Artykuły w czasopismach na temat „Dredging”
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Shah, Yogesh. "Revolutionizing Dredging Practices with Smart Dredging Management System". International Journal of Science and Research (IJSR) 13, nr 3 (5.03.2024): 1862–68. http://dx.doi.org/10.21275/sr24328135539.
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Eke, C. C., L. Frank, U. P. Ahaji, V. Ezeh, C. C. Amadi i P. O. C. Okeke. "Dredging of Harbours and Rivers: Review of Practices and Associated Environmental Impacts." IIARD INTERNATIONAL JOURNAL OF GEOGRAPHY AND ENVIRONMENTAL MANAGEMENT 9, nr 5 (13.10.2023): 22–36. http://dx.doi.org/10.56201/ijgem.v9.no5.2023.pg22.36.
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Dredging of harbors and rivers is essential for waterway accessibility and infrastructure enhancement. This review explores key aspects of dredging, including types, applications, environmental concerns, mitigation strategies, and insightful case studies. This paper highlights the importance of dredging in improving water transport and related sectors. It covers diverse dredging types and applications such as Maintenance dredging, Capital dredging, Environmental dredging and Land Reclamation showcasing their adaptability to different project needs. It examines environmental issues linked to dredging and proposes effective mitigation methods. These measures address sediment disturbance, habitat disruption, and water quality degradation. There were two case histories which are The panama Canal Expansion and The Rhine river dredging in Europe illustrating practical dredging applications. These cases offer insights into both successful practices and challenges encountered during project execution. This, summarizes key findings and provides sustainable dredging recommendations. These include enhanced planning, monitoring, and the integration of eco-friendly technologies.
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Joseph, B. "Dredging Orientalism". Eighteenth-Century Life 38, nr 2 (1.04.2014): 120–26. http://dx.doi.org/10.1215/00982601-2646209.
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Zheng, Jian Xin, Chuan Shao Liu i Yue Hong Tian. "Design of New-Type Vertical Dredging Equipment for Coal Bunker". Advanced Materials Research 228-229 (kwiecień 2011): 568–73. http://dx.doi.org/10.4028/www.scientific.net/amr.228-229.568.
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A new-type of dredging equipment for the coal bunker is designed to solve the clogging problem, which avoids the disadvantages of the existing dredging technology used in the collieries. The new dredging method borrows ideas from air cannon dredging technology, and applies dynamic high pressure generation principle. In the process of dredging, the rubber bullet in the launch canister is accelerated by the controlled high pressure air, and impacts the coal in the arch with high speed so as to recover the coal bunker. The dredging mechanism and process are expatiated and the main structures of the dredging equipment are introduced. The structure of the new type dredging equipment for the coal bunker is simple and the equipment is of high adaptability and safety.
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Kalashnikov, Arsenii A. "Design solution for the dredging slots production". Russian Journal of Water Transport, nr 72 (20.09.2022): 208–15. http://dx.doi.org/10.37890/jwt.vi72.306.
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The article discusses the issue of design solution for the dredging slots production in the Ob River section. An important challenge in the dredging and straightening works production is the issue of the dredging slots stability. The experience of researching the issue is considered, a brief review of the literature is presented. The necessity of developing design solution for the dredging slots production, necessity of dredging slots stability. Field data were obtained and analyzed in the course of track works on the Ob River cripples. A Design solution for the dredging slots production is proposed. The ways of further research of the dredging slots stability issue are outlined.
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Boris, Talgamer. "Assessing the capacity of dredging excavations to place dredging tailings dumps in the course of deep and man-made placer mining". Izvestiya vysshikh uchebnykh zavedenii. Gornyi zhurnal, nr 3 (20.06.2022): 44–54. http://dx.doi.org/10.21440/0536-1028-2022-3-44-54.
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Introduction. The dredge stern is often backed up by dredging tailings in the course of deep and man-made placers dredging. One of the reasons for that is the decreased capacity of dredging excavations at the dumping point caused by collapsed pit walls, which is not taken into account by known design methods. Research objective is to evaluate the degree of the developed space capacity reduction at dredging pits for dredging tailings storage, depending on the dredging conditions. Methods of research. Capacity prediction for a dredging excavation for dredging tailings storage should consider natural slope formation of open pit walls during the period of dredge advance to a distance equal to the distance of the poop decks from the face. The degree of reduction in dredging excavation lower part receiving capacity should be set based on pit walls flattening, which depends on rock composition (cohesiveness degree), loose deposits thickness, face width, and dredge working parameters. Results. The results of graphic-analytical calculation revealed that dredging excavation lower part receiving capacity is reduced from 3 to 10% due to pit walls collapse as loose deposits thickness increases from 10 to 34 m for the most favorable face width of a 380-liter dredge, which may result in a significant increase in dredge stern backing up by dredging tailings. Conclusions. At deep and man-made placers, when calculating the parameters of a dredging tailings dump, it is recommended to introduce an amendment into the existing methods, that considers the developed space lower part capacity reduction due to pit walls collapse.
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Yehao, Kang, Li Shuaihao i Ji Houlin. "Overview and Prospect of Underwater Desilting Robot". Journal of Engineering Research and Reports 25, nr 9 (28.09.2023): 97–111. http://dx.doi.org/10.9734/jerr/2023/v25i9984.
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The serious accumulation of sludge in the water outlet of the South to North Water Diversion Project poses a constraint on the sustainable development of the water ecosystem and the long-term development of the water storage system. Silt accumulation may lead to problems such as deterioration of water quality, damage to water ecosystems, and water level decline. In order to solve the problem of sludge accumulation, it is necessary to carry out dredging and dredging work for the water body at the outlet of the water outlet. Dredging can restore water capacity, maintain ecological balance, and contribute to the sustainable management of water systems. At present, there are still many shortcomings in the existing dredging technology for small and medium-sized water bodies on the market, which is difficult to meet the requirements of dredging in the South to North Water Diversion Project. Therefore, it is very important and necessary to develop new dredging robots to meet the environmental dredging needs. This article is based on the background of water dredging and control at the exit of the South to North Water Diversion Project. Through in-depth analysis of existing dredging robot technology and underwater robot technology, and combined with research status at home and abroad, it is planned to provide guidance and direction for the design and development of underwater dredging robot humans with environmental protection dredging functions in the future.
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Greene, Paul, George Follett i Clint Henker. "Munitions and Dredging Experience on the United States Coast". Marine Technology Society Journal 43, nr 4 (1.10.2009): 127–31. http://dx.doi.org/10.4031/mtsj.43.4.2.
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AbstractA number of dredging projects have unknowingly and unfortunately encountered munitions and explosives of concern (MEC). MEC have been discovered on dredges (e.g., in dragheads, cutterheads, pump casings) and at the dredged material placement site. Detonations have occurred that have either damaged the dredge plant or have even sunk the dredging vessel. A number of recent dredging projects have proactively addressed MEC issues before the start of construction, thereby greatly reducing overall risk and MEC cleanup costs. This paper explains common dredging equipment, discusses techniques useful in reducing the inherent risks of dredging in sediments containing MEC, and discusses lessons learned during various dredging projects involving MEC.Application of MEC avoidance and exclusion techniques during dredging operations is minor compared to the enormous cost of post-dredging MEC cleanup. Most importantly, it is possible to avoid exposing the public to explosive safety hazards and minimize those to workers with proper planning and execution.
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Bashir, Mohammad Obaidullah Ibne. "Application of Artificial Intelligence (AI) in Dredging Efficiency in Bangladesh". Annals of Emerging Technologies in Computing 6, nr 1 (1.01.2022): 74–88. http://dx.doi.org/10.33166/aetic.2022.01.005.
