OpenUCT :: Browsing by Subject "Environmental and Geographical Science"

Browsing by Subject "Environmental and Geographical Science"

Now showing 1 - 20 of 274

Open Access
4000 years of environmental and climate change at Eilandvlei : a palynological investigation into the late Holocene palaeoenvironment of the Wilderness Embayment
(2015) Du Plessis, Nadia; Meadows, Michael E
It is a well-known fact that the South African palaeoenvironmental record is fairly limited, mainly because the environmental conditions here do not lend themselves to the preservation of proxy data sources. This being said, new evidence is emerging from the Wilderness Embayment along the Southern Cape coast of South Africa. This area is of particular interest from a palaeoclimate perspective due to its location within the small year round rainfall zone of South Africa, while the presence of both Fynbos and Afrotemperate forest within this region further highlights the importance of studies in the area. This study presents a new high resolution late Holocene pollen and charcoal record from Eilandvlei, extending from c. 3 800 cal yr BP to present. The record is marked by several significant periods -- largely corresponding to the timing of the three events that typify the late Holocene: the Neoglacial, the Medieval Climate Anomaly and the Little Ice Age. The record also encompasses the arrival of European colonists in the region ca. 1800 AD, marked by the appearance of Pinus, with subsequent notable fluctuations in other taxa, e.g. Podocarpus and Stoebe-type, possibly the expression of the anthropogenic effect on the landscape. This high resolution record thus highlights significant, albeit short term, fluctuations in climate and vegetation patterns along the Southern coast of South Africa and adds to the inadequate records available for the region thus far.
Open Access
A framework for resource maintenance and enhancement
(1996) Audouin, Michelle Ann; Griggs, Richard
Our understanding of how to integrate the goals of development and those of the environment, is our map or instruction manual on practically addressing the current global environmental crisis. Our knowledge provides us with the means by which we can "do things in the world or cope with events (Sayer, 1992:59)." In this dissertation, increasing this understanding is not only the guide to the development of a framework for resource maintenance and enhancement, but also the means by which we maintain and enhance resources. To establish 'a map' for integrating environmental and developmental goals the concept of sustainable development, with its strategies for various resource sectors, was expanded and explained in the Brundtland Report (World Commission on Environment and Development (WCED), 1987). The Report defined sustainable development as aiming "to meet the needs of present generations, without compromising the ability of future generations to meet their own needs (Lebel and Kane, 1987)." It includes two components: the concept of needs, especially those of the world's poor; and the idea of limitations that are imposed by technology and society on the environment to meet those needs (Lebel and Kane, 1987).
Open Access
A remote sensing assessment of irrigation land use land cover change in the Sokoto Rima River Basin, Nigeria
(2021) Abdulmajid, Aminu; Eckardt, Frank; Odera, Patroba
This study examines the expansion and utilisation of Fadama irrigation in the Sokoto Rima River Basin using the ground yield and remote sensing data. Decadal land use land cover (LU/LC) change detection was conducted using remotely sensed data from Landsat 4,5,7 ETM for 1988, 1998 and Landsat 8 OLI for 2018 using a digital classification and a cloud-based classification provided by Google Earth Engine (GEE) API, with an overall accuracy of 97% in 1988, 92% in 1998 and 90% in 2018. Additionally, the Normalised Difference Vegetation Index (NDVI) derived from MODIS, GEE NDVI, and the Landsat was used to assess the crop yield patterns of the irrigation farming at the Fadama sites in conjunction with the limited ground yield data from 2000-2005, and was found to be a positive change over the years. The result generated from the classification was juxtaposed with observable field characteristics of the LU/LC identified. The decadal trend between 1988 to 1998 saw an increase of 114% in dam surface water and 166% of the natural vegetation, while the nonvegetated areas and the Fadama areas decreased in size by -100% and -65% respectively. Between 1998 and 2018, the reverse of the previous pattern was observed, with water and vegetated areas decreasing in their surface area in hectares by -80% and -23% respectively. Non-vegetated areas increased by 3% while Fadama areas increased in size by 112%, indicating that the Fadama areas were under-utilised by - 65% of the total hectarage in the past, and in recent years a 47% increase was recorded between the two periods. In addition, the Standardised Precipitation and Evapotranspiration Index (SPEI) data from 1950 was used to analyze the meteorological and hydrological drought pattern at four locations within the basin and was found to be a moderate drought. The SPEI data was then correlated with the Global Surface Water Explorer data to observe the surface water dynamics and to show the drought extent around Bakolori, Goronyo, Jibia, Wurno and Zobe dams. The result showed that the dams are shrinking in size due to risen temperature and consequent evaporation caused by moderate drought and water use for irrigation. Lastly, this research uncovers the utilization of the Fadama in recent years by 47%, but with mismanagement of the resources in the Sokoto Rima River floodplain because not all the irrigation fields are put into cultivation, with 39,907 ha put into use from the planned irrigation of 105,472 ha in the entire basin. Therefore, this research recommends a proper intervention of the government to promote and enhance sustainable management of the Fadama lands, water, and the vegetation resource. This should be done in consideration of the deteriorating climate to close yield gaps, with much emphasis on engaging the local farmers by monitoring yearly ground yield data and ensuring all incentives are distributed effectively to brace an active and sustainable management of the entire basin and its vast resource.
