scholarly journals Effects of Beach Nourishment Project on Coastal Geomorphology and Mangrove Dynamics in Southern Louisiana, USA

2021 ◽  
Vol 13 (14) ◽  
pp. 2688
Author(s):  
Marcelo Cancela Lisboa Cohen ◽  
Adriana Vivan de Souza ◽  
Kam-Biu Liu ◽  
Erika Rodrigues ◽  
Qiang Yao ◽  
...  
Keyword(s):  
Beach Nourishment ◽  
Tidal Flats ◽  
Avicennia Germinans ◽  
High Rate ◽  
Shoreline Retreat ◽  
Coastal Barrier ◽  
Sediment Volume ◽  
Waves And Currents ◽  
Crest Height ◽  
Dune Crest

Relative sea-level (RSL) rise associated with decreased fluvial sediment discharge and increased hurricane activity have contributed to the high rate of shoreline retreat and threatened coastal ecosystems in Port Fourchon, Louisiana, USA. This study, based on QuickBird/drone images (2004–2019) and LIDAR data (1998–2013), analyzed the impacts of shoreline dynamics on mangroves (Avicennia germinans) and marshes before and after the initiation of a beach nourishment project in 2013. The coastal barrier and dune crest migrated landward between 1998 and 2013. Meanwhile, the dune crest height increased between 1998 and 2001, then decreased in 2013, probably due to hurricane impacts. The total sediment volume along this sandy coastal barrier presented an overall trend of decline in the 1998–2013 period, resulting in a wetlands loss of ~15.6 ha along 4 km of coastline. This has led to a landward sand migration onto muddy tidal flats occupied by Avicennia germinans (1.08 ha) and Spartina (14.52 ha). However, the beach nourishment project resulted in the advancement of the beach barrier from Nov/2012 to Jan/2015, followed by a relatively stable period between Jan/2015 and Mar/2019. Additionally, both the dune crest height and sediment volume increased between 2013 and 2019. This set of factors favored the establishment and expansion of mangroves (3.2 ha) and saltmarshes (25.4 ha) along the backbarrier environments after 2013, allowing the tidal flats to keep pace with the RSL rise. However, waves and currents caused shoreline erosion following the beach nourishment project between Oct/2017 and Nov/2019, threatening wetlands by resuming the long-term process of shoreline retreat.

Coastal Engineering Analysis, Field Measurements, Numerical Modeling and Design for the Optimized Extension of the Beach in Ras Al-Ardh Area, Salmiya, Kuwait

2019 ◽  
Author(s):  
S. Neelamani ◽  
Bassam N. Shuhaibar ◽  
Khaled Al-Salem ◽  
Yousef Al-Osairi ◽  
Qusaie E. Karam ◽  
...  
Keyword(s):  
Numerical Modeling ◽  
Sandy Beach ◽  
Field Measurements ◽  
Beach Nourishment ◽  
Beach Sand ◽  
Design Parameters ◽  
Model Study ◽  
Sea Bed ◽  
Waves And Currents ◽  
Tourism Enterprises

Abstract Maintaining and retaining a quality sandy beach is a primary requirement for attracting people and tourists in any coastal country. Tourism Enterprises Company (TEC) in Kuwait owns 230 m long sandy beach in Ras Al-Ardh Sea Club, Salmiya, Kuwait. The beach has been eroding because of strong hydrodynamics forces from waves and currents. TEC wants to develop a stable sandy beach of 30 m wide. Kuwait Institute for Scientific Research (KISR), Kuwait is assigned to carry out the required scientific studies. In order to make sure a stable quality beach will exist, KISR has carried out the needed studies, which involves the field measurements such as bbathymetry survey, current and tidal variations, physical characteristics of beach soil, beach and sea bed profile, establishing the design parameters such as waves, currents, tide and wind. Hydrodynamic model study using DELFT3D model for the present and for the proposed extended groin conditions with beach nourishment were carried out. Also numerical modeling using GENESIS model to understand the future shore line changes due to the proposed development was carried out. Design of Groins to estimate the weight of armor units and weight of inner layers were carried out. The particle size and quantity of sand needed for reclamation of 30 m wide beach was estimated. Based on the study, it is recommended that the sandy soil to be used for 30 m wide beach nourishment should have D50 greater than 0.42 mm (say 0.5 mm) and D10 greater than 0.25 mm. The borrow pit much be selected by keeping this soil characters in mind. It is recommended to use a submerged offshore breakwater in order to retain the beach sand in place and for reducing the maintenance nourishment. Otherwise, large quantity of the capital nourished beach sand will escape into the deeper water due to strong current coupled with waves and steep seabed slopes. Environmental Impact Study was carried out as per Kuwait Environment Public Authority requirements to bring out the impacts due to beach filling and the construction submerged offshore barrier and extension of east groin for a distance of 30 m. TEC will implement the recommendations for developing the beach in Ras Al-Ardh sea club and will be useful to attract more people to use this beach.

