Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2011. / ENGLISH ABSTRACT: In the study, six irrigation schemes based in the Eastern Cape have been considered and evaluated, according to two levels of supply (LOS) of irrigation water. The two levels of supply are that of a commercial irrigator and that of a smallholder irrigator. The irrigation infrastructure for each of the six schemes was designed, and the associated costs determined, for each level of supply. The primary objective of the study is to determine the impact of infrastructure costs and irrigation areas on the target user, either the commercial or the smallholder irrigator. This is related directly to the assumption that lower water volumes are used by the smallholder irrigator. The study addresses the impact of different designs on the amount of water used, land utilised and resultant costs of the infrastructure. The initial capital costs and the on-going operational and maintenance costs (O&M) for each level of supply for each of the schemes have been calculated. The evaluation of the two LOS has shown that the capital cost for the commercial LOS is approximately 18 % higher than for the smallholder LOS and the O&M costs 6 % to 36 % higher. The schemes that were investigated can be grouped into five general scheme types. The first type is gravity schemes, which need rehabilitation, while the bulk supply is in place with no augmentation or rehabilitation required. The second is pumped scheme which is in need of rehabilitation, while the bulk supply is in place with no augmentation or rehabilitation required. The third type includes run-of-river schemes where water is abstracted and pumped directly to the lands. The fourth type includes run-of-river schemes where water is abstracted and pumped to storage. The fifth type is the gravity scheme where the bulk supply needs to be installed as part of the scheme. These types are then grouped and can be used to give guidance on the anticipated costs dependant on the scheme type and the required level of service. A further objective of the research is to determine the impact on the smallholder irrigators who find themselves on a commercial LOS system. This can be either on a scheme that has already been designed, or on a new system. The evaluation of the commercial under-utilised LOS and the smallholder LOS has shown that the commercial capital cost is 18 % higher and the O&M costs 5 % to 29 % higher. The study further aligns the estimated costs with the farmer typology providing a broader understanding of the design to be adopted for different levels of supply. This provides the linkage between farmer types, the design to be implemented and the anticipated costs thereof. / AFRIKAANSE OPSOMMING: As deel van hierdie narvorsing word ses verskillende besproeiingsskemas in die Oos-Kaap ten opsigte van twee voorsieningsvlakke ondersoek. Die twee voorsieningsvlakke ter sprake is vir ‘n kommersiële en kleinboerdery opset. Die besproeiingsinfrastruktuur is vir elk van die ses besproeiingsskemas ontwerp en ‘n kosteberaming vir elk van voorsieningsvlakke gedoen. Die hoofdoelwit van hierdie verslag is om te bepaal wat die impak van kostes en besproeiingsareas op beide kommersiële- en kleinboerderye is. Dit is direk gebaseer op die aanname dat kleinboerderye minder water gebruik. Die verslag ondersoek die impak van verskillende ontwerpe op waterverbruik, besproeiingsoppervlak benodig en die gevolglike infrastruktuurkostes. Die aanvanklike kapitaalkostes asook bedryfs- en onderhoudsuitgawes (B&O) vir elk van die voorsieningsvlakke, is vir elk van die besproeiingskemas bereken. Die resultaat van die ondersoek van die twee voorsieningsvlakke het aangetoon dat die kapitaalkoste van kommersiële besproeiingskemas 18 % hoër as die van kleinboerderye is, en bedryfs- en onderhoudsuitgawes 6 tot 36 % hoër. Die skemas wat ondersoek is, kan in vyf algemene skema tipes verdeel word. Die eerste is die gravitasieskemas wat rehabilitasie benodig terwyl die hooftoevoer in plek is met geen uitbreidings- of rehabilitasiebehoeftes. Die tweede is pompskemas wat rehabilitasie benodig terwyl die hooftoevoer in plek is met geen uitbreidings- of rehabilitasiebehoeftes. Die derde is rivierskemas waar besproeiingswater direk uit die rivier na die landerye gepomp word. Die vierde is rivierskemas waar besproeiingswater direk uit die rivier na a reservoir gepomp word. Die vyfde skema tipe is die gravitasieskemas waar die hooftoevoer ook gebou moet word as deel van die skema. Die skema tipes kan gebruik word om leiding te verskaf ten opsigte van verwagte skema kostes afhangende van die skema tipe en vereiste voorsieningsvlak. ‘n Verdere doelwit van die studie is om die impak op kleinboere te bepaal wat op ‘n kommeriële voorsieningsvlak boer. So ‘n stelsel kan ‘n gevestigde of nuwe stelsel wees. Die resultaat van die ondersoek van die onderbenutte kommersiële voorsieningsvlak en die kleinboerdery voorsieningsvlak het gewys dat die kapitaalkoste van kommersiële besproeiingskemas 18 % hoër as die van kleinboerderye is, en bedryfs- en onderhoudsuitgawes 5 tot 29 % hoër. Die verslag vereenselwig die verwagte kostes met die tipe boerdery en verskaf ‘n beter begrip van die tipe ontwerp wat elk van die voorsieningsvlakke benodig. Dit verskaf dus die verband tussen die tipe boerdery, die ontwerp benodig en die verwagte projekkostes.