STATUS OF MEASUREMENT TECHNIQUES FOR COASTAL SEDIMENT TRANSPORT

The known methods for measuring coastal sediment transport in the fiel d may be described and categorized as total traps, suspension traps, t racers, optics, acoustics, impact, conductivity, and radiation. There are different applicable situations and reasons for using each of the methods, relative to each other and to models. Each technique has a un ique history of development, theory of use, means of translating the d ata into sediment transport, advantages and limitations, practical tri cks for successful use, problems encountered in their use, and solutio ns to these problems. Different methods are applicable to problems of different temporal and spatial scales, ranging from fractions of a sec ond to years and from millimeters to kilometers. Some methods measure bedload, others suspension, and some total transport. Some devices mea sure only sediment concentration or velocity and must be used in combi nation with other methods to determine transport. Some measure only lo ngshore transport, some cross-shore, and others will measure either. T he accuracy and cost of the methods may be compared. Despite the pleth ora of available methods, it is still not possible to make detailed or accurate field measurements of suspensions of mixed sizes, suspension very close to the seabed, or bedload. For these situations, older and cruder methods of traps and tracers are still used. There does not ap pear to be a systematic plan and program for correcting these measurem ent deficiencies. (C) 1998 Elsevier Science B.V. All rights reserved.