Longshore sediment transport : applied wave power approach, field data analysis and evaluation of formulae

[摘要] ENGLISH ABSTRACT:The process of sand being moved parallel to the coast by wave and current action is called longshore(sediment) transport. Knowledge oflongshore transport is essential for the design of breakwaters atharbour entrances, for navigation channels and for calculating the amount of dredging they require,for beach improvement schemes and for the determination of the stability of inlets and estuaries.Different aspects oflongshore transport have been investigated, namely, (1) analysis offield data, (2)evaluation oflongshore transport formulae and (3) the development of the wave power approach asan alternative method to calculate longshore transport.In the development of a better understanding oflongshore sediment transport, the following has beendone for the first time: (1) a comprehensive data set has been compiled covering almost a full rangeof conditions occurring on natural beaches; and (2) virtually all longshore transport formulae havebeen evaluated against this extensive data set. A new improved method, the applied wave powerapproach, has been developed and extensively calibrated against the same data set. Based on thisevaluation, guidelines are now available for design engineers as to which are the best bulk anddetailed predictors oflongshore sediment transport. These are respectively, the recalibrated Kamphuisformula and the applied wave power approach.Another useful first, is the derivation of confidence intervals for a longshore transport formula,showing what accuracy can be obtained and that accurate predictions are now possible. In addition,it has now been determined what the minimum required measurement period should be and what themost cost-effective way is for obtaining the true long-term mean net longshore transport rate at aparticular site.

[发布机构] Stellenbosch University