Thesis (M. Comm.) -- Central University of Technology, Free State, 2007 / From the Stone Age, each nation or group of people has had a distrust of those different from themselves. This is evidenced in various ways, for example, social welfare given to local residents only, scornful names given to foreigners and other ethnic groups and rituals designed to keep themselves separate from others. These incidents of diversity resulted into an unplanned and emergent set of norms, values and beliefs that exert enormous influence on the way in which an organisation operates, how organisational structure is developed, the integration and adaptation of internal and external relationships, as well as the orientation of the underlying values of the organisation. The main aim of changing culture is to improve organisational performance. To achieve this aim, it requires an understanding of the underlying assumptions and values that determine what is important in an organisation as well as assessment of the impact of culture on operational efficiency. The impact of organisational culture is identified through the negative and positive outcomes of mining activities, and is illustrated by employee satisfaction, job commitment, organisational loyalty, turnover, absenteeism and productivity. The aim of this research study was to identify the characteristics of organisational culture and evaluate the impact of organisational culture on gold mining activities in the Free State. The methodology used in this study comprises of empirical as well as a literature study. Questionnaires and interviews were used to gather information for the empirical study. The empirical study revealed that firstly, organisational culture is created partially by leaders, and that one of the most critical functions of leadership is the creation and the management of culture. Lastly, organisational culture emerges when employees think, believe and act according to the pressures and priorities of their environment. Unfortunately, employees do not set aside their cultural values and lifestyle preferences when they come to work. It is the responsibility of the management to create an environment that is conducive to a healthy working environment. This study established that the necessity to control the workforce productivity need not be accompanied by ruthless or aggressive exploitation of cultural management, but by reliance on employees’ capability to exercise judgement to cope effectively with environmental uncertainty. Rules, norms and strategies developed cannot “fit” every circumstance but encourage conformity rather than creativity, and compliance rather than commitment.

Thesis (MBA)--Stellenbosch University, 2003. / ENGLISH ABSTRACT: Corporate cu~ure is the foundation of businesses today and in every way underties the way business is done. The discovery and subsequent mining of gold during the last century have shaped the gold-mining corporate cu~re; it gave birth to racial segregation and laid the foundation of the system in which the industry finds itse~ today. The purpose of this study is to uncover the deeper patterns of corporate cu~ure that drive visible behaviour and attitudes. Once the root metaphor or main undertying assumptions of the gold-mining corporate cutture have been determined, a process of multilevel, frame-breaking, radical transformation can be initiated. A 'paradigm interplay' approach, which describes cu~re as an explicit variable and an implicit root metaphor, was adopted. Within this frameworK the study aims to explore concepts and meanings of corporate cu~re in a hermeneutic fashion by uncovering the human, expressive, symbolic texture of life in a gold mine. The frameworK provided a way of thinking about organisations, not to present 1001s' or 'methods' for managing or transforming culture, but to think culturally and holistically about the process of transformation. An in-depth investigation into Schein's 'three levels of cu~re' model was necessary in order to derive at the core transformational aspect of the gold-mining corporate culture. An analysis of Schein's model indicated that behavioural characteristics are shaped and determined by undertying values, beliefs and attitudes, which are shared among members of the organisation. If not