Open Access
A study of urban form; its analysis and its implications for sustainable settlements in desert environments, with Walvis Bay as a case study
(1996) Munster, Detlev O
The purpose of this dissertation is to prove that there are urban forms that are appropriate to the desert environment, and that such forms together with basic design principles, can provide substantive design-oriented steps towards the environmental goal of sustainability in an urban context. The term "sustainability" has often been applied at a global level and is a holistic concept that tries to find solutions to a number of global issues. However, many of these problems are highly visible at an urban level, whereby the year 2000 over 50% of the world population is expected to manifest itself in urban areas. Sustainability therefore needs to be addressed at an urban level, a level which is closer to the people who both consume the most resources and produce the most waste. Among the many strategies available for addressing sustainability at a number of levels, sustainability as reflected in city design has played a small role. The stark reality that our living environments influence our daily activities and consumption patterns, and that these have been reflected in an unsustainable manner in many western settlements due to the physical layout of settlements, needs to be addressed. The planning system (with design as both a component· thereof and a result of the planning process) has a major role to play in addressing issues of sustainability from a physical perspective. Much research has been done on urban sustainability and urban form in the European context and is still developing. However, little research has been undertaken on the issues of urban sustainability in arid zones. Arid zones can be considered as the last frontiers of urban and rural expansion, and the prevailing trends of the last 30 years have indicated that these areas are experiencing rapid urbanisation. Due to extreme climatic conditions, it would be expected that these settlements. would develop within the constraints and opportunities such environments present. However, contemporary desert settlements have been founded on planning principles and standards adopted from other regions that are not arid in nature. This has resulted in settlements being inappropriate for their environments. Determining what is appropriate is rather difficult, especially from a physical perspective and could be perceived as very static. A proposition was therefore made to determine whether or not a sustainable urban form for desert environments existed, and whether there were specific design principles for desert settlements. This was intended to produce basic guidelines, which could then be used to facilitate discussion. The development of a coastal zone management plan (CZMP) for the Erongo region in Namibia, provided the opportunity to investigate the proposition. The CZMP required that a variety of issues (biophysical, infrastructural, legal, social, institutional, etc.) be investigated and presented in a baseline report. This baseline report highlighted a number of urban problems (such as urban sprawl, high infrastructural costs, and accessibility problems), which. need to be addressed by the coastal zone management plan. Walvis Bay, a settlement within the CZMP area, and a settlement in an arid zone (namely within the coastal area of the Namib Desert) proved to be an interesting case study, one that could be used to verify the proposition. Urban sustainability, urban morphology and urban design are discussed in detail in this dissertation, in order to present the theoretical tenets with which urban forms can be analysed, and from which an appropriate urban form can be developed for arid zones. Various tenets and principles of sustainability are addressed, and principles pertaining to sustainable design are outlined. Of notable significance is the fact that human design interacts with the natural world. A relationship can therefore be said to exist between the natural and human environments. Urban morphology is presented as a basis for illustrating that settlements develop from a number of influencing factors. Furthermore, the discussion of urban morphology also reveals the agendas which shape settlements, thereby giving certain settlements particular forms. The contempary debate between the respective merits of sprawling and compact settlements, raises a number of implications for sustainability. However, this dissertation proposes that the adoption of a compact settlement could achieve the means of sustainability better. The discussion of urban design emphasises the relationship between the built and natural environments, while at the same time presenting vital attributes that all settlements should either have or strive towards. Empirical research on urban settlements in the desert environments of Israel, Australia and the United States, and research on ancient and Arabic settlements in general, highlights design principles that could enhance the sustainability of settlements in desert environments. From many of the older settlements in the middle east, valuable lessons can be learnt regarding urban form in desert environments, lessons which are still applicable today. Walvis Bay's urban environment