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Dredging

About: Dredging is a research topic. Over the lifetime, 3300 publications have been published within this topic receiving 28325 citations.


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Journal ArticleDOI
TL;DR: In this paper, the authors quantified the force required to break C. chione shells in relation to fishing impacts and dredge damage and concluded that most shell damage was attributable to compaction within the sediment.
Abstract: The smooth clam Callista chione is exploited by a fleet of dredgers along the southwestern coast of Portugal and suffers from a high incidence of shell damage. The force required to break C. chione shells in relation to fishing impacts and dredge damage is quantified. Fishing trials and shell-strength measurements (compression and compaction experiments) were performed to determine whether shell damage was attributable to the direct impact of the dredge teeth or to sediment compaction. A three-dimensional model of C. chione was subjected to simulated force by the finite element method. Analyses of damage areas and breakage patterns revealed two groups of samples, one containing the samples from compression experiments and another with the samples from dredging and compaction experiments, suggesting that most shell damage was attributable to compaction within the sediment. Information is provided to help improve the design of bivalve dredges, by increasing both length and angle of the dredge teeth, which would reduce the compaction force and distribute it differentially within the sediment, forcing upward movement of the bivalves.

25 citations

DOI
05 Aug 1997
TL;DR: In this paper, a weir jetty system was constructed at the mouth of the, Colorado River, Texas, and river discharge was diverted from this mouth in 1992, and an evaluation of project impacts on longshore sediment transport was performed to determine the effectiveness of the project at preserving an open, navigable channel while preventing excessive erosion along adjacent beaches.
Abstract: In 1985, a weir jetty system was constructed at the mouth of the, Colorado River, Texas, and river discharge was diverted from this mouth in 1992. An evaluation of project impacts on longshore sediment transport was performed to determine the effectiveness of the project at preserving an open, navigable channel while preventing excessive erosion along adjacent beaches. This evaluation included both physical and numerical analysis of pre- and post-project conditions at the Colorado River mouth. Analysis of site data revealed that under the dredging and mechanical bypassing schedule followed during the first 8 years after jetty construction, the project resulted in significant trapping and sorting of sediment transported alongshore. Numerical modeling of the design maintenance dredging plan confirmed the plan to be sufficient for achieving project objectives. However, the entrance channel has continued to shoal considerably more rapidly than was anticipated during the project design.

25 citations

Journal ArticleDOI
TL;DR: In this article, the authors assessed the water and benthic conditions of Dokai Bay to describe the recovery of the bay and to monitor the effects of environmental recovery projects on the bottom environment.

25 citations

Journal ArticleDOI
15 Mar 2016
TL;DR: In this article, two methods of disposition were tested to evaluate the impacts of dredged material dumped at two adjacent sites (one million cubic metres at each) on the inner shelf of the Bay of Seine in France.
Abstract: Studies on the consequences of dredging on estuarine morphology and its sedimentary dynamics are common, but the impacts of dumping dredge spoil in coastal open settings are rarely found in scientific literature. An experimental study was conducted over the period 2012-2013 to monitor the physical impacts of dredged material dumped at two adjacent sites (one million cubic metres at each) on the inner shelf of the Bay of Seine in France (eastern part of the English Channel, La Manche). As recently reinforced in the EU Marine Strategy Framework Directive (MSFD), knowledge on the location and intensity of human impacts (e.g. on marine ecosystems) is critical for effective marine management and conservation. So, two methods of disposition were tested to evaluate the impacts of dumping on the environment and thus propose recommendations for future dumping. The strategy is based on a Before-After-Control-Impact (BACI) approach, in which the spatio-temporal variability was studied by analysing the morphological and sedimentological characteristics over a period of 28 months, from November 2011 to April 2014, also including recovery of the seafloor after cessation of the dumping activities. The first experimental dumping operation (MASED) was carried out regularly for 8 months at a single point and generating a conical deposit of 5 m in height, while the second dumping (MABIO) lasted for 12 months involving four steps in the dumping process. In the second case, a wider area was covered, leading to the formation of a smaller deposit of 2 m in height. The dumped deposits consisted of muddy fine sand, whereas the inner shelf seafloor in this area is covered with fine to medium sand. As a result, muddy fine sand accumulated at or near the two dumping sites, with a maximum mud (i.e. particles 4 Φ) content of 50% compared to<5% before dumping operations. Videos obtained from a LVB200 Seabotix ROV, highlighted the heterogeneity of the sea floor around the dumping areas. Due to hydrodynamic forcing (wave climate and tidal currents), about 50% (MABIO) and 75% (MASED) of the volume of dredged material remained at the end of the dumping periods. After dumping ceased, a further 5% of material for MABIO and 20% for MASED, was transported out of the study area. For the latter, a spreading of fine particles was observed extending from the conical deposit towards the south west. To favour long-term exploitation, a more dispersive dumping over a wider surface area is recommended (e.g. MABIO)

24 citations

Journal ArticleDOI
TL;DR: In this article, the impact of dredging on macrobenthic communities was studied in an unaltered zone, the Getares inlet of Algeciras Bay (SW Spain).
Abstract: The impact of dredging on macrobenthic communities was studied in an unaltered zone, the Getares inlet of Algeciras Bay (SW Spain). The data obtained before, during and after dredging in a time series spanning 5 years revealed the re-establishment of directly affected communities and of physicochemical substrate characteristics within 1 month of the end of dredging, although 2 years later there was a confusing biological impoverishment of the whole inlet. After 4 years, there was a high degree of population re-establishment, both on the bottoms directly affected by the works and on neighbouring areas, that was partly due to the hydrodynamic conditions. Before this type of activity is undertaken, each case should be studied regarding viability, the environmental medium where it will take place, the best time of year, and the type of dredging to be used.

24 citations


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Performance
Metrics
No. of papers in the topic in previous years
YearPapers
2023189
2022438
202170
2020119
2019150
2018131