scholarly journals ESTUftRINE RESPONSE TO DREDGING IN THE TWEED RIVER, AUSTRALIA

1980 ◽  
Vol 1 (17) ◽  
pp. 96
Author(s):  
Bruce M. Druery
Keyword(s):  
Sediment Transport ◽  
Field Measurements ◽  
Gold Coast ◽  
Lower Estuary ◽  
Sediment Routing ◽  
Marine Sand ◽  
Tidal Hydraulics ◽  
The Impact ◽  
Hydraulic Processes

Between mid 1974 and mid 1975,760,000 m3 of sand was dredged from the bed of the Tweed River for the purpose of nourishing cyclone damaged beaches of the Gold Coast (Queensland). A comprehensive field data programme was established in 1976 to record the changes in the hydraulic processes of the Tweed River brought about by the dredging. The field measurements demonstrated that the dredged area was being infilled with sediments of both marine and estuarine origin. The dredging increased tidal ranges throughout the lower estuary, the effect being more pronounced at low water. Sediment bedload rates were estimated from detailed measurements of bedforms and used to calibrate a sediment transport formula. The formula was used in conjunction with a 1 Dim. numerical model of tidal hydraulics to simulate estuarine shoal dynamics by means of a simple sediment routing technique. The results showed that the dredging had altered the tidal hydrodynamics so as to enhance the ebb transport of sediment towards the dredged hole. In the long term it was found that the sediment transport switched to a weak net upstream movement of sediment. The detailed hydraulic mechanisms involved are discussed. The study demonstrates that the impact of dredging can be minimised by location upstream of the entrance plug of marine sand.

Climate change impact on NW Shelf seabed evolution and its implication for offshore pipeline design

2008 ◽  
Vol 48 (1) ◽  
pp. 171 ◽  
Author(s):  
Fangjun Li ◽  
Cedric Griffiths ◽  
Tristan Salles ◽  
Chris Dyt ◽  
Ming Feng ◽  
...  
Keyword(s):  
Climate Change ◽  
Sediment Transport ◽  
High Energy ◽  
Change Scenario ◽  
Seabed Sediment ◽  
Impact Of Climate Change ◽  
Offshore Pipeline ◽  
Pipeline Design ◽  
The Impact

In this paper, the impact of climate change on seabed sediment transport in the north-western region of the Australian Exclusive Economic Zone (EEZ) has been investigated by a state-of-the-art numerical sediment transport model, Sedsim. It links the environmental forces and seabed response into a dynamic sedimentation system. Although numerical implementation of some forcing and responses is approximate, it is a significant step forward in understanding the nature of potential long-term seabed changes as well as in evaluating the likely impact of climate change on the northwest Australian continental shelf. It was found that: the modelled high-energy climate change scenario produced 17% and 38% increases on total volumes of seabed transport in the northern and southern part of the Australian northwest region respectively; the Indonesian ThroughFlow (ITF), the Leeuwin Current (LC) and high energy waves (associated with tropical cyclones) play the most important roles in large-scale long-term evolution of the NW seafloor; offshore pipeline design could usefully incorporate the changed risk profiles due to long-term non-stationarity of climate-derived forcing processes.

scholarly journals The Impact of Submerged Breakwaters on Sediment Distribution along Marsh Boundaries

Water ◽  
2020 ◽  
Vol 12 (4) ◽  
pp. 1016 ◽  
Author(s):  
Iacopo Vona ◽  
Matthew Gray ◽  
William Nardin
Keyword(s):  
Salt Marsh ◽  
Sediment Transport ◽  
Wave Breaking ◽  
Sediment Trapping ◽  
Sediment Distribution ◽  
Design And Implementation ◽  
Study Results ◽  
Average Wave ◽  
The Impact

Human encroachment and development on coastlines have led to greater amounts of armoring of shorelines. Breakwaters are a common feature along coastlines, which are used to dampen wave energy and protect shorelines from flash floods or overwash events. Although common, their effects on sediment transport and marsh geomorphology are poorly understood. To address this gap, our study quantifies the effects of breakwaters on sediment transport and marsh evolution under different wave regimes using Delft3D-SWAN, a dynamic geomorphodynamic numerical model. Model configurations used the same numerical domain, but scenarios had different sediments, waves, tides, basin slopes and breakwater distances from the shoreline to explore how waves and tidal currents shape coastal margins. Model results suggested breakwaters were responsible for an average wave damping between 10–50%, proportional to the significant wave height across all modeled scenarios. Shear stress at the beginning of the marsh and the volume of sediment deposited at the end of the simulation (into the marsh behind the breakwater) increased on average between 20–40%, proportional to the slope and distance of the breakwater from the shoreline. Sediment trapping, defined as the ratio between the volume of sediment housed into the salt marsh behind and away from the breakwater, was found to be less than 1 from most model runs. Study results indicated that breakwaters are advantageous for wave breaking to protect shorelines from the wave’s energy, however, they might also be an obstacle for sediment transport, negatively affecting nourishment processes, and, consequently, impeded long-term salt marsh survival. Identifying a balance between waves dampening and shoreline nourishment should be considered in the design and implementation of these structures.

scholarly journals MODELLING OF THE IMPACT OF A WAVE FARM ON NEARSHORE SEDIMENT TRANSPORT

