In recent years, coastal regions worldwide have experienced some of the most devastating hurricanes, such as Harvey and Ida, which resulted in immense human and capital loss. Unfortunately, global climate change, particularly sea-level rise, only amplifies their consequences since hurricanes and the associated storm-induced flooding become more frequent and deadlier. The goal of my work is to develop and implement tools towards effective strategies for resilient and sustainable cities, against storm hazards amidst climate change. We propose a comprehensive optimization framework to search, evaluate, and optimize over a multitude of potential solutions, under various budget and societal constraints. Our models yield significant monetary and efficiency improvements, and importantly, are created and updated based on stakeholders’ feedback (e.g., mayor’s office, transportation agencies, etc.). Case studies in New York City will be demonstrated.

Thesis (MScEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Sea-level rise due to climate change results in deeper water next to existing coastal structures, which in turn enables higher waves to reach these structures. Wave overtopping occurs when wave action discharges water over the crest of a coastal structure. Therefore, the higher waves reaching existing structures will cause higher wave overtopping rates. One possible solution to address increasing overtopping, is to raise the crest level of existing coastal structures. However, raising the crest level of a seawall at the back of a beach, will possibly obstruct the view to the ocean from inland. Alternatively, recurves can be incorporated into the design of both existing and new seawalls. The recurve wall reduces overtopping by deflecting uprushing water seawards as waves impact with the wall. The main advantage of seawalls with recurves is that their crest height can be lower, but still allow for the same wave overtopping rate as vertical seawalls without recurves. This project investigates the use of recurve seawalls at the back of a beach to reduce overtopping and thereby reducing the required wall height. The objectives of the project are twofold, namely: (1) to compare overtopping rates of a vertical seawall without a recurve and seawalls with recurves; and (2) to determine the influence that the length of the recurve overhang has on the overtopping rates. To achieve these objectives, physical model tests were performed in a glass flume equipped with a piston type wave paddle that is capable of active wave absorption. These tests were performed on three different seawall profiles: the vertical wall and a recurve section with a short and a long seaward overhang, denoted as Recurve 1 and Recurve 2 respectively. Tests were performed with 5 different water-levels, while the wall height, wave height and period, and seabed slope remained constant. Both breaking and non-breaking waves were simulated. A comparison of test results proves that the two recurve seawalls are more effective in reducing overtopping than the vertical seawall. The reduction of overtopping can be as high as 100%, depending on the freeboard and wave conditions. Recurve 2 proves to be the most efficient in reducing overtopping. However, in the case of a high freeboard (low water-level at the toe of the structure), the reduction in overtopping for Recurve 1 and Recurve 2 was almost equally effective. This is because all water from the breaking waves is reflected. Even for the simulated lower relative freeboard cases, the recurve walls offer a significant reduction in overtopping compared with the vertical wall. A graph is presented which shows that the length of the seaward overhang influences the overtopping performance of the seawall. As the seaward overhang length