scholarly journals DYNAMICS AND MORPHOLOGY OF SAND BANKS IN THE SURF ZONE OF OUTER TIDAL FLATS

1974 ◽  
Vol 1 (14) ◽  
pp. 50
Author(s):  
Harald Gohren
Keyword(s):  
North Sea ◽  
Surf Zone ◽  
Tidal Flats ◽  
Wind Drift ◽  
Side Slope ◽  
Set Up ◽  
Strong Erosion ◽  
Crest Height ◽  
Sea Coast ◽  
North Sea Coast

Extended sand banks ranging up to some hundred acres with a crest height in the MHW-level are typical structures of the outer tidal flats of the south-eastern North Sea coast (Fig. 1). Primary forms grow up in the surf zone at the sea-side tidal flat border. They are formed like bars and migrate towards the coast with a surprisingly high velocity, up to 150 m/year. The movement is caused by strong erosion on the sea-side slope - which is shaped beach-like - and deposition at the steeper land-side (lee-side) slope. It was found that surf action at the bar is linked with strong unidirectional currents across the crest, Up to 100 cm/s. The currents are most likely generated by wave set-up in front of the bank and by wind-drift water motion.

scholarly journals Laboratory Investigation on the Evolution of a Sandy Beach Nourishment Protected by a Mixed Soft–Hard System

Water ◽  
2018 ◽  
Vol 10 (9) ◽  
pp. 1171 ◽  
Author(s):  
Alessandra Saponieri ◽  
Nico Valentini ◽  
Marcello Di Risio ◽  
Davide Pasquali ◽  
Leonardo Damiani
Keyword(s):  
Sediment Transport ◽  
Sandy Beach ◽  
Surf Zone ◽  
Drainage System ◽  
Beach Nourishment ◽  
Mixed Solution ◽  
Shoreline Retreat ◽  
Submerged Breakwater ◽  
Positive Effects ◽  
The Mean

A new experimental campaign on a 2D movable-bed physical model, reproducing a typical nourishment sandy beach profile, is being carried out in the wave flume of the Laboratory of Coastal Engineering at Politecnico di Bari (Bari, Italy). The main aim is to assess the short-term evolution of a sandy beach nourishment, relying on a mixed solution built on the deployment of a Beach Drainage System (BDS) and a rubble-mound detached submerged breakwater. This paper aims at illustrating the experimental findings. Tests presented herein deal with both unprotected and protected configurations, focusing on the hydrodynamic and morphodynamic processes under erosive conditions. Results show that, with respect to the unprotected conditions, BDS reduces the shoreline retreat and the beach steepen within swash and surf zone as well. Moreover, a reduction of net sediment transport rate is observed. When BDS is coupled with the submerged sill, a reversal of the prevalent direction of the net sediment transport seaward occurs offshore the sheltered region. Less considerable positive effects on shoreline retreat are induced by the submerged structure, whereas the mean beach slope remains quite stable. Secondary effects of drain on the submerged sill performance are also highlighted. BDS reduces wave-induced setup on beach, by mitigating the mean water level raising, typically experienced by such structures.

