Дисертації з теми "Sand dunes South Australia"

Includes bibliographical references.
Sand is a resource in high demand for urban expansion and development. Sand mining operations are often located on the edges of cities. The Macassar Dunes are an important source of building sand for the City of Cape Town. The area is located within the Cape Floral Kingdom, the smallest and richest of the six floral kingdoms of the world. The Macassar Dunes area has been identified as a core flora conservation site due to its unique habitat diversity and quality. South Africa is a developing country and this case study is used to highlight the tensions that arise between the need to provide building sand for development and the need for integrated and accountable management that allows for the sustainable functioning of natural physical and ecological processes as well as enhanced social and economic benefits for people.

Thesis (MScEng (Civil Engineering))--University of Stellenbosch, 2011.
ENGLISH ABSTRACT: The hypothesis postulated in this research, namely that the effectiveness of natural and constructed buffer dune systems can be assessed by a set of indicators that defines the integrity of the dune system and triggers informed management decisions, was evaluated and proved to be essentially true. Two key objectives, namely (1) the identification of key indicators that define the buffer dune integrity; and (2) the development of a scientifically defendable and practical checklist-based method of gathering qualitative information on the identified key indicators so as to guide decision-making at municipal level formed the core of the study. The six dune integrity indicators that collectively define the risk profile of a particular site along the Southern Cape coastline are (1) the degree of protection from prevailing wave energy, (2) the characteristics of the dominant winds and sand supply during the dry season, (3) the relative height of the foredune, (4) the degree of pressure on the buffer dune due to humans, (5) the vulnerability of the type of coastline to erosion, and (6) the coastline stability considering the prevailing coastal processes. The first two indicators relate to the natural (permanent) characteristics of the site and can be defined by experts and presented in the form of a risk and vulnerability atlas layer for direct use by non-experts. The third and fourth indicators relate directly to the implementation of proactive assessment and appropriate management actions to ensure a high level of buffer dune integrity. The last two indicators allow for management intervention to reduce the vulnerability but may entail costly engineering solutions and require expert input. A conceptual risk profile assessment procedure and a decision support guideline incorporating these indicators were developed and evaluated for relevance and practicality through a series of workshops with municipal officials along the south coast of South Africa. It was seen that although some initial basic training may be required, carrying out rapid assessments of the environmental status of key components of an identified human–nature system, such as a buffer dune, is practical and achievable by non-experts.
AFRIKAANSE OPSOMMING: Die hipotese wat in hierdie navorsing gepostuleer is, naamlik dat die doeltreffendheid van natuurlike en geboude bufferduinstelsels geassesseer kan word deur ’n stel aanwysers wat die integriteit van die duinstelsel bepaal en ingeligte bestuursbesluite tot gevolg het, is getoets en bewys hoofsaaklik waar te wees. Twee sleuteldoelwitte, naamlik (1) die identifisering van sleutelaanwysers wat die bufferduinintegriteit bepaal; en (2) die ontwikkeling van ’n praktiese kontrolelys-gebaseerde metode wat wetenskaplik verdedigbaar is om kwalitatiewe inligting oor die geïdentifiseerde sleutelaanwysers in te samel ten einde besluitneming op munisipale vlak te bevorder, vorm die kern van die studie. Die ses duin-integriteitsaanwysers wat gesamentlik die risikoprofiel van ’n bepaalde terrein langs die kuslyn bepaal, is (1) die graad van beskerming teen die heersende golfenergie, (2) die kenmerke van die dominante winde en sandbron gedurende die droë seisoen, (3) die relatiewe hoogte van die voorduin, (4) die graad van druk op die bufferduin as gevolg van mense, (5) die eroderingskwesbaarheid van die soort kuslyn, en (6) die kuslynstabiliteit met inagname van die kusprosesse. Die eerste twee aanwysers het betrekking op die natuurlike (permanente) eienskappe van die terrein en kan deur kundiges bepaal word en in die vorm van ’n kaart in ’n risiko-enkwesbaarheidsatlas aangebied word vir direkte gebruik deur niedeskundiges. Aanwysers 3 en 4 hou direk verband met die implementering van tydige en deurlopende proaktiewe assessering en gepaste bestuursaksies om ’n hoë vlak van bufferduinintegriteit te verseker. Aanwysers 5 en 6 bevorder bestuursaksies om kwesbaarheid te verminder, maar kan moontlik duur ingenieursoplossings inhou en kundige insette benodig. ’n Konseptuele risikoprofielassesseringsprosedure en ’n besluitondersteuningsriglyn wat die aanwysers insluit, is ontwikkel en geëvalueer vir toepaslikheid en uitvoerbaarheid deur ’n reeks werkswinkels met munisipale amptenare aan die suidkus van Suid-Afrika. Hoewel aanvanklike basiese opleiding nodig kan wees, bly dit dat vinnige assessering van die omgewingstatus van sleutelkomponente van ’n geïdentifiseerde mens–natuurstelsel, soos ‘n bufferduin, prakties en haalbaar deur niedeskundiges is.