espoused, these in turn rest upon sets of undertying assumptions that are the innermost core of corporate cu~re. One such a se~ the nature of human relationships, had been identified as the main undertying theme behind the vested interests as well as ingrained paradigms that exist on both sides of a racially divided workforce. The historical background of the industry and cultural perceptions created a shared assumption set that shaped these deep-rooted, embedded mindsets, affecting human relationships significantly. The study made it clear that any transformation attempt could be possible only when one goes deeper than the stated values and norms to understand the undertying assumptions and the true nature of human relationships that drive the visible behaviour and attttudes. The central dimension of this study, the nature of human relationships, referred to the opposing concepts of individualism versus communalism. These opposing paradigms are manifested in the two main management approaches or corporate cultures that exist in South Africa. Many suggested that the acknowledgement and utilisation of the Afrocentric value system, Ubuntu, alongside a Westem individualistic corporate culture are imperative to improve relationships in general and promote humanism. This study proposed that the humane spirit of Ubuntu, a spirit of trus~ caring and respect for human dignity, should be 'married' with the Westem approach to management instead of Ubuntu being adopted as a single framework that may be perceived negatively by the current business community. Thinking culturally', the purpose phrase of this study, succeeded therefore in abandoning the eitheror kind of thinking in favour of a more holistic 'both-and' way of doing. A desired culture of trust, honesty, openness, integrity and non-<liscrimination are sought after - a morally and ethically acceptable corporate culture where empowered employees are inspired rather than driven. Transformation is about the intellectual, social, spiritual and, most important, the emotional resources of the organisation. The 'senses of awareness' that are fundamental to the spirit of Ubuntu, originate from an understanding of our own emotions and secondly the emotions of others. Emotional intelligence is emerging as a major contributor to self-regu lation and is a crucial ingredient of the transformation process of the gold-mining corporate cu~ure . The study recommends the process of transformation can be initiated by creating a focal even~ a moment of concem about the current predicament in which the organisation or, more importa~ the individual finds itse~lhimse~. An act of confrontation may provide a moment of insight that will lead to a reinterpretation of historical and current events. In the process of insight or reflection an increase in seW-knowledge is gained that leads to a new beginning. This study calls for a willingness to change, a motivation to "switch cognitive gears' from an automatic haM of mind to active, conscious reflection of what is right and what is wrong. ~ also calls upon the individual to make the gold mines and South Africa a better place in which to work and live. / AFRIKAANSE OPSOMMING: Die organisasiekultuur van 'n maatskappy is nie alleen die "gom" wat die besigheidsinstelling en sy onderafdelings bind nie, maar in 'n hoe mate ook die onderliggende rede waarom die besigheidsinstelling bestaan. Die punt sal aan die hand van die goudmynbedryf geillustreer word. Die ontdekking en gepaardgaande ekstraksie van goud gedurende die laaste eeu het die organisasiekultuur van die mynwese gevorm. Dit het help beslag gee aan rasse segregasie en het die grondslag gelê vir die sisteem waarin die industrie homself bevind. Die doel van hierdie studie is om die dieper aspekte van organisasiekultuur bloot te Iê - aspekte wat optrede en die sigbare gesindheid aandryf. Die grondliggende paradigma, kern metafore en aannames van die goudmyn industrie sal daarom eers bepaal moet word voordat 'n radikale transformasieproses geinisieer kan word. 