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The various consequences of climate change pose a significant threat to developments near the coast. These threats include saltwater intrusion, coastal erosion and flooding. In the coastal context, the climate change effect often raising the most concern is that of sea-level rise. Much work has therefore been done on the linear setback caused by a rise in sea-level. In order to get the full picture of possible changes caused by sea-level rise, the secondary effects of a rising sea-level also need to be considered. Sea-level rise could cause changes to the nearshore wave climate and could have impacts such as coastal erosion and changes to the coastline shape. The primary objective of this study was therefore to investigate the effects of sea-level rise on the nearshore wave climate and, consequently, the coastline stability. Other consequences of climate change considered in this study include increasing average wave heights and a rotation of offshore wave directions. The many headland-bay beaches on the South African coastline are generally in a state of dynamic equilibrium and find their planforms based on the local wave climate. Changes to the wave climate may therefore disrupt the equilibrium shapes of these bays. This study was therefore also aimed at investigating the effects of the changes to the wave climate on the stability of headland-bay beaches. The three consequences of climate change expected to affect the nearshore wave climate were identified as (1) sea-level rise; (2) an increased wave height; and (3) changing offshore wave angles. Although changes to storm frequency and intensity are also possible, the impacts of these changes were not studied. In order to assess the impacts of the three considered changes on a typical headland-bay beach, two numerical models were set up for Mossel Bay – a headland-bay beach on the southern coast of South Africa. The modelling approach included a wave transformation model to calculate nearshore wave climates from offshore data and a coastline model to assess the stability of the bay under the changed nearshore wave climates. The model results indicated that the rising sea-level alone would cause changes in the nearshore wave direction. These changes were shown to alter the longshore sediment transport regime such that rotations are expected in the south-western corner and eastern end of Mossel Bay. These rotations do not include the cross-shore effects of inundation and erosion, as suggested by models such as the Bruun Model. The results for an increased offshore wave height were inconclusive. The southerly rotation in offshore wave angles was shown to affect the nearshore wave angles. These changes affected the longshore transport regime such that the outward sediment transports were reduced. A minor accretion resulted in the centre of the bay for a 1° southerly rotation in offshore wave angles. For a 2° rotation, the extent of accretion increased and shifted towards the eastern end of the bay, primarily due to the dominance of south-westerly waves in the local wave climate. A valuable observation was made regarding the current stability of Mossel Bay. Inter-tidal reefs are present along three sections of the bay. These reefs protect the coastline such that the current bay shape contains sharp bends between the reefs. Under a rising sea-level, however, the effect of the reefs will become less pronounced. If a water level should be reached where these reefs become less significant, the planform of the bay is expected to smooth out through a significant redistribution of sediment. This smoothing effect was shown to cause erosion of the coastline in the order of 80m near the town of Klein Brak River. / AFRIKAANSE OPSOMMING: Die verskeie gevolge van klimaatsverandering bied ‘n merkwaardige bedreiging vir ontwikkelings naby die kus. Hierdie bedreigings sluit die versouting van varswaterbronne, kuserosie en oorstromings in. Vir kusgebiede is seevlakstyging gereeld die effek van klimaatsverandering wat die meeste kommer wek. Dus is heelwat navorsing rakende die direkte erosie as gevolg van seevlakstyging reeds gedoen. Om die volle beeld van die gevolge van ‘n stygende seevlak te verkry, is dit egter nodig om ook die sekondêre effekte hiervan in ag te neem. Seevlakstyging kan veranderinge in die golfklimaat naby die kus veroorsaak, en kan impakte soos kuserosie en veranderende baaivorms tot gevolg hê. Die primêre doel van hierdie studie is dus om die effek van seevlakstyging op die golfklimaat by die kus en gevolglik die stabiliteit van die kuslyn, te ondersoek. Benewens die styging van die seevlak word die effekte van groter gemiddelde golfhoogtes en die rotasie van diepsee golfrigtings ook in hierdie studie ondersoek. Die vele landpunt-baaie (headlandbay beaches) op die Suid-Afrikaanse kus is meestal in ‘n dinamiese ekwilibriumtoestand, waarvan die vorm deur die lokale golfklimaat bepaal word. Veranderinge aan dié golfklimaat mag dus die ekwilibrium vorms van sulke baaie versteur. Hierdie studie het dus ook die stabilititeit van landpuntbaaie onder ‘n veranderende golfklimaat ondersoek. Die drie gevolge van klimaatsverandering wat verwag word om die golfklimaat naby die kus te beïnvloed is geïdentifiseer as (1) seevlakstyging; (2) vergrote golfhoogtes; en (3) veranderende diepsee golfhoeke. Veranderinge aan die frekwensie en intensiteit van storms is ook moontlike gevolge van klimaatsverandering, maar die impakte hiervan is nie in die studie ondersoek nie. Twee numeriese modelle is toegepas om die impak van die drie bogenoemde gevolge op Mosselbaai – ‘n tipiese landpunt-baai aan die suidkus van Suid-Afrika – te ondersoek. ‘n Golfmodel is ingespan om die golfklimaat naby die kus te bepaal waarna ‘n kuslynmodel gebruik is om die stabiliteit van die baai onder die veranderde golfklimaat te ondersoek. Die resultate van die studie dui daarop dat die golfhoeke naby die kus beïnvloed word deur seevlakstyging. Daar is aangetoon dat dié veranderinge die langsstroomvervoer sodanig sal verander dat kuslynrotasies in die suid-westelike hoek asook die oostelike rand van Mosselbaai verwag word. Hierdie rotasies sluit nie die lineêre landwaartse verplasing van die kuslyn as gevolg van erosie en oorstroming in nie. Die effek van vergrote golfhoogtes kon nie met akkuraatheid ondersoek word nie. Daar is wel gevind dat die suidwaartse rotasie van diepsee golfhoeke rotasies in die golfklimaat naby die kus veroorsaak. Hierdie rotasies verander die langsstroom sedimentvervoer sodanig dat die uitwaartse sedimentvervoer verminder word en ‘n klein opbou van sediment in die middel van die baai vir ‘n 1° diepsee rotasie verwag word. Vir ‘n 2° suidwaartse rotasie is daar ‘n groter opbou van sediment wat verder ooswaarts veplaas is. Die ooswaartse veplasing is primêr ‘n gevolg van die oorheersing van suid-westelike golftoestande in die golfklimaat. ‘n Waardevolle gevolgtrekking rakende die huidige stabiliteit van Mosselbaai is ook gemaak. Langs drie gedeeltes van die Mosselbaaise kus word riwwe in die gebied tussen hoog- en laagwater aangetref. Hierdie riwwe beskerm die kus sodanig dat skerp kinkels in die vorm van die baai tussen die riwwe gesien kan word. Wanneer die seevlak styg, word die beskermende effek van die riwwe egter minder doeltreffend. Indien ‘n watervlak bereik word waar dié effek genoegsaam verminder is, word daar verwag dat die baai deur ‘n merkwaardige verplasing van sediment die kinkels sal uitstryk. Deur hierdie proses word erosie in die orde van 80m naby die dorp van Klein Brakrivier verwag.