increases, the wave overtopping rate decreases. However, for high freeboard cases the length of the seaward overhang becomes less important. The graph gives designers an indication of how recurves can be designed to reduce seawall height while retaining low overtopping. It is recommended that further model tests be performed for additional overhang lengths. Incorporation of recurves into seawall design represents an adaptation to problems of sea-level rise due to global warming / AFRIKAANSE OPSOMMING: Stygende seevlak as gevolg van klimaatverandering, veroorsaak dat dieper water langs bestaande kusstrukture voorkom. Gevolglik kan hoër golwe hierdie strukture bereik. Golfoorslag vind plaas wanneer water oor die kruin van ‘n kusstruktuur, hoofsaaklik deur golfaksie, spat of vloei. Dus sal hoër golfhoogtes tot verhoogde golfoorslag lei. Een moontlike oplossing vir hierdie verhoogde golfoorslag is om die kruinhoogte van bestaande kusstrukture te verhoog. In die geval van ‘n seemuur aan die agterkant van ‘n strand, kan hoër strukture egter die see-uitsig na die see vanaf die land belemmer. Om hierdie probleem te vermy, kan terugkaatsmure in die ontwerp van bestaande en nuwe seemure ingesluit word. Terugkaatsmure verminder golfoorslag deurdat opspattende water, afkomstig van invallende golwe terug, na die see gekaats word. Die grootste voordeel van ‘n terugkaatsmuur is dat hierdie tipe muur ‘n laer kruinhoogte as die vertikale seemuur sonder ‘n terugkaatsbalk, vir dieselfde golfoorslagtempo kan hê. Hierdie projek ondersoek dus die gebruik van terugkaatsmure aan die agterkant van ‘n strand met die doel om golfoorslag te verminder en sodoende die vereiste muurhoogte te verminder. Die doelwit vir die projek is tweeledig: (1) om die golfoorslagtempo van terugkaatsmure te vergelyk met dié van ‘n vertikale muur sonder ‘n terugkaatsbalk; en (2) om die invloed van die terugkaatsmuur se oorhanglengte op die golfoorslagtempo te bepaal. Om bogenoemde doelwitte te bereik, is fisiese modeltoetse in ‘n golfkanaal, wat met ‘n suiertipe golfopwekker toegerus is en wat aktiewe golfabsorbering toepas, uitgevoer. Hierdie toetse is op drie verskillende seemuurprofiele, naamlik ‘n vertikale muur en ‘n terugkaatsmuur met ‘n kort en lang oorhang, genaamd “Recurve 1” en “Recurve 2” onderskeidelik, uitgevoer. Die muurhoogte, die seebodemhelling asook die golfhoogte en –periode is tydens al die toetse konstant gehou. Vir elke profiel is toetse by 5 verskillende watervlakke vir beide brekende en ongebreekte golwe uitgevoer. Uit die toetsresultate is dit duidelik dat terugkaatsmure meer effektief as vertikale mure is om golfoorslag te beperk. Die vermindering van golfoorslag kan tot 100% wees, afhangende van die vryboord en golftoestande. Daar is bevind dat “Recurve 2” golfoorslag die effektiefste verminder. In die geval van hoë vryboord (lae watervlak by die toon van die struktuur) is daar egter gevind dat “Recurve 1” en “Recurve 2” die golfoorslag feitlik ewe goed beperk. Dit is die geval aangesien alle water van die brekende golwe weerkaats word. In die geval van ‘n lae vryboord, word die voordeel van die terugkaatsmuur teengewerk deurdat daar ‘n kleiner verskil in golfoorslagtempo’s tussen die drie profiele is. ‘n Grafiek is voorgelê wat wys dat die lengte van die terugkaatsmuur se oorhang golfoorslag beperk. ‘n Groter oorhanglengte van die terugslagmuur veroorsaak ‘n groter vermindering in golfoorslag. Vir gevalle met ‘n hoë vryboord, is daar egter gevind dat die oorhanglengte van die terugslagmuur minder belangrik is. Hierdie grafiek gee ontwerpers ‘n aanduiding van hoe terugslagmure ontwerp kan word met ‘n lae hoogte terwyl ‘n lae oorslagtempo behou word. Die gebruik van terugslagmure bied ‘n aanpassing vir die probleme van seevlakstyging, as gevolg van klimaatverandering.