'n Benadering van "paradigma wisselwerking" ("tussenspel") is gevolg waarvolgens kultuur beskryf word as 'n eksplisiete verandelike en 'n implisiete kern metafoor. Binne hierdie raamwerk word konsepte en betekenisse van organisasiekultuur binne 'n hermeneutiese metodiek ondersoek. Die doel daarvan is om die menslike, ekspressiewe en simboliese tekstuur van lewenswyse binne die goudmynbedryf te interpreteer. Die raamwerk verskaf 'n denkwyse oor organisasies wat nie daarop gerig is om spesifieke metodes of stappe daar te stel vir die bestuur of transformasie van organisasiekultuur nie. Die doelwit is om kultureel en holisties te dink oor die proses van transformasie. 'n Indiepte ondersoek van Schein se 'drie vlakke' van kultuur was noodsaaklik om die kern transformasie aspek van die Suid Afrikaanse goudmyn kultuur te ontrafel. Daar is bevind dat gedragseienskappe gevorm en bepaal word deur die gesamentlike onderliggende waardes, oortuigings en gesindhede van lede van 'n organisasie. Hierdie eienskappe skakel in by 'n reeks onderliggende aannames wat die binneste kern van organisasiekultuur uitmaak. Die aard van menslike verhoudings, 'n onderliggende aanname, is ge"identifiseer as die hoofonderliggende tema agter die bestaande belange sowel as die ingewortelde paradigmas wat bestaan aan beide kante van die rasverdeelde werksmag. Die historiese agtergrond van die industrie en die kulturele persepsies het 'n gedeelde reeks aannames daargestel wat diep-gewortelde denkpatrone en denkgietsels gevorm het en wat menslike verhoudings aansienlik beinvloed. Die studie maak duidelik dat enige transformasiepoging alleenlik moontliik is indien daar dieper as die bepaalde waardes en norme gedelf word om die onderliggende aannames en denkwyses asook die aard van menslike verhoudings te bepaal wat die sigbare optrede en gesindheid van mense dryf. Die sentraie dimensie van die studie, naamlik die aard van menslike verhoudings, berus op die opponerende konsepte van individualisme en kommunalisme. Hierdie twee konsepte, en die paradigmas wat hulle aandui, word gemanifesteer in die twee hoof bestuursraamwerke van organisasiekultuur wat in Suid Afrika bestaan. Baie navorsers suggereer dat die erkenning en gebruikmaking van die Afrosentriese waardesisteem, Ubuntu, naas 'n westerse individualistiese organisasiekultuur, noodsaaklik is om 'n outentieke humanisme, en verhoudinge in die algemeen te bevorder. Die studie stel voor dat die humane (mens-georianteerde) gees van Ubuntu, 'n gees van vertroue, omgee en respek vir menswaardigheid, saamgesnoer word met die westerse benadering tot bestuur, in plaas daarvan om Ubuntu as 'n enkele raamwerk aan te neern wat dalk negatief waargeneem kan word deur die moderne sakesektor. Die kulturele denkwyse wat gegenereer is in hierdie studie het dus geslaag daarin om die 'of-die-eenof- die-ander' denkwyse te vervang met 'n meer holistiese 'en-en' manier van dink en doen. 'n Kultuur van vertroue, opregtheid, integriteit en geen diskriminasie is noodsaaklik, ofte wel 'n morele en eties aanvaarbare organisasiekultuur waar bemagtigde werkers geinspireer word eerder as gedryf word. Transformasie is gemoeid met die intellektuele, sosiale, spirituele en van groot belang, die emosionele hulpbronne van 'n organisasie. Die aksent op selfbewussyn, wat fundamenteel is vir die gees van Ubuntu, word gegenereer deur 'n verstaan van ons eie emosies, en tweedens die verstaan van die emosies van ander. Emosionele intelligensie het onlangs te voerskyn gekom as 'n belangrike bydraer tot self-regulasie. Dit is 'n beslissende bestanddeel in die transformasieproses van die organisasiekultuur van die goudmynbedryf. Die studie stel voor dat die transformasieproses geinisieer kan word deur 'n spesifieke gebeurtenis wat die fokus word, 'n oomblik van besorgdheid rakende die huidige predikament waarin die industrie of meer belangrik, die individu homself/haarself bevind. Konfrontasie is selfs nodig vir 'n ontwikkeling van 'n oomblik van insig wat aanleiding kan gee tot 'n reinterpretasie van historiese en huidige gebeure. Tydens die proses van insig of nabetragting word 'n toename in selfkennis opgedoen wat lei tot 'n nuwe begin. Die studie vestig die aandag op 'n noodsaaklikheid van 'n verandering van gesindheid en aanvaarding van die eis tot verandering. Dit sluit in 'n verbintenis om kognitiewe 'ratte' te verander vanaf 'n outomatiese sienswyse na 'n aktiewe, bewuste refleksie van wat is reg en wat is verkeerd. Dan kan die goudmyne en Suid Afrika in geheel 'n beter plek gemaak word om in te leef en te werk.

