Dredging

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

Physical effects related to relict sand dredging for beach nourishment in the Tyrrhenian sea: the Anzio case

Abstract: Nonnis, O, Paganelli, D.,Proietti, R, and Nicoletti, L., 2011. Physical effects related to relict sand dredging for beach nourishment in the Tyrrhenian sea: the Anzio case. Journal of Coastal Research, SI 64 (Proceedings of the 11th International Coastal Symposium), 1380 – 1384. Szczecin, Poland, ISSN 0749-0208 Bea ch nourishment has been used for several years as a means to solve the problem of coastal erosion, and it is considered to be one of the main tools for coastal management. It is however known that relict sand dredging can have a number of physical and biological effects on the marine environment. The main physical effects are related to morphological and sedimentological changes on the sea bottom and to the alteration of the chemicalphysical characteristics of the water column due to sediment input. This paper aims to examine the physical effects of the dredging activities carried out in three sites of the Anzio (Rome, Italy) relict sand deposit in the central Tyrrhenian sea. A multi-year environmental survey was carried out to analyze different environmental parameters in order to assess the effects of relict sand mining on the marine environment. In particular, this paper reports the results of the grain size analysis and of the morphological and bathymetric surveys (high-resolution side scan sonar imagery and bathymetric maps) carried out before and after the dredgings, in order to identify the features and the extensions of the actuallty-impacted areas.

Dredging induced changes in zooplankton community and water quality in Dal Lake, Kashmir, India

Abstract: A study was conducted from July 2013 to June 2014 to assess the outcome of dredging activity on the water characteristics and zooplankton community structure in Dal Lake An assessment was done with respect to alterations in physico-chemical parameters and zooplankton community changes in pre-dredged and post-dredging periods The results showed a considerable reduction in Secchi transparency while water depth, conductivity, total dissolved solids, nitrate and total phosphorous concentrations increased noticeably in post dredging scenario Variations in the values of dissolved oxygen, pH and temperature as a result of dredging were not statistically significant The environmental changes as a result of dredging activity affected the structure and distribution of zooplankton community; the abundance of rotifers decreased, while the crustaceans increased The prominent taxa were Brachionus sp, Keratella cochlearis, Bosmina longirostris, Chydorus sphaericus and Diaptomus sp Key words: Dredging, water quality, zooplankton, rotifer, crustacean

Sustainable sediment management in coastal infrastructures through an innovative technology: preliminary results of the MARINAPLAN PLUS LIFE project

Abstract: The paper aims to show the preliminary monitoring and field test results of the innovative technology tested in the framework of the MARINAPLAN PLUS LIFE project for sustainable management of sediment in harbour areas. The technology is based on a patented jet pump that will be able to keep the seabed at a certain level over the time through a continuous removal of silting sediments. Preliminary field tests were performed to optimise the design of the demo plant and a monitoring plan was devised to evaluate the technical, economic and environmental impacts of the technology, in particular in comparison with dredging. The preliminary tests showed promising results in terms of efficacy and efficiency of the sediment by-passing device. At the maximum sediment removal capacity, the ejector tested in Cervia showed a sediment flow rate of about 2 m3 h−1, with an electric consumption of about 3.5 kW, and an influence diameter of about 5–7 m, after 15 days of working operation. On the basis of the preliminary results, a 10-ejector demonstrator plant has been designed and realised, and it is now in operation. The analysis of sediment and marine flora and fauna in the installation area in comparison with control areas indicates the negative impact of cyclic dredging in the harbour inlet area. The innovative technology promoted by the MARINAPLAN PLUS LIFE project is a promising solution to manage sediment siltation in harbour areas through a cost-effective and low environmental impact technology. The monitoring of the demo plant operation is fundamental to fully validate the technology and to demonstrate its efficacy and sustainability.

Regional Sediment Management Studies of Matagorda Ship Channel and Matagorda Bay System, Texas

Abstract: : Three research and development programs within the US Army Engineer Research and Development Center (ERDC) have collaborated to investigate regional sediment management strategies within the Matagorda Bay system, emphasizing the excessive shoaling in the upper reach of the Matagorda Ship Channel (MSC). These three R&D programs were the Regional Sediment Management (RSM) Program, Coastal Inlets Research Program (CIRP), and Dredging Operations and Environmental Research (DOER) Program. Extensive shoaling in the upper reach of the MSC in recent years has resulted in the need for annual maintenance dredging. The increasing channel shoaling rate is likely due to the placement of dredged material into adjacent open water sites west of the channel and the migration of these fluidized sediments back into the channel. It is suspected that active sedimentation in upper Lavaca Bay also contributes to the high shoaling rate in the MSC. Stronger wave action in Lavaca Bay and Matagorda Bay during fall and winter months evidently increases the amount of suspended sediment, especially cohesive sediment, and promotes more sediment deposition in the MSC. Numerical simulations were conducted to investigate the existing Matagorda Bay conditions and three alternatives as proof-of-concept to reduce sediment deposition in the upper MSC: 1) a confined artificial island south of Port Comfort, located in the northeast portion of the bay to contain the dredged material from the upper channel, 2) extension of an existing geotube east of the upper channel to close the gaps between dredged material placement areas, and 3) three new placement areas west of the navigation channel. The present study showed these alternatives could effectively reduce the channel shoaling rate. Options to reduce maintenance dredging by surveying the channel such that the fluid mud interface could be defined are also discussed.