2012 ◽  
Vol 1 (33) ◽  
pp. 66 ◽  
Author(s):  
Raul Gonzalez ◽  
Qingping Zou ◽  
Shunqi Pan
Keyword(s):  
Sediment Transport ◽  
Large Scale ◽  
Morphological Changes ◽  
Field Measurements ◽  
Integrated Modelling ◽  
Shear Stresses ◽  
Nearshore Sediment Transport ◽  
Wave Farm ◽  
The Impact ◽  
Modelling System

This paper presents the results from an integrated modelling system investigating the effects of a wave farm on nearshore sediment transport. Wave Hub project is a large scale demonstration site for the development of the operation of arrays of wave energy generation devices located at the southwest coast of the UK where multiple field measurements took place. The two-way coupled SWAN and ROMS models with nested modelling system were set up at the Wave Hub site and run with and without a wave farm. The model results show that the presence of the wave farm has significant impacts on the nearshore circulation, bed shear stresses and sediment transport. The morphological changes are also altered by the wave farm. The study is the key element for the wave resource characterization and environmental impact assessment of the wave farm.

The impact of hydropeaking on sediment transport

2021 ◽  
Author(s):  
Daniel Buček ◽  
Martin Orfánus ◽  
Peter Dušička ◽  
Peter Šulek
Keyword(s):  
Sediment Transport ◽  
Renewable Energy Sources ◽  
Field Measurements ◽  
Bedload Transport ◽  
Hydropower Plant ◽  
Energy Sources ◽  
Hydropower Plants ◽  
Daily Scale ◽  
Flexible Management ◽  
The Impact

AbstractVariable renewable energy sources, e.g. solar and wind power, require flexible management of energy sources to stabilize the power grid. Immediate changes in power generation and power usage is compensated for by the operation of hydropower plants. This subsequently leads to frequent flow fluctuations – hydropeaking downstream of the hydropower plant. This study examines the short-term impacts of hydropeaking of hydropower plants on the sediment transport using numerical morphodynamic model. The model is calibrated to field measurements and subjected to various hydropeaking scenarios on daily to sub-daily scale. Based on this study, the effect of hydropeaking of hydropower plant 23.42 km upstream of the studied river section would have negligible effect on the bedload transport in the studied cross section.

Suppressed, but Not Forgotten

2011 ◽  
Vol 70 (1) ◽  
pp. 5-11 ◽  
Author(s):  
Beat Meier ◽  
Anja König ◽  
Samuel Parak ◽  
Katharina Henke
Keyword(s):  
Memory Trace ◽  
Thought Suppression ◽  
Test Phase ◽  
Indirect Test ◽  
Final Test ◽  
Test Experiment ◽  
And Control ◽  
Cue Words ◽  
The Impact

This study investigates the impact of thought suppression over a 1-week interval. In two experiments with 80 university students each, we used the think/no-think paradigm in which participants initially learn a list of word pairs (cue-target associations). Then they were presented with some of the cue words again and should either respond with the target word or avoid thinking about it. In the final test phase, their memory for the initially learned cue-target pairs was tested. In Experiment 1, type of memory test was manipulated (i.e., direct vs. indirect). In Experiment 2, type of no-think instructions was manipulated (i.e., suppress vs. substitute). Overall, our results showed poorer memory for no-think and control items compared to think items across all experiments and conditions. Critically, however, more no-think than control items were remembered after the 1-week interval in the direct, but not in the indirect test (Experiment 1) and with thought suppression, but not thought substitution instructions (Experiment 2). We suggest that during thought suppression a brief reactivation of the learned association may lead to reconsolidation of the memory trace and hence to better retrieval of suppressed than control items in the long term.

Examining the Impact of the Disabled Youth Peer Development Initiative: What are the Long-Term Outcomes?

2003 ◽  
Author(s):  
Teresa Garate-Serafini ◽  
Jose Mendez ◽  
Patty Arriaga ◽  
Larry Labiak ◽  
Carol Reynolds
Keyword(s):  
Long Term Outcomes ◽  
The Disabled ◽  
The Impact

The Impact of Different Treatments on Long-Term Symptoms in Vestibular Schwannoma

2014 ◽  
Vol 75 (S 02) ◽  
Author(s):  
Morten Lund-Johansen ◽  
Øystein Tveiten ◽  
Monica Finnkirk ◽  
Erling Myrseth ◽  
Frederik Goplen ◽  
...  
Keyword(s):  
Vestibular Schwannoma ◽  
The Impact

The influence of inflation targeting on the pass-through effect of the exchange rate

2018 ◽  
pp. 70-84
Author(s):  
Ph. S. Kartaev ◽  
Yu. I. Yakimova
Keyword(s):  
Developing Countries ◽  
Monetary Policy ◽  
Exchange Rate ◽  
Inflation Targeting ◽  
Policy Regime ◽  
Short And Long Term ◽  
The Exchange Rate ◽  
Pass Through ◽  
The Impact

The paper studies the impact of the transition to the inflation targeting regime on the magnitude of the pass-through effect of the exchange rate to prices. We analyze cross-country panel data on developed and developing countries. It is shown that the transition to this regime of monetary policy contributes to a significant reduction in both the short- and long-term pass-through effects. This decline is stronger in developing countries. We identify the main channels that ensure the influence of the monetary policy regime on the pass-through effect, and examine their performance. In addition, we analyze the data of time series for Russia. It was concluded that even there the transition to inflation targeting led to a decrease in the dependence of the level of inflation on fluctuations in the ruble exchange rate.

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