is analysed through an understanding of the basic performance dimensions inherent in urban forms, as well as urban form patterns and elements, sustainability principles and the vital attributes that urban environments should have. From this analysis, it becomes clear that certain urban forms are more suitable for desert environments, and that, as a consequence of an inappropriate urban form, Walvis Bay is unsustainable. By combining design principles of the Arabic settlements with aspects of a compact settlement, an appropriate urban form can be achieved. The attainment of a sustainable urban form (and one that encompasses the concept of "liveability") can be achieved for Walvis Bay, through the concrete suggestions made through this dissertation's analysis. This dissertation is a facilitating study, proceeding largely by a review of the existing literature on the subject. This "literature review", together with an analysis of Walvis Bay, is intended to present design principles for a sustainable urban form for desert environments.
Open Access
A study on slope instability above Chapman's Peak Drive, Cape Peninsula, South Africa
(2002) Scott, Duncan George James
[page iv ] Chapman's Peak Drive was constructed along a natural unconformity below Chapman's Peak, a suite of slopes that rise directly from the ocean to their summit. A seemingly increased frequency of rockfalls and the death of a young woman in December 1999 led to the closing of the Drive as a public thoroughfare. At the beginning of the year 2000 Chapman's Peak Drive featured in both local and international media because of the wildfires that swept through this area and large portions of the rest of the Cape Peninsula. This led to a heightened public awareness of the obvious physical danger to traffic on Chapman's Peak Drive. This problem of a rockfall activity onto Chapman's Peak Drive is not a new, or unexpected, one as all roads constructed within mountainous terrain will inevitably experience some sort of mass movement of slope material onto their surface at some stage.
Open Access
A systematic review of climate adaptation planning in African cities
(2023) Madhi, Yasirah; Taylor, Anna
In recent years the need for climate change adaptation has become increasingly important. Adaptation planning is understood to be the process by which actors identify, develop, test, and prioritise strategies and measures to reduce climate risk. In Africa, climate projections predict higher temperature increases than the rest of the globe. Africa is a rapidly urbanizing continent and its urban population is expected to rise to 59% by 2050. Thus, reducing climate risks and leveraging any emerging climate-related opportunities in cities will be a key component of tackling climate change across the continent. In the last few decades, the number of publications on climate adaptation has been increasing considerably. This growing body of climate adaptation research is in need of consolidation in order to draw meaningful lessons from place-specific and hazard-specific studies. This study aimed to collate and review peer-reviewed literature on climate adaptation planning in African cities in order to consolidate fragmented information and establish what is known about how climate adaptation is occurring at the urban scale. Using the systematic review process, relevant documents on the topic were identified and extracted using specific inclusion and exclusion criteria to delimit and broadly characterize the body of literature focusing on climate adaptation planning in an urban African context. Due to the scope and constraints of a minor dissertation, only a sub-set of documents underwent full-text review using thematic content analysis. The code used for thematic analysis was developed through an abductive process using Hunter et al. (2020) and Ford et al. (2015)'s coding categories as a framework. A total of 84 papers were considered suitable for inclusion. The geographical distribution of urban adaptation planning literature was established with most papers stemming from southern Africa (56), followed by East (19), West (17), and North Africa (5). No publications dealt with urban climate adaptation in Central Africa. The country with an overwhelming number of publications was South Africa (40). The majority of the literature was authored by researchers based in institutions outside of Africa (54%). Papers were broadly categorised into articles that tested, developed, prioritised, or identified strategies to reduce climate risk. The papers testing strategies to reduce climate risk were chosen for full-text analysis. South Africa was excluded from the final sub-set in order to focus on assimilating knowledge from elsewhere across the continent. 11 papers underwent the coding processes. Flooding was identified as the main climatic driver of adaptation and most papers emphasized the need for stakeholder engagement and communication. This study showed the value of applying a systematic review methodology to identify trends and consolidate research on the planning aspects of climate adaptation in African cities. It argues for extending the full-text thematic analysis to the entire set of literature identified to strengthen theory development based on empirical knowledge from urban African contexts.
