Magister Scientiae - MSc (Environ & Water Science)

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The ecohydrology of the Fransehoek Trust Wetland: water, soils and vegetation.
(University of the Western Cape, 2010) Kotzee, Ilse; Raitt, Lincoln; Samson, Roeland
The research was driven by a need to increase the knowledge base concerning wetland ecological responses, as well as to identify and evaluate the factors driving the functioning of the Franschhoek Trust Wetland. An ecohydrological study was undertaken in which vegetation cover, depth to groundwater, water and soil chemistry were monitored at 14 sites along three transects for a 12 month period. The parameters used include temperature, pH, electrical conductivity (EC), sodium, potassium, magnesium, calcium, iron, chloride, bicarbonate, sulphate, total nitrogen, ammonia, nitrate, nitrite and phosphorus. T-tests and Principal Component Analysis (PCA) were used to analyze trends and to express the relationship between abiotic factors and vegetation. Results reflect the strong influence of hydrology, microtopography and nutrient availability in structuring vegetation composition in the wetland. The wetland has been classified as a palustrine valley bottom with channel wetland, which is predominantly groundwater-fed (phreatrotropic), but receives surface water inputs as well. Small scale gradients of microtopography allow for differences in flooding frequency and duration resulting in hydrologically distinct sites which differ chemically. Three zones were distinguished in the wetland. Hollows or low sites were characterized by intermittent flooding and drying and higher nutrient concentrations in soil and groundwater. High sites which were rarely or never flooded exhibited higher groundwater temperature and ammonia as well as iron in soils and groundwater. The inundated sites remained flooded throughout the year and were characterized by high nitrate and nitrite in soil as well as high EC, magnesium, bicarbonate, sulphate and phosphorus in groundwater. The limited availability of nitrogen in the wetland favoured plant types Typha capensis, Paspalum urvillei and Juncus .kraussii which are able to either fix nitrogen or store nitrogen during more favorable conditions. The main chemical concentration changes take place between summer and winter. The Principal Component Analyses suggest that sodium, chloride, potassium, ammonia and phosphorus are the dominant ions determining the chemistry of groundwater. Increased abstraction from the table mountain aquifer to supplement human demand may put the wetland at risk of degradation. Intensified agriculture and other land use in the area are likely to increase pollution loads into the wetland causing shifts in nutrient availability and vegetation composition. Continued and long term monitoring is essential to ensure effective management of the wetland and is highly recommended. Closer partnerships between wetland managers and scientists as well as community awareness and involvement through a volunteer monitoring programme should be encouraged
Determining the socio-economic value of groundwater: Franschhoek case study
(2011-12-01) Pearce, Darian; Xu, Yongxin; Brendonck, Luc
The Western Cape, a province of South Africa is facing increased pressure to develop new supplies of fresh water to cater for the regions rapidly growing demand. Groundwater is being explored as a possible contributor to the freshwater supply. Development of the resource has been slow despite the existence of significant potential groundwater resources in the form of several shallow primary aquifer systems and an extensive secondary aquifer formation known as the Table Mountain Group (TMG) Aquifer. This slow development may be attributed primarily to a lack of awareness amongst key stakeholders and general ignorance in the water market with regards to the potential of this resource.