Thesis (MBA)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: DRDGOLD is a mining company forming part of the declining South African gold industry. During the turn of the century, the opportunity to innovate the business model arose. Without proactive intent, DRDGOLD tapped into the opportunity and revised their business model with great success. The success is evident in the improvement of headline earnings from 2002 to 2012. To discuss the changes to the business model, the author conducted a literature review on business models and innovation. From the review, the author selected the Osterwalder Business Model Canvas as the most suitable framework to discuss the changes of the business model. The Osterwalder Business Model includes the business-centric approach and is thus favoured for this discussion. First, the business model was populated with the information to have a comprehensible business model, and secondly, the changes to the business model were identified. The information for the study was sourced from public company documentation, mainly annual reports, secondary sources like Datamonitor, and interviews with four members of the leadership team. The four interviewees were Niel Pretorius, chief executive officer (CEO), Kobus Dissel group financial manager, Charles Symons, chief operating officer (COO), and Craig Barnes, chief financial officer (CFO). The four members had a long-standing relationship with the company and were part of the change process that took place at the company. The period before the study made the business model innovation possible. Firstly, the long mining history around Johannesburg produced the mine dumps that formed the core resource of the operations. Secondly, the craze to buy anything that looks like gold during the end of the 1990s introduced DRDGOLD to the surface retreatment operations with the purchase of Crown. The environment of the operations started to change, not only the operating environment, but also the other stakeholders. The importance of the community grew, the dividend yield to the shareholder increased in importance, the engagement with the regulators changed to a proactive engagement, and the environment was managed for a long-term perspective. The risks and returns for DRDGOLD started to misalign. The risk of pursuing the underground operations further increased considerably and unintentionally drove the costs up. Within the context of South Africa, the returns of underground operations started to erode as unscheduled stoppages increased. These stoppages were caused by events outside the control of the company, for example power failures, seismic activities and labour unrest. DRDGOLD repositioned itself as a factory that has a high throughput in material on a 24/7-operation rooster. The yields are significantly lower than the underground operations, but the risk of the new setup is also reduced greatly. Seismic activity does not impact the operations anymore. The production time of the operations has increased with less unscheduled stoppages. DRDGOLD changed to have itself valued on the discounted cash flow (DCF) method. The company’s share price is now valued on the DCF method based on the operational revenues. This is contrary to the gold mining industry valuation of South African mines. These mines are mainly valued on the reserves statement multiplied by the commodity price. The share price of DRDGOLD is heavily leveraged on the spot price of gold and the exchange rate of the South African Rand (ZAR) to the United States Dollar (US$). Any movement in these two indicators will have a significant impact on the share price.

D.Litt. et Phil. (History) / Please refer to full text to view abstract

Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Engineering, 1988. / Mining induced fracturing and associated deformations can commonly be observed around deep gold mining excavations. As the rockmass behaviour and the stability of the excavations are directly influenced by these processes, a proper understanding of this influence would certainly improve current mining practices with respect to blasting, rock breaking, support design and mining lay-outs. The main subject of this thesis is the physics of failure and post failure behaviour of rock and similar materials. Failure is denned here as a state at which the material has been subjected to fracture and/or damage processes. The applicability of commonly used constitutive models in representing such failure and post failure processes has been investigated mainly by means of numerical simulations. Mechanisms which control fundamental fracture and damage processes have been analysed by comparing the results from relevant laboratory experiments with numerical models. Linear elastic fracture mechanics has been applied to explain and simulate the formation of large scale extension fractures which form in response to excessive tensile stresses. Using the flaw concept it is demonstrated that these fractures not only initiate and propagate from the surface of an opening in compressed rock, but that so called secondary fracturing can be initiated from within the solid rock as well. The effect of geological discontinuities such as bedding planes, faults and joints on the formation of (extension) fractures has also been investigated and it has been shown how the presence of such discontinuities can cause the formation o f additional fractures. Micro mechanical models have been, used to investigate the interaction and coalescence processes of micro fractures. It was found that the formation of large scale extension fracturing can be explained from such processes, but so called shear fractures could not directly be reproduced, although such a possibility has been claimed by previous researchers. The formation of shear fractures is of