Open Access
Accelerating productive energy access for the just transition among vulnerable communities; a case study of West Nile, Uganda
(2023) Amanubo, Amos; Sparks, Debbie
Sustainable enhancement of energy security has been considered crucial for a just transition towards low carbon sustainable socio-economic development including poverty eradication, job creation and decent employment, food security, among others. Nevertheless, multidimensional energy poverty is still a widespread phenomenon, profound in low-income economies such as Uganda, more so in the rural areas. To investigate the key issues underlying productive energy access and energy-livelihood interlinkages in the context of micro and small enterprises, this research carried out a case study survey of 129 enterprises in West Nile, Uganda, where previous studies mainly focused on household energy consumption. Data were analysed based on the Multidimensional Energy Poverty Indices (MEPI) framework, capturing how the 4A's dimensions of accessibility, availability, affordability and acceptability reinforce or constrain energy choices. The study found that most enterprises rely on grid (43%), then solar PV (16%) and lastly fuel generator (10%) to meet their energy needs, while 31% are energy bricoleurs who diversified their energy sources to guarantee energy security. The prevailing source of energy used is closely associated with socioeconomic enabling or disabling factors such as gender, education, business type, and market and finance based factors. Further, the results show that several enterprises experienced severe challenges in all dimensions of the 4A's framework, and strong interlinkages existed between energy access and the livelihoods of the enterprise owners. Policies and programmes that seek to address productive energy access should be multidimensional, and should consider gender, education and capacity building, and the key types of enterprises driving the local economy. The potential of solar PV should be reinforced using innovative financial mechanisms and product design to ensure it is both affordable and suited for the needs of the local businesses. Addressing productive energy access should be considered as one of the key strategies to promote sustainable livelihoods.
Open Access
Accessing green space in Cape Town : a case study of public perceptions of green space and barriers of access in eight nature reserves and conservation areas within Cape Town
(2015) Milliken, Julia; Anderson, Pippin
In an increasingly urbanised world, addressing the need for access to urban green space has become a pertinent topic of interest. In Cape Town, South Africa, a city of immense biodiversity and unique spatial development, the issue of accessing urban green spaces is particularly important. Environmental and ecological advocates call for conservation of green space, to preserve the rare biodiversity of the region, while pressures for continued development to accommodate the City's growing population override land conservation policy aspirations. The legacy of post-apartheid development is still strongly entrenched in Cape Town, resulting in an inequitable and in efficient city form. Access to quality green space remains problematic in Cape Town. This research seeks to discover how accessible urban green spaces are in Cape Town, and, if barriers exist, whether they are physical, economic, or socially driven. The author has undertaken a case study method approach to conduct this research, focusing on eight nature reserves or conservation areas managed by the City of Cape Town in the southern and eastern suburbs of the City. Key informant interviews (n= 6) were conducted, as well as qualitative and quantitative surveys of park users and the general public. Park users (n= 672) were surveyed on site, at one of the eight green spaces, while the public (n= 317) were surveyed at the nearest commercial shopping area adjacent to the green space. Outcome measures included demographic information, suburb of residence, mode of transport, reasons for choosing mode of transport, frequency of green space visits, and reasons for visiting. Results show the majority of park users accessed the green space by personal vehicle, and very few park users took public transport (n= 3). The majority of users resided in suburbs within two kilometre s of the green space. Park users varied in age, yet young adults aged 16-19 and elderly over the age of 80 accounted for only 2.8% and 1.8% of those surveyed, respectively. The ethnic breakdown of those surveyed was not indicative of Cape Town's ethnic breakdown, according to the 2011 Census, with white South Africans and coloured South Africans accounting for 50% and 39%, respectively. Over a quarter of the public surveyed identified 'lack of information' or 'unaware of what park offers' as the reason for not visiting the green space. Safety and security was a common concern among both park users and the public; many expressed concern about visiting the green space alone, or traveling alone due to issues of security in the adjacent neighbourhoods. From the data gathered in this research, the author concludes that barriers exist in the access of quality green spaces within Cape Town, and include, but are not limited to, issues of proximity, public transport, safety and security, spatial development of the City, varied green space interests, and information barriers. These issues vastly alter how users engage in these eight different green spaces. Further research may be conducted in a more expansive study on Cape Town's green spaces, including small local green spaces in neighbourhoods throughout the City, which may yield interesting results on the access and barriers to access of urban green spaces.