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: This study focuses on the water demand of selected residential properties with access to groundwater in serviced areas of the Cape Peninsula. This winter rainfall region is typified by hot and dry summer months, corresponding to peak garden water demand. Water restrictions in the area are relatively common and primarily target outdoor use. Groundwater serves as an alternative source of water to some consumers in the area, but little is known about the extent of such use and the impact thereof on potable water demand. A major part of the area is underlain by a primary, unconfined aquifer that has been reported to have high exploitation potential. Its unconsolidated sand and shallow water table provides ideal conditions for small scale groundwater abstraction. Several owners of properties situated above the aquifer unit have capitalised on this and utilise groundwater as an alternative to potable water, mostly for garden irrigation purposes. The main objective of this research was to investigate the average extent of the expected reduction in average annual municipal water demand due to private groundwater use at the selected properties in the study area. The methodology involved abstracting data from the City of Cape Town’s registration process for the private use of non-potable water. The data was recorded between 2000 and 2006 and was available only in hard copy format. The registration data was used to identify residential properties with access to private groundwater sources, based on the physical addresses recorded on the registration forms. The rate of groundwater abstraction was not recorded during the registration process, nor was any of the properties spatially referenced. The data set contained information for 4 487 properties, of which 3 764 could ultimately be used in the analysis. Data from a recent hydro-census in Hermanus (which was done by others prior to this study) was used to test the intended research method first. This trial investigation involved only 114 properties and was used to streamline the proposed methodology for application on the full-scale analysis of the City of Cape Town data. Each address was captured electronically, verified manually and filtered to extract only those representing residential properties for which groundwater use was registered. In order to identify the properties spatially, the addresses had to be converted to coordinates through a procedure called geocoding, so as to plot each spatially and obtain the attributes such as stand size, position and the unique Surveyor General’s code. This was necessary in order to link the addresses to the municipal treasury system and obtain their latest available water consumption records using a commercial software package that incorporates consumer information. Next the actual annual water consumption figures were compared with recently published water demand guidelines based on stand size as single explanatory variable. The selected residential stands were divided into pre-defined stand size categories. The average water consumption of all the stands in each size category was calculated and compared with the suggested water demand as per the guidelines used, based on the centre value of the size range of each category. The results of the comparative analysis confirm findings from two earlier studies where lower municipal water use was reported for residential properties with access to groundwater in a summer rainfall region. The results further showed that the mean average annual potable water demand of consumers in the study area with access to groundwater was on average 31.4% lower than those considered without such access in the same region. This represents an average reduction of 333 l/stand/day (about 10 kl/stand/month) in the potable water demand of the selected residential stands. This study therefore confirms that serviced residential stands with access to private groundwater sources in the Cape Peninsula have lower average metered water consumption from the municipal supply system. / AFRIKAANSE OPSOMMING: Hierdie studie fokus op die water anvraag van geselekteerde residensiële erwe met toegang tot grondwater in gedienste woongebiede van die Kaapse Skiereiland. Die gebied is ‘n winterreënvalstreek, met warm, droë somermaande wat saamval met piek water aanvraag vir tuinbou. Waterbeperkings in die area is relatief algemeen, veral op die buitegebruik van water. Grondwater dien as alternatiewe bron vir sommige verbruikers, maar kennis oor die omvang van sulke gebruik, sowel as die impak wat dit het op die aanvraag na drinkbare water is beperk. Die grootste deel van die gebied ter sprake is geleë bo ‘n onbegrensde hoof waterdraer, met berigte hoë ontginningspotensiaal. Die ongekonsolideerde sand en hoë watertafel is ideal vir kleinskaalse grondwateronttrekking. Heelwat van die eienaars van grond wat bo hierdie akwafeer geleë is het die situasie uitgebuit en gebruik grondwater as alternatief vir drinkwater, veral vir tuinbesproeiïng. Die hoofdoel van hierdie navorsing was om die gemiddelde omvang van die verwagte vermindering in gemiddelde jaarlikse munisipale