Thesis (PhD)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: All of the Ports along the South African coastline are subject to bound infragravity wave action to a greater or lesser degree, for example, at the Ports of Saldanha Bay on the west coast and Ngqura on the south-east coast. Saldanha Bay harbour principally services loose- and liquid-bulk carriers and the Ngqura harbour mainly services container ships. The long wave actions when severe cause moorings to be broken, ships to leave the quay and loading to stop. This research has confirmed that the sea surface is a multifractal structure characterised by many singularities ranging from highly irregular or rough features to smooth or calm features. Any wave train is comprised of the full range of these features to various degrees and in varying percentages of occupancy. Notwithstanding this problem, relatively little is known about them in the South African context due to the fact that they cannot be visually detected and specialised, sophisticated equipment is required to physically measure them. The country is currently planning the development of a new port and the expansion of others for larger ships. Under these circumstances this research is seen to be appropriate from the point of view of obtaining a new method for the characterisation of these hazardous wave conditions. The objective of the research was achieved. This was to identify a set of fractal dimensions that describe the surface geometry of a hazardous bound infragravity wave sea state. In order to achieve the objective, a set of fractal dimensions was firstly determined from video imagery of an open water wave field, by analysing a set of single point time series data derived from the imagery. This has been done in order to be able to visually compare the derived set of fractal dimensions with video imagery of the sea surface that they represent. It also has the advantage of proving that fractal methods of analysis are applicable for the study of sea surface single point time series data. Secondly, periods when long wave action occurs at both Saldanha Bay and Ngqura harbours were identified by the presence of their actions in the harbours. Thirdly, single point time series data recorded by the Council for Scientific and Industrial Research (CSIR) were obtained during the identified periods as well as two days before these times and fractal sets of dimensions for the periods were determined. This was achieved by means of the following methods of analysis: ● The rescaled range (R/S) method, ● The Multifractal Detrended Fluctuation Analysis (MDFA) method, ● The Power Spectral Density (PSD) method in both the Fourier and the wavelet domains, and ● The Wavelet Transform method. Fourthly, the fractal data sets from each harbour were compared to confirm that the sets of dimensions for the hazardous sea state are clearly different from those of the non-hazardous sea state and can be used to describe the condition. Finally, the fractal sets of dimensions for hazardous sea states at both harbours were compared to identify any variances between them. During the research it was found that a hazardous sea state could be profiled for identification purposes and for complementing the currently determined significant wave height and peak period details by means of fractal indices. These indices were identified by comparison with a similar set of indices for nonhazardous sea states at the same location, as part of a ‘calibration’ process and clearly identified shifts in the Holder exponents of the sea states enabled the unambiguous identification of the hazardous condition. Having completed the research and analysis work, the author has identified other areas of coastal engineering, besides the identification of hazardous bound infragravity wave sea states, where a study of multifractal geometry could be applied advantageously. / AFRIKAANSE OPSOMMING: Alle hawens langs Suid Afrika se kuslyn is tot ‘n meerdere of mindere mate onderworpe aan gebonde infragravitasie golf aksie. Hierdie probleem is egter veral straf by die hawens van Saldanhabaai aan die weskus en Ngqura, aan die suidooskus. Saldanhabaai voorsien dienste hoofsaaklik aan massa draers van los stowwe en vloeistof, terwyl Ngqura hoofsaaklik houerskepe bedien. Die lang golf aksies veroorsaak dat ankertoue breek en die skepe die kaai verlaat, sodat laai van die skepe tot stilstand kom. In die loop van hierdie navorsing is gevind dat die seevlak ‘n multifraktale struktuur is, met singulariteitseienskappe wat wissel van hoogs onreëlmatig of rowwe eienskappe tot gladde, reëlmatige eienskappe. Enige golfreeks behels die volle omvang van hierdie eienskappe in verskillende grade en wisselende teenwoordigheids persentasies. Die navorsing is gefokus op die geometrie van gebonde infragravitasie golfaksie seetoestande, wat oral langs die Suid Afrikaanse kuslyn voorkom, en in twee hawens ‘n beduidende bedreiging vir vasgemaakte skepe is. Ondanks die probleem, is min bekend oor hierdie toestande in Suid Afrikaanse konteks, omdat hulle nie visueel bespeur kan word nie en spesiale gesofistikeerde gereedskap nodig is om