low tide terrace).  Beach profile data were collected with the main objective of measuring the beach width and evaluate nourishment longevity.</p><p>Results show that grain size variability, higher at beach face, is dominated by local energy beach conditions rather than to changes related to the nourishment.</p><p>Morphological data shows that beach nourishment had a relatively low longevity as two years after the nourished beach present roughly the same width as priori to nourishment.</p><p>While supralittoral samples were defaunated, medio and infralittoral ones exhibited extremely low diversity. Assemblages were dominated by small-size polychaetes, bivalves and isopods. No statistically significant differences were found in assemblage composition regarding pre- and post-sand nourishment, year seasons, tidal zones and control stations.</p><p>In conclusion, Belharucas beach exhibited high resilience to the sand nourishment, preserving its morphodynamics and ecosystem conditions.</p><p> </p><p>The authors would like to acknowledge the financial support FCT through project UIDB/50019/2020 – IDL and through the strategic project UIDB/MAR/04292/2019 - MARE and ECOEXA project (MAR-01.04.02-FEAMP-0016)</p>

scholarly journals Benthic microalgae under the influence of beach nourishment in the Gulf of Odessa (the Black Sea)

2013 ◽  
Vol 19 (2) ◽  
pp. 120-128 ◽  
Author(s):  
Anastasiya Snigirova
Keyword(s):  
Grain Size ◽  
Black Sea ◽  
Beach Nourishment ◽  
Fine Sand ◽  
Benthic Microalgae ◽  
The Black Sea ◽  
Shore Protection ◽  
The North ◽  
Sand Nourishment ◽  
Sand Grain Size

Abstract Snigirova A., 2013: Benthic microalgae under the influence of beach nourishment in the Gulf of Odessa (the Black Sea) [Paplūdimių papildymo smėliu poveikis bentosinių dumblių bendrijoms Odesos įlankoje (Juodoji jūra)]. - Bot. Lith., 19(2): 120-128. The coast of the Gulf of Odessa (Odessa Bay) in the north-western part of the Black Sea is exposed to abrasive processes, which lead to its destruction. One of the measures for landslides stabilization is sand nourishment, which was held on the beach of the gulf in October 2007. As a result of shore protection works, the sand grain size on the beaches of Odessa has decreased by 53% on average. The influence of sand grain size on the abundance and biomass of benthic microalgae was investigated. Benthic microalgae were presented mostly by Bacillariophyta and Dinophyta. Other groups of Chlorophyta, Cyanophyta and Cryptophyta were less presented. The abundance and biomass of algae increased threefold and fourfold, accordingly, as a result of sand nourishment. Significant influence of fine sand particles on the biomass and abundance of microalgae was revealed. However, the structure of algological assemblages changed because of the increase of mixotrophic groups of algae contribution.

scholarly journals THE EFFECTIVE METHOD OF BEACH NOURISHMENT PLACEMENT

2018 ◽  
pp. 66
Author(s):  
Hyun Dong Kim ◽  
Shin-ichi Aoki ◽  
Nobuhisa Kobayashi ◽  
Susumu Onaka
Keyword(s):  
Grain Size ◽  
Environmental Impacts ◽  
Sandy Beach ◽  
Beach Nourishment ◽  
Vicious Circle ◽  
Erosion Effect ◽  
Sand Nourishment ◽  
Incident Waves ◽  
Economical Alternative

When erosion occurs, sandy beach cannot maintain the sufficient sand width and the foreshore slope becomes steeper by the frequent erosion effect. As a result, the beach is trapped in a vicious circle of becoming vulnerable by the incident waves. In order to repair or protect the erosive beach, beach nourishment can be used as a countermeasure while minimizing the environmental impacts. However, beach nourishment is not a permanent solution and requires periodic renourishment after several years. To alleviate such problem, minimizing the period of renourishment must be an economical alternative. In that respect, selecting the optimum grain size of the sand for the beach nourishment is very important. Generally, larger grain sized sand is more resistant to the erosion, thus extending the period of renourishment. In addition to selecting the optimum grain size of the sand nourishment, determining the durability as well as maintaining the familiarity of the users of the native sand should be considered.

scholarly journals Evaluation of Effect of Beach Nourishment Considering Grain Size on Chigasaki Coast