Open Access
Acid deposition in the Eastern Transvaal Highveld
(1985) Böhm, Maraget
The Transvaal Highveld has one of the largest potentials for air pollution in South Africa. The area around Witbank and Middleburg in the eastern Transvaal Highveld, is highly industrialized with several coal-fired power stations, burning coal dumps and heavy industries. The pollution levels in this area have been the centre of much dispute in recent years, and yet little emphasis has been placed on the severity of atmospheric deposition despite the fact that acid deposition is a major world-wide environmental concern. This study focusses on the chemistry and severity of atmospheric depositions to the south and south-east of the Witbank-Middleburg Power and Industrial Complex. Bulk depositions were sampled at seven sites during the year August 1982 to August 1983 and rain samples covered five sites for four of the six months of the 1983/84 rainy season.
Open Access
Air quality and climate change in the greater Cape Town area
(2009) Kalognomou, Evangelia-Anna; Hewitson, Bruce; Tadross, Mark
The work presented in this dissertation stems from the link that exists between meteorological conditions and the significant accumulation of air pollutants in large urban agglomerations. The research focuses on the Greater Cape Town Area (GCTA), where temperature inversions lead to high air pollutant concentrations and episodes of air pollution. As local meteorological conditions are often manifestations of larger weather producing phenomena (e.g. anticyclones), the work presented studies the changes that may occur in the synoptic conditions associated with temperature inversions, which will consequently affect the rate of occurrence of air pollution episodes. After a brief introduction of the topic, background information on the relevant legislation and the actions taken towards an air pollution abatement strategy and a detailed literature review, the high levels of air pollution in the GCT A during winter and especially during the morning peak hour traffic and their link to temperature inversions are studied in detail for the year 2002. The large scale circulation and its link to temperature inversions are studied through the application of the Self-Organizing Maps technique using NCEP-DOE Reanalysis 2 data and making use of the findings for the year 2002. The synoptic states most associated with temperature inversions are found to be the anticyclonic conditions caused by the South Atlantic High Pressure (SAHP) system and the west coast trough associated with berg winds bringing dry continental air towards the GCT A. The 2002 data also show that more air pollution episode days are associated with west coast troughs than with the SAHP system and the average strength of the temperature inversions associated with west coast troughs is found to be approximately 50 % higher than that associated with the SAHP system. The Global Circulation Models (GCMs) ECHAM5, CNRM-CM3 and CSIRO-MK3.5 are used to study the potential changes in the future climate of the area under the IPCC A2 emissions scenario. ECHAM5 shows a small increase in the synoptic states associated with anticyclonic influence over the south western part of South Africa and CNRM-CM3 shows a small increase in both the synoptic states associated with anticyclonic influence and those associated with a west coast trough. Both models show a small decrease in the synoptic states associated with cold fronts. CSIRO-MK3.5 was not found to adequately reflect the current climatology in the domain, making it difficult to distinguish between model bias and future climate trends.
Open Access
Alluvial sedimentology and geomorphology of a cut and fill sequence on the Dassieboskloof River, Wuppertal, Southwestern Cape
(2007) Shaw, Arabel C
The unique and well preserved fluvial sequences within the valleys of the Cederberg Mountains of the Western Cape, South Africa, provide the opportunity for palaeoenvironmental reconstruction which will add to the sparse evidence from across southern Africa. The location of the study site at the edge of two physio-climatic zones provides insight into the controversy surrounding the characteristics of Late Quaternary environments in this semi-arid winter rainfall region. It is already accepted that the southwestern Cape behaved out of phase with the rest of southern Africa during Quaternary climatic fluctuations and resulted in significantly different environmental conditions. The discovery of an extensive sedimentary sequence south of Wuppertal in the northern Cederberg on the Dassiebosldoof River provides colluvium package overlain by a laminated and interbedded fluvial sedimentary package approximately eight metres thick, demonstrating a change in conditions from deposition to incision ( cut-and-fill). Physical, geochemical and mineralogical analysis is used to characterise the sediments as well as mapping and ground trothing of the contemporary fluvial dynamics across a portion of the Moordenaarsgat River and eastward draining Tra-Tra River; a detailed investigation of the depositional environment will expand the palaeoenvironmental record for the region, and the two adjacent climatic zones (Cederberg and arid Karoo). This research will contribute to a more detailed understanding of geomorphology in the northern Cederberg and the driving mechanisms, which are extremely significant when assessing and managing potential future aridification and its impact on this fragile landscape.