wateraanvraag weens die privaat gebruik van grondwater by die geselekteerde erwe in die studiegebied te ondersoek. Die metodiek het die onttrekking van data uit die Stad Kaapstad se registrasieproses vir die privaat gebruik van nie-drinkbare water behels. Hierdie data, wat tussen 2000 en 2006 vasgelê is, was slegs in harde kopie formaat beskikbaar. Die registrasie data is gebruik om woonerwe te identifiseer met toegang tot privaat grondwater bronne, volgens die fisiese adres verskaf op die registrasie vorms. Die tempo van grondwater onttrekking was nie opgeneem gedurende die registrasie proses nie, so ook nie ruimtelike aanwysings na die ligging van die eiendomme nie. Die datastel het inligting bevat oor 4 487 eiendomme, waarvan 3 764 uiteindelik bruikbaar was in die analise. Data van ‘n onlangse hidro-sensus in Hermanus (wat deur ander gedoen is voor die aanvang van hierdie studie) is gebruik om die beoogde navorsingsmetodiek eers te toets. Die toetsondersoek het slegs 114 eiendomme behels, en is gebruik om die voorgestelde metodologie meer vaartbelyn te maak voor toepassing op die volskaalse analise van die Stad Kaapstad data. Elke adres is elektronies vasgevang, met die hand geverifiëer, en dan gefilter om slegs die residensiele eiendomme waarvoor grondwater gebruik geregistreer is, te behou. Om die ruimtelike verwysing van die eiendomme verder te kon indentifiseer, moes die adresse omskep word in koördinate om sodoende die erwe te kon posisioneer en die erfgrootte, posisie en die unieke Landmeter Generaal kode van elke erf te verkry. Dit was nodig sodat die adresse aan die munisipale stelsel gekoppel kon word om sodoende die jongste beskikbare waterverbruik rekords te verkry deur gebruik te maak van ‘n kommersiële sagteware pakket wat verbruikers-inligting inkorporeer. Hierna is die werklike jaarlikse waterverbruik syfers vergelyk met onlangs gepubliseerde wateraanvraag riglyne, gebaseer op erfgrootte as enkel verklarende veranderlike. Die geselekteerde woonerwe is toe in voorafgekose kategorië verdeel volgens erfgrootte. Die gemiddelde waterverbruik van al die erwe binne elke grootte-kategorie is bereken en vergelyk met die voorgestelde wateraanvraag volgens die riglyne, gebaseer op die middelpuntwaarde van die grootte strekking van elke kategorie. Die resultate van die vergelykende analise staaf die bevindinge van twee vroeër studies wat laer munisipale watervebruik rapporteer vir residensiële eiendomme met toegang tot grondwater in ‘n somerreënvalgebied. Die resultate wys ook dat die gemiddelde jaarlikse drinkbare water aanvraag van verbruikers in die studiegebied wie toegang het tot grondwater, gemiddeld 31.4% laer is as dit van verbruikers wie beskou word sonder sulke toegang in dieselfde streek. Dit verteenwoordig ‘n gemiddelde vermindering van 333 l/erf/dag (rondom 10 kl/erf/maand) in die aanvraag na drinkbare water van die geselekteerde woonerwe. Hierdie studie bevestig dus dat gedienste residensiële erwe met toegang tot privaat grondwater bronne in die Kaapse Skiereiland laer gemiddelde gemeette waterverbruik vanuit die munisipale toevoerstelsel het.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Since the construction of the causeway and the jetty during the early 1970’s in Saldanha Bay, various alterations to the coastline in the area of the Langebaan Lagoon mouth were observed. These alterations include the erosion of Langebaan Beach located near the town of Langebaan. An investigation was undertaken to identify the possible impact these structures had on the hydrodynamics and sediment transport of the Saldanha Bay and Langebaan Lagoon systems, focusing on the entrance to the Langebaan Lagoon. A two-dimensional numerical model was implemented for this investigation. The outdated information available for the generation of a bathymetry, which indicated the conditions prior to the erosion of Langebaan Beach, complicated the calibration process. However, calibration of the numerical model was acceptable. Due to the bathymetry not providing an indication on the current situation at the Langebaan Lagoon mouth, the results from the numerical model were approached with caution, providing an overview of the hydrodynamics present in Saldanha Bay and Langebaan Lagoon and would be able to broaden the understanding of the impact the causeway and jetty had on the hydrodynamics and sediment transport of Saldanha Bay and Langebaan Lagoon. Results provided by the sediment transport model only provide an indication on the effect tidal variations and wind forcing have on the bay and lagoon and not realistic total sediment transport rates due to the omission of wave action during the modelling process. Results from the numerical model, based on tidal oscillations and wind forcing only, have indicated that no major impact on the hydrodynamics and sediment transport were experienced due to the construction of the causeway and the jetty. During the investigation of the impact of various extreme water level and extreme wind conditions, it has been observed that a 1 in 100 year wind velocity across the longest fetch towards Langebaan Beach resulted in the greatest velocities prior to the construction of the causeway and the jetty, and after the construction of the causeway and the jetty tidal storms, or storm surge, generated the greatest velocities and thus the most sediment transport in the main channels of the mouth of the Langebaan Lagoon. From this investigation it was recommended that future studies would require an updated survey of the area, to ensure accurate modelling of the conditions as experienced during field surveys. Further recommendations on the investigation of sediment transport were the inclusion of wave action to provide realistic results. Wave action is a fundamental part of sediment transport along the coastline. / AFRIKAANSE OPSOMMING: Sedert die konstruksie van die breekwater en die kaai gedurende die vroeg 1970’s in Saldanhbaai, is verskeie veranderings aan die kuslyn in die gebied van die Langebaan strandmeer mond waargeneem. Hierdie veranderinge sluit in die erodering van Langebaan Strand, geleë naby die dorp van Langebaan. 