hulle fisies te kan meet. Daar word tans beplan om ‘n nuwe hawe te ontwikkel, wat hierdie navorsing veral gepas maak, met die doel om ‘n meer volledige beskrywing van hierdie bedreigende golftoestande te weeg te bring. Die doel van die navorsing is om ‘n stel fraktale dimensies te identifiseer wat die oppervlakgeometrie van ‘n bedreigende gebonde infragravitasie golf-seetoestand omskryf. Hierdie dimensies kan dan gebruik word om ‘n indentifiserende profiel van die seetoestand te teken om die inligting tans beskikbaar oor beduidende golfhoogte en piektye, aan te vul. Om hierdie doel te bereik is ‘n stel fraktale dimensies eerstens bepaal deur middel van videobeelding van ‘n oopwater golfveld. ‘n Stel enkelpunt tydserie data, afgelei van die beelding, word dan ge-analiseer. Dit het visuele vergelyking tussen die afgeleide stel fraktale dimensies en die videobeelding van die seevlak wat dit verteenwoordig het, moontlik gemaak. ‘n Verdere voordeel is dat dit bewys het dat fraktale analisemetodes toepaslik is vir die bestudering van seevlak enkelpunt tydreeks data. Tweedens is die tye wanneer lang golfaksie teenwoordig was in die hawens by Saldanha en Ngqura, vasgestel deur die uitwerking daarvan in die hawens. Derdens is enkelpunt tydreeks data wat deur die WNNR aangeteken is vir die vasgestelde tydperke, sowel as twee dae voor elke tydperk, verkry en is fraktale dimensiestelle vir elke tydperk vasgestel. Vierdens is die fraktale datastelle van albei die hawens vergelyk om te bevestig dat die stelle dimensies vir bedreigende seetoestande duidelik verskil van die vir niebedreigende toestande, en dus geskik is om die seetoestand te beskryf. Ten slotte is die fraktale dimensiestelle vir bedreigende seetoestande in die twee hawens vergelyk om enige verskille tussen hulle te bepaal. Na voltooiing van die navorsing en analise is ander gebiede van kusingenieurswese behalwe die bepaling van bedreigende gebonde infragravitasie golf seetoestande, identifiseer waar multifraktale geometrie ook tot voordeel aangewend kan word.

Magister Artium (Development Studies) - MA(DVS) / The seaweed Gracilaria gracilis has been shown in previous studies to have potential for mariculture along the West Coast of South Africa. However, the selection of suitable sites is crucial for the success of a farming enterprise. The variables important in the success or sustainability of suspended raft culture, and the environmental factors influencing these variables, were identified through a literature review. A suitable site was defined as a site with surface water temperature of between 10 and 17 "C, water depth of between 2 and 10 m below surface, and wave heights of less than 4 m. Data and information about these factors were obtained from sources such as the Sea Fisheries Research Institute, the SADCO database, the CSIR and from volunteers in St Helena Bay. The objectives of this study were to convert available data into formats that could be used in a Geographical Information System (GIS), and to predict suitable and available sites for suspended cultivation of Gracilaria gracilis in Saldanha Bay, Langebaan Lagoon and St. Helena Bay. Data were converted to digital format and data layers created. Each data layer represented suitable and unsuitable areas. Areas with existing mariculture, harbours, ship traffic zones and other uses were excluded to determine the real available areas. The Saldanha Bay-Langebaan lagoon system and St Helena Bay, have sites that show potential for suspended cultivation of G. eracilis. The total sizes of the areas selected as suitable are 975.4 ha in Saldanha Bay and 474.8 ha in St. Helena Bay. Some sites predicted as suitable are located in areas known to be subject to conditions not suitable for seaweed mariculture, and led to the conclusion that the accuracy of input data or method of analysis must be improved.

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: South Africa presently faces a serious and much-acknowledged energy capacity deficit. The Department of Energy are determined to address this capacity crisis by creating several new power plants between 2010 and 2030, as stipulated in the “Integrated Resource Plan 2010”. A Combined Cycle Gas Turbine (CCGT) power plant is proposed to add 2370 MW of capacity to the national grid. The “new-build” CCGT plant will use natural gas as a feedstock for energy generation. The plant is destined to begin energy generation by 2019, and will ramp up to full capacity by 2030. Following a review of the existing natural gas sources and the nascent gas network in South Africa, Liquefied Natural Gas (LNG) has been identified as the most suitable immediate source of natural gas feedstock for the CCGT. LNG fuel must be imported into South Africa aboard large, special purpose LNG Carrier (LNGC) vessels. LNGC vessels require a designated marine import terminal in order to offload the super-cooled and potentially flammable cargo. Saldanha Bay, located on the South West coast of South Africa, has been selected by Transnet as a preferred location for LNG terminal development. A review of LNG technology reveals the need for mandatory onshore LNG