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The integration of Artificial Intelligence (AI) into the dredging systems and dredging machinery used in "capital" and "maintenance" dredging in Bangladesh can enhance the efficiency of the machines and dredging process, enabling the operators to perform regular and repetitive dredging tasks safely in the rivers, ports, and estuaries all over the country. AI, including Big Data, Machine Learning, Internet of Thing, Blockchain and Sensors and Simulators with their catalytic potentials, can systematically compile and evaluate specific data collected from different sources, develop applications or simulators, connect the stakeholders on a virtual platform, store lakes of information without compromising their intellectual rights, predicting models to harness the challenges, minimise the cost of dredging, identify possible threats and help protect the already dredged areas by giving timely signals for further maintenance. Furthermore, the application of AI modulated dredging devices and machinery can play a significant role when monitoring aspects becomes crucial, keeping environmental impacts mitigated without affecting the quality of the human environment. This study includes the evaluation of the application of AI – its prospect and challenges in the existing dredging systems in Bangladesh against the backdrop of the challenges faced in capital and maintenance dredging in the major rivers – and assess whether such inclusion of AI is likely to minimise the cost of dredging in the rivers of Bangladesh and facilitate the materialisation of the objectives of Bangladesh Delta Plan 2100.This paper studies the organisation's infrastructural requirement for the integration of AI into dredging systems, using benchmarking such as 1- "Understanding AI Ready Approach", 2-"Strategies for Implementing AI", 3-"Data Management", 4-"Creating AI Literate Workforce and Upskilling", and 5-"Identifying Threats" concerning the management and dredging operations of Bangladesh Inland Water Transport Authority (BIWTA), under Bangladesh Ministry of Shipping and Bangladesh Water Development Board (BWDB). The paper also uses several case studies such as channel dredging to show that the use of AI can bring a significant change in the dredging operations both in reducing the cost of dredging and in terms of harnessing the barriers in adaptive management and environmental impacts.
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Li, Jian Yong, Chao Zhang, Hong Lu Su, Fang Yi Li, Shun Shun Qin i Zi Wu Liu. "The Simulation and Application of Whip-Impact Sediment Dredging Technology". Applied Mechanics and Materials 303-306 (luty 2013): 2871–75. http://dx.doi.org/10.4028/www.scientific.net/amm.303-306.2871.
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Focusing on the dredging problem in Yellow River irrigation district, the whip-impact sediment dredging technology is put forward in the Xingjiadu Irrigation District. The finite element model of dredging process is built and the flow characteristic and behavior under design condition is studied, which can provide a theoretical basis for the feasibility of the whip-impact sediment dredging technology. Also, it can provide effective measures for the improvement of sediment dredging effects and whip-impact equipments.
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Ko, Eui-Jeong, Dong-Kyun Kim, Eun-Song Jung, Yu-Ji Heo, Gea-Jae Joo i Hyun-Woo Kim. "Comparison of Zooplankton Community Patterns in Relation to Sediment Disturbances by Dredging in the Guemho River, Korea". Water 12, nr 12 (7.12.2020): 3434. http://dx.doi.org/10.3390/w12123434.
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This study aimed to determine whether a swimming-type (planktonic and epiphytic) zooplankton group compared with the taxonomic group is appropriate to indicate the environmental changes caused by dredging. Water sampling in the littoral zone was conducted from 2007 to 2015, including the dredging period from October 2010 to June 2012. The water quality, number of species, population densities, and biotic indices were compared for both dredging period and grouping type. Nine of 11 water quality parameters were changed by the dredging period. The results showed that the rotifer and planktonic groups were consistently dominant. In all groups, population density was the lowest during the dredging period. After dredging, both the number of species and population density increased only in the epiphytic group. The dominant species, including Polyarthra vulgaris, Brachionus calyciflorus, B. rubens, and Bosmina longirostris, were included in the planktonic group for 9 years. Evenness did not differ, but diversity increased after the dredging period. This study showed that zooplankton could be used as a supplemental biological assessment tool for evaluating the impact of river dredging.
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Silveira, Paula Cilene Alves da, Delzenira Silva do Nascimento da Costa, Samara Aranha Eschrique, Leandro Mendes Lima i Emanuelle Sousa Sodré. "DREDGING IN THE ITAQUI PORT AREA, MARANHÃO - BRASIL: EFFECTS ON THE COMPOSITION AND ABUNDANCE OF ICHTHYOPLANKTON". Revista Contemporânea 4, nr 7 (12.07.2024): e5082. http://dx.doi.org/10.56083/rcv4n7-112.
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Assessments of the effects of dredging on biological resources show decreases in density and abundance of species as a result of dredging activity in port areas. Ichthyoplankton samples were taken before, during and after dredging at the Itaqui port complex west of the Golfão Maranhense. The trawls were drawn horizontally on the surface with a duration of 5 minutes. A plankton net of cone-cylindrical type was used, equipped with a flow meter. 677 fish larvae were collected, obtaining a total of 17 species. Significant effects of dredging were observed on species richness during the three stages. The species Anchoviella lepidentostole was dominant before dredging and its abundance reduced during the dredging, which is causing as consequence behavioral disturbance of these organisms. The Engraulidae family was dominant in this study and this may be a consequence of the greater resistance of their representatives to the changes in the environment caused by dredging. However, the results showed us that dredging activity influences the composition, density and abundance of these organisms.
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Wang, Yi, Xian Fei Huang i Ji Wei Hu. "Study on Release Potential of Heavy Metals in Sediments from Baihua Lake by Dredging Simulation". Advanced Materials Research 878 (styczeń 2014): 545–50. http://dx.doi.org/10.4028/www.scientific.net/amr.878.545.
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Baihua Lake is a key drinking water source for Guiyang City located on Guizhou Plateau in southwest China, however it has been seriously contaminated with various contaminants, such as nitrogen, phosphorus, and heavy metals. To solve this problem, some researchers have recommended dredging the lake sediment to remove these contaminants. The present research was aimed to assess the potential risk of five selected heavy metals (Cd, Cu, Cr, Hg and As) if the sediment dredging measure was taken for remediation of this water body. Core sediments collected from the site Guanyinshanzhuang were used to simulate the release of heavy metals in sediment from Baihua Lake if sediment dredging was carried out. The core sediments were dredged at 10 cm, 20 cm and 30 cm levels. The core sediments were then put into the lake again after simulation dredging to investigate their release potential in one day, five days, nine days and fifteen days. The mobility of selected heavy metals in the sediments were determined using the toxicity characteristic leaching procedure (TCLP) developed by the United States Environmental Protection Agency (USEPA). The results indicated that the release potential of the heavy metals varies with dredging depth and the lasting time after dredging. Cr and As showed the lowest release ability among the heavy metals under study followed by Cu. The release amount of Cd increased with the lasting time after dredging. Hg showed no clear trends of release at 10 cm dredging depth. At 20 cm and 30 cm dredging depth, Hg presented a small release in the five days after simulation dredging, and then no release in the following ten days. In fifteen days after simulation dredging, the percentages of the heavy metals extracted with TCLP were in the order of Cd (8.85%) > As (3.41%) > Cu (1.37%) > Hg (0.79%) > Cr (0.61%) at dredging depth of 10 cm, Cd (10.22%) > Hg (2.73%) > Cu (1.74%) >As (1.47%)> Cr (1.41%) at dredging depth of 20 cm, and Cd (10.38%) > As (2.07%) > Hg (2.51%) > Cu (1.74%) > Cr (0.87%) at dredging depth of 30 cm.
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Xiong, Qiao, i Han Bin Xiao. "Inverse Kinematics and Dynamics Simulation of a Dredging Clamshell". Applied Mechanics and Materials 364 (sierpień 2013): 107–11. http://dx.doi.org/10.4028/www.scientific.net/amm.364.107.
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This paper proposes a problem of flat dredging because of the phenomenon of overdredging casuing bottom roughness in dredging engineering and presents the formulation of the inverse kinematics and dynamics simulation of a dredging clamshell. A dynamical model of dredging clamshell is built based on Adams and the position analysis is firstly performed by adding a general point motion to the dredging clamshell. By analyzing and solving kinematics equations in inverse, movement curves of the steel wire ropes are obtained, and the pulling force curves are acquired by dynamics simulation. The results show that the method automatically generates inverse dynamic solutions and the movement curves are intuitive and can offer help to the flat dredging control scheme effectively.
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Marnane, Michael, Travis Elsdon, Tony Rouphael, Claus Pedersen, Kiri Peat i Ceri Morgan. "Enhancing environmental performance during Wheatstone dredging through science and innovation". APPEA Journal 57, nr 2 (2017): 502. http://dx.doi.org/10.1071/aj16125.
