Thesis (PhD)--University of Stellenbosch, 2001. / 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 at
harbour 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 as
an alternative method to calculate longshore transport.
In the development of a better understanding oflongshore sediment transport, the following has been
done for the first time: (1) a comprehensive data set has been compiled covering almost a full range
of conditions occurring on natural beaches; and (2) virtually all longshore transport formulae have
been evaluated against this extensive data set. A new improved method, the applied wave power
approach, has been developed and extensively calibrated against the same data set. Based on this
evaluation, guidelines are now available for design engineers as to which are the best bulk and
detailed predictors oflongshore sediment transport. These are respectively, the recalibrated Kamphuis
formula 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 the
most cost-effective way is for obtaining the true long-term mean net longshore transport rate at a
particular site. / AFRIKAANSE OPSOMMING: Die proses waarvolgens sand ewewydig aan die kus deur golf- en stroomwerking vervoer word, word
langsstrandse (sediment-) vervoer oflangsvervoer genoem. Kennis van langsvervoer is noodsaaklik
vir die ontwerp van golfbrekers by hawe-ingange, navigasiekanale en vir die berekening van die
hoeveelheid baggerwerk daarvoor benodig, strandverbeteringskemas en vir die bepaling van die
stabiliteit van inlate en getyriviere.
Verskillende aspekte van langsvervoer is ondersoek, naarnlik, (1) die ontleding van velddata, (2) die
beoordeling van langsvervoerformules en (3) die ontwikkeling van die golfdrywingsbenadering as 'n
altematiewe metode om langsvervoer mee te bereken ..
Tydens die ontwikkeling van 'n beter begrip van langsstrandse sedimentvervoer is die volgende vir
die eerste keer gedoen: (1) 'n omvattende datastel is versamel wat bykans aIle toestande wat aan
natuurlike strande voorkom, dek; en (2) feitlik aile langsvervoerformules is teen hierdie uitgebreide
datastel beoordeel. 'n Nuwe verbeterde metode, die aangewende golfdrywingsbenadering, is
ontwikkel en omvattend teen dieselfde datastel geyk. Gebaseer op hierdie beoordeling, is riglyne nou
vir ontwerp-ingenieurs beskikbaar rakende watter totaal- en detail-iangsvervoervoorspellers die beste
is. Dit is onderskeidelik die hergeykte Kamphuisformule en die aangewende golfdrywingsbenadering.
Nog 'n nuttige eerste is die afleiding van betroubaarheidsgrense vir 'n langsvervoerformule, wat wys
watter akkuraatheid nou haalbaar is en dat noukeurige voorspellings nou moontlik is. Verder is dit
nou vasgestel wat die vereiste meettydperk behoort te wees en wat die mees koste-effektiewe manier
is waarop die ware langtermyn-gemiddelde netto langsvervoertempo by 'n spesifieke terrein verkry
kan word.
| Identifer | oai:union.ndltd.org:netd.ac.za/oai:union.ndltd.org:sun/oai:scholar.sun.ac.za:10019.1/52327 |
| Date | 12 1900 |
| Creators | Schoonees, Jacobus Stefanus |
| Contributors | Rooseboom, A., Stellenbosch University. Faculty of Engineering. Dept. of Civil Engineering . |
| Publisher | Stellenbosch : Stellenbosch University |
| Source Sets | South African National ETD Portal |
| Language | en_ZA |
| Detected Language | Unknown |
| Type | Thesis |
| Format | 1 v. (various foliations) : ill. |
| Rights | Stellenbosch University |
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