Application of multivariate statistics and Geographic Information Systems (GIS) to map groundwater quality in the Beaufort West area, Western Cape, South Africa
(UWC, 2013) Solomon, Henok Goitom; Siad, Abdi Mohamoud
Groundwater in arid and semi-arid areas like the Karoo region of South Africa is an important source of domestic, agricultural and industrial source of fresh water. As a scarce resource, it requires extensive quality control and protection through innovative methods and efficient strategies. The town of Beaufort West and its vicinity use groundwater as a major source of municipal and private water supply. Forty nine groundwater samples were collected from spatially referenced boreholes located in and around the town of Beaufort West and were analyzed for EC, pH, TDS,TH, SAR, TA, Ca2+, Mg2+, Na+, K+, HCO3-, Cl-, NO3- and SO42- according to SANS 241 standards and tested for ionic balance. The groundwater of the study area was characterized using WHO and South African drinking water quality standards as well as TDS and Salinity hazard classifications. These comparisons and classifications characterized the groundwater of the study area as hard to very hard, with low to medium salinity hazard. These results are in accordance with the dominance of the ions Ca2+, Na+, HCO3 - and Cl- in the groundwater samples. Linear relationships between the hydrochemical variables were analysed through correlation and multiple regression analysis to relate the groundwater quality to the underlying hydrogeochemical processes. These linear relationships explained the contribution of the measured variables towards the salinity, hardness and anthropogenic contamination of the groundwater. The groundwater of the study area was also assessed using conventional trilinear diagrams and scatter plots to interpret the water quality and determine the major ion chemistry. The conventional methods highlighted the sources of the hydrochemical variables through analysis and interpretation of rock-water interaction and evaporations processes. To supplement these conventional methods and reveal hidden hydrogeochemical phenomenon, multivariate statistical analyses were employed. Factor analysis reduced the hydrochemical variables into three factors (Hardness, Alkalinity and Landuse) that characterize the groundwater quality in relation to the source of its hydrochemistry. Furthermore, combination of Cluster (CA) and Discriminant analyses (DA) were used to classify the groundwater in to different hydrochemical facies and determine the dominant hydrochemical variables that characterize these facies. The classification results were also compared with the trilinear diagrammatic interpretations to highlight the advantages of these multivariate statistical methods. The CA and DA classifications resulted in to six different hydrochemical facies that are characterized by NO3 -, Na+ and pH. These three hydrochemical variables explain 93.9% of the differences between the water types and highlight the influence of natural hydrogeochemical and anthropogenic processes on the groundwater quality. All the univariate, bivariate, multivariate statistical and conventional hydrogeochemical analyses results were analyzed spatially using ArcGIS 10.0. The spatial analysis employed the Inverse Distance Weighted (IDW) interpolation method to predict spatial distribution of unmeasured areas and reclassification of the interpolation results for classification purposes. The results of the different analyses methods employed in the thesis illustrate that the groundwater in the study area is generally hard but permissible in the absence of better alternative water source and useful for irrigation.
Social sustainability of golf developments in Knysna: an analysis of community perceptions
(2013) Voigt, Inge; Boekstein, M.S.; Brooks, S.
An aspiring golfing destination has emerged along South Africa‟s Garden Route in the Western Cape, the town of Knysna. Also known as the oyster of the Garden Route, Knysna has blossomed with development over the past years and attracted investors, developers and residents across international borders. Rapid urbanization and development have interrupted the social sustainability of the town‟s local community and as this trend continues so too does the fragmentation of its social sustainability. This research has placed its focus on Knysna‟s biggest local employers and one of the strongest tourist attractions, namely the golf developments. However this research investigates the perceptions of Knysna‟s community towards these elitist establishments, illustrating that Knysna‟s biggest contributors to employment and tourism revenue, may just be the greatest threat to its social sustainability.
Influences of river flows on recruitment success of Fynbos riparian vegetation along selected high gradient streams in the Western Cape, South Africa
(University of the Western Cape, 2014) Magoba, Rozwivhona Faith; Mazvimavi, D.; Brown, C. A.
Riparian vegetation occurs in two distinct zones, the wet bank and the dry bank. Knowledge on how the flow regime influences the zonal structure of riparian vegetation is required to mitigate the adverse effects of water resource utilization on riparian vegetation. The first objective of this study was to determine whether flow exerts a physical influence on zonal structure pre- or post-recruitment. An examination of the survival of seedlings and saplings was conducted along Western Cape rivers to investigate seedling persistence and survival on lateral zones. A comparison of the ratios of seedlings, saplings and adults in different riparian zones for the years, 2004, 2011 and 2013, was carried out. The results suggest that in general seeds are deposited randomly on the banks, where they germinate and become seedlings. Seedlings that become established at locations unsuitable for their persistence into adulthood are removed either by high flows or perish during dry conditions. Thus, lateral zonation eventually develops due to species differences in tolerance to conditions at different positions on the banks. The second objective was to explore the effects of the reduction in dry season low flows on the recruitment success of riparian species at sites upstream and downstream of abstraction points. At most sites plants were arranged into different lateral zones and the numbers of species between upstream and downstream sites were not significantly different. There were significant differences in the abundances between up- and downstream sites, with the loss of herbaceous plants and sedges at downstream sites, both of which favour moist conditions. Also, in the absence of dry season flows, the seedlings of dry bank tree species recruited closer to the channel than those at the sites with summer flows. The shifting of the dry bank into the channel narrows the channel, which may affect the hydraulic pressures exerted during floods. The spatial arrangement in the riparian zone has as much to do with flow conditions post recruitment as it does with conditions during recruitment. This shows that the structure of riparian plants is determined not only by whether or not the minimum flows are met, this points to the need to reinstate the naturally variable flow and adopting a holistic approach for the understanding and management of aquatic systems.