Open Access
An analysis of discharge and water quality of an urban river and implications for stormwater harvesting
(2020) Aziz, Fahad; Winter, Kevin
Development in urban catchments often result in rivers being converted into large stormwater canals where stormwater is removed as quickly as possible to prevent flooding. A combination of elevated peak flows, increased nutrients and contaminants and reduced biotic richness are typical features of these urban waterways. This study explored the dynamics of an urban river in Cape Town by using high-resolution monitoring sensors and loggers to analyse and model real-time discharge and water quality data during and after 14 rainfall events. Discharge and water quality data were collected from the Liesbeek River at three sites during the rainfall events. As expected, the upper most sampling site had the lowest discharge and pollution load, compared to sites in the middle and lowest reaches of the river. An analysis showed significant correlations between the discharge and electrical conductivity at all three sampling sites. Rainfall was the primary factor in altering discharge and electrical conductivity. Predictive modelling using selected rainfall designs indicated that average discharge and total volume increases with increasing rainfall. Linear regression analysis for electrical conductivity indicated a strong relationship whereby an increase in discharge resulted in a decrease in electrical conductivity. This study revealed the discharge and water quality of stormwater in the Liesbeek River during rainfall events showed the improved water quality conditions in the river during the rainfall events particularly after the peak discharge. Furthermore, the implications of this study revealed that the Liesbeek River can become a water source for recharging groundwater and aquifers.
Open Access
An Assessment of Heavy Metal Concentrations in Surface Sediments from the Knysna Estuary
(2022) Armitage, Michael Philip Anthony; Meadows, Michael Edward
This research presents an analysis of surficial sediment samples in respect of total heavy metal concentrations, sediment grain size, and total organic carbon within 36 surface sediment samples from the Ashmead Channel in the Knysna Estuary. 15 surface sediment samples were also analysed from Chongming Island in the Yangtze Estuary of the People's Republic of China, and the results compared between the two systems, in addition to other South African and global estuaries with similar characteristics to Knysna. Metals analysed were Cr, Cd, Cu, Zn, Hg, As, and Al. Statistical analyses, including Pearson's Product–Moment correlation, enrichment factor analysis, and the assessment of heavy metal contamination were conducted between the variables to determine patterns of difference and similarity between the sites, as well as to determine the degree of contamination in the Knysna sediments. Results from Knysna were also compared to those from previous studies in the area. This study found that the Knysna sediments are not highly contaminated with heavy metals in relation to South African Revised National Action List levels, however, the degree of enrichment in the sediment has increased by a substantial margin over the past 20 years. Mean metal concentrations in Knysna are Cr: 7.37mg/kg, Cd: 1mg/kg, Cu: 6.43mg/kg, Pb: 7.43mg/kg, Zn: 57.4mg/kg, Hg:< 1 mg/kg, As: < 1mg/kg, and Al: 2138mg/kg. Mean enrichment factor classes of the concerning metals are Cr: 1.69, Zn: 3.89, Pb: 2.56, and Cu: 2.33. Upon comparison with sediments from Chongming Island, it was noted that the sediment in the Yangtze has much higher background heavy metal concentrations than Knysna. The study also found that the degree of enrichment in relation to background concentrations for the sediment sites in Knysna was surprisingly similar to that seen in the Yangtze estuary for select metals, despite the Yangtze being a highly polluted system. It must be noted that the results from the Ashmead Channel likely indicate greater contamination than what is present in the entire Knysna Estuary, due to the close proximity of a number of contaminant sources, as well as flow restrictions. The Yangtze also experiences much higher sediment accumulation rates, therefore reducing the degree of enrichment. This study, therefore, shows the value of frequent contaminant monitoring in the Knysna Estuary and recommends that additional work be conducted in the system to develop the picture of heavy metal contamination, in addition to other pollutant enrichment, in the system. Furthermore, this study demonstrates that the comparison of different estuarine environments can be a useful tool for understanding the severity of heavy metal contamination in these systems.