2007 ◽  
Vol 54 ◽  
pp. 631-635
Author(s):  
Takaaki UDA ◽  
Genji AOSHIMA ◽  
Takumi YAMANO ◽  
Atsushi YOSHIOKA ◽  
Kou FURUIKE ◽  
...  
Keyword(s):  
Grain Size ◽  
Beach Nourishment

An Experimental Study of Changes of Beach Profile and Mean Grain Size Caused by Tsunami-Like Waves

2012 ◽  
Vol 284 ◽  
pp. 1303-1312 ◽  
Author(s):  
Jie Chen ◽  
Zhenhua Huang ◽  
Changbo Jiang ◽  
Bin Deng ◽  
Yuannan Long
Keyword(s):  
Experimental Study ◽  
Grain Size ◽  
Beach Profile ◽  
Mean Grain Size

Large Scale Experimental Storm Impact on Nourished Beach Using Cobble-Gravel-Sand Mix

2015 ◽  
Author(s):  
Jannette B. Frandsen ◽  
Régis Xhardé ◽  
Francis Bérubé ◽  
Olivier Gauvin Tremblay
Keyword(s):  
Grain Size ◽  
Large Scale ◽  
Tidal Range ◽  
Initial Slope ◽  
Coastal Protection ◽  
Quebec City ◽  
Beach Profile ◽  
Wave Impact ◽  
Sediment Grain Size ◽  
Sand Mixture

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.

The intertidal sanding up of the Seine-Maritime coast (Normandy, France): Sedimentological and geochemical approaches.

2020 ◽  
Author(s):  
Bastien Peuziat ◽  
Stéphane Costa ◽  
Bernadette Tessier ◽  
Anne Murat ◽  
Gwendoline Gregoire
Keyword(s):  
Grain Size ◽  
Chemical Elements ◽  
Statistical Processing ◽  
Fluorescence Analysis ◽  
Coarse Grained ◽  
Tidal Range ◽  
Geochemical Data ◽  
Beach Profile ◽  
Littoral Drift ◽  
Geochemical Parameters

<p>The Seine-Maritime coastline (France) is a macro-tidal environment (8 m tidal range), developing along an epicontinental sea, the English Channel. The SW-NE coast is opened to westerly atmospheric flows, generating occasionally wind sea with energetic waves (Hs: 4.65 m decennial return). High chalk cliffs and a wide marine erosion platform partially hidden on its upper part by a flint pebble beach, characterise this 130 km long coast.</p><p>Observations since the end of the 1990’s show a recent and massive sanding up of the marine erosion platform. This raises the question of the origin of the sandy fraction and the sedimentary dynamics on the intertidal area.</p><p>We present herein an innovative method that combine grain-size and geochemical analysis in order to highlight sand sources and transport direction along these rocky coast.</p><p>Sixteen beaches were sampled during low tide and fair-weather conditions. At each site, 3 samples were collected along the cross-shore beach profile (from the pebbly upper beach to the low tide limit).</p><p>Grain-size results show that for all sites, medium to coarse-grained sands dominate in the upper beach (mode 315-400µm) while fine sands dominate in the middle and low foreshore (mode 160-250µm). A decrease in grain-size is thus evidenced from the upper beach to the low foreshore.</p><p>The geographical variability of the sand composition and consequently sources was determined on the basis of geochemical data. In order to avoid the granulometric effect on the data, X-Ray fluorescence analysis (xSORT, SPECTRO AMETEK) were performed on the two major grain-size modes of each sample. Eighteen calibrated chemical elements (Si, S, K, Ca, Ti, V, Mn, Fe, Ni, Ga, As, Br, Rb, Sr, Y, Pb, Th and U) were measured at each station. Statistical processing performed step by step on the data allows to gradually reduce the number of significant geochemical parameters. Finally, 4 major elements (Si, Ca, Sr, K) as well as the ratio Sr/Ca have been considered as the best proxies of sample discrimination and potential source.</p><p>The first results indicate a longshore gradient of Si and Ca, especially for the finest sands (160-200µm). From SW to NE, i.e. in the direction of the littoral drift, and whatever the position across the beach profile, there are an enrichment in Si (sands are more siliciclastic) and an impoverishment in Ca.</p><p>This gradient highlights differentiated longshore sediment transport and sorting, in relation probably with sediment sources (siliclastic sands vs bioclastics sands).</p>

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