The Last Glacial Maximum (LGM) was a period of massive range contraction for numerous taxa, including the water-dispersed mangrove species, Rhizophora mangle L. Following the LGM, R. mangle expanded poleward via propagule transport by ocean currents. In this study, we use microsatellite loci to characterize the genetic structure of nine R. mangle populations and compare potential expansion pathways that resulted in the colonization of the Florida peninsula and Caribbean islands. Results show comparatively greater genetic connectivity between the Caribbean mainland and Florida, a similar pattern between West Africa and Caribbean islands, and substantial admixture on the island of San Salvador, the Bahamas. We conclude that Florida and Caribbean island R. mangle populations were likely recolonized via different expansion pathways. Estimates of recent migration rates are low and populations are structured into three regions (Caribbean mainland, Caribbean islands, Florida). These findings provide insight for future management and conservation initiatives. / Includes bibliography. / Thesis (M.S.)--Florida Atlantic University, 2014. / FAU Electronic Theses and Dissertations Collection

Beach nourishment provides an excellent opportunity for the study of intensified sediment transport gradients and associated morphological changes in a natural setting. The objectives of this study are to quantify and predict longshore and cross-shore transport gradients induced by 1) beach nourishment, 2) different storm wave conditions, and 3) the annual wave climate and long-term sediment supply. The details of sediment transport rates and gradients induced by gradual processes and high-energy events are analyzed on a macro-scale. Well-planned monitoring of the 2004 Upham Beach nourishment project in west-central Florida collected high-spatial and -temporal resolution field data. Three hurricanes passed by the project soon after nourishment was complete.Post-nourishment planform adjustment occurs immediately after nourishment via diffusion spit development at the end transitions. Thus, the initiation of planform adjustment may be abrupt, rather than gradual as pred icted by the typical diffusion models. Diffusion spit formation is dominant during relatively calm wave conditions on coasts with low wave heights and tidal ranges.Profile equilibration also may be an event-driven, rather than a gradual, process. Rapid profile equilibration following nourishment occurred not only due to hurricane passage, but also during a winter season. The duration between nourishment and the passage of the first high-energy event is an important factor controlling the time scale of profile equilibration.The passage of three hurricanes generated different wave conditions and induced different sediment transport directions, rates, and gradients due to their variable proximities to the project area. The direction of cross-shore transport was governed by wave steepness. Onshore sediment transport occurred during a storm event, in contrast with the concepts of gradual onshore transport during mild wave conditions and abrupt offshore transport during storm events, as cited in the literature.By formulating sediment budgets on various temporal and spatial scales, both event-driven and average transport rates and gradients can be resolved. Annual average transport rates for a region should not be arbitrarily applied to nourished beaches; rather, sediment budgets formulated with high-spatial and -temporal resolution field data should be formulated during the design phase of future nourishment projects.

The legislative management of Off-Road Vehicles (ORVs) on beaches has evolved over a period of time in response to a range of influences and changing circumstances within the various social, institutional, economic and biophysical systems. The impact of ORVs on beaches in South Africa is multifaceted and when viewed holistically incorporates the interaction between the biophysical, social, economic and institutional environments. This Study focuses only on the legislative and biophysical environments associated with the impact of ORVs on beaches. Sustainable coastal development draws attention to the "process" character of sustainable development that needs to be worked towards over time in an iterative manner. It highlights the need to take into account the current reality of prevailing circumstances, the uncertainty of the future, limited understanding of coastal ecosystems and communities, and the complex interactions between and within the human and non human components of the environment. An understanding of the ecological integrity and effective governance dimensions (being the focus of Study), although only two of the five dimensions of sustainable coastal development, contributes towards an understanding of the sustainability of the impact of ORVs on beaches within the South African context. The legislative environment is investigated from the management perspective of the national Department of Environmental Affairs and Tourism. This Study determines whether effective governance is being achieved through the ongoing management of the impact of ORVs on South African beaches. The institutional management at a national level has resulted in the conditional banning of ORVs from beaches, which has resulted in promoting the ecological integrity of beaches, therefore contributing towards sustainable coastal development. The physical system is investigated where appropriate in terms of the biophysical parameters within which ORVs are managed on beaches within the inter-tidal zone as per the ORV General Policy (1994). In order to understand the biophysical system within which ORVs are managed, the existing literature and research concerning the impact of ORVs on beaches is reviewed, including existing literature on beach geomorphology and beach biota. A Case Study Area was selected for an experimental investigation to determine the biophysical impact of ORVs on sandy beaches. The experiment was conducted at Leven Point, north of Cape Vidal situated on the KwaZulu-Natal north coast within the St Lucia Marine Reserve. The ORV General Policy (1994) has been superseded by the ORV Regulations (2001), which do not however, specify the biophysical delineation of the management of ORVs on beaches. This Study has included recommendations applicable to the management of ORVs on beaches in South Africa in terms of the ORV Regulations (2001). These recommendations advocate the conservation of the dynamic biophysical environment of the inter-tidal zone on beaches, and the need to take a sustainable coastal development approach to applications for Recreational Use Areas (RUAs) in terms of the ORV Regulations (dated 21 December 2001). / Thesis (M.Sc.)-University of Natal, Durban, 2003.