'n Ondersoek is onderneem om die moontlike impak van die bogenoemde strukture op die hidrodinamika en sedimentvervoer van die Saldanhabaai en die Langebaan strandmeer stelsels, veral die strandmeer se kanale, met die fokus op die ingang na die Langebaan strandmeer te ondersoek. 'n Twee-dimensionele numeriese model is gebruik vir hierdie ondersoek. Die verouderde inligting van die seebodem wat beskikbaar was vir die opwekking van die numeriese model het die kalibrasieproses bemoeilik. Alhoewel hierdie proses bemoeilik is kon ‘n aanvaarbare kalibrasie bereik word. Aangesien die gemodelleerde area en die werklike area nie ooreengestem het nie is resultate van die numeriese model omsigtig benader en die resultate geskik gevind om die kennis oor die moontlike impak wat die breekwater en die kaai op die hidrodinamika en sedimentvervoer van Saldanhabaai en die Langebaan strandmeer het, te verbreed. Resultate uit die sedimentvervoer model verskaf slegs ‘n aanduiding van die sedimentvervoer wat deur gety veranderings en wind gegenereer word. Werklike sediment vervoer sal die effect van golfaksie ook in ag moet neem, wat in hierdie studie uitgesluit is. Golfaksie is van kardinale belang by sediment vervoer langs ‘n kuslyn. Resultate van die numeriese model, gebaseer op gety en wind alleen, het aangedui dat geen groot impak op die hidrodinamika en sedimentvervoer as gevolg van die konstruksie van die breekwater en die kaai in Saldanhabaai ervaar word nie. Gedurende die ondersoek van die impak van verskeie ekstreme watervlak en uiterste windtoestande, is dit opgemerk dat 'n 1 in 100 jaar windsnelheid oor die langste stryklengte na Langebaan Strand gelei het tot die grootste vloei snelhede in die hoofkanale voor die konstruksie van die breekwater en die kaai. Na die konstruksie van die breekwater en die kaai is gevind dat gety storms die grootste snelhede en dus ook die meeste sedimentvervoer gegenereer het by Langebaan Strand. Uit hierdie ondersoek is dit aanbeveel dat toekomstige studies opgedateerde opmetings van die gebied moet uitvoer wat akkurate modellering, gebaseer op die toestande soos in die veld, sal verseker. Verdere aanbevelings oor die ondersoek van sediment vervoer is die modellering van .golfaksie wat van kardinale belang is in sediment vervoer langs ‘n kuslyn en dus meer realistiese resultate sal lewer.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: Since 1994 the government of South Africa has spent substantial amounts of money on the development and expantion of infrastructure to include the previously disadvantaged. Each year the amount spent on infrastructure increased, and still the poor is marginalised. The title proposes that there should rather be a focus on creating a sustainable environment to deliver infrastructure. The economy, unemployment, people living in poverty and level of human resources determine the environment in which infrastructure is delivered. South Africa is on a growth path towards 2030 that aims to reduce unemployment by aproximately 10% and increase the economic growth rate 5% per annum. Key challenges that inhibits economic growth were identified by the National Planning Commision (NPC). These key challenges such as poverty, poor education, unsatisfactory public tranport and a divided society represent the environment that South Africa is currently operating in. If these key challenges could be addressed and nullified a sustainable environment could be reached. The purpose of this thesis is to investigate a sustainable environment to deliver infrastructure. Existing models will be analysed and the key principles will then be incorporated in the development of the proposed Infra-Connect Model. Strategic Planning and decision-making tools will also assist in the process towards developing the Infra-Connect Model. The theoretical results that are obtained are positive. It conforms to the goals that are set out based on the key challenges presented by the NPC. The financial resources are found to be distributed more effectively and the poor is empowered to take part in the economic activities and hence a sustainable environment to deliver infrastructure is created. / AFRIKAANSE OPSOMMING: Sedert 1994 is daar aansienlike bedrae bestee op die opgradering en uitbreiding van infrastruktuur. Steeds is die huidige infrastruktuur nie voldoende nie en onontwikkeld. Die behoeftiges is steeds uitgesluit uit die ekonomiese aktiwiteite en gemarginaliseer. Hierdie verhandeling beoog om die fokus te plaas op die skepping van ‘n volhoubare omgewing wat die ontwikkeling van infrastruktuur tot gevolg het. Die omgewing verwys na die ekonomie, die behoeftiges, vlak van werkloosheid, en die kwaliteit van onderrig en mense ontwikkeling. Suid Afrika is in die proses om ‘n groeiplan saam te stel vir 2030. Onbevredigende dienslewering, ‘n verdeelde samelewing, en onvoldoende onderrig is onder andere faktore wat die groei van Suid Afrika verhinder om ‘n positiewe, kompeterende land teen 2030 te wees, soos geïdentifiseer deur die National Planning Commision. Hierdie faktore verhoed dat Suid Afrika positiewe ekonomiese groei ervaar. Die doel van die verhandeling is om die skepping van ‘n volhoubare omgewing wat infrastruktuur lewering tot gevolg sal hê, te ondersoek. Bestaande modelle word geanaliseer en gebruik om ‘n model vir munisipaliteite saam te stel wat sal help om fondse reg aan te wend en die druk rondom infrastruktuur lewering te verlig. Die teoretiese uitkomstes is positief en daar is gevind dat die model die bepalende faktore aanspreek. Die behoeftiges is na afloop van die model beter af waar hul bemagtig is en ‘n werksgeleentheid gebied word. Die gevolg is dan ‘n verlaging in die werkloosheidskoers en ‘n verwagting dat Suid Afrika se ekonomie positief sal groei. Voldoende lewering van infrastruktuur en dienste word dan ook verwag. Sodoende word ‘n volhoubare omgewing geskep vir effektiewe ontwikkeling en lewering van infrastruktuur en basiese dienste.

