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Three dimensional sediment transport measurements by acoustics

Objective



The primary objective of TRIDISMA is to develop, test and evaluate a prototype instrument to measure sediment transport close to the sea bed. The new instrument will simultaneous measure profiles of the suspended sediment concentration, sediment size and the three components of the fluid velocity, with high temporal (1-10 Hz) and spatial (<1 cm) resolution. The range of operation will be of the order of one metre but a secondary objective will be to extend the capabilities of the instrument to operate very close to the bed, within 10 cm, and to examine problems involved in measuring bed load. To minimise disturbance of the systems under investigation, high-frequency acoustics will be used throughout, although ancillary instrumentation will be used in the instrument evaluation and calibration, and for the bed load transport measurements.
Engineers, Port and Harbour Authorities, Dredging companies, Fisheries and Pollution scientists, as well as coastal oceanographers and geomorphologists, desperately need an accurate instrument to measure sediment transport in coastal and estuarine waters. Most existing instruments for use in the marine environment measure either flow (in one or more directions) or suspended sediment concentration, by optical or acoustic transmittance or backscatter. None is able to rapidly profile the concentration, size and the three-dimensions of flow, necessary for a realistic measurement of transport, particularly close to the sea bed where much of the sediment transport can occur. TRIDISMA will develop and test a prototype instrument, based on non-intrusive acoustic methods, which will be used to evaluate the basic technologies associated with Coherent Doppler and Correlation techniques. Results from TRIDISMA will provide a specification which can be used for the future development of a commercial to fill this important gap in available instrumentation.
TRIDISMA has drawn together European partners with wide and extensive experience in the design, construction and use of high-frequency acoustic backscatter instrumentation for measuring suspended sediment concentrations in the marine environment. They are experienced in the acoustic theory, transducer design and signal processing necessary to advance technology to simultaneously measure the sediment concentration, size and the three components of fluid velocity. In addition to many routine coastal, beach and estuary deployments, the partners in TRIDISMA have used their acoustic instruments to measure profiles of suspended sediment concentration in the MAST II C-STAB, STARFISH and VERIPARSE programmes.

Funding Scheme

CSC - Cost-sharing contracts

Coordinator

UNIVERSITY OF EAST ANGLIA
Address
University Plain
Norwich
United Kingdom

Participants (6)

Danmarks Tekniske Universitet
Denmark
Address

2800 Lyngby
NATURAL ENVIRONMENT RESEARCH COUNCIL
United Kingdom
Address
Bidston Observatory
L43 7RA Birkenhead
STICHTING WATERLOOPKUNDIG LABORATORIUM (WL/DELFT HYDRAULICS)
Netherlands
Address
185,Rotterdamseweg 185
2600 MH Delft
TECHSONIC SARL
France
Address
Route Des Alisiers Bat. B
06600 Antibes
THOMSON MARCONI SONAR SAS
France
Address
Route De Sainte-anne-du-portzic
29601 Brest
University of Bath
United Kingdom
Address
Claverton Down
BA2 7AY Bath