Open Access
Analysing urban flood risk in low-cost settlements of George, Western Cape, South Africa : investigating physical and social dimensions
(2008) Benjamin, Mogammad Ameen; Holloway, Ailsa
The main theoretical question of the research concerns the importance of considering both the physical and social dimensions of urban flood risk. The following analytical questions are therefore considered: i) What constitutes urban flooding? ii) What processes influence the urban flood hazardscape? iii) What makes people vulnerable to urban flooding? iv) How does one assess urban flood risk? A realist and constructivist society-environment epistemology are considered. In particular, the platform generated through the aforementioned epistemologies for opening up the opportunity to incorporate an integrated hazardscape and vulnerability paradigm for integrated urban flood risk management is considered. The research adopts an analytical framework that includes elements of the Pressure and Release model, the Sustainable Urban Development framework and the Extended Alternative Adjustments framework to study flood risk in lowcost settlements. The research incorporates a review of the damage following three extreme weather events over George during 2006 and 2007. It selects a worst affected low-cost settlement for further flood risk analysis. In the flood risk assessment the research investigates the flood hazardscape of the settlement and physical adjustments undertaken by residents. Human flood vulnerability and vulnerability adjustments undertaken by the residents are also investigated. The research adopts a participatory hazardscape methodological approach drawing from hydrological methods within the physical sciences and qualitative methods from within the social sciences. Both primary and secondary sources are considered. The findings allow for a guiding Urban Flood Risk Circulation framework that explains the importance of considering both the flood hazardscape and human vulnerability in urban flood risk management.
Open Access
An analysis of diatoms as biological indicators of water quality in rivers of the Western Cape
(2015) Slingers, Oliver; Winter, Kevin
In South Africa the systematic collection of water samples from surface waters and the collation of results is the responsibility of the Department of Water and Sanitation, previously the Department of Water Affairs and Forestry. Local authorities and private contractors are also responsible for conducting water quality tests for reporting purposes. In most cases, samples are collected by hand at predetermined sites and intervals across the country, and are tested for a standard set of parameters that covers various physical, chemical and bacteriological water quality measures. This approach and method of monitoring is time consuming, expensive and requires a high level of skills and capacity to achieve a representative and reliable sample. There is no immediate substitute, although there is a resurgence of interest in the use of bio-indicators in monitoring rivers. In this study, diatoms are investigated as an indicator of water quality because of the relative abundance of species and the ease with which they can be collected in the field, and the establishment of taxonomies of species that are aligned to pollution levels. There is limited knowledge about diatoms species found in lotic conditions, and in seasonal conditions in a Mediterranean climate where the surface water is slightly acidic. This study investigates the use diatoms in lotic waters of the Western Cape and compares this information to surface water quality measurements in the upper and middle course of the Berg River. The study commences by establishing baseline information of diatoms species for the upper to middle section of the Berg River which coincides with sites where surface water samples are regularly collected by the Department of Water and Sanitation. The study was conducted over a 12 month period in order to analysis the response of species to seasonal change and in relation to changing conditions at various point sources of where there is a known discharge into the Berg River. Species and population will be compared to the typological classification of diatom species and in relation to surface water quality. The study seeks to understand how diatoms respond to acidic waters of the Berg River; to measure the response of diatoms to changes in the water quality along the length of the river; and to determine the response of diatom species to point sources discharging water of varying quality into the river.
Open Access
Analysis of land-cover change in the Kogmans River (H3) secondary catchment : impact of land degradation and river management on flood severity
(2005) Rogatschnig, Daniel; Meadows, Michael E
This study aims to understand what role the landscape, and the management thereof, played in the March 2003 floods in the Kogmans River catchment. The Kogmans River (H3) secondary catchment is situated in the Klein (Uttle) Karoo region of the Western Cape, approximately 170km east of the city of Cape Town.