storage and regasification facilities, land area requirements, demands of different LNGC types and the characteristics of dedicated LNG jetties and terminals. Floating, offshore and traditional LNG terminals are discussed. The objective of this thesis is to review potential terminal sites and conceptual layouts in Saldanha Bay, and via a Multi Criteria Analysis, to present three distinct LNG terminal layout options for further consideration. The conceptual layouts will address technical concerns such as berth orientation and layout, safe navigational access to the terminal, mandatory onshore infrastructure and optimisation of berth operations. Saldanha Bay as a port location is studied and the importance of local environmental features is highlighted. Potential terminal development sites are identified following a review of nautical and terrestrial restrictions. Four conceptual site layouts are proposed, providing jetty locations and orientations in the Bay. The sites are located in North Bay, Hoedjiespunt, and two in Big Bay. Several Key Design Parameters (KDP’s) are identified as having a critical bearing on the ultimate layout, operation and feasibility of an LNG terminal in Saldanha Bay. The sensitivity and influence of the KDP’s at each of the four conceptual sites is investigated. Analysis of KDP effects leads to the development of design variation options at the sites. Twelve terminal layout schemes are ultimately derived. A Multi Criteria Analysis (MCA) is performed to rank the 12 terminal layout schemes in terms of technical efficacy. A sensitivity study is conducted to justify the selection of MCA parameter weights. The three top-scoring schemes are recommended for more detailed pre-feasibility investigation. The three terminal layout schemes, located in Big Bay and Hoedjiespunt, make use of both standard trestle jetties and floating LNG technologies. The thesis has shown that a number of viable sites and layouts for LNG terminals exist in Saldanha Bay and demonstrates a systematic analysis of design issues leading to preferred options. The thesis concludes by outlining the next steps in the process towards a final terminal scheme selection. / AFRIKAANSE OPSOMMING: Suid-Afrika ervaar huidig ‘n drastiese energie kapasiteit verlies. Die Departement van Energie is vasbeslote om die energie krisis aan te spreek deur verskeie nuwe kragstasies tussen 2010 en 2030 op te rig, soos beskryf in die “Integrated Resource Plan 2010”. ‘n Gekombineerde Siklus Gas Turbine (GSGT) kragstasie is voorgestel om ‘n verdere 2370 MW by te voeg tot die nasionale krag netwerk. Die “nuut-geboude” GSGT kragstasie sal natuurlike gas as brandstof vir kragopwekking gebruik. Die kragstasie is beplan om teen 2019 krag op te wek, en sal teen 2030 volle kapasiteit loop. Na ‘n ondersoek van die bestaande natuurlike gas bronne en gas netwerke in Suid Afrika, is Vloeibare Natuurlike Gas (VNG) geïdentifiseer as die huidiglike beskikbare bron van brandstof vir die GSGT. VNG moet ingevoer word aanboord spesiaal geboude VNG vaartuie. VNG vaartuie benodig ‘n spesifieke mariene invoer terminaal om die vlambare vloeistof mee af te laai. Saldanhabaai, aan die Suid-Westerlike kus van Suid Afrika, is as verkose area vir die VNG terminaal ontwikkeling geïdentifiseer deur Transnet. ‘n Oorsig van VNG tegnologie bevind dat VNG stoorplek en vergassings fasiliteite, land area, verskeie VNG vaartuie en karakteristieke van VNG terminale benodig word. Verskeie VNG terminale word bespreek in hierdie studie. The doel van hierdie tesis is om die potensiële terminaal bou-terrein en konseptuele ontwerpe in Saldanhabaai, deur middel van ‘n multi-kriteria analise (MKA), in drie verskillende ontwerp moontlikhede voor te stel. Saldanhabaai, as hawe, is bestudeer en belangrike omgewings aspekte is geïdentifiseer. Potensiële terminaal bou-terrein is geïdentifiseer na aanleiding van seevaart en land beperkings. Vier konseptuele bou-terreine is voorgestel wat jetty posisies en orientasies aandui. Die bou-terreine is in Noordbaai, Hoedjiespunt, en twee in Big Bay. Verskeie Sleutel Ontwerp Parameters (SOP’s), wat ‘n kritieke rol speel in die uiteindelike orientasie, werking en effektiwiteit van die VNG terminaal in Saldanhabaai, is geïdentifiseer. Die sensitiwiteit van die SOP’s by elk van die vier voorgestelde moontlikhede, is ondersoek. ‘n Ontleding van die effek van die SOP’s het variasie in die ontwerp moontlikhede by die verskillende bouterrein tot gevolg. Twaalf terminaal orientasie skemas is voorgestel. ‘n MKA is uitgevoer om ‘n ranglys van opsies te produseer in terme van tegniese effektiwiteit. Dit is voorgestel dat die top drie opsies verder ondersoek moet word. Die drie terminaal orientasie skemas, wat voorgestel word vir die Big Bay en Hoedjiespunt areas, maak gebruik van standaard jetties en drywende VNG tegnologie. Hierdie tesis bevind dat ‘n aantal uitvoerbare bouterreine en orientasies in Saldanhabaai moontlik is. ‘n Sistematiese analise van ontwerps kwessies wat na verkose opsies lei, word ook in die tesis ge-adresser. Die voorgestelde stappe in die besluitneming van ‘n finale terminaal skema vorm die slot van die tesis.