Thesis (MScEng)--Stellenbosch University, 2013. / ENGLISH ABSTRACT: The Strand is located within False Bay and frequently encounters large quantities of wave overtopping over the coastal defences. This results in the damage of property and infrastructure and causes streets to be flooded. Physical modelling tests were done by a consultancy firm to determine a solution by making use of a recurve structure at the back of the beach. This study is an expansion of the previous physical modelling that was done and focuses on several factors that were not tested by the consultancy firm that could have an influence on the overtopping rate and provide additional information on the recurve design. These tests were: (i) the effectiveness of the proposed recurve wall design in reducing overtopping was compared to a vertical wall; (ii) the influence that modifications to the beach profile such as the beach slope, beach width and beach level have on the overtopping rate; and (iii) the sensitivity of overtopping to changes in wave period was tested. The information gathered from these tests was used to propose a possible solution for the Strand. Numerical modelling was done with Delft3D-Wave to determine the wave height at the back of the beach using a nested grid. The waves at the Strand are depth limited and therefore very sensitive to changes in water level. By altering the beach level the model showed how the significant wave height at the back of the beach changes. First estimates of overtopping were determined using the relevant empirical calculations from the EuroTop Manual 2007 for a vertical seawall. No estimate could be made for the recurve wall since it did not fall in the valid range of the equations. From the physical modelling it was found that the overtopping reduced significantly from a vertical to a recurve seawall by a factor of about 50% depending on the wall height. All the prediction methods tested proved to be accurate in estimating the overtopping when the ratio of freeboard to significant wave height was ≤1.83. For non-breaking wave conditions the beach profiles that were gently sloped (1:50) and wide produced more overtopping than the beach profiles that were steep (1:10) and narrow. Increasing the beach level only decreased the overtopping if the water depth was shallow enough to cause the waves to break before they reached the back of the beach. Overtopping was found to increase with longer wave periods until the wave period became too long and the waves broke offshore which resulted in the overtopping decreasing. Possible solutions to overtopping were proposed based on two beach levels and the implementation of a recurve seawall. Revised crest levels for the wall were made along the length of the beach for both the 1:20 and 1:100 year water levels. / AFRIKAANSE OPSOMMING: Die Strand is in Valsbaai geleë en ervaar dikwels baie oorspoeling deur golwe bo-oor kusverdedigingswerke. Dit lei tot skade aan eiendom sowel as aan infrastruktuur en veroorsaak dat strate oorstroom. Fisiese modelleringstoetse is deur ’n konsultasiefirma gedoen om ’n oplossing te probeer vind deur van ’n teruggebuigde struktuur aan die agterkant van die strand gebruik te maak. Hierdie studie is ’n uitbreiding van die vorige fisiese modellering wat gedoen is en fokus op verskeie faktore wat nie deur die konsultasiefirma getoets is nie. Dit kan moontlik ’n invloed op die oorspoelingstempo hê en verskaf bykomende inligting oor die ontwerp van die terugbuiging. Hierdie toetse is: (i) die doeltreffendheid van die voorgestelde ontwerp van die teruggebuigde strandmuur in die vermindering van oorspoeling word vergelyk met ’n vertikale muur; (ii) die invloed wat veranderinge aan die strandprofiel soos die helling van die strand, die wydte van die strand asook die strandvlak op die oorspoelingstempo het; en (iii) die sensitiwiteit van oorspoeling op veranderinge in golfperiode is getoets. Die inligting wat uit hierdie toetse verkry is, word gebruik om ’n moontlike oplossing vir die Strand voor te stel. Numeriese modellering is met Delft3D-Wave gedoen om die golfhoogte aan die agterkant van die strand vas te stel deur van ’n genestelde ruitenet gebruik te maak. Die golwe by die Strand word deur diepte beperk en is dus baie sensitief vir veranderinge in die watervlak. Deur die strandvlakke te verander het die model getoon hoe die betekenisvolle golfhoogte aan die agterkant van die strand verander. Die eerste beramings van oorspoeling is bepaal deur van die relevante empiriese berekenings uit die EuroTop-handleiding 2007 vir ’n vertikale strandmuur gebruik te maak. Daar kon geen beraming vir die teruggebuigde muur gemaak word nie aangesien dit nie binne die geldige bereik van die vergelykings val nie. Uit die fisiese modellering is daar vasgestel dat oorspoeling noemenswaardig met ’n gemiddeld van ongeveer 50% verminder is, afhangend van die muurhoogte. Al die voorspellingmetodes wat getoets is was akkuraat in die beraming van die oorspoeling wanneer die verhouding van vryboord tot betekenisvolle golfhoogte ≤1.83 was. Vir nie-brekende golftoestande het strandprofiele met ’n lae helling (1:50) en wat wyd was meer oorspoeling tot gevolg gehad as strandprofiele wat steil (1:10) en nou was. ’n Verhoging in die strand se vlakke het die oorspoeling slegs verminder indien die diepte van die water vlak genoeg was om die golwe te laat breek voordat hulle die agterkant van die strand bereik het. Oorspoeling is gevind om te vermeeder met verlengde golflengte tot dat die golflengte só lank geword het dat die golwe in dieper water begin breek wat aanlieding tot verminderde oorspoeling gegee het. Daar word moontlike oplossings vir oorspoeling voorgestel gebaseer op twee strandvlakke en die implementering van ’n teruggebuigde strandmuur. Voorgestelde golfkruinvlakke vir die muur is al langs die lengte van die strand gemaak vir beide die 1:20- en 1:100-jaar watervlakke.