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Dredging for the Chevron-operated Wheatstone LNG Project, near Onslow, Western Australia, involved movement of approximately 30 Mm3 of material over 23 months to provide safe navigation for LNG export as well as trunkline installation and stabilisation. Dredging was carried out in a sub-tropical, inshore environment near to biological benthic communities including corals, seagrasses, macroalgae and filter feeders, deemed sensitive to elevations in turbidity and/or sedimentation associated with dredging. Science and innovative technology was used to proactively and adaptively management dredging in order to afford a high level of environmental protection. Water quality data was transmitted via satellite to Perth where it was compared, daily, against management triggers derived from scientific analysis of an extensive dataset collected during a previous, nearby, dredging program. Accurate hindcast modelling, combined with MODIS satellite imagery, provided oversight of the extent and cause of observed turbid plumes, while forecast modelling provided predictions of the potential impacts of upcoming dredging activities, allowing for proactive changes to dredging activities to minimise potential impacts. Monitoring of benthic communities was undertaken using remotely operated underwater vehicles (ROVs) and water quality monitoring in the latter part of the program was undertaken using remotely operated Wave Gliders (Liquid Robotics), both of which resulted in significant safety improvements and cost savings and over traditional monitoring methods. Post-dredging surveys of benthic communities indicated that, despite their proximity to dredging activities and the enormity of dredged volumes, no detectable impacts had occurred as a result of dredging.
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Liaoyuan, Wang, Liu Zhiqiang i Li Zhiguang. "Robot Design of Underwater Building Surface Dredging - Structural Design". Journal of Engineering Research and Reports 26, nr 1 (2.01.2024): 1–9. http://dx.doi.org/10.9734/jerr/2024/v26i11058.
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In order to improve the efficiency of dredging, reduce the cost of dredging and ensure the safety of operation, this paper designs an underwater building surface dredging robot (hereinafter referred to as "underwater dredging robot"), which mainly includes the following aspects. The structure of underwater dredging robot is planned and divided into dredging system, walking system, driving system and support system. According to the actual work situation and the characteristics of each system, the scheme selection and structure design are carried out, and the overall layout scheme is obtained. The materials of the support system are selected and its force under different working conditions is analyzed. Through finite element analysis and modal analysis, it is verified that its reliability meets the requirements and there is no resonance phenomenon in the work.
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Tejani, James. "Dredging the Future". Southern California Quarterly 96, nr 1 (2014): 5–39. http://dx.doi.org/10.1525/scq.2014.96.1.5.
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Modern Los Angeles and Southern California emerged through the utilization and development of its coastal estuaries and wetlands, which became possible only at the turn of the twentieth century with the advent of new industrial machinery. The interaction between technology and environment in turn shaped city makers’ and residents’ vision of possibility, opportunity, and urgency as they looked out from Los Angeles to a changing West, nation, and world. While historians are familiar with the political and social conflict and cultural shifts that propelled Los Angeles and Southern California’s development as a metropolis, this article proposes that the region’s development is also due to the interplay of land and water, of mud and machine, and of transforming human perceptions of distance and connection.
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Hodgkiss, John. "Dredging up problems". Marine Pollution Bulletin 22, nr 12 (grudzień 1991): 577. http://dx.doi.org/10.1016/0025-326x(91)90237-m.
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Tavrizov, V. M. "Dredging over an underwater crossing using a suction dredging vessel". Hydrotechnical Construction 29, nr 3 (marzec 1995): 148–56. http://dx.doi.org/10.1007/bf01545807.
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Boulcott, Philip, Colin P. Millar i Rob J. Fryer. "Impact of scallop dredging on benthic epifauna in a mixed-substrate habitat". ICES Journal of Marine Science 71, nr 4 (3.01.2014): 834–44. http://dx.doi.org/10.1093/icesjms/fst197.
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Abstract Experimental scallop dredging was conducted to assess the vulnerability of emergent epifauna on hard substrates. Three sites were sampled before and after dredging to examine changes in the coverage of faunal turf (hydroid and bryozoan) assemblages and the composition of the wider epifaunal community. Each site had an “impact” box that was dredged, a control box that was in an area that was still open to fishing, and a control box in a special area of conservation (SAC) that had not been fished for two years. Community composition differed significantly after dredging in two of the three sites, with dredged communities becoming less similar to those in the SAC. There was no clear evidence that dredging in the impact boxes reduced the coverage of faunal turfs on hard substrates. However, the coverage of faunal turfs on hard substrates in the SAC was typically greater than in areas that were still being fished commercially, consistent with a dredging effect. The results highlight the role that substrate morphology might play in modifying the severity of dredging effects. This has relevance to marine spatial management, as it suggests that emergent epifauna living on hard substrates that are morphologically suited to dredging, such as pebble and cobble substrates, could be particularly vulnerable to dredging.
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Wang, Lijun, Yehao Kang, Yibo Wang, Zeyong Zhao, Liyang Shang, Xiaona Song, Donglai Xu i Ruixue Cheng. "Optimization Design of a Winch Suction Underwater Dredging Robot Using Orthogonal Experimental Design". Journal of Marine Science and Engineering 12, nr 5 (29.04.2024): 741. http://dx.doi.org/10.3390/jmse12050741.
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In marine engineering and water conservancy projects, dredging often occurs due to silt accumulation, which can impede the long-term development of water ecosystems and water storage systems. To enhance dredging efficiency and the performance of dredging machines, a novel type of winch suction underwater dredging robot was designed. Computational fluid dynamics software was utilized to establish a fluid model of the robot’s winch suction dredging device and conduct model simulation experiments. The simulation test results were used to investigate the factors influencing dredging performance and their impact laws. Five key factors—namely, the reamer rotational speed, reamer arrangement angle, water flow rate, inlet pipe diameter, and outlet pipe diameter—were selected for consideration. By setting up various sets of factor levels, the significant influence of different factors on dredging efficiency was examined. Analysis of variance was employed to analyse the results of the orthogonal experimental design, leading to the identification of optimal factor levels and the establishment of an optimal scheme group. The results of the optimal scheme were verified, demonstrating a 13.049% increase in dredging efficiency and a 19.23% decrease in power consumption of the sludge pump compared to the initial experimental setup. The performance of the optimal program surpassed that of all the experimental designs and met the design requirements.
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Gilkinson, Kent D., Donald C. Gordon, Kevin G. MacIsaac, David L. McKeown, Ellen L. R. Kenchington, Cynthia Bourbonnais i W. Peter Vass. "Immediate impacts and recovery trajectories of macrofaunal communities following hydraulic clam dredging on Banquereau, eastern Canada". ICES Journal of Marine Science 62, nr 5 (1.01.2005): 925–47. http://dx.doi.org/10.1016/j.icesjms.2005.03.009.
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Abstract A hydraulic clam dredging experiment, designed to mimic offshore commercial dredging practices, was carried out at a depth of approximately 70 m on a sandy seabed on Banquereau, on the Scotian Shelf, eastern Canada. The experiment was designed to study the separate and combined effects of dredging through three treatment boxes (Dredging Only, Dredging and Discarding, Discarding Only) and two spatially separated reference boxes. In all, 270 taxa were identified from grab samples. Of these, four bivalves are targeted in the commercial fishery (Arctica islandica, Cyrtodaria siliqua, Mactromeris polynyma, and Serripes groenlandicus) while 266 taxa were non-target species. Sample biomass was dominated by the propellerclam, C. siliqua, and the echinoderm, Echinarachnius parma, while the polychaete, Spiophanes bombyx, was the numerical dominant. The dredges captured 33 invertebrate and two fish taxa, although >80% of the catch biomass comprised propellerclams and echinoderms. Immediately after dredging, most macrofaunal species decreased in abundance, with the greatest declines inside dredge furrows (which covered 53–68% of the area inside the dredged boxes). Large numbers of propellerclams were excavated to the seabed surface, with a large proportion showing massive damage. There were few signs of discards on the sediment surface. Recovery trajectories of target and non-target species were followed for 2 years. Following initial declines in abundance and biomass of most taxa immediately after dredging, there were marked increases in abundance of polychaetes and amphipods after 1 year. Two years after dredging, abundances of opportunistic species were generally elevated by ≫100% relative to pre-dredging levels. Two years after dredging, average taxonomic distinctness had decreased (i.e. taxonomic relatedness between species had increased) due, in part, to increased numbers of species of certain polychaetes and amphipods, while communities had become numerically dominated (50–70%) by S. bombyx. It is concluded that the disturbed community was still in the colonizing phase 2 years after dredging. The mobile brittlestar, Ophiura sarsi, displayed increases in abundance ranging from 200% to 300% in the dredged and reference boxes over the 2-year post-dredging. A similar response of non-target macrofauna in the reference boxes suggests, possibly, a coincident natural recruitment pulse. Dredging resulted in pronounced, sustained reductions in biomass (up to 67%) of the target bivalves with no signs of recovery after 2 years. Recruitment of target bivalves (>1-mm shell length) was very low throughout the experimental area during this interval.