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.

Thesis (Ph. D.)--University of Adelaide, National Centre for Petroleum Geology & Geophysics (NCPGG) /Dept. of Geology & Geophysics, 1993.
At head of title: "NERDDC/SENRAC Research Project." Three folded maps in pocket. Two microfiches in pocket. Includes bibliographical references (leaves 155-187).

Bibliography: pages 120-128.
The study is primarily concerned with the identification of topographical dunes and their classification as either sand ramps or climbing dunes. Topographical dunes in two semi-arid regions, namely the southern Kalahari (a summer rainfall region) and the Breede River Valley (a winter rainfall region), were investigated. The study also evaluates the palaeoenvironmental significance of the topographical dunes and attempts a palaeoenvironmental reconstruction within the study regions. The two different rainfall regimes facilitated regional comparisons with respect to environmental change, most particularly during the Quaternary. The methodology comprises a review of current literature on topographical dunes, an examination of aerial photography to identify topographical dunes in South Africa and field work to ground truth the dunes. Field sampling, laboratory work (granular composition analysis, pH, conductivity and scanning electron microscopy) as well as statistical analyses (principal component and cluster analyses) were employed to assist in the palaeoenvironmental reconstruction. The results of the laboratory and statistical analyses do not reveal any obvious differences with respect to structure, particle size, pH, conductivity, chemical composition and the surface texture of the grains between, the different topographical dunes. The dunes comprise homogeneous quartz sand that was emplaced against topographical barriers as a result of aeolian processes. They are therefore classified as climbing dunes rather than sand ramps. Three optically stimulated luminescence dates were determined for a topographical dune from each study region. Samples from the Prynnsberg 2 dune in the southern Kalahari are dated to 100 years, and it is suggested that this is due to current reworking of the Kalahari sands from the extensive linear dune field and from the Orange River. It is proposed that the southern Kalahari topographical dunes are currently episodically active. From the Sandput dune in the Breede River Valley, three probable humid phases are identified: 762 kyr, 28.2 kyr and 9.9 kyr. These humid periods may be coupled with episodes of cooling, which supports results from previous studies. This finding has important implications for future climatic changes in the winter rainfall region of South Africa, implying that warming in the Western Cape may be associated with a decrease in precipitation. Lastly, a short historic overview of aerial photographs shows that topographical dunes are susceptible to human impacts in the form of agriculture, overgrazing, sand quarrying and through the construction of dams and weirs on rivers.

A study of the dynamics and functions of a coastal dunefield at the Bushman’s River Mouth in Kenton-on-Sea was conducted to provide essential information for the formulation of a management strategy based on an ecosystem approach. Bi-monthly tacheometric surveys were undertaken at the Westbourne Road Car Park dunefield to investigate the sedimentological processes. Changes in the topography, the amount and rate of sand accretion were monitored. Accretion and progradation were the dominant long-term sedimentological processes at the site. Long-term spatial variation in these processes corresponded to the temporal pattern of sedimentation in the river mouth while short-term variation resulted from dynamics inherent to the types of dunes present. Factors affecting aeolian accretion at the site are topography, river mouth configuration, dune types and the presence of vegetation as well as the seasonal wind regime. A vegetation study, recording species present, cover and abundance of the plants along the surveyed transects, was also conducted to examine the progressive establishment of vegetation. Five plant communities were discerned namely, saltmarsh, pioneer, enriched pioneer, open scrub, closed scrub and scrub-thicket communities. The spatial distribution of these communities coincided with the north-westerly development of the sandbank. A successional trend in community change occurred along a gradient of increasing diversity, complexity and age. Initially, autogenic changes wrought by pioneer species facilitated the recruitment and survival of other species and commenced succession at the study site. Multiple successional pathways were discussed in relation to subsequent species establishment that occurred after facilitation. The amalgamation of ecological data with a social study in the form of public perception surveys allowed for a greater understanding of the present interactions between the ecosystem and the demands placed on it. The area primarily functions as a recreational site that offered numerous beach and water-related activities. A lack of information regarding the ecology and management programmes influenced public perception of the environment and management issues in general. Different management perspectives and the use of the information presented in this study were also discussed.