particular- interest as violent failure of rock, which is subjected to compressive stresses only, is often associated with such fractures. In an all compressive stress environment, only shear deformations would allow for the relief of excess stress and thus energy. The formation of shear fractures is associated with complex mechanisms and shear fractures can therefore not directly be represented by tingle cracks. In contrast to the propagation of tensile fractures, which can readily be explained by traditional fracture mechanics in terms of stress concentrations around the crack tip, the propagation of shear fractures requires a different explanation. In this thesis an attempt has nevertheless been made to reproduce shear fractures by direct application of fracture mechanics. This his been done by representing a shear fracture as a single crack and by assuming fracture growth criteria which are either based on critical excess shear stresses, or on a maximum energy release. Both criteria are completely empirical and require a value for the critical shear resistance in the same way as a critical tensile resistance is required to represent the formation of tensile fracture; , The determination of a critical tensile resistance ( Kk ) is relatively straight forward, as the formation of tensile fractures from a pre-existing flaw can be reproduced and observed in standard laboratory tests. The determination of a critical shear resistance is, however, not a common practice, as the formation of a shear fracture from a pre-existing flaw is very infrequently observed. The application of shear fracture growth criteria nevertheless resulted in plausible fracture patterns, which suggests that such criteria are realistic. It is argued here however that the formation of shear fractures cannot be associated with primary fracture growth, but rather with the localisation of failure and damage in an area which is subjected to plastic deformation. The application of fracture mechanics is therefore not correct from a fundamental point of view as these processes are not represented. For this reason plasticity theory has also been applied in order to simulate failure in general, and shear failure localisation in particular. It was in principle possible to reproduce the shear fractures with the use of this theory, but numerical restraints affected the results to such an extent that most of the simulations were not realistic. Plasticity theory can also be extended to include brittle behaviour by the use of so called strain softening models. The physical processes which lead to brittle failure are however not directly represented by such models and they may therefore not result in realistic failure patterns. It was in fact found that strain softening models could only produce realistic results if localisation of failure could be prevented. The effect of numerical restraints becomes even more obvious with a strain softening model in the case of failure localisation. While the plasticity models appear inappropriate in representing brittle failure, they demonstrated that plastic deformations can be associated with stress changes which may lead to subsequent brittle fracturing. Although only indirect attempts have been made to reproduce this effect, as appropriate numerical tools are not available, it is clear that many observations of extension fracturing could be explained by plastic deformations preceding the brittle fracturing processes. Many rocks are classified as brittle, but plastic deformation processes often occur during the damage processes as well. The sliding crack for instance, which is thought to represent many micro mechanical deformation processes in rock, directly induces plastic deformations when activated. A pure brittle rock, which may be defined as a rock in which absolutely no plastic deformation processes take place, may therefore only be of academic interest as it is inconceivable that such a rock materiel exists. Only in such an academic case would (linear) elastic fracture mechanics be directly applicable. As plastic deformation processes do play a role in real rock materials it is important to investigate their influence on subsequent brittle failure processes. The elastic stress distribution, which is often used to explain the onset of brittle fracturing, may be misleading as plastic deformations can substantially affect the stress distribution . -recediny fracture initiation. In an attempt to combine both plastic and brittle failure, use has been made of tessellation models, which in effect define potential fracture paths in a random mesh. The advantage of these models is that various failure criteria, with or without strain softening potential, can be used without the numerical restraints which are normally associated with the conventional continuum models. The results of these models are also not free from numerical artefacts, but they appear to be more realistic in general. One o f the m;ij, r conclusions based on these results is that shear failure does not occur in a localised fashion, but is associated with the uniform distribution and extension of damage. Shear failure, which can be related directly to plastic failure, can however induce brittle, tensile, failure due to stress redistribution. While the theories of fracture mechanics and plasticity are well established, their application to rock mechanical problems often leads to unrealistic results. Commonly observed firacture patterns in rock, loaded in compression, are most often not properly reproduced by numerical models for a combination of reasons. Either a model concentrates on the discrete fracturing processes, in which case the plastic deformation processes are ignored, or plasticity is represented, but brittle failure is pooxiy catered for. While theoretically a combination of