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Barry, Jon, Sian Boyd i Robert Fryer. "Modelling the effects of marine aggregate extraction on benthic assemblages". Journal of the Marine Biological Association of the United Kingdom 90, nr 1 (19.08.2009): 105–14. http://dx.doi.org/10.1017/s0025315409990737.
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This paper develops models of the initial impact of marine aggregate extraction on a benthic assemblage. We predict the effect of dredging on species numbers and abundance assuming spatial randomness of individuals. We extend the model to allow for spatial clustering of individuals using a Matern process. Data from a controlled field experiment are used to develop a framework for estimating species reduction. This involves modelling the spatial pattern of individuals before dredging using a Matern process, the impact of dredging at an individual level, and the probability that a species is not seen in a post-dredging survey. The framework was used to estimate that, of the 41 species that were seen in a pre-dredging survey but not in a post-dredging survey, between 0 and 14 were eliminated (with 95% likelihood) rather than escaped detection. The most likely number eliminated was 4.
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Beck, Tanya M., i Kelly Legault. "DREDGING OPTIMIZATION OF AN INLET SYSTEM FOR ADJACENT SHORE PROTECTION PROJECTS USING CMS AND GENCADE". Coastal Engineering Proceedings 1, nr 33 (15.10.2012): 34. http://dx.doi.org/10.9753/icce.v33.management.34.
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St. Johns County encompasses a 24-km beach and inlet system located in northeast Florida (United States) that includes several interconnected Federal Navigation and Shore Protection Projects that must be managed within a regional context to reduce cost, share sediment, and optimize the volume of sand within the littoral system. The objective of this study is to investigate optimal dredging volumes and intervals, and to determine the beach placement volume and renourishment interval to maintain two Shore Protection Projects. The Coastal Modeling System (CMS) was applied to analyze the morphological impact on the sediment dynamics for ebb-tidal delta mining at St. Augustine Inlet over 1.4-year simulations. Results determined that dredging scenarios under 4 Mill cu yd removed did not significantly modify the ebb-tidal delta. The CMS modeling results on sustainable dredging volumes, combined with historical infilling rates, provided constraints with which to develop dredging and beach fill scenarios for GenCade, a 1-D numerical model that predicts shoreline change. GenCade was applied to evaluate sediment management alternatives for dredging intervals of 5, 7 and 10 years, and varying beach fill volumes and placement lengths. Results indicate that imposing a 10-year dredging interval to the navigation project and ebb delta with the maximum dredging quantity of 3 million cubic yards will yield the best performance of the regional projects of St. Johns County. GenCade calculates future sediment budgets for various management scenarios, and can provide an essential benefit in determining optimal dredging periods for coordinated regional efforts to save in mobilization and demobilization costs for dredging and beach fill placement.
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Zhong, Ji-Cheng, Ju-Hua Yu, Xiao-Lan Zheng, Shuai-Long Wen, De-Hong Liu i Cheng-Xin Fan. "Effects of Dredging Season on Sediment Properties and Nutrient Fluxes across the Sediment–Water Interface in Meiliang Bay of Lake Taihu, China". Water 10, nr 11 (8.11.2018): 1606. http://dx.doi.org/10.3390/w10111606.
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The influence of dredging season on sediment properties and nutrient fluxes across the sediment–water interface remains unknown. This study collected sediment cores from two sites with different pollution levels in Meiliang Bay, Taihu Lake (China). The samples were used in simulation experiments designed to elucidated the effects of dredging on internal loading in different seasons. The results showed that dredging the upper 30 cm of sediment could effectively reduce the contents of organic matter, total nitrogen, and total phosphorus in the sediments. Total biological activity in the dredged sediment was weaker (p < 0.05) than in the undredged sediment in all seasons for both the Inner Bay and Outer Bay, but the effect of 30-cm dredging on sediment oxygen demand was negligible. Dredging had a significant controlling effect on phosphorus release in both the Inner Bay and Outer Bay, and soluble reactive phosphorus (SRP) fluxes from the dredged cores were generally lower (p < 0.05) than from the undredged cores. In contrast, NH4+-N fluxes from the dredged cores were significantly higher (p < 0.05) than from the undredged cores in all seasons for both sites, this indicates short-term risk of NH4+-N release after dredging, and this risk is greatest in seasons with higher temperatures, especially for the Inner Bay. Dredging had a limited effect on NO2−-N and NO3−-N fluxes at both sites. These results suggest that dredging could be a useful approach for decreasing internal loading in Taihu Lake, and that the seasons with low temperature (non-growing season) are suitable for performing dredging projects.
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Lai, Hsin-Hung, Kuei-Hu Chang i Chien-Liang Lin. "A Novel Method for Evaluating Dredging Productivity Using a Data Envelopment Analysis-Based Technique". Mathematical Problems in Engineering 2019 (21.01.2019): 1–22. http://dx.doi.org/10.1155/2019/5130835.
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The increase in the frequency of extreme weather has caused the impact of natural disasters to become more extensive. Natural disasters reduce the effective storage capacity of reservoirs and affect their normal function. Reservoir dredging is a key issue in the management of water resources and is a complicated multiple-attribute decision-making (MADM) problem. The traditional assessment of dredging productivity has been performed using a labor productivity method to evaluate the related issues of dredging performance. However, the traditional labor productivity method only deals with the single-input/single-output evaluation factor for various forms of productivity. The traditional labor productivity method cannot address complicated MADM problems in the assessment of dredging productivity. To resolve the limitations of the traditional labor productivity method, this paper extended data envelopment analysis (DEA) and proposed a novel method for evaluating dredging productivity. The proposed method can handle various combinations of evaluation factors (single-input, multi-input, single-output, and multioutput). Three real cases of reservoir dredging are applied to verify the effectiveness of the proposed method. The simulation results show that the proposed method can be applied generally and correctly assesses the related issues of dredging performance.
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Vdovina, Olga N., Dmitry M. Bezmaternykh i Evgeniya N. Krylova. "Restoration of macrozoobenthos after dredging on Lake Manzherokskoe (Republic of Altai, Russia)". Ecosystem Transformation 5, nr 2 (2022): 26–34. http://dx.doi.org/10.23859/estr-220323.
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Dredging is the activity of excavating soil and performing other soil operations in order to expand and increase the depth of water bodies. Under conditions of increased pollution, dredging operations may cause certain damage to aquatic ecosystems in general and to particular aquatic species. The changes in the composition and structure of benthic invertebrate communities have been studied in Lake Manzherokskoe in different periods: before dredging (2007), two weeks after the dredging has been started (2018), and 3 years after the dredging activities have been finished (2021). In 2021, there was an increase in species diversity and quantitative indicators of the development of benthic communities comparing to the period of dredging completion. Our data indicated the restoration of macrozoobenthos community in the lake to a certain extent. Later, this process may end in complete restoring with an increase in the water level in the lake and a significant decrease in the technogenic load on bottom communities.
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Wu, Yuwei, Hui Zeng, Jun Hu, Xingyue Ren i Xiang Xue. "Finite Element Study on Temperature Field of Underwater Dredging Devices via the Artificial Ground Freezing Method". Geofluids 2022 (7.06.2022): 1–12. http://dx.doi.org/10.1155/2022/7502693.