Thesis (MEng)--Stellenbosch University, 2013. / Please see accompanying Errata document to be viewed with original document. / ENGLISH ABSTRACT: The current housing backlog facing the informal residents of South Africa is daunting. With current research showing that the backlog is not shrinking fast enough, the stakeholders of the formal and informal housing sector are facing an immense challenge. Most houses constructed after 1994 utilised conventional brick and mortar construction, with alternative means of building homes taking up a negligible share in the total housing supply. The purpose of this study is to test the feasibility of container-based homes as an alternative to brick and mortar homes in South Africa’s low-cost housing supply according to the triple constraints of project management i.e. cost, time and quality. Social acceptance and environmental sustainability are also analysed as two secondary parameters that will influence container-based projects. These parameters form the basis of the three pillars of sustainability, i.e. economic, societal and environmental parameters, which indicates the feasibility of a new design implementation. Two test cases for the feasibility study were designed. The first case considers a modular single-storey residential home, equivalent to standard “Breaking New Ground” housing solutions. The second test case considers a multi-storey, medium-density residential building, capable of housing multiple families .The test cases represent possible container-based solutions, with traditional brick and mortar construction (single and multi-storey) acting as the control solution. The three sustainability parameters act as benchmarks of each solutions’ feasibility, with the control solution acting as the counter-performance example. The comparison of the economic parameter relies on the cost of each design case, its construction time and the quality of the end-product. The bills of quantities were measured against a conventional building type, and it was found that a single-storey solution will prove more costly than a small brick and mortar home. However, the multi-storey solution proves to be feasible when compared to a concrete three-storey structure. Regarding time, the construction of an Intermodal Steel Building Unit (ISBU) home is up to 3 times faster compared to a conventional house. The end-product quality will depend on the quality system used by the contractor and its correct implementation; thus it is not an important dividing factor when comparing conventional versus Alternative Building Technology (ABT) systems. The societal parameter of an ISBU solution rests on its acceptance by the beneficiaries. Traditionally, resistance has met ABT home implementation, as stakeholders consider them as inferior products. A comprehensive survey was carried out in an informal settlement to test this statement. The results show that the majority of beneficiaries prefer conventional homes, unless the ABT home resembles its conventional counterpart. The environmental sustainability of a new product relies primarily on the carbon footprint of the materials and methods used. This was tested by comparing the impact of an ISBU solution with a conventional solution. The “upcycling” (as opposed to recycling) of used containers provides a large environmental benefit when comparing it to newly constructed brick for conventional homes, and thus the impact is lower. The findings of the study show that a single-storey solution utilising containers proves ineffective, as it is more expensive per square meter than a conventional home. However, a multi-storey container solution is feasible, as it is lower in cost (than comparative conventional solutions), faster to construct, allows for higher density expansion of settlements and is more environmentally friendly. / AFRIKAANSE OPSOMMING: Die enorme behuisingsagterstand van informele nedersetters in Suid-Afrika skep 'n geweldige uitdaging vir die rolspelers in die formele behuisingsektor. Huidige navorsing toon dat hierdie agterstand nie vinnig genoeg verminder nie, en baie mense verkeer in nood. Die meerderheid van huise wat opgerig is sedert 1994 maak gebruik van konvensionele baksteen en sement konstruksie, terwyl alternatiewe maniere van konstruksie 'n nietige aandeel het. Die doel van hierdie studie is om die bruikbaarheid van skeepshouer-gebaseerde huise te bepaal in teenstelling met konvensionele baksteen en sement huise, spesifiek vir die lae-koste behuisingsgeval in Suid-Afrika. Dit word uitgevoer volgens die "drietallige beperking" beginsel van projekbestuur, naamlik koste, tyd en kwaliteit parameters. Addisioneel word die sosiale aanvaarbaarheid sowel as die omgewingsvriendelikheid van die konsep getoets teen konvensionele maniere van konstruksie. Hierdie parameters vorm saam die “drie pilare van volhoubaarheid”, wat betrekking het tot ekonomiese-, sosiale- en omgewings-aspekte. Twee toetsgevalle is ontwerp volgens argitektoniese en tegniese standaarde sowel as gemeenskap benodigdhede. Die eerste geval is ontwerp as 'n enkel-verdieping huis, met behulp van modulêre skeepshouers. Die tweede geval is 'n meertallige-verdieping, medium-digtheid residensiële gebou wat verskeie families kan huisves. Die toetsgevalle modelleer verskeie skeepshouer oplossings, terwyl konvensionele konstruksie oplossings dien as beheer gevalle. Elke geval word volgens die drie volhoubaarheids beginsels getoets, met die beheer gevalle wat dien as die teen-prestasie voorbeelde. Die vergelyking van die ekonomiese parameter berus op die koste van elke ontwerp, sy konstruksietyd en die eindproduk kwaliteit. Die lys van hoeveelhede is gemeet teen dié van ʼn konvensionele huis, en daar is bevind dat die enkelverdieping skeepshouer-geval veel duurder sal wees. Die meertallige-verdieping geval aan die ander kant, maak gebruik van baie kostebesparings metodes, en lyk uitvoerbaar. Die tyd-aspek wys dat die konstruksie m.b.v. “Intermodal Steel Building Units” (ISBUs) tot en met 3 keer vinniger te wees teenoor ʼn konvensionele huis. Die eindproduk kwaliteit hang af van die tipe kwaliteit stelsel wat die kontrakteur gebruik, sowel as die korrekte toepassing van hierdie stelsel; dus is dit nie ʼn skeidende faktor tussen alternatiewe en konvensionele boumetodes nie. Die gemeenskaplike aspek van die gebruik van alternatiewe konstruksie berus op die aanvaarding van die huisbewoners. Gemeenskappe het tradisioneel nie ʼn hoë dunk van Alternatiewe Bou-Tegnologie (ABT) behuising nie, aangesien hulle dit as swak kwaliteit bestempel. Om hierdie stelling te toets is ʼn opname uitgevoer in ʼn informele nedersetting. Die resultate wys dat die meerderheid inwoners die konvensionele opsie verkies. Daar is wel bevind dat die inwoners ʼn ISBU huis sal oorweeg indien dit ʼn visuele ooreenkoms toon met ʼn konvensionele huis. Die omgewingsvolhoubaarheid van ʼn nuwe produk berus hoofsaaklik op die koolstof-voetspoor van die materiale en boumetodes wat gebruik is. Hierdie aspek is getoets deur ʼn ISBU oplossing se omgewings-impak te meet teen dié van ʼn konvensionele huis. Die “upcycling” voordeel wat skeepshouers gebruik gee ʼn groot voordeel teenoor die konstruksie van konvensionele huise, siende dat min nuwe materiale gebruik word. Dus is die totale omgewings impak laer as die van ʼn konvensionele huis. Die bevindinge van die navorsing wys dat ʼn enkelverdieping ISBU oplossing onprakties is in terme van koste per vierkante meter, aangesien dit veel duurder as ʼn konvensionele metode is. Die meertallige-verdieping geval is wel uitvoerbaar, aangesien dit ʼn laer koste tot gevolg het, vinniger gebou word, hoër-digtheid behuising bevorder en meer omgewings-vriendelik is.

