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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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TL;DR: In this article, a double monitoring system for turbidity control was used during the dredging operation of the Port of Genoa (Italy) to study the concentration of total suspended solids, the physical characteristics of the water column, and the winds and currents determining the hydrodynamic characteristics of a port.
Abstract: The potential negative effects of dredging on a sensitive marine environment (e.g. phanerogamic meadows, beaches, benthic populations) can be justification for restrictions on the dredging project or the creation of a dredging monitoring plan. The dredging of the Port of Genoa (Italy) provided the opportunity to study the concentration of total suspended solids, the physical characteristics of the water column, and the winds and currents determining the hydrodynamic characteristics of the port, and to test a double monitoring system for turbidity control. In the dredging operation of the Port of Genoa, we positioned a couple of fixed monitoring systems operating 24/7, consisting each of a conductivity–temperature–depth probe and two acoustic Doppler current profilers (ADCP), near the two port entrances to monitor turbidity and currents. To make the monitoring strategy more efficient, to periodically control the data transmitted by the fixed stations and to ensure coverage of those areas not covered by the fixed monitoring system, a vessel equipped with a vertical ADCP and a conductivity–temperature–depth probe with a turbidimeter periodically followed the dredger during its daily operations. Using the data acquired during the pre-dredging and dredging phases, we considered turbidity and suspended solids variations caused by the dredging operation to study the evolution of the plume. The trailing suction hopper dredge (TSHD) plume extended from the surface throughout the entire water column at a distance of 50 m, with higher turbidity close to the bottom. At a distance of 200 m, the plume was much reduced. Instead, at a distance of 50 m, the turbidity produced by the backhoe was lower than that measured around the TSHD, while at a distance of 100 m the plume was reduced with only noticeable values near the bottom. Finally, we compared the turbidity data of the dredging with the background conditions near the Posidonia oceanica meadow present near the port. The data presented in this paper indicate that the choice of a combined monitoring system can be a good practical solution for reaching two different objectives: (a) to follow the evolution and movement of the turbid plume, and ensure that it does not flow out of the port, contaminating the surrounding area or damaging nearby coastal habitats or the Posidonia oceanica meadows; and (b) to study the differences between the turbid plumes created by two dredging tools (backhoe and TSHD) under different wind–wave conditions.

22 citations

Jicheng, Zhong, Chengxin, Fan, Lu, Zhang, Edward, Hall, Shi-Ming, Ding, Bao, Li, Guofeng, Liu 
01 Jan 2010
TL;DR: In this article, the denitrification problem is addressed by denitrifying denitra-tion, which is defined as denitreconstruction of a denitred property.
Abstract: 为学习沉积在沉积在 denitrification 上挖出的效果的一个实验通过 undredged (控制) 的一个年孵化被执行并且在实验室挖出核心。挖出上面 30 厘米沉积能显著地影响沉积的物理化学的特征。在挖出的沉积的有机物的更少的降级在实验期间被发现。在沉积的 Denitrification 率被乙炔阻塞技术估计,并且从 216 ~ 1027 nmol N2/(g 干燥重量(dw )汯 吗?

22 citations

01 Jan 2002
TL;DR: In this article, the basin-scale effect of dredging and disposal of dredged material (dredging operations) and natural estuarine processes was analyzed to compare the basin scale effect of DAG operations and natural processes.
Abstract: Suspended sediment concentration (SSC) data from San Pablo Bay, California, were analyzed to compare the basin-scale effect of dredging and disposal of dredged material (dredging operations) and natural estuarine processes. The analysis used twelve 3-wk to 5-wk periods of mid-depth and near-bottom SSC data collected at Point San Pablo every 15 min from 1993-1998. Point San Pablo is within a tidal excursion of a dredged-material disposal site. The SSC data were compared to dredging volume, Julian day, and hydrodynamic and meteorological variables that could affect SSC. Kendall's T, Spearman's p, and weighted (by the fraction of valid data in each period) Spearman's pw correlation coef- ficients of the variables indicated which variables were significantly correlated with SSC. Wind-wave resuspension had the greatest effect on SSC. Median water-surface elevation was the primary factor affecting mid-depth SSC. Greater depths inhibit wind-wave resuspension of bottom sediment and indicate greater influence of less turbid water from down estuary. Seasonal variability in the supply of erodible sediment is the primary factor affecting near-bottom SSC. Natural physical processes in San Pablo Bay are more areally extensive, of equal or longer duration, and as frequent as dredging operations (when occurring), and they affect SSC at the tidal time scale. Natural processes control SSC at Point San Pablo even when dredging operations are occurring.

22 citations

Journal ArticleDOI
01 Dec 2018
TL;DR: Wang et al. as mentioned in this paper used different types of hard and soft solutions for coastal protection against erosion were used in Shandong, especially at the Yellow River Delta and city center waterfront, and Groynes, jetties and breakwater are used on the north and east sandy coast of the Peninsula.
Abstract: Shandong has more than 70% of natural coasts are under erosion. Coastal erosion started from the 1970’s and became a very serious problem at 1990’s. The dramatic decrease of sediment supplies from rivers caused rapid erosion at the delta and estuary areas, especially in the abandoned Yellow River Delta. Most sandy coasts along the Peninsula were eroded due to lack of sand supply and interruption of alongshore sediment drift, sand dredging from the beach or the offshore area caused serious erosion during short time. Sea-level rise causes slow but constant shoreline retreats and became a more serious threat. Different types of hard solutions for coastal protection against erosion were used in Shandong. Seawalls are most widely used, especially at the Yellow River Delta and city center waterfront. Groynes, jetties and breakwater are used on the north and east sandy coast of the Peninsula. Hard approaches are effective to protect the coast erosion but not change the erosion causes and led secondary impact on the coast. Soft engineering solution or the combined solutions are taken into acts. Beach nourishment is mostly considered as the better soft solution, especially to those tourists attracting sandy beaches along the Shandong coast. Long term monitoring and continuous lessons learning from the coastal erosion management will be adaptive for better coast solution in the future.

22 citations


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