Rehabilitation is a dynamic process influenced by factors related to more than one field of ecology. It is therefore necessary to consider all these components when assessing the rehabilitation, although in the initial stages the successful revegetation of the disturbed areas is the most important criterion. Richards Bay Minerals, on whose mining site this project was carried out, is dredge mining heavy minerals on the north coast of Natal, where they have rehabilitated mined areas since 1978. This project has been carried out to establish: 1) The success of their dune forest rehabilitation using quantitative techniques. 2) The available seed bank in their rehabilitation stands. 3) The similarities in the succession taking place in rehabilitation stands compared to the revegetated stands in the vicinity of Richards Bay. 4) The best methods for creating alternative vegetation communities, especially grasslands, with a high species diversity on the mined tailings. This study reviews only the success of rehabilitation of the natural vegetation but other studies focusing on the insect, reptile, mammal and bird populations are also being undertaken by other researchers. No particular method of determining the success of vegetation rehabilitation has been chosen by restoration ecologists. Therefore in this study a broad range of quantitative techniques were used to show whether successional changes are occurring in the vegetation and physical environment. The results obtained from sampling the rehabilitated vegetation have shown that both the species richness and diversity are increasing as the returned vegetation matures. Levels of soil properties such as Sodium, Phosphate, Calcium and percentage organic matter have also risen with increasing stand age. Community complexity is also increasing with stand age, and TWINSPAN and DECORANA plots have separated out the differently aged stands based on their differences. A "pilot" study was done on the seed bank present in the rehabilitation stands. This has shown the presence of large amounts of early successional, mostly herbaceous species. Seeds of later successional and woody species were scarce which may be a result of the sampling intensity used. However seeds of late successional ground cover species were found in the older stands. Comparisons between the natural revegetation of disturbed areas in the vicinity of Richards Bay and the rehabilitation stands revealed similarities in both species composition and complexity. Species richness and diversity values are comparatively similar for the younger revegetated and older rehabilitation stands, and lWlNSPAN and DECORANA analysis techniques clustered the samples recorded from these areas in close proximity on their relative plots. The oldest revegetated sites contain a number of species found in the rehabilitated vegetation but as Acacia karroo has thinned-out in these stands many of these other species are now mature individuals. Attempts at rehabilitating an area of grassland at Richards Bay Minerals has not produced satisfactory species diversity and experimental manipulations were used to try and increase the diversity of the existing Eragrostis curvula dominated community. Of the several treatments used for the manipulation, a combination of burning and further topsoiling was the most successful in reducing Eragrostis importance and in increasing the species richness. Grassland topsoil spread directly onto the bare tailings produced an extensive vegetation covering over a short period but species richness was not significantly greater than for the existing Eragrostis dominated grassland, and further treatments and management needs to continue if this technique is to be employed. Only a limited amount of alien infestation of the rehabilitated areas was evident from the sampling undertaken during this research. As the removal of alien plants is an ongoing process and the rehabilitation stands are continuously monitored to identify any new invaders, this is not expected to become a problem. From the results of work done overseas and the rehabilitation carried out in South Africa it appears that it is possible to return natural vegetation communities on mined areas. That this is a lengthy process is to be expected but by manipulating the vegetation and continuously monitoring the process it may be possible to speed up development. Areas in need of further research have been identified based on the findings of this project. This will help to reinforce the undertaking of management proposals that will enhance the vegetation recovery and the success of the rehabilitation programme.

碩士
國立中山大學
海下科技暨應用海洋物理研究所
103
To study the characteristics of sand dunes in the South China Sea (SCS) and its effects on sound propagation, the pilot experiment of the Acoustic Sand Dune Experiment was carried on in May 2012, used a multi-beam echo sounder collecting the topographic data. The intensive observation phase of the Sand Dune Acoustic Experiment in May 2013 is planed based on the resluts of the pilot experiment, which achieve finer measurement: multi-beam echo sounder. The characteristics of sand dunes can be obtained by comparing the results of 2012 and 2013. Furthermore, the acoustic experiment was conducted in 2013; the acoustic recorders were deployed at the center and the source was towed with a 5 km radius circle to obtain the energy fluctuation under different sand dunes structure. This data was used to discuss the impact on multipath effect and energy distribution caused by sand dunes. Moreover, two numerical models: BELLHOP and RAM-PE were applied to model the propagation effects in sand dune field. The results shows that sand dunes on the upper continental slope in SCS were extended in the northeast-southwest direction; and most of its amplitude are less than 10 m, only few were observed over 20 m. From the survey results of this two years, we can see the amount of variation was small and from experiment data and numerical modeling, we can see that the sand dunes will have significant impact on multipath effect, ans also cause a great loss near sea surface. In addition, without considering the sand dunes, when the terrain change from upslope to downslope, signal energy will concentrate on the surface layer of water. This research can be used as a reference for future experiments, and be further applied to discuss the acoustic communication performance caused by the sand dunes.