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Increased urbanization has led to undesirable increases in the discharge of refuse waste and pollutants in urban and rural rivers. Blockages and river pollution adversely affect navigation and aquatic ecosystems and cause flooding during the flood season. Regular riverbed dredging is essential to protect local ecosystems and maintain waterways’ health. However, the current dredging methods cause secondary pollution during dredging. This study examined a new river dredging method with a parametric analysis of its reliability for different construction environments. ADINA software solved the temperature field model using the finite element method to build a three-dimensional transient heat conduction model. The analysis determined the distribution and development of the temperature field during the freezing process and the effective dredging range of the frozen device. We compared thermal conductivities, specific heat capacities, freezing device sizes, initial ground temperatures, and brine cooling plans to examine the effect of the soil’s thermophysical properties and construction environment on the dredging area of the freezing device.
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Boyd, S. E., D. S. Limpenny, H. L. Rees i K. M. Cooper. "The effects of marine sand and gravel extraction on the macrobenthos at a commercial dredging site (results 6 years post-dredging)". ICES Journal of Marine Science 62, nr 2 (1.01.2005): 145–62. http://dx.doi.org/10.1016/j.icesjms.2004.11.014.
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Abstract Benthic recolonization was investigated at a site historically used for the extraction of marine sand and gravel. The main objective was to assess the effects of different levels of dredging intensity on the recolonization of benthic fauna and sediments. Preliminary observations from this study indicated that the fauna within an area of seabed exposed to high dredging intensities remained in a perturbed state some 4 years after the cessation of dredging. Thereafter, annual monitoring surveys of the benthos and sediments at the “treatment” and “reference” sites have followed the recolonization process. Results from univariate and multivariate data analyses show that distinct differences in the nature of assemblages at sites exposed to high and lower levels of dredging intensity persist at least 6 years after the cessation of dredging. This paper presents the physical and biological findings 6 years after dredging, together with a generic framework for evaluating post-cessation recolonization studies.
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Williams, Brad, i Bill Townsend. "Rock, sediment and fishermen—insights on community engagement from the Ichthys LNG Project dredging program". APPEA Journal 55, nr 2 (2015): 435. http://dx.doi.org/10.1071/aj14070.
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The Ichthys LNG Project is one of the most complex oil and gas developments ever attempted. One challenge of the construction phase was undertaking a major dredging program to create a safe shipping channel and berthing area for LNG carriers through Darwin Harbour to the onshore processing facilities at Bladin Point. Dredging was also undertaken to create a trench in Darwin Harbour for the gas export pipeline. The dredging program took about 16 months to remove more than 16 Mm3 of rock and sediment, with a six month break during the first dry season due to environmental uncertainties. Ongoing discussions with key stakeholders and the community prior to the start of dredging affirmed the social, cultural and economic values placed on Darwin Harbour by local residents. Plans were developed to provide key stakeholders and the wider community with transparent information on the project’s dredging, environmental monitoring and research findings. The key focus of the campaign was marine safety and an integrated and tailored approach was used to deliver this message. Valuable insights and lessons were gained from other major dredging programs undertaken in Australia and used in planning. The Ichthys LNG Project dredging program included a combination of initiatives that, when implemented together, led to environmentally and socially responsible outcomes.
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Lawrence, Susan, James Grove, Peter Davies, Jodi Turnbull, Ian Rutherfurd i Mark Macklin. "Historical dredge mining as a significant anthropomorphic agent in river systems: A case study from south-eastern Australia". Holocene 31, nr 7 (25.03.2021): 1158–74. http://dx.doi.org/10.1177/09596836211003272.
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Bucket dredging to mine and extract gold and tin from rivers is a global industry that has had a range of negative effects on physical environments. These include the destruction of riparian soil profiles and structures, artificial channel straightening and loss of in-stream biodiversity. In this paper we evaluate the immediate effects and long-term consequences of bucket dredging on rivers in Victoria and New South Wales during the period 1900–1950. High quality historical sources on dredge mining are integrated with geospatial datasets, aerial imagery and geomorphological data to analyse the scale of the dredging industry, evidence for disturbance to river channels and floodplains and current land use in dredged areas. The study demonstrates that the environmental impact of dredging was altered but not reduced by anti-pollution regulations intended to control dredging. An assessment of river condition 70–100 years after dredge mining ceased indicates that floodplains and river channels continue to show the effects of dredging, including bank erosion, sediment slugs, compromised habitat and reduced agricultural productivity. These findings have significant implications for river and floodplain management.
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Gangga, Rahadhian Adhitya, i Santi Novani. "Decision Analysis of Offshore Channel Maintenance Dredging in PT. PQR". Indonesian Journal of Multidisciplinary Science 2, nr 10 (30.07.2023): 3463–73. http://dx.doi.org/10.55324/ijoms.v2i10.587.
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The offshore channel maintenance dredging completion date, which was performed by PT. ABC (PT. PQR’s contractor) using crane barge XYZ, was delayed to 19 May 2023 (43.4 days delayed). Two main problem were identified using Kepner Tregoe Situation Analysis (KT-SA) based on the company data processing and one most main contributing problem (lack of daily sediment production; the initial plan was 1500 m3/day) then be analyzed using Kepner Tregoe Problem Analysis (KT-PA) and the root cause was constructed using cause-map with brainstorming method included in the process between author and some of PT. ABC dredging crew in crane barge XYZ. Substitute, Combine, Adapt, Modify, Put on another use, Eliminate, Rearrange (SCAMPER) technique then be brought in the brainstorming session with PT. ABC dredging crew on crane barge ABC to bring alternative solutions for the root cause of the problem. Furthermore, the SCAMPER result be brought to brainstorming with PT. PQR dredging operation assistant manager, as the problem holder and matter expert, and filtered to three most possible alternative solutions. These three most possible solutions then examined using Simple Multiple Attribute Rating Technique (SMART) method with eight stages were performed. The criteria used in this method are offshore channel dredging project cost, offshore channel dredging project schedule, coordination with other entity, and permit to work (PTW) & derogation. The objectives of this research are knowing what factors affecting the dredging project in PT. PQR offshore channel case and the alternative solution to be brought in the next offshore channel maintenance dredging.
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Lazarenko, E. M., i A. B. Chernykh. "Features of labor regulation of transport workers". Sociology and Law, nr 1 (24.03.2022): 89–96. http://dx.doi.org/10.35854/2219-6242-2022-1-89-96.
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The current legislation has gaps and contradictions in the legal regulation of labor relations of workers of sea and river transport, in particular when regulating the labor of workers in the dredging fleet. The article discusses the problems of establishing the qualification characteristics of some of them, as well as the peculiarities of the working conditions of workers in the dredging fleet. The gaps in the norms of the current legislation of the legal regulation of labor of certain categories of workers, in particular, those associated with the performance of dredging fleet workers directly dredging, as a type of hydrotechnical construction work.
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Stryjecki, Robert, Andrzej Zawal, Tomasz Krepski, Edyta Stępień, Edyta Buczyńska, Paweł Buczyński, Stanisław Czachorowski i in. "Anthropogenic transformations of river ecosystems are not always bad for the environment: Multi-taxa analyses of changes in aquatic and terrestrial environments after dredging of a small lowland river". PeerJ 9 (29.09.2021): e12224. http://dx.doi.org/10.7717/peerj.12224.
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Rivers are one of the most commonly transformed aquatic ecosystems. Most papers present significantly negative effects of activities such as dredging or channel regulation on the ecological status of rivers. The purpose of this work was to compare the response of various groups of invertebrates (Mollusca, Hydrachnidia, Odonata, Heteroptera, Coleoptera and Trichoptera) to an intervention involving dredging in conjunction with the removal of riparian vegetation. Habitat diversity increased after the dredging, and more individuals and species were caught than before the dredging. The increase in habitat diversity after the dredging translated into an increase in the species diversity of most investigated groups. Individual groups of invertebrates showed varied responses to the dredging, depending on the role of the terrestrial phase in their life cycle: the greater the role of the terrestrial phase in the life cycle, the more the group was affected by changes in the terrestrial environment following the intervention. In consequence, the intervention had the greatest negative impact on insects, and among these, on adult Odonata. The following conclusions can be drawn: (1) Dredging can benefit a previously anthropogenically transformed river ecosystem by increasing habitat diversity; (2) Odonata are particularly useful for assessing the impact of this type of intervention on invertebrate communities. They can be considered good indicators of habitat disturbances in both aquatic and terrestrial ecosystems.
