Sediment Waves

Geohazard or Geofeature?
The term ‘sediment waves’ was fully established in a special issue of Marine Geology and refers to large-scale depositional bedforms in various parts of the world’s oceans. These undulating objects usually have tens of metres to a few kilometres in wavelength and a height of several metres. The genesis is believed to be a near-bottom current, a turbidite current or both. The main issue about the sedimentary wavy features was, and is, to distinguish them from soft sediment deformations (creep). The methods used for such determinations are accurate processing of seismic sections to reveal whether the faults are real, measuring... (read more)
2013-12-04 11:25:17

Sediment-erosion Measurement Technology

Partrac, UK, has introduced the Genesis Altimeter, a technology designed to measure small-scale changes on seabed elevation levels. The device takes high-resolution measurements of sediment erosion and deposition on the seabed, enabling users to determine the impacts of sediment movements on ecological and environmental systems. In most coastal and estuarine settings, the seabed elevation (water depth/bathymetry) changes due to the processes of sediment and sediment deposition on a daily basis. More pronounced changes occur when wave energy can penetrate to the seabed during winter storms. Changes in seabed level greater than ~0.10 – 0.15m can be detected using conventional single-... (read more)
2012-08-01 11:58:12

Monitoring of Sediment Displacement

During current pipelaying activities in German waters for the North Stream pipeline between Russia and the EU, Aqua Vision BV performed vessel-based tracking of water column characteristics in the vicinity of dredging and pipelaying activities. The measurement programme involved monitoring during two pipelaying phases: dredging and pipelaying. Combining high-resolution data collection (using Acoustic Doppler Current Profilers) and real-time plume detection software (ViSea-PDT) makes it possible to map the size and concentration of sediment plumes. This information is subsequently used to validate predictions based on numerical modelling studies.Sediment monitoring is part of a larger monitoring programme, involving modelling studies and moored... (read more)
2010-11-22 09:15:35

Camera Assisting Sediment Coring

UK-based bespoke marine engineering company Ocean Scientific International Ltd (OSIL) have released a camera system designed to be mounted to deep sea sediment corers. The self-contained system will allow users to record the corer deployment and review the footage on recovery of the corer to check the system has deployed correctly, aid analysis of the sample and re-deployment of the corer, and offer a laser ranged view of the sediment itself via a graticule scale. The camera is attached to the corer and can be programmed at the surface to turn on and begin recording at a specific depth (i.e.... (read more)
2015-12-01 11:23:50

Sediment Stability Instrumentation Added to 'Sediment? Solved' Range

Aquatec Group has expanded the 'Sediment? Solved' range to include instrumentation to measure surface sediment stability, with the addition of Partrac’s benthic flumes and Cohesive Strength Meter (CSM). The Cohesive Strength Meter is a field instrument that directly measures the surface erodibility of marine, fluvial and terrestrial sediments. It permits rapid assessment of sediment critical entrainment stress and provides a relative measure of erosion rate. This information is important for the understanding of benthic habitat stability, contaminated sediment dispersal, river bank and agricultural land stability, and the geomorphology of estuaries and coastal areas. Partrac’s Voyager II sea flume is an... (read more)
2017-06-21 09:09:09

Sediment Sensor LISST-200X

Geometius, The Netherlands, has introduced the LISST-200X of Sequoia Scientific as the successor of the LISST-100X. The device is a small-size submersible particle size analyser with integrated depth and fast response temperature sensors to improve profiling data. This model measures particle sizes from 1 to 500 microns at up to 600 metres water depth. It outputs the mean size and total volume concentration as analogue voltage or digital while simultaneously storing the full size distribution internally for later downloading. The LISST-200X measures particle size and concentration in rivers, streams, ports, harbours, coasts and oceans, whether for biological, sediment transport or... (read more)
2016-04-11 08:57:47

Sumatra Tsunami: Sediment Trenches Implicated

The devastating power of the 2004 Boxing Day Sumatran-Andaman earthquake and unusual geological characteristics of the seabed and underlying sediments south of the epicentre contributed to the ensuing tsunami, the deadliest recorded in modern times. The findings come from a US-led team involving researchers based at the UK National Oceanography Centre in Southampton. The researcher's findings imply that tsunami hazards may be more severe along continental margin regions where trenches contain thick compacted and strong sediment. "Our findings published in the scientific journal Nature Geoscience will help Earth scientists assess earthquake hazard and the risk of large destructive tsunamis globally,"... (read more)
2011-06-23 08:41:23

Horizontal ADCP Real-time Suspended Sediment Monitoring

PDT-H is Aqua Vision’s toolbox for the existing horizontal ADCP software suite, ViSea-H DAS. This toolbox lets the user quantify sediment concentrations and fluxes from horizontal ADCP data. PDT-H calculates suspended sediment fluxes by extrapolating the vertical concentration profile. The toolbox also lets the user post-process and optimise self-contained horizontal ADCP data with e.g. grain size distribution, calibration coefficients, etc. The development and testing of PDT-H has been carried out in close cooperation with the Port of Hamburg. CEO, Peter Meijer, said that developing PDT-H was the logical next step for the ViSea-H DAS software suite. He added that Aqua... (read more)
2014-05-01 09:09:14

Global Sediment Observations for the Dredging Industry

Coastal engineering and dredging companies often require an assessment of the suspended sediment concentrations. At the project proposal stage, this information is needed to assess the amount of work to be done and the costs involved and once dredging or construction is underway, information on suspended matter concentrations may be required for monitoring the environmental impact of the dredging or construction work. ARGOSS has developed a new service to produce maps of suspended sediment concentrations, based on satellite remote sensing data. The service has been demonstrated successfully in the Berbice estuary, an area of slowly migrating mudbanks in Guyana, and... (read more)
2008-01-01 01:00:00

Acoustic Profiler Simplifies Suspended Sediment Measurements

The AQUAscat 1000LT acoustic profiler by Aquatec (UK) has been developed to make measurement of suspended sediment easier. The AQUAscat 1000LT observes profiles of suspended sediment concentration of up to 2.5m using multi-frequency acoustics. Profiling allows sediment dynamics such as re-suspension and entrainment to be explored, which is not possible with single point measurements. The instrument is supplied with user-friendly post-processing software that allows the mean particle size and concentration to be calculated from the acoustic backscatter output. The self-contained design and rechargeable battery make it easy to deploy and maintain. Suitable for use to 200m, the new AQUAscat can... (read more)
2016-02-16 08:35:59
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