these models might lead to better representations and simulations, numerical problems do affect all models to a certain extent and a practical solution is not immediately available. The results of numerical models can therefore only be analysed with caution and the underlying assumptions and numerical problems associated with a particular technique need to be appreciated before such results can be interpreted with any sense. Many of the problems are identified here and this may assist researchers in the interpretation of results from numerical simulations. Laboratory experiments, which have been chosen for analyses, involve specimens which have been subjected to compressive stresses and which contain openings from which failure and fracturing is initiated. Such specimens are less subjective to boundary influences and are far more representative of conditions around mining excavations than typical uni- and tri-axial tests. The uniform stress conditions in these latter tests allow boundary effects to dominate the stress concentrations, and thus failure initiation, in the specimens. The large stress gradients, which can be expected to occur around underground excavations, are not reproduced in such specimens. As a consequence failure is not u atained within a particular area, but spreads throughout the complete specimen in the uni- and tri-axial tests. Specimens containing openings are therefore far more likely to reproduce the fracture patterns which can be observed around deep level mining excavations. Numerical simulations of brittle, tensile fracturing around mining excavations resulted in consistent fracture patterns. Fracture patterns could however be strongly influenced by the presence of geological (pre-existing) discontinuities such as bedding planes. Although tensile stresses are often assumed to be absent around deej: <y vel excavations because typical hanging- and foot-walls are subjected to compressive horizontal strain and thus stress, the numerical models identified alternative locations o f Ix 'sile stress and also mechanisms which could induce secondary tensile stresses, A failure criterion has therefore been identified as the most likely cause of large scale fracturing while shear fracturing may only occur in the absence of such tensile stresses .and only as a consequence of failure localisation in damaged rock rather than fracture propagation (in solid rock). Geological discontinuities can easily induce tensile stresses vVher mobilised and may even replace the mining induced fractures by offering a more efficient meat s for energy release. The latter possibility is a true three dimensional issue which has not be en addressed any further in this study, but may be very relevant to jointed rock. Although dynamic failure has not directly been addressed, one of the micliamsms lor brittle, and thus stress relieving, failure under compressive strass conditi ons has been investigated in detail, namely shear fracturing. Shear fractures are effect vely the only discontinuities which allow for stress relief under such conditi ons', in the ibaence of preexisting, geological discontinuities, and are therefore quite rele vant to dynamic rock failure, such as rock bursts, in deep level mining conditions. Potential mechanisms for shear fracture formation and the numerical simulation of these features have been investigated and this may especially assist further research into rock bursts.

A research report submitted to the Faculty of Engineering and the Built Environment, University of the Witwatersrand, in partial fulfilment of the requirements for the degree of Master of Science in Mining Engineering. February, 2016 / Mineral Resource estimation provides an assessment of the quantity, quality, shape and grade distribution of a mineralised deposit. The resource estimation process involves; the assessment of data available, creation of geological and/or grade models for the deposit, statistical and geostatistical analyses of the data, as well as determination of the appropriate grade interpolation methods. In the grade estimation process, grades are interpolated/extrapolated into a two or three – dimensional resource block model of a deposit. The process uses a search volume ellipsoid, centred on each block, to select samples used for estimation. Traditionally, a global orientated search ellipsoid is used during the estimation process. An improvement in the estimation process can be achieved if the direction and continuity of mineralisation is acknowledged by aligning the search ellipsoid accordingly. The misalignment of the search ellipsoid by just a few degrees can impact the estimation results. Representing grade continuity in undulating and folded structures can be a challenge to correct grade estimation. One solution to this problem is to apply the method of Dynamic Anisotropy in the estimation process. This method allows for the anisotropy rotation angles defining the search ellipsoid and variogram model, to directly follow the trend of the mineralisation for each cell within a block model. This research report will describe the application of Dynamic Anisotropy to a slightly undulating area which lies on a gently folded limb of a syncline at Driefontein gold mine and where Ordinary Kriging is used as the method of estimation. In addition, the optimal Dynamic Anisotropy resolution that will provide an improvement in grade estimates will be determined. This will be achieved by executing the estimation process on various block model grid sizes. The geostatistical literature research carried out for this research report highlights the importance of Dynamic Anisotropy in resource estimation. Through the application and analysis on a real-life dataset, this research report will put theories and opinions about Dynamic Anisotropy to the test.