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Kraan, Casper, Theunis Piersma, Anne Dekinga, Anita Koolhaas i Jaap van der Meer. "Dredging for edible cockles (Cerastoderma edule) on intertidal flats: short-term consequences of fisher patch-choice decisions for target and non-target benthic fauna". ICES Journal of Marine Science 64, nr 9 (22.10.2007): 1735–42. http://dx.doi.org/10.1093/icesjms/fsm153.
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Abstract Kraan, C., Piersma, T., Dekinga, A., Koolhaas, A. and van der Meer, J., 2007. Dredging for edible cockles (Cerastoderma edule) on intertidal flats: short-term consequences of fisher patch-choice decisions for target and non-target benthic fauna. – ICES Journal of Marine Science, 64. Intertidal flats in the Dutch Wadden Sea are protected by national and international treaties. Still, mechanical dredging for edible cockles Cerastoderma edule was allowed in 74% of 1200 km2 of intertidal flats. Cumulatively, between 1992 and 2001, 19% of the intertidal area was affected by mechanical cockle-dredging at least once. On the basis of a grid of 2650 stations sampled annually, we evaluate the extent to which cockle-dredging from 1998 to 2003 was selective with respect to non-target macrozoobenthic intertidal fauna. In all 4 years that comparisons could be made, to-be-dredged areas contained greater diversity of macrobenthic animals than areas that remained undredged. Targeted cockles were 2.5 times more abundant in areas that were to be dredged shortly, but other species also occurred in higher densities in these areas. Small amphipods and some bivalves occurred less in to-be-dredged areas than elsewhere. In terms of short-term responses to dredging, four non-target species showed a significant decrease in abundance 1 year after dredging. Only Tellina tenuis showed an increase a year after dredging.
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Krausfeldt, Lauren E., Jose Victor Lopez, Catherine Margaret Bilodeau, Hyo Won Lee i Shelby L. Casali. "Change and stasis of distinct sediment microbiomes across Port Everglades Inlet (PEI) and the adjacent coral reefs". PeerJ 11 (13.01.2023): e14288. http://dx.doi.org/10.7717/peerj.14288.
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Deep water ports are human built coastal structures that by definition welcome ship traffic and disturbance. Evidence is accumulating that enhanced port activities such as dredging or deepening have negatively affected nearby natural habitats. Port Everglades Inlet (PEI) is a large active South Florida cargo port for over two million people and lies adjacent to coral reefs, dwindling mangroves, and recreational beaches. In this study, the microbial communities of PEI and adjacent reef sediments were characterized to serve as indicators for change due to dredging and assess anthropogenic influence on these sensitive ecosystems by sequencing the V4 region of 16S rRNA ahead of a large-scale port deepening event. For the first time, this study established baseline bacterial community characterizations and their patterns of diversity prior to and after a maintenance dredging event. PEI samples were collected for two consecutive years 2020 (Phase I, before maintenance dredging) and 2021 (Phase II, after maintenance dredging) from PEI sediments and adjacent coral reef sediments. In spite of their proximity and tidal connections through the PEI, reef and PEI sediment microbial communities were distinct. Changes in microbial diversity within the intracoastal waterway (ICW), a route for community exchange or transfers, were the greatest after maintenance dredging occurred. Microbial diversity in reef sediments also changed after dredging, indicating potential influence from resuspended sediments due to an associated increase in trace metals and decrease in cyanobacterial diversity. Sediments were identified as a possible source of human and coral pathogens, although dredging did not affect the relative abundances of these indicator microorganisms. This study highlighted the utility and relative ease of applying current molecular ecology methods to address macroscale questions with environmental management ramifications.
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Fu, Xiaoyi. "Simulation Study on Sea-Rail Intermodal Diversion Operation of Container Terminal in the Beilun Port Area of Ningbo Zhoushan Port". Scientific and Social Research 6, nr 6 (9.07.2024): 86–96. http://dx.doi.org/10.26689/ssr.v6i6.7175.
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With the continuous development of global trade, the Beilun port area of Ningbo Zhoushan Port, as an important node of international shipping, its efficient and orderly container dredging operation is crucial to ensure the overall operational efficiency of the port and the stability of the regional supply chain. However, the actual operation is faced with multiple constraints such as fluctuating berth utilization rate, complex truck scheduling, tight yard space, and so on, which need to be optimized by scientific means. To achieve more efficient container transport, it is necessary to further optimize and improve sea-rail intermodal transport to improve the efficiency of port container operations. Therefore, this paper is based on the background of the rapid development of sea-rail intermodal transport of port containers, focusing on the problem of dredging operation of container terminals in the Beilun port area of Ningbo Zhoushan Port, through the analysis of the characteristics and influencing factors of container dredging operation, research on the optimization of container dredging scheme and put forward optimization scheme for the problem of dredging in Beilun Port Area of Ningbo Zhoushan Port, which is aimed at improving the efficiency and economy of container dredging operation and the efficiency of container dredging operation in Beilun port area through the advanced modeling and simulation technology. Through advanced modeling and simulation technology, it aims to effectively improve the efficiency and economy of container dredging operations in the Beilun port area, to cope with the increasing throughput pressure and the challenges of a complex logistics environment, and to provide theoretical support and practical guidance for the development of China’s sea-railway intermodal transport.
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Vijverberg, Thomas, Michiel Reneerkens, Han Winterwerp, Olaf Scholl i Y. Haruna. "SEDIMENT DYNAMICS IN LAGOS HARBOUR - RECONNAISSANCE ON EFFECTS OF DREDGING". Coastal Engineering Proceedings 1, nr 33 (25.10.2012): 75. http://dx.doi.org/10.9753/icce.v33.sediment.75.
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Due to economic growth, Lagos Harbour is expanding. Capital dredging is needed to allow larger vessels to call the port. As harbour siltation is already a problem, increase of maintenance dredging is a worry. In the past no data was available to understand the hydraulics and sediment transport to estimate maintenance dredging volumes. This paper presents the reconnaissance of the sediment dynamics in the harbour, based on field data and MIKE21 model simulations. Measurements of sediment concentration, salinity and flow velocity show that estuarine circulation occurs, transporting sediment from the ocean into the port. However, more upstream in the Commodore channel, at the location where dredging will be carried out, this circulation is small. Model simulations show that at that location, bed shear stresses are large, also after dredging. Therefore, fine sediment can not accumulate in the deepened areas and this will not result in large dredging volumes. Sand transport however can cause sedimentation, as bed forms can migrate. These mechanisms are also observed in initial sand transport simulations, but need to be studied further to fully understand the sediment dynamics in the harbour.
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Mallick, Nayan, Kevin B. Johnson i Charles A. Jacoby. "The Effect of Environmental Dredging of Muck on an Assemblage of Benthic Amphipods". Journal of Marine Science and Engineering 11, nr 2 (17.02.2023): 444. http://dx.doi.org/10.3390/jmse11020444.
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To yield environmental benefits, fine sediments with ~10% organic matter, termed muck, were dredged from a tributary to the Indian River Lagoon. Key changes were documented by sampling amphipods, sediments, and the water column near the bottom before dredging, and approximately one month and one year after dredging. Overall, muck yielded the fewest taxa, muck or sediments in creeks that were dredged yielded a moderate number of taxa, and undisturbed sediments in the lagoon yielded the highest number of taxa. Amphipods did not appear in areas with muck until one month and one year after dredging. In contrast, amphipods in sediments that were not muck decreased after dredging. Increases in the occurrence of amphipods paralleled increases in concentrations of dissolved oxygen and decreases in the water, silt/clay, and organic content of sediments. Overall, results indicated that conditions for amphipods were improved by removing muck, and that dredging sandier sediment led to decreased taxonomic richness and numbers of amphipods, which resembled the effects of navigational dredging. Thus, this study suggested that managers should consider the type of sediment to be dredged when permitting projects.