The importance of understanding the ecological functioning of coastal dune systems is emphasized as being fundamental to the correct management of the dune landscape. Dune vegetation along the Eastern Cape coastline, from Cape St Francis in the west to Kei Mouth in the east was described in terms of the distribution and phytochorological affinities of the taxa. At a regional scale species distribution was strongly influenced by both the climate, particularly rainfall, and the phytochorological affinities of the taxa. Seven communities were defined using TWINSPAN, and the interrelationships between these communities in anyone area appeared to be linked to a successional gradient. Dune Slacks are thought to play a key role in this successional sequence, and a temporal study of this community led to a conceptual model of plant succession in these dunefields. Climate, particularly rainfall and wind, are major factors influencing plant succession. Wind-borne sand causes the slacks to migrate in an easterly direction under the influence of the predominantly westerly winds, although easterly winds, mainly in summer months may reverse these trends. Autogenic changes appeared to be important in this succession, and a comparative study of a good example of a primary succession at Mtunzini in Natal was undertaken to elucidate the main mechanism of change. Eight communities that were identified here were concluded to be distnbuted along a gradient of increasing age, with successional changes predictable, linear and directional. Species were grouped in distinct zones along the continuum and edaphic changes (decrease in soil pH, increase in organic matter and exchangeable bases) were related to the community based changes in species composition. The mechanism of change supported the facilitation model of plant succession which is a modification of the original Clementsian concept. Similar results were found in the Eastern Cape, but due to the harsh environment, multiple pathways of succession exist. Data from this study lent support to the model of plant succession developed earlier, and confinned that the dune slacks played an important role in this facilitation by acting as centres of diversity. The foredunes were found to have an indirect role in protecting these slacks from salt spray and sand movement. The central theme of the management studies was to investigate the ecological consequences of recreational pressure within the dune environment. Current levels of beach utilization at East London were lower than other beaches in South Africa, but a general trend of increasing utilization due to sociopolitical changes can be expected. The suitability of questionnaire surveys to assess aspects such as the adequacy of facilities, perceptual carrying capacity and the beach users opinion of natural vegetation and preference for particular beaches was demonstrated. The dune vegetation was found to be sensitive to human trampling, but at current levels, the ecological carrying capacity will not be exceeded since results of the aerial census counts and questionnaire survey revealed that few people entered sensitive zones such as the coastal forest. More detailed long term studies on the susceptibility of dune vegetation to both trampling and off-road vehicle impacts revealed a low resilience of dune plant communities to these effects. Although susceptibility differed between the three communities tested, generally the greatest amount of damage occurred after the first few passages, and vehicles caused a more significant decrease in height when compared to trampling. Recovery rates were slow and low levels of repeated damage were sufficient to retard or prevent the recovery of the plants. Stricter control of vehicle use on beaches is therefore required, and in high use zones the ecological carrying capacity should be increased by providing access tracks if possible, or if not possible, by restricting access. A historical account of the process of dune stabilization showed that although first initiated in 1845, indigenous species were only used in the past three decades. The use of alien species has resulted in problems such as a reduction in the ecological integrity and aesthetic appeal of coastal systems. The techniques applied in the stabilization of drift sands with indigenous vegetation have been successful, as revealed by a quantitative survey of 17 sites in the Eastern Cape. Sites were grouped by multivariate analysis on the basis of their species composition, and variability between sites was dependent on the types of species planted. Selection of suitable species is therefore important and is discussed with respect to their natural distribution along the coast. The long term objective of stabilization should be the creation of functional, diverse, aesthetic ecosystems, since the intrinsic and economic value of the dune landscape for tourism lies therein. However, detailed studies should be undertaken prior to implementing a manipulative process such as dune stabilization, since ecological processes may be disrupted. An understanding of such processes is therefore important if one wishes to effectively manage the dune landscape.