Thesis (MScEng)-- Stellenbosch University, 2013. / ENGLISH ABSTRACT: Speed-flow-density relationships are the most useful tools in the highway design and planning process. They are useful in predicting the roadway capacity, in determining the adequate level-of-service of traffic flow and in determining travel time for a given roadway. Two-lane two-way rural highways constitute the vast majority of the rural road network in South Africa. Nowadays in the Western Cape and other provinces of South Africa, the speed-flow-density relationships normally used for rural transportation studies are derived from the Highway Capacity Manual, which reflects the traffic conditions in the North American situation. Since the North American traffic conditions may be different from the South African conditions, a need to investigate speed-flow-density relationships on these highways in South Africa arises in order to justify any investment made on these roads. In this context, a video technique was used to collect traffic flow data during morning peak hours on two rural two-lane two-way highways in the Western Cape Province in order to investigate these relationships. Through the use of Adobe premiere C.S 6 software, travel time of individual vehicles and distance headways were measured and used in computation of average speed and average density. Several researchers have developed models to describe the relationships between traffic characteristics on uninterrupted flow facilities. In this study, some of these models were tested using collected data in order to investigate which model fits the data satisfactorily. Statistical methods were used to evaluate the ability of each model to predict the flow characteristics over the whole range of data. Average speed and density data were used through regression analysis to perform curve fitting and testing of these developed models. In the next stage, the model which provided a best representation of the data on each section was selected and through the application of the steady-state equation (2.1), flow-density and speed-flow relationships were established on these sections. The available data were also used to investigate the impact the observation time has on the speed-flow curve and the resulting capacity value. Finally, the developed speed-flow curves were used to determine the capacities of the study sections. These capacity values were used to determine if the shoulder usage contributes in increasing the capacity of two-lane two-way highways by comparing them to the capacity provided by HCM. / AFRIKAANSE OPSOMMING: Spoed-vloei-digtheid verhoudings is baie handig in die beplanning en ontwerp van paaie. Dit kan ook gebruik word in die voorspelling van kapasiteit, diensvlak en reistyd. Twee-laan twee-rigting paaie maak die grootste deel van die Suid-Afrikaanse padnetwerk uit en vir die beplanning daarvan word van Amerikaanse spoed-vloei-digtheid verhoudings gebruik gemaak aangesien daar nog nie voorheen ‘n studie hiervan in SA gemaak is nie. Video-opnames is gebruik om verkeersvloeidata op twee paaie in die omgewing van Stellenbosch te versamel. Die reistyd en digtheid van individuele voertuie is tydens spitstye waargeneem. Die data is gebruik om te bepaal watter modelle die beste is om die spoed-vloei-digtheid verhoudings vir hierdie paaie te modelleer. Die beste modelle is dan gebruik om die kapasiteit van die paaie te bepaal en dit te vergelyk met die Amerikaanse waardes.

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.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Standards define target reliability levels that govern the safety of designed structures. These target levels should be around an economic optimum for the class of structure under consideration. However, society may have safety requirements in excess of that required to achieve an economic optimum. The LQI criterion can be used to determine society’s willingness to invest in safety, thereby defining a minimum acceptable safety- or reliability level. This thesis determines economically optimised reliability levels for reliability class two concrete structures in South Africa, over a range of typical input parameters. Rackwitz’s (2000) approach is used here, adjusted for the South African context. The structure is described using a simple limit state function, defined as the difference between load and resistance, with resistance a function of a global safety parameter. South African construction costs, costs of increasing safety, failure costs and discount rates are used in the objective function for economic optimisation. Life Quality Index (LQI) theory is used as a basis to derive society’s willingness to pay (SWTP) for safety and the corresponding reliability level is found by applying the LQI criterion. In the South African context the derivation of SWTP presents some challenges, which is discussed. Situations where the minimum required reliability would exceed the economically optimum reliability level are discussed. Various reliability based cost optimization case studies are conducted covering a broad range of typical concrete design situations. From these case studies a range of target reliability indices are derived for typical concrete structural components and failure modes. Obtained values are compared to current South African target levels of reliability provided by the South African loading code and recommendations are made. The approach used by Rackwitz (2000) is compared with results obtained from case studies and used as basis to estimate optimum reliability levels for other types of buildings. Functions are written in MATLAB to allow replication of the study for others seeking to derive optimum reliability indices. / AFRIKAANSE OPSOMMING: Standaarde spesifiseer teiken betroubaarheidsvlakke wat die veiligheidsvlak van ontwerpte strukture bepaal. Hierdie teikenvlak moet rondom die ekonomiese optimum wees vir die klas van struktuur onder oorweging. Die samelewing verkies moontlik ‘n hoër veiligheidsvlak as wat deur die ekonomiese optimum dikteer word. Die LKI (Lewens Kwaliteit Indeks) maatstaf kan gebuik word om die samelewing se bereidwilligheid om in veiligheid te belê te bepaal en sodoende ‘n minimum veiligheidsvlak bepaal. Hierdie tesis bepaal die ekonomiese optimum betroubaarheidsvlak vir klas twee beton strukture in Suid-Afrika vir wisselende parameters. Rackwitz (2000) se benadering word in hierdie studie gebruik en is aangepas vir Suid-Afrikaanse omstandighede. Die struktuur word beskryf deur ‘n eenvoudige limiet staat funksie, gedefinieer as die verskil tussen die las en weerstand, met die weerstand as die funksie van ‘n globale veiligheidsparameter. Suid-Afrikaanse konstruksie koste, veiligheidsvermedering koste, falingskoste en diskonteer koerse word gebruik vir optimering. Die LKI teorie word gebruik om SBB (Samelewing Bereidheid om te Belê) vir veiligheid af te lei en die ooreenkomstige betroubaarheidsvlak word bepaal deur die LKI maatstaf toe te pas. In die afleiding hiervan vir Suid-Afrikaanse omstandighede is sekere uitdagings teegekom wat bespreek word. Situasies waar die minimum betroubaarheidsvlak hoer is as die ekonomiese optimum word bespreek. Verskillende betroubaarheids gebaseerde optimering gevalstudies word gedoen op tipiese beton struktuur elemente. Van hierdie gevalstudies is optimum betroubaarheidsindekse vir die tipiese beton elemente en galingsmodusie afgelei. Die betroubaarheidsindekse word vergelyk met huidige betroubaarheidsindekse soos wat voorgeskryf is in die Suid-Afrikaanse laskode (SANS10160-1(2011)). Rackwitz (2000) se benadering word vergelyk met die resultate van die gevallestudies en word gebruik as basis om optimum betroubaarheidsvlakke vir ander tipes geboue te voorspel. MATLAB funksies is geprogrameer om minimum en optimum betroubaarheidsindekse af te lei.