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Islam, Md Kabirul, Numan Al Kibriya i Md Maruf Dustegir. "Impact Analysis of Sand Dredging from Alluvial Tidal River". E3S Web of Conferences 40 (2018): 03036. http://dx.doi.org/10.1051/e3sconf/20184003036.
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The Government of Bangladesh has planned to make a large build up area (BUA) in a newly developed sedimentary point bar (locally known as ‘Char’) at Lebukhali along the northern bank of Payra river in the southern part of the country. From a study it was revealed that, this sedimentary bar has to be raised by 3.45 meters from MSL to keep it free from any extreme events (like tidal and storm surge effects) for 100 years return period. Accordingly, it was planned to collect the required filling material (estimated 57.6 million m3 of sand/soil) by dredging the same river bed. In Bangladesh dredging of river is very popular and widely undertaken to collect filling and construction material, but its adverse impact on river bed, bank and adjacent areas are hardly probed. This study aimed at analyzing the adverse impacts of dredging from Payra River bed. Four alternative sand bars have been identified as dredging area at varying distances located both upstream and downstream of the proposed site. The dredging impacts were analyzed for different boundary conditions. The study is based on physical survey (topographic and bathymetric surveys), historical data and numerical model analysis. Numerical model is applied through Delf 3D to investigate the impact on flow parameters: flood depth and velocity magnitude. Continuous field visit and observations were made through last one year to observe real impact. The analysis revealed that dredging of any of the bars have resulted changes in flow field. The distance of dredging point does not control the flow field rather the dredging volume, depth and upstream conditions determine the effect on bank erosion. As such, the dredging locations have been prioritized considering the least possible effects on river bank erosion and founded that little erosion is taking place for both upstream and downstream region. However, the long term impacts in other areas of the river need to be investigated as the time pass.
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Oga Omoyemi, Azeez. "An investigation into the impacts of dredging on aquatic and terrestrial lives in Oto-Awori local council development area, Lagos state, Nigeria". Global Journal of Ecology 9, nr 1 (21.06.2024): 084–93. http://dx.doi.org/10.17352/gje.000100.
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This study investigated the impacts of dredging on aquatic and terrestrial lives in the Oto-Awori Local Council Development Area (OALCDA) of Lagos State, Nigeria. Descriptive Survey Design was adopted for the study. The target population of the study comprised all the residents of OALCDA. Two hundred respondents were sampled using a simple random technique. The instrument for data collection was a structured questionnaire. The questionnaire was personally administered by the researcher and collected by him. Seven research questions and two hypotheses guided the study. Frequency count, bar chart, percentage, and mean were used to answer the research questions while the hypotheses were tested at 0.05 level of significance using t - test and Chi-square. The findings of the study were as follows: plant and animal species were high before the commencement of the dredging operation, but became low after its commencement. The main reason for embarking on dredging operation in the study area was found to be for monetary gain from the sale of excavated materials. The relationship between aquatic organism loss and dredging was found to be significant. It was therefore recommended among others that there should be pre and post-dredging environmental impact assessments to better understand the extent of impacts of dredging on living things and the environment, and proper awareness should be created on the consequences of dredging operations. The elected chairman of Oto-Awori Local Council Development Area and his team should raise awareness among the people on the impact of their actions on both aquatic and terrestrial species and initiate a comprehensive remediation program with stringent monitoring. Higher institutions within the study area should partner with relevant bodies to organize seminars on educating the residents on what dredging is, the purpose of dredging, and its impacts on the ecosystem as a whole, since the loss of medicinal and research species has an efficacy impact on the teaching and learning of science.
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Ajiwibowo, Harman, i Munawir B. Pratama. "Hydrodynamic changes impacted by the waterway capital dredging in Cikarang Bekasi Laut channel, West Java, Indonesia". Water Practice and Technology 15, nr 2 (23.04.2020): 450–59. http://dx.doi.org/10.2166/wpt.2020.032.
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Abstract This paper presents one-dimensional numerical modeling using MIKE 11 to simulate the impact of capital dredging on the hydrodynamics of the Cikarang Bekasi Laut (CBL) channel flow. The CBL channel is located in Bekasi Regency, West Java Province, Indonesia. The river discharges upstream, and tidal fluctuations at the sea boundary were the governing parameters of the hydrodynamic model. Data such as river centerline, cross-sections, tidal elevation, and river discharges were compiled to construct the model. The instantaneous record of water level and river discharge data were used as model validation. The model results give decent validation when compared to water level and river discharge field data. Dredging on the canal is planned to be carried out across 19 km from the estuary to the upstream to allow large vessel navigation. The modeling results show that during the wet season, dredging affects the water level and river flow up to 25 km upstream, while during the dry season, dredging affects the hydrodynamics only up to 20 km upstream. It can be concluded that the canal dredging does not have a significant impact in terms of surface water elevation in the canal upstream. The critical finding is that the bed shear stress is significantly increased upstream of the dredging plan at kilometer 19, showing that there is potential riverbed erosion threat in the area. It is recommended to conduct a sedimentation study to predict the impact of sedimentation change from the dredging.
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Setiawan, Rachman. "PARAMETRIC ANALYSIS ON OFF-SHORE DREDGING PROCESS USING CUTTER SUCTION DREDGERS". ASEAN Engineering Journal 6, nr 1 (19.05.2015): 37–46. http://dx.doi.org/10.11113/aej.v6.15477.
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Nowadays, cutter-suction dredgers are widely used in off-shore tin mining around South East Asia region, especially in Indonesia. So far, the effectiveness of the dredging process is arguably due to the skills and experience of individuals who operate the dredgers. No sufficient guidelines, standard operating procedures exist on how to operate the dredgers effectively based on scientific facts and factual data on the mining environment. This paper discusses the effectiveness of the dredging process in a cutter suction dredger (CSD). The influence of various parameters is studied through parametric simulation based on theoretical approach developed by Miedema and Vastbloom, with a number of adaptations from the original model in order to obtain a better approximation. A specific CSD design is used as a case study. From the parametric analysis, it is found that, dredging capacity is highly affected by the cutting thickness and swing speed, rather than the dredging depth. With the limit of pump capacity and dredge power, the optimum cutting thickness is approximately 75% for the dredger in question, adjustable through the swing speed during operation. Moreover, the dredging forces are highly affected by the cutter rotational speed and soil type, whilst lightly affected by the dredging depth. For dredging harder soils, the dredge forces increase by up to 68%, for the dredger in question, hence the operational parameters must be adjusted, i.e. by lowering the swing speed, however maintaining higher rotational speed, in order to have a safe and optimum operation.
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García Alba, J., A. G. Gómez, R. O. Tinoco López, M. L. Sámano Celorio, A. García Gómez i J. A. Juanes. "A 3-D model to analyze environmental effects of dredging operations – application to the Port of Marin, Spain". Advances in Geosciences 39 (1.04.2014): 95–99. http://dx.doi.org/10.5194/adgeo-39-95-2014.
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Abstract. Historically, the study of dredging processes has depended on physical laboratory tests. The IH-Dredge model has been developed to simulate these processes numerically. It simulates the evolution of the seabed, sediment and toxic substances involved in dredging operations. The model has been calibrated and validated with experimental data, and it has been applied in a dredging operation in the Port of Marin, Spain.
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Wang, Feng. "Automatic Dredging Robot for Metallurgical Drainage Trench Based on Virtual Design Technology". Advanced Materials Research 490-495 (marzec 2012): 2115–19. http://dx.doi.org/10.4028/www.scientific.net/amr.490-495.2115.
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The artificial dredging method is now used for the closed-type drainage trench of Tangshan Iron and Steel Co. Ltd., with low operation efficiency and large labor intensity. A new kind of dredging robot was presented in order to completely replace the human to clean the trench automatically. It is mainly composed of the crawler type walking mechanism, dredging chain bucket, silt conveying belt, and silt conveying carriage. Due to the adoption of the operating mode of mechanized dredging and mechanized conveying, the robot can enable the workers to get rid of the bad working environment thoroughly and overcome the various problems resulting from the artificial method. The 3D solid modeling and virtual assembly were conducted and the stability was analyzed by the use of Pro/E. It has been proved that under the condition of full load, the robot can implement the dredging operation stably and efficiently, which means that the design of the robot is feasible and effective.