Thesis submitted in fulfilment of the requirements for the degree of Doctor of Philosophy. School of Animal, Plant and Environmental Science, University of the Witwatersrand, Johannesburg, South Africa. October 2016. / Mining has negative impacts on the environment in many different ways. One method developed to quantify some of these impacts is Landscape Function Analysis (LFA) and this has been accepted by some mining companies and regulators. In brief, LFA aims at quantifying the organization of vegetative and landscape components in a landscape into patches along a transect and quantifying, in a relative manner, three basic processes important to landscape functioning, namely: soil stability or susceptibility to erosion, infiltration or runoff, and nutrient cycling or organic matter decomposition. However, LFA is limited in large heterogeneous environments, such as those around mining operations, due to its localized nature, and the man hours required to collect a representative set of measurements for such large and complex environments. Remote sensing using satellite-acquired data can overcome these limitations by sampling the entire environment in a rapid and objective manner. What is required is a method of connecting these satellite-based measurements to LFA measurements and then being able to extrapolate these measurements across the entire mine surface. The aim of this research was to develop a method to use satellite-based hyperspectral imagery to predict landscape function analysis (LFA) using partial least squares regression (PLSR). This was broken down into three objectives: (1) Collection of the LFA data in the field and validation of the LFA indices against other environmental variables collected at the same time, (2) validation of PLSR models predicting LFA indices and various environmental variables from ground-based spectra, and (3) production of risk maps based on predicting LFA indices and above-ground biomass using PLSR models and Hyperion satellite-based hyperspectral imagery. Although the study was based in grasslands at two mining regions, West Wits and Vaal River, a suitable Hyperion image was only available for Vaal River. A minimum of 374 points were sampled for LFA indices, ground-based spectra, above-ground biomass and soil cores along 2880 m of LFA transect from both mine sites. Soil cores were weighed fresh before sieving with a 2 mm sieve to separate root and stone fractions. The sieved soil fraction was tested for pH, EC, SOM, and for the West Wits samples, organic nitrogen and total extractable inorganic nitrogen. There was one modification to the LFA method where grass patches were collapsed into homogenous units as it was deemed not feasible to sample 180 m transects at grass tuft scales of 10 – 30 cm, but other patch definitions followed the LFA manual (Tongway and Hindley, 2004). Evidence suggested that some of the different patch types, in particular the bare/biological soil crust – bare grass – sparse grass patch types, represented successional stages in a continuum although this was not conclusive. There also was evidence that the presence or absence of cattle play a role in some processes active in these grasslands and erosion is mainly through deflation, rain splash and sheet wash. Generally the environmental variables supported the LFA indices although the nutrient cycling index was representative of above-ground nutrient cycling but not below-ground nutrient cycling. Models derived with PLSR to predict the LFA indices from ground-based spectral measurements were strong at both mine sites (West Wits: LFA stability r2 = 0.63, P < 0.0001; LFA infiltration r2 = 0.75, P < 0.0001; LFA nutrient cycling r2 = 0.73, P < 0.0001; Vaal River: LFA stability r2 = 0.39, P < 0.0001, LFA infiltration r2 = 0.72, P < 0.0001, LFA nutrient cycling r2 = 0.54, P < 0.0001), as were PLSR models predicting above-ground biomass (West Wits above-ground biomass r2 = 0.55, P = 0.0003; Vaal River above-ground biomass r2 = 0.79, P < 0.0001) and soil moisture (West Wits soil moisture r2 = 0.45, P = 0.0017; Vaal River soil moisture r2 = 0.68, P < 0.0001). However, for soil organic matter (r2 = 0.50, P < 0.0001) and EC (r2 = 0.63, P < 0.0001), Vaal River had strong prediction models while West Wits had weak models for these variables (r2 = 0.31, P = 0.019 and r2 = 0.10 and P < 0.18, respectively). For EC, the wide range of soil values at Vaal River in association with gypsum crusts, and low values throughout West Wits explained these model results but for soil organic matter, no clear explanation for these site differences was identified. Patch-based models could accurately discriminate between spectrally well-defined patch types such