Debatten om strandskydd har varit ett aktuellt ämne sedan riksdagen antog den första permanenta strandlagen år 1953. Sveriges 290 kommuner och 21 regioner innehar varierande geografiska förutsättningar och ställs inför olika utmaningar. Landsbygdens krympande utveckling gav upphov till framväxten av LIS men har framväxten av LIS bidragit till en ökad strandnära bebyggelse? Utbytet mellan stad och land är idag mer intensivt än tidigare. Uppsatsen syftar till att undersöka vilka faktorer som påverkar utvecklingen av strandnära bebyggelse och skapa förståelse varför det byggs fler strandnära byggnader på olika geografiska platser. Vidare syftar uppsatsen till att kartlägga den strandnära bebyggelsen i Sveriges samtliga 290 kommuner och 21 regioner för år 2018. Syftet har resulterat i följande frågeställningar: Hur ser utbredningen av strandnära bebyggelse ut i Sveriges kommuner och regioner och var är strandnära bebyggelse mest koncentrerat? Vilka faktorer påverkar strandnära bebyggelse? Har utpekandet av LIS-områden bidragit till mer strandnära bebyggelse? För att besvara frågeställningarna genomfördes en totalundersökning med den kvantitativa metoden sekundäranalys av offentlig statistik. Studiens kartläggning av strandnära bebyggelse år 2018 visade att det byggdes mest i städer och i anslutning till städer med pendlingsavstånd. Om hänsyn till demografin och befolkningsmängden beaktades visade studien att det byggdes mest på landsbygden. Studien visade att faktorerna geografisk komposition, antal sjöar och antal kilometer strandlinje påverkar hur mycket det byggs i strandnära läge medan faktorn politisk styre inte hade någon påverkan. Vidare visade studien att kommuner med utpekade LIS-områden inte har påverkat eller bidragit till en ökad strandnära bebyggelse i jämförelse med kommuner som inte har utpekade LIS-områden. / The debate on shoreline protection has been a topical issue since the Swedish Parliament adopted the first permanent law of shoreline protection in 1953. Sweden's 290 municipalities and 21 regions have varying geographical conditions and are faced with various challenges.The shrinking development of rural areas gave rise to the growth of LIS, but does the emergence of LIS contribute to an increase in beach development? The exchange between city and countryside is more intense today than before. The essay aims to investigate which factors affect beachfront development and create an understanding of why more beachfront buildings are being built in different geographical locations. Furthermore, the essay aims to analyze the beachfront development in all of Sweden's 290 municipalities and 21 regions for 2018. The purpose has resulted in the following issues: How does the distribution of beachfront buildings look like in Sweden's municipalities and regions, and where is beachfront development most concentrated? What factors affect beachfront development? Has the designation of LIS-areas contributed to more beachfront development? To answer the following issues, a comprehensive survey was conducted by using the quantitative method secondary analysis of official statistics. The study's survey of beachfront development in 2018 showed that it was built mostly in cities and connected to cities with commuting distances. If the demographic and population is taken into consideration, the study showed that it was built mostly in the countryside. The study showed that the factors geographical composition, number of lakes, and number of kilometers of shoreline affect the number of buildings close to the beach, while the factor political governance did not affect. Furthermore, the study showed that municipalities with designated LIS-areas have not affected or contributed to increased beachfront development, in comparison with municipalities that do not have designated LIS-areas.

Strandskyddet upprättades för att trygga tillgången till strandområden för allmänheten och för att skydda djur- och växtliv från exploatering. Landsbygdsutveckling i strandnära lägen (LIS) togs fram för att inom ramen av översiktsplanering ge kommuner möjlighet till utveckling av landsbygden. LIS har dock visat sig otillräckligt i vissa avseenden och många kommuner i Sverige har uttryckt missnöje med strandskyddslagen. Syftet med studien är att bidra till en bättre landsbygdsutveckling genom att undersöka hur kommunernas framtagande av LIS-områden ser ut i Dalarnas län. Förslag på förändringar pågår i en strandskyddsutredning och därför ska studien även undersöka hur kommunerna i fortsättningen tänker arbeta med strandskyddsutredningen. Studien använder sig av tre olika metoder. Inledningsvis granskades miljöbalken, översiktsplaner samt strandskyddsutredningen. Vidare genomfördes intervjuer och enkäter, som besvarades av utvalda personer på kommunerna. Kommunerna använder sig av ytterligare kriterier i deras översiktsplaner som inte förekommer i lagtexten. Exempel på dessa kriterier är vatten och avlopp, infrastruktur, service och attraktivt område. Dessa kriterier är mer av betydelse för de ekonomiska faktorerna. Kommunerna i denna studie är positiva till att strandskyddslagstiftningen ses över, eftersom de anser att LIS-tillägget är svårtolkat. Kommunerna har däremot många åsikter om strandskyddsutredningen och menar att den fokuserar på fel saker. Länsstyrelsen kommer fortfarande ha stort inflytande och kommunerna menar att beslut om att helt eller delvis upphäva strandskydd i stället bör ske på