Macroalgae and seagrass contribution to gastropods in sub-tropical and temperate tidal flats

2008 ◽  
Vol 89 (2) ◽  
pp. 399-404 ◽  
Author(s):  
Hideyuki Doi ◽  
Masatoshi Matsumasa ◽  
Mamoru Fujikawa ◽  
Keiichi Kanou ◽  
Takao Suzuki ◽  
...  
Keyword(s):  
Stable Isotopes ◽  
Benthic Communities ◽  
Tidal Flats ◽  
Food Sources ◽  
Snail Species ◽  
Terrestrial Plants ◽  
Gastropod Species ◽  
High Productivity ◽  
Intertidal Flats ◽  
Waves And Currents

Macroalgal and seagrass communities are widely distributed in marine and brackish shallow water and have high productivity. The primary production in marine costal areas is often transported to intertidal flats by waves and currents and beached on the flats. Thus, we hypothesized that the macroalgae and seagrasses are food sources for benthic communities on intertidal flats where some gastropod species often dominate. We performed comparisons of food sources among different gastropod species on sub-tropical and temperate tidal flats (26° and 38°N, respectively), and used isotope mixing models using carbon and nitrogen stable isotopes. A mixing model for stable isotopes, IsoSource, revealed that main food sources for three snails were macroalgae (50–56%) and seagrass (39–45%) at the temperate site. The contributions of terrestrial plants, sediment organic matter and benthic microalgae were weaker than those of macroalgae and seagrasses. At the sub-tropical site, snails fed mainly on macroalgae. The differences in food sources between snail species were not remarkable, although the nitrogen values were slightly different. It would thus appear that macroalgae and seagrass play an important role in the food webs not only in their own habitats but also on the adjacent tidal flats.

Mud Cracks and Polygons on Ice Push Ridges, in Tidal Flats of the St. Lawrence Estuary

1974 ◽  
Vol 11 (3) ◽  
pp. 489-494 ◽  
Author(s):  
Jean-Claude Dionne
Keyword(s):  
Water Level ◽  
Tidal Flats ◽  
The South ◽  
Lawrence Estuary ◽  
Waves And Currents ◽  
South Shore ◽  
Break Up ◽  
St Lawrence Estuary

Mud cracks and polygons form during summer in tidal flats of the south shore of the St. Lawrence Estuary. They occur near mean low water level at the top surface of ice push mud ridges formed during winter and break-up. They are a source of mud clasts which settle in the surroundings when carried away by waves and currents.

scholarly journals Estimation of Sediment Distribution Based on Bathymetry Alteration (2014-2016) in the Inner Bay of Ambon, Maluku, Indonesia

Jurnal Segara ◽  
2019 ◽  
Vol 15 (2) ◽  
Author(s):  
Guntur Adhi Rahmawan ◽  
Wisnu Arya Gemilang ◽  
Ulung Jantama Wisha ◽  
Ruzana Dhiauddin ◽  
Koko Ondara
Keyword(s):  
Water Depth ◽  
Marine Ecosystem ◽  
High Rate ◽  
Sediment Distribution ◽  
Single Beam ◽  
Sediment Volume ◽  
Water Region ◽  
Position Data ◽  
The Difference ◽  
2D And 3D

The development of Ambon city is centered around Ambon Bay. As the major area of marine and social activities, changes occurred directly affect to the degraded of the bay water region. Sedimentation is the major issue that has been occurring. Marine ecosystem can be potentially disrupted by the high rate of sedimentation in the Inner Bay of Ambon (TAD). This study aims to determine the distribution of sediment volume within the bay. Bathymetry of TAD was surveyed by using transducer (Echosounder Echo track CVM Teledyne Odom Hydrographic Single Beam), which the depth of certain position was connected to GPS to record all the position data accurately. The field data are then analyzed spatially modelled in the form of 2D and 3D maps, overlaid with the past bathymetry data to calculate the difference between water depth and sediment volume during that period (2014-2016). The depth of TAD in 2014 ranged between 0 – -42 meters, whilst, in 2016 the water depth slightly changed to 0 – -44 meters. The reduction of the water depth is observed in the 25 – 125 m from shoreline, where the bed thickness alteration observed ranged from 0.1 - 1.4 m. Total volume of sediment augmentation reached 13,236,182 m3 that covers about 67.67 Ha. Tidal current speed ranged averagely from 0-1.2 m/s which has a tremendous influence on sediment transport in TAD. The bay mouth that is funnel-shaped enclosed area triggers a high transport mechanism on its surrounding. If ongoing, these conditions may endanger the environment and biota survival ability.