The water footprint of selected crops within the Olifants/Doorn Catchment, South Africa
(University of the Western Cape, 2014) Manamathela, Sibongile Amelia; Mazvimavi, Dominic; Gush, Mark
Rapidly increasing global population is adding more pressure to the agricultural sector to produce more food to meet growing demands. However the sector is already faced with a challenge to reduce freshwater utilisation as this sector is currently using approximately 70% of global water freshwater resources. In South Africa, the agriculture sector utilizes approximately 62% of freshwater resources and contributes directly about5% to the Gross Domestic Product. South Africa is a water scarce country receiving less than 500mm/year of precipitation in most parts of the country, and consequently approximately 90% of the crops are grown under irrigation. Studies have evaluated irrigation practices and crop water use in the country. However information is lacking on the full impact of South African horticultural products on freshwater resources. The water footprint concept can be used to indicate the total and source (blue/green) of water used to produce the crops. Information about water footprint (WF) can be used for identifying opportunities to reduce the water consumption associated with production of vegetables and fruits at the field to farm- gate levels, including the more effective use of rainfall (green water) as opposed to water abstracted from rivers and groundwater (Blue water). It can also be used to understand water related risks associated with the production of crops and facilitate water allocation and management at catchment/water management scale. While the potential value of water footprint information is well recognized there is still inadequate knowledge on how best to determine the water footprints of various crops within a local context. The aim of this study was to determine the water footprint and the crop water productivity of navel oranges, pink lady apples and potatoes produced with the Olifant/Doorn water management area in South Africa.The water footprint of the navel oranges, pink lady apples and potatoes assessed following the water footprint network method was 125 litres/ kg, 108 litres/kg and 65 litres/ kg respectively. The study concluded that water footprint studies should be carried out on the whole catchment instead of one farm in order to assess the sustainability of the process.
Assessing groundwater-surface water interaction as a decision-making tool licensing water use South Africa : case study area of Gevonden farm
(University of the Western Cape, 2015) Biyela, Mfundi Cyril; Kanyerere, T.
Assessing groundwater-surface water interaction as a decision-making tool licensing water use South Africa: Case study area of Gevonden Farm is the title of the current study with the context that arises from the use of GRAII methodology which uses quaternary catchment boundaries for groundwater abstraction water use licence application assessment during decision making. The problem is that the quaternary catchment scale approach does not provide the scientific bases for site specific scale. The current study argues that such approach provides realistic, practical information at site specific scale and therefore informs the issuing of licences more accurately. The aim of the current study is to improve understanding of how the assessment of groundwater abstraction water use licence should be carried out at a site specific scale to improve decision making during licence issuance. The objective of the study is to outline the scientific study and demonstrate how the investigation that leads to the decision making can be conducted. The study was carried out using hydraulic methods such as pumping test and geochemical analysis method. Hydraulic properties were determined and chemical elements were analysed for and compared with the SANS 241 water quality standards for domestic and agricultural use. Hydraulic properties such as hydraulic conductivity (K), transmissivity (T), yield and storativity (S) were determined. Major and minor ions that are required to be analysed for domestic and agricultural water use were analysed. Piper diagrams and FC method were used to analyse data. The piper diagrams plotted indicated that surface water is mixing with groundwater and that means there is connection between groundwater and surface water. The chemical elements analysed for were compared with SANS 241 water quality standards for domestic and agricultural use. The water quality on the investigated site can be categorized as having good water quality. A sustainable yield estimated from the two boreholes (BH03 and BH05) which was 1.02 Ɩ/s. The available drawdown estimated with reference to the boreholes water strikes that were determined by EC profiling were 135 mbgl from both boreholes. The study recommends the issuance of water use licence with conditions that chemistry of water should be analysed for once a quarter and boreholes water levels should be analysed for once a month.
A comparative assessment of the quantity and sources of water used by alien invasive prosopis spp and indigenous Acacia karroo in the Northern Cape Province
(University of the Western Cape, 2015) Ntshidi, Zanele; Mazvimavi, D.; Dzikiti, S.