S. plumosum patches but were less successful with patch types that were spectrally similar such as the bare/biological soil crust – bare grass – sparse grass patch continuum. Clustering similar patch types together before PLSR modelling did improve these patch-based spectral models. To test the method proposed to predict LFA indices from satellite-based hyperspectral imagery, a Hyperion image matching 6 transects at Vaal River was acquired by NASA’s EO-1 satellite and downloaded from the USGS Glovis website. LFA transects were partitioned to match and extract pixel spectra from the Hyperion data cube. Thirty-one spectra were separated into calibration (20) and validation (11) data. PLSR models were derived from the calibration data, tested with validation data to select the optimum model, and then applied to the entire Hyperion data cube to produce prediction maps for five LFA indices and above-ground biomass. The patch area index (PAI) produced particularly strong models (r2 = 0.79, P = 0.0003, n =11) with validation data, whereas the landscape organization index (LOI) produced weak models. It is argued that this difference between these two essentially similar indices is related to the fact that the PAI is a 2-dimensional index and the LOI is a 1-dimensional index. This difference in these two indices allowed the PAI to compensate for some burned pixels on the transects by “seeing” the density pattern of grass tufts and patches whereas the linear nature of the LOI was more susceptible to the changing dimensions of patch structure due to the effects of fire. Although validation models for the three LFA indices of soil stability, infiltration and nutrient cycling were strong (r2 = 0.72, P = 0.004; r2 = 0.66, P = 0.008; r2 = 0.70, P = 0.005, n = 9 respectively), prediction maps were confounded by the presence of fire on some transects. The poor quality of the Hyperion imagery also meant great care had to be taken in the selection of models to avoid poor quality prediction maps. The 31 bands from the VNIR (478 – 885 nm) portion of the Hyperion spectra were generally the best for PLSR modelling and prediction maps, presumably because of better signal-to-noise ratios due to higher energy in the shorter wavelengths. With two satellite-based hyperspectral sensors already operational, namely the US Hyperion and the Chinese HJ-1A HSI, and a number expected to be launched by various space agencies in the next few years, this research presents a method to use the strengths of LFA and hyperspectral imagery to model and predict LFA index values and thereby produce risk maps of large, heterogeneous landscapes such as mining environments. As this research documents a method of partitioning the landscape rather than the pixel spectra into pure endmembers, it makes a valuable contribution to the fields of landscape ecology and hyperspectral remote sensing. / LG2017

A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfilment of the requirements for the degree of Master of Science. Johannesburg, South Africa, 2015. / Unable to load abstract

A research report submitted to the Faculty of Science, University of the Witwatersrand, Johannesburg, in partial fulfillment of the requirements for the degree of Master of Science in Environmental Science / Pollution originating from mine tailings is currently one of the environmental problems South Africa has to deal with. Because of the large number of tailings impoundments and their changing status, authorities are battling to keep their records and controls up to date. This project is aimed at investigating the use of remote sensing as a way of conducting surveys of mine tailings efficiently, regularly and at a low cost. Mine tailings impoundments of the Witwatersrand in Gauteng provide an ideal study area because of the large number of tailings dams of different sizes and conditions and the availability of satellite images and aerial photographs covering the area. Tailings impoundments conditions are analysed through satellite images, airborne multi-spectral data and aerial photographs captured during the Safari 2000 dry season campaign. Remote sensing interpretation of colour composites of multi-spectral bands, Principal Components and supervised and unsupervised classifications are the methods of analysis used. The overall goal of the project has been achieved through the production of a comprehensive database of tailings impoundments and their rehabilitation status, in an accessible format, containing identity, coordinates, area, rehabilitation status and owner of each tailings impoundment, map them and end up with a comprehensive database of tailings impoundment on the Witwatersrand. / AC2017

No description available.