Holocene sedimentary infilling of a tide-dominated estuarine mouth. The example of the macrotidal Seine estuary (NW France)

2010 ◽  
Vol 181 (2) ◽  
pp. 87-98 ◽  
Author(s):  
Bernadette Tessier ◽  
Nicolas Delsinne ◽  
Philippe Sorrel
Keyword(s):  
Sea Level Rise ◽  
Sea Level ◽  
Late Holocene ◽  
High Energy ◽  
High Rate ◽  
Seine River ◽  
Incised Valley ◽  
Fine Grained ◽  
Coastal Barrier ◽  
Seismic Reflection Profiles

Abstract The results of a seismo-stratigraphic study performed to study the Holocene sedimentary infilling at the mouth of the Seine River are presented. Combined data comprise very high resolution seismic reflection profiles, vibrocores, up to 4.5 m long, radiocarbon dating and old bathymetric charts. The infill is divided into two main stages: the transgressive systems tract, relative to the early Holocene high rate of sea-level rise, from 9000 to 7000 cal B.P., made of fine-grained, organic-rich, tidal flat to swamp deposits; the highstand systems tract, relative to the middle to late Holocene low rate of sea-level rise, from 7000 to 3000 cal B.P., characterized by the development of the high energy estuarine body above the main axis of the incised valley. Simultaneously, on the southern edge of the valley, a coastal barrier constructed above a bedrock plateau under the dominant action of waves. At 3000 cal B.P., probably in relation to a major climatic deterioration, the destruction of the barrier occurred and the tidal estuarine body expanded finally over the whole incised valley area. The rate of sea-level rise and the bedrock morphology appear to be the two main key-factors that control the sedimentary infilling architecture of this macrotidal, tide-dominated estuarine setting at the pluri-millenium Holocene time scale. Also, rapid climate changes determine part of the infill pattern, especially during the late Holocene sea-level highstand context.

Structure of Palladium Single-Crystal Films Prepared by Flash Evaporation onto (001) NaCl Substrates

1970 ◽  
Vol 28 ◽  
pp. 456-457
Author(s):  
L. E. Murr ◽  
G. Wong
Keyword(s):  
Single Crystal ◽  
High Vacuum ◽  
Ultra High Vacuum ◽  
High Rate ◽  
Flash Evaporation ◽  
Optimum Load ◽  
Single Crystal Films ◽  
Crystal Films ◽  
A Current

Palladium single-crystal films have been prepared by Matthews in ultra-high vacuum by evaporation onto (001) NaCl substrates cleaved in-situ, and maintained at ∼ 350° C. Murr has also produced large-grained and single-crystal Pd films by high-rate evaporation onto (001) NaCl air-cleaved substrates at 350°C. In the present work, very large (∼ 3cm2), continuous single-crystal films of Pd have been prepared by flash evaporation onto air-cleaved (001) NaCl substrates at temperatures at or below 250°C. Evaporation rates estimated to be ≧ 2000 Å/sec, were obtained by effectively short-circuiting 1 mil tungsten evaporation boats in a self-regulating system which maintained an optimum load current of approximately 90 amperes; corresponding to a current density through the boat of ∼ 4 × 104 amperes/cm2.

Rapid Freezing of Freeze-Etch Specimens

1980 ◽  
Vol 38 ◽  
pp. 752-755
Author(s):  
A. Elgsaeter ◽  
T. Espevik ◽  
G. Kopstad
Keyword(s):  
Low Temperature ◽  
Metal Surface ◽  
Relative Velocity ◽  
Thermal Contact ◽  
High Rate ◽  
Rapid Freezing ◽  
Temperature Decrease ◽  
Freeze Etching

The importance of a high rate of temperature decrease (“rapid freezing”) when freezing specimens for freeze-etching has long been recognized1. The two basic methods for achieving rapid freezing are: 1) dropping the specimen onto a metal surface at low temperature, 2) bringing the specimen instantaneously into thermal contact with a liquid at low temperature and subsequently maintaining a high relative velocity between the liquid and the specimen. Over the last couple of years the first method has received strong renewed interest, particularily as the result of a series of important studies by Heuser and coworkers 2,3. In this paper we will compare these two freezing methods theoretically and experimentally.

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