en kommunal nivå eftersom lokalkännedomen är högre hos kommunerna. Resultatet av studien är en mall med kriterier för kommunerna i Dalarnas län som kan användas vid utpekning av LIS-områden och fungerar som underlag för kommuner att använda i geografiska informationssystem samt multikriterieanalyser för att utveckla landsbygden. Mallen visar att kriterier som biologisk mångfald; riksintresse naturvärden; landsbygdsutveckling samt befintlig bebyggelse värderas högt av kommunerna. / The Swedish shore protection law aims to make shores accessible to the public and provide good conditions for plants and animals. Therefore, a shore protection law was established that protects against exploitation. Rural development in shore sites (LIS) was implemented within the boundaries of city planning, as a tool for the Swedish municipalities to develop the countryside. LIS has proven to be insufficient, and a lot of the Swedish municipalities have expressed dissatisfaction with the LIS addition. The purpose of this study is to contribute to an improved rural development by examining the process behind the selected rural development sites (LIS) by the municipalities. The Swedish government is currently investigating the public shore protection laws, and the investigation might lead to significant changes to the laws. This study will also compile the municipalities view on the ongoing investigation and how it might impact rural development in the future. This study utilizes three different methods. Initially a document study was performed in order to gain knowledge on the subject, followed by an interview and survey by the participating municipalities. When suggesting suitable locations for LIS, the municipalities use some criteria beyond the ones addressed by the Shore Protection laws. Examples of these type of criteria are sewer systems, infrastructure, service, and attractiveness of the area. These criteria are highly valued because of the economic opportunities that they provide. Every municipality’s overall perception of which areas that are suitable for LIS, is based on a selection of different criteria. These areas are further investigated to decide whether exploitation is possible. This investigation is done with different aspects in mind, such as, natural values, cultural environment and flooding. The municipalities in this study are all in favor of changing the public shore protection laws because the execution is problematic and difficult to interpret. However, they proclaim that the ongoing investigation by the government is focusing on the wrong areas and that the suggested law changes are not enough to further enhance the development of the Swedish countryside. The result of this study is a table containing different criteria that the municipalities in Dalarna county can use when designating their rural development shore sites (LIS) in geographical information systems. The criteria table shows that public health, biodiversity, rural development, natural values and existing buildings, are highly valued by the municipalities.

One tool of the economic planner is Benefit Cost Analysis (BCA). This model's accuracy in describing human behavior has been criticized, particularly for uncertain and intertemporal choices. To the extent this holds, the model will be inaccurate in assessing benefits of shoreline protection measures and will provide reduced insight into policy choices. From a review of economic, psychology and geography literature, three points of criticism are: - when faced with losses, individuals tend not to be averse to risk, - when faced with low probability hazards, individuals tend to ignore the hazard altogether (truncate low probability), - when faced with choices over time, individuals have different rates at which they trade off benefits now versus later. Typically, applications of BCA do not account for these observations. The main objective of the study was to determine whether these criticisms are supported, and to draw conclusions regarding government policy for the flooding and erosion hazards on the Lakes. A Benefit Cost model was formulated to describe the individual shoreline property owner's behavior with respect to undertaking structural measures to mitigate flooding and/or erosion. To test the model, property owners on Lakes Erie, Ontario and Michigan were surveyed by mail. Experimental questions, focussing on the intertemporal and uncertain nature of the hazard protection choice were developed. The econometric analysis suggested that: - individuals varied in their time preference rate, - the probability of low chance events was truncated by many respondents, - on average respondents were not risk averse, and - the above phenomena helped explain the choice to take protective action. Using a market rate for discounting in the BCA can provide inaccurate benefit estimates. Observed time preference rates may provide a better measure. Subsidized hazard insurance has been suggested to encourage self protection. Disregard for low probabilities, coupled with a lack of risk aversion, suggest such a program would not be successful. Subsidized loans for shore protection may be unsuccessful. Many people displayed a time preference rate above the market loan rate, yet they did not borrow. Information programs may be useful in promoting a better understanding of the hazards which may be faced by residents. / Ph. D.

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.