Invasive alien plants (IAPs) are often reported to use more water than indigenous plants. Inaddition, IAPs have an ability to adapt to harsh environmental conditions and they tend to spread at rapid rates, thereby threatening the country’s water resources, agricultural land, and biodiversity. Much of South Africa is expected to get drier in future due to climate change and the new climatic conditions are also predicted to accelerate the rate at which alien plants will spread. Approximately 10 million hectares are currently estimated to have been invaded by alien plants in South Africa, with an estimated average annual rate of spread of more than 5%. The first objective of this study was to compare the water use by deep rooted tree species which include invasive alien Prosopis (sp) trees and the co-occurring indigenous A. karroo. These trees are growing in a flood plain of a groundwater dependent catchment in the Northern Cape Province. Both species are dependent on groundwater and thus compete with local communities for this resource. The second objective was to determine the sources of water that the trees were using in order to understand the impacts of each species on groundwater resources. Transpiration was measured using the heat ratio method of the heat pulse velocity sap flow technique while the volumetric soil water content was monitored at several depths down the soil profile using automated capacitance soil water content probes. Weather data was collected using an automatic weather station. Stable isotopes of oxygen and hydrogen from plant, soil and groundwater samples were analysed to determine the sources of water used by the trees. Average tree density was approximately 613 stems per hectare for Prosopis compared to about 100 stems per hectare for A. karroo. Comparative measurements of water use shows that the annual stand level transpiration from Prosopis invasions was approximately 353 mm/year while that from A. karroo was only about 137 mm/year. Differences in stand transpiration were a result of the higher plant density for Prosopis than A. karroo. There were no significant differences in the transpiration rates of the two species for trees with a similar transpiring leaf area. Application of a two compartment linear mixing model for the oxygen isotope ratio during the peak transpiration period in summer showedthat Prosopis derived 23% of its water from the unsaturated zone and 77% from the saturated zone. A. karroo on the other hand derived 53% of its water from the unsaturated zone and47% from the saturated zone. Diurnal fluctuations in groundwater levels were strongly related to the transpiration dynamics of both species. This supports the observation that these deep rooted trees have substantial impacts on groundwater at the study site. Root sap flow patterns of Prosopis showed evidence of hydraulic redistribution wherein the groundwater abstracted by the tap roots was deposited in the shallow soil layers by lateral roots. However, the root sap flow patterns of A. karroo growing adjacent to the Prosopis did not show this phenomenon.
Transport and fate of chemical and microbial tracers at University of Western Cape (UWC) campus site, Cape Flats aquifer of South Africa
(University of the Western Cape, 2016) Haricombe, Erin; Kanyerere, T.; Nel, Jacobus Martinus
Extreme weather events in combination with geographical changes in groundwater utilization, groundwater availability, aquifer recharge, and ultimately changes in the quality of water resources, are expected in the future. As a consequence of changing weather patterns and urbanization the demand for groundwater is likely to increase in certain areas. We know that most waterborne pathogenic health epidemics are associated with contamination of farm water and wastewater. There is however limited understanding of the nature and extent of chemical, physical and biological processes that control the fate and transport of the microorganisms in primary and secondary aquifers. In this thesis, transport results are reported, where E. coli and PDR1 were selected as the biological tracers transported through a primary aquifer at the University of the Western Cape. In conjunction with the microbes salt and Rhodamine (chemical tracers) were injected to compare their fate and transport mechanism in the primary aquifer medium. A series of controlled Darcy experiments under laboratory and field conditions were conducted. Each provided a different data and information. The results from laboratory studies were used to improve design of the field studies. In both cases, the data collected provided information on fate and transport of microbes in groundwater. The field design phase of the experiment was an up-scaling of the laboratory phase of this project. The amount of chemical tracers injected into the aquifer was increased in proportion to the size of the research site. Tracer tests using chemical and microbial tracers were conducted simultaneously. Results of laboratory tests demonstrate a 5 times slower transport of microbes, compared to tests with salts during the laboratory phase. The salts at field scale show a breakthrough occurring after 2 days whereas the microbes –did not break through during the 28 days of the observation period. A new borehole was drilled closer to the pumping borehole to eliminate distance or travel time, but this had no effect on field results for the microbes.
Investigating groundwater governance arrangements for unconventional gas exploration and production in main Karoo Basin, South Africa
(University of the Western Cape, 2016) Matshini, Athenkosi; Kanyerere, Thokozani; Pietersen, Kevin Claude
South Africa relies on coal and imported crude oil for most of its energy. The possible production of shale gas in the main Karoo Basin of South Africa provides a potential opportunity to diversify the primary energy mix. However, shale gas exploration and production is associated with environmental impacts that include potential groundwater contamination. Protecting groundwater resources involves an effective governance regime in place to regulate such risks on groundwater resources. This study made use of a qualitative approach to investigate groundwater governance arrangements in relation to the proposed shale gas development. Further, the study developed and used an analytical framework to assess groundwater governance provisions and capacity at local level for shale gas development.