碩士
國立臺灣大學
工程科學及海洋工程學研究所
104
There are many underwater sand dunes caused by the internal wave located in the depth of 160 meters to 600 meters in northern South China Sea. The largest amplitude of these sand dunes is about 16m. Underwater acoustic transmission is affected by this topographic feature, and also has three dimensional effects. In this research the 2-D and 3-D underwater acoustic propagation models (RAM and FOR3D respectively), are used to simulate acoustic propagation in the region. There is starter issue to be resolved for the high-impedance, low-loss ocean bottom of the region. RAM with self-starter is overly initialized, thus the initial field is produced to match with the source beam-pattern. A tunable Gaussian starter is then used to avoid over initialization, which is a proper starter for the moored source. The acoustic field received at VLA emitted from the moored source is simulated with the proper starter. Results show temporal variations with respect to that of water column, and three dimensional effects over sand dunes.

碩士
國立臺灣大學
工程科學及海洋工程學研究所
102
There are many underwater sand dunes in the upper continental slope at the depth of 160m to 600m in northern South China Sea. These sand dunes are special as they are the largest sand dunes observed with amplitude up to 16m. Underwater acoustics transmission will be affected by these sand dunes and in turn produce the three dimensional effects. Due to the variation of topography in this area, if we use the 2-D (r,z) model, it will ignore the variation of horizontal direction and cause the θ-coupling disappear, causing us unable to describe the three-dimensional effects of the sand dunes completely. So, the 3-D underwater acoustic propagation model, FOR3DW (based on the cylindrical coordinates, the wide-angle version of FOR3D) is used to analyze the 3D effects caused by the sand dunes in South China Sea. In order to identify the causes generating 3D effects, ideal sinusoidal topography of different amplitudes, crest-to-crest intervals, and angles between the propagation direction and the orientation of dunes are studied. Then the actual environmental inputs from the experimental sites in the northern South China Sea are used to do the 3D calculations, which are used to plan for 3D acoustic propagation in the experiment conducted in June 2014. The 3D simulation is compared with the experimental data. Good match of data and simulation are found in some periods, while there are discrepancies in other time which demands future investigation.

Bibliography: leaves 291-315.
x, 315 leaves, [9] leaves of plates : ill. (chiefly col.), maps ; 30 cm.
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, Dept. of Geology and Geophysics, 1998?

碩士
國立臺灣大學
工程科學及海洋工程學研究所
104
On the continental slope of Northern South China Sea, there are many special terrain, Sand dune. Because of this special topography, when the sound conducts underwater, it will be affected by these sand dunes and cause strong scattering and coupling effects. In this study, three different acoustic models (2D: RAM, Nx2D, 3D: FOR3D) are used to investigate the acoustic characteristic on seabed-dune terrain, and analyze coupling effect caused by the conduction under South China Sea within the coherence time. In numerical simulation, we use three-dimensional value(r, z, θ) that based on three-dimensional parabolic equation to observe the coupling effect (θ-coupling), which produced by horizontal acoustic transformation. We used mobile sound source (EMATT) during the experiments, found that the phase perturbation will make significant impact on the variation of sound pressure level (SPL). To observe the phase perturbation need to notice the complex of sound pressure and the coherence time, which defined as the duration when SPL decreases 1dB. From the comparison of simulation and experimental data. First, we found the topography of sand dunes will affect the TL and coherence time a lot. Second, the model and experiment display that there has significant difference in TL along with change of topography. Third, when the propagating way vertical with the sand dune, the coherence time is longer and can’t be find coupling effect. Forth, when the propagating way parallels with the sand dune, there has significant coupling effect from the simulation of FOR3D, In the future, plus more ocean environment, improving the initial condition in FOR3D, updating the software, correspond the actual situation of the ocean more.

At head of title: "NERDDC/SENRAC Research Project."
Three folded maps in pocket
Two microfiches in pocket
Bibliography: leaves 155-187
118, [70] leaves, [23] leaves of plates : ill. (chiefly col.), maps ; 30 cm. + 2 microfiches
Title page, contents and abstract only. The complete thesis in print form is available from the University Library.
Thesis (Ph.D.)--University of Adelaide, National Centre for Petroleum Geology & Geophysics (NCPGG) /Dept. of Geology & Geophysics, 1993