Open Access
An analysis of rainy season characteristics over the Limpopo region
(2005) Phaladi, Raesetje Florina; Reason, Chris
This thesis investigates characteristics of the summer rainy season over the Limpopo region that are important to the agricultural sector and other user groups. The Limpopo region supports a large rural population dependent on rain-fed agriculture as well as significant biodiversity, particularly in the Kruger National/Limpopo Transfrontier Park and is vulnerable to severe flood and drought events. REcently, the region has been impacted by severe drought (2002-2004) and flooding in late summer 2000. The rainy season characterisitcs investigated are the frequency of wet and dry spells during the rainy season and the onset date of the season.
Open Access
Antarctic sea-ice extent, Southern hemisphere circulation and South African rainfall
(1998) Hudson, Debra Alison; Hewitson, Bruce
The study examines the response of an atmospheric general circulation model (OCM) to a reduction in Antarctic sea-ice extent during summer and winter, with emphasis on non-polar and southern African climates. Following an evaluation of the OCM, the control and perturbation simulations are analysed. The controls are forced by prescribed, observed sea surface temperatures (SSTs) and sea-ice extents, while in the perturbation simulations sea-ice is reduced and replaced with SSTs. The introduced anomalies are derived from an algorithm based on observed ice variability. The simulations are restarts of an AMIP (Atmospheric Model Intercomparison Project) configured simulation, and two summers (1979/80 and 1984185) and two winters (1980 and 1985) have been selected for the study. Three replicates have been performed for each time period for both the control and perturbation conditions.
Open Access
Anticipation, significance and response to ecosystem impacts of large dams
(2000) Clarke, Christopher; Khagram, Sanjeev; Aylward, Bruce
This paper provides a brief overview of the context, scope, methodology and salient findings emerging from a survey of 125 large dams in 52 countries world-wide. This global Cross-Check Survey was one of four key work programme components integral to the world Commission on Dams, initiated in Gland, Switzerland in 1997. In particular the paper gives a brief overview of some of the key issues responsible for significant ecosystem impacts and highlights key responses practices in a variety of different regions and countries world-wide.
Open Access
The application of the surface energy balance system model to estimate evapotranspiration in South Africa
(2013) Gibson, Lesley Anne; Eckardt, Frank; Jarmain, Caren; Su, Bob (Z)
In a water scarce country like South Africa with a number of large consumers of water, it is important to estimate evapotranspiration (ET) with a high degree of accuracy. This is especially important in the semi-arid regions where there is an increasing demand for water and a scarce supply thereof. ET varies regionally and seasonally, so knowledge about ET is fundamental to save and secure water for different uses, and to guarantee that water is distributed to water consumers in a sustainable manner. Models to estimate ET have been developed using a combination of meteorological and remote sensing data inputs. In this study, the pre-packaged Surface Energy Balance System (SEBS) model was used for the first time in the South African environment alongside MODerate Resolution Imaging Spectroradiometer (MODIS) satellite data and validated with eddy covariance data measured in a large apple orchard (11 ha), in the Piketberg area of the Western Cape. Due to the relative infancy of research in this field in South Africa, SEBS is an attractive model choice as it is available as open-source freeware. The model was found to underestimate the sensible heat flux through setting it at the wet limit. Daily ET measured by the eddy covariance system represented 55 to 96% of the SEBS estimate, an overestimation of daily ET. The consistent underestimation of the sensible heat flux was ascribed to sensitivities to the land surface air temperature gradient, the choice of fractional vegetation cover formula as well as the height of the vegetation canopy (3.2 m) relative to weather station reference height (2 m). The methodology was adapted based on the above findings and was applied to a second study area (quaternary catchment P10A, near Grahamstown, Eastern Cape) where two different approaches for deriving surface roughness are applied. It was again demonstrated that the sensible heat flux is sensitive to surface roughness in combination with land surface air temperature gradient and again, the overestimation of daily ET persisted (actual ET being greater than reference ET). It was concluded that in complex environments, at coarse resolution, it is not possible to adequately describe the remote sensing derived input parameters at the correct level of accuracy and at the spatial resolution required for the accurate estimation of the sensible heat flux.

Browsing by Subject "Environmental and Geographical Science"

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