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Filina - Dawidowicz, Ludmiła, i Wojciech Durczak. "Organization of ship traffic during dredging works on a selected section of the Świnoujście – Szczecin fairway". Inżynieria i Budownictwo LXXIX, nr 7-8 (31.08.2023): 402–7. http://dx.doi.org/10.5604/01.3001.0053.7989.
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The need to carry out dredging works within the framework of the “Modernization of the Świnoujście-Szczecin fairway to a depth of 12.5 meters” project on the Świnoujście – Szczecin fairway forced the need to change the organization of ship traffic on this fairway. The purpose of the article is to assess the organization of ship traffic on a selected section of the Świnoujście – Szczecin fairway after the introduction of new solution for its organization during dredging works. An analysis of vessel traffic density maps and traffic time records along the selected section of fairway during its dredging was carried out in the article. It was found that the solution introduced during the dredging of the selected section of the fairway did not contribute to delays in the movement of ships entering and leaving the ports of Szczecin and Police. The research results can be used by seaports planning dredging works using non-standard solutions
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Fernández-Fernández, Sandra, Caroline C. Ferreira, Paulo A. Silva, Paulo Baptista, Soraia Romão, Ángela Fontán-Bouzas, Tiago Abreu i Xavier Bertin. "Assessment of Dredging Scenarios for a Tidal Inlet in a High-Energy Coast". Journal of Marine Science and Engineering 7, nr 11 (6.11.2019): 395. http://dx.doi.org/10.3390/jmse7110395.
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The high energetic wave climate of the North Atlantic Ocean causes important morphological changes at Figueira da Foz coastal system (W Portugal), which is comprised of sandy beaches and the Mondego estuary-inlet. The submerged sandbar at the inlet mouth is highly dynamic inducing short waves shoaling and breaking processes that can entail navigation problems towards the local harbor. Therefore, coastal dredging operations are performed to guarantee safe navigation. Nevertheless, these operations have a limited temporal effectiveness and require a high annual budget to be accomplished. The goal of this research is to seek long-life dredging alternatives using modeling tools (i.e., Delft3D model suite). Delft3D model is used to simulate the morphological evolution of five dredging scenarios during a three-month winter period under three wave climate scenarios. The bed level differences at the dredged area and at the inlet mouth for each scenario are analyzed in comparison with numerical solutions obtained in a reference scenario (i.e., no-dredging). Results highlight morphological changes at the dredged inlet and surrounding areas and their effectiveness in extending the operational lifetime of inlet dredged operations on dredging configuration and wave climate conditions. These findings are the basis for selecting the most suitable dredging scenario to this coastal region under current wave climate conditions.
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Kar Soon, Tan, i Julian Ransangan. "Dredging-induced shell damages to hard clam (Meretrix meretrix): a Malaysian case study". Aquatic Living Resources 32 (18.12.2018): 1. http://dx.doi.org/10.1051/alr/2018025.
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The hard clam (Meretrix meretrix) is a popular edible shellfish in South and Southeast Asia, being heavily exploited by hand dredging in Marudu Bay, Malaysia. The current study was performed to evaluate the shell damages caused by this artisanal dredging gear. Samplings were conducted in triplicates at two sites using both hand dredging and hand collecting (control) sampling methods. The shell length and total weight, damage areas and breakage patterns of each clam were recorded. A questionnaire survey was conducted with local bivalve harvesters to gather information on the fishing pressure in Marudu Bay. Results revealed that the efficiency (fishing yield) of hand dredging gear was three times higher than hand collecting. However, hand dredging gear causes lethal shell damages to small hard clams (<3cm in shell length). Hard clam harvesting is the main occupation of most fishermen in Kg. Popok, but most of them do not comply with the minimum harvesting size established by the fishery department. Moreover, most of the stakeholders are not aware of the negative impacts of hand dredging to the sustainability of the hard clam fishery in Marudu Bay. Therefore, organizing more awareness programs combined with introducing community-based fishery management are highly recommended to promote the sustainability of this artisanal fishery.
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Qi, S., X. Zhang, D. Wang, J. Zhu i C. Fang. "Study of Morphologic Change in Poyang Lake Basin Caused by Sand Dredging Using Multi-temporal Landsat Images and DEMs". ISPRS - International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences XL-1 (7.11.2014): 355–62. http://dx.doi.org/10.5194/isprsarchives-xl-1-355-2014.
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Sand dredging has been practiced in rivers, lakes, harbours and coastal areas in recent years in China mostly because of demand from construction industry as building material. Sand dredging has disturbed aquatic ecosystems by affecting hydrological processes, increasing content of suspended sediments and reducing water clarity. Poyang Lake, connecting with Yangtze River in the lower reaches of the Yangtze River, is the largest fresh water lake in China. Sand dredging in Poyang Lake has been intensified since 2001 because such practice was banned in Yangtze River and profitable. In this study, the morphologic change caused by sand dredging in Poyang Lake basin was analysed by overlaying two DEMs acquired in 1952 and 2010 respectively. Since the reflectance of middle infrared band for sand dredging vessel is much higher than that of water surface, sand dredging vessels were showed as isolated grey points and can be counted in the middle infrared band in 12 Landsat images acquired in flooding season during 2000~2010. Another two Landsat images (with low water level before 2000 and after 2010) were used to evaluate the morphologic change by comparing inundation extent and shoreline shape. The following results was obtained: (1) vessels for sand dredging are mainly distributed in the north of Poyang Lake before 2007, but the dredging area was enlarged to the central region and even to Gan River; (2) sand dredging area reached to about 260.4 km<sup>2</sup> and is mainly distributed in the north of Songmen Mountain and has been enlarged to central of Poyang Lake from the distribution of sand vessels since 2007. Sand dredged from Poyang Lake was about 1.99 × 10<sup>9</sup> m<sup>3</sup> or 2448 Mt assuming sediment bulk density of 1.23 t m<sup>−3</sup>. It means that the magnitude of sand mining during 2001–2010 is almost ten times of sand depositions in Poyang Lake during 1955–2010; (3) Sand dredging in Poyang Lake has alternated the lake capacity and discharge section area, some of the watercourse in the northern channel was enlarged by more than 1 km when in low lake level. This study is useful to understand the change of hydrological system, especially the drying up trend in Poyang Lake in recent autumns and winters.
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McLaverty, C., OR Eigaard, GE Dinesen, H. Gislason, A. Kokkalis, AC Erichsen i JK Petersen. "High-resolution fisheries data reveal effects of bivalve dredging on benthic communities in stressed coastal systems". Marine Ecology Progress Series 642 (28.05.2020): 21–38. http://dx.doi.org/10.3354/meps13330.
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Commercial dredging for blue mussels (Mytilus edulis) and oysters (Ostrea edulis, Crassostrea gigas) constitute the main bivalve fisheries in Denmark. These activities predominantly take place in Limfjorden, a large microtidal sound, and in the Inner Danish waters. Both areas are shallow, estuarine, receive high nutrient inputs from agriculture, and are of nature conservation interest (Natura 2000 sites), thus presenting challenges for an ecosystem approach to fisheries management. Using high-resolution fisheries data (~10 m), we investigated the effects of bivalve dredging on benthic communities at both local (Natura 2000 site) and regional (fishery-wide) scales. Regionally, our results showed that dredging intensity correlated with shifts in species composition and reduced community biomass. We were, however, unable to detect an effect of dredging on community density, trait richness, and trait composition. These metrics were significantly related to other environmental drivers, such as sediment organic content (negative) and mussel bed biomass (positive). At the local scale, the observed relationships between dredging, biomass, and species composition varied significantly. This occurred as dredging impacts were greater in areas that contained suitable reference conditions and experienced relatively low levels of disturbance. By contrast, communities which experienced high nutrient loading, regular anoxic events, and high natural variability were relatively unaffected by dredging. Our results therefore highlight the importance of spatial scales in fishing impact estimations. Furthermore, we demonstrate how targeted sampling, high-resolution fisheries data, and suitable reference areas can be used to detect fishery effects in coastal areas that are highly stressed by eutrophication.