Hydrogeophysical characterisation of shallow coastal aquifers in the Western Cape, South Africa
(University of the Western Cape, 2017) Manyama, Kinsley; Kanyerere, Thokozani
Coastal aquifers present a key groundwater resource for freshwater supply in many coastal zones of Africa, and its availability is largely driven by the physical hydrogeological properties. An understanding of the aquifer properties in coastal areas is fundamental in that these aquifers present unique resource largely controlled to a very large extent by its geological and hydrological features and process. This study thus analysed information of resistivity variation of formations, drilling samples, water levels and slug test data, in an attempt to characterise aquifers in the coastal region of the Heuningnes Catchment, Western Cape. This was in an effort to address the issue of limited knowledge on key hydrogeological properties of aquifers in coastal regions. Resistivity survey results indicated that the shallow aquifers in the study area were limited in extent, had a poor potential, with resistant layers occurring below shallow, high conductive formations. The long profile of the wellpoints revealed that the area is underlain by various layers of material of consolidated to unconsolidated form. The hard rocks formations are overlain by sandy materials of fluvial origin, and clay material with marine deposits (mollusc shells). This findings were in agreement with the results of the resistivity models. In addition, the findings indicated that the saturation thickness of the aquifers was also small. The findings of the study on aquifer properties indicated that, hydraulic conductivity (K), transmissivity (T) and borehole yields were generally poor and small. Estimates of K and T ranged from 0.0030 to 0.2856 m/day and from 0.0008 to10.993 m2/day accordingly, while average borehole yields were at 0.55 l/s, with productivity of the aquifers classified as low to moderate. These were indicative of a low permeability environment, with low yielding formations. An updated conceptual groundwater flow model developed in this study, revealed a rather compacted groundwater flow systems, in which local and intermediate flows were dominant. These findings in this study support the view that aquifers in coastal regions were predominantly characterised by shallow depth, patchy distribution and low potential.
The use of GIS, statistical and risk assessment tools to evaluate aquifer vulnerability to potential contaminants
(The University of the Western Cape, 2017) Barbeau, Lucien Keith; Kanyerere, T.O.B
An aquifer is a body of permeable rock which can contain or transmit groundwater. It is a low cost water supply for domestic and agricultural use. Routine monitoring of aquifers is important to prevent contamination and its consequences. One of the advantages of routine monitoring of aquifer is the provision of continuous information on quality and quantity of water. The research problem for the current study is the lack of implementing of routine monitoring interventions to provide continuous updated information on water quality and quantity for various uses. The impact of continuous decrease in the annual rain fall due to the global warming is mostly felt by the countries in the Sub-Saharan Africa and most especially in the water tight rural community of South Africa. Consequently, aquifers represents the only reliable source of water for economic sustainability, agricultural production and healthy living in this part of the world. Routine monitoring of aquifer is therefore very important for prevention of its vulnerability.
Using the pollution-index method to assess water quality in the upper Olifants River Catchment, Mpumalanga Province.
(University of the Western Cape, 2017) Oberholster, Petrus Fredrik; Kanyerere, Thokozani
The upper Olifants River catchment, situated in Mpumalanga Province, South Africa, is one of the main sources of water for this region. This region face challenges to guarantee future water security due to intensive land use activities e.g. mining, energy production, and agriculture activities. South Africa is the sixth largest producers of coal in the world and the Witbank (eMalahleni) coal fields, situated in the catchment, represents the largest conterminous area of active coal mining in South Africa. The second largest irrigation scheme (Loskop dam Irrigation Board) is also found below the Loskop Dam in the upper Olifants River catchment. The irrigation scheme of + - 480 km of irrigation channels provides water for a R1 Billion export industry of citric fruits to the European Union. Furthermore, the Olifants River in Mpumalanga is also a trans-boundary river that initially flows northwards before curving in an easterly direction through the Kruger National Park and into Mozambique where it joins the Limpopo River before discharging into the Indian Ocean. Although the Olifants River is one of the main river systems in South Africa, it has been described as one of the most polluted rivers in southern Africa, with Loskop Dam acting as a repository for pollutants from the upper catchment of the Olifants River system. Because Loskop Dam is of strategic important for the whole region the aim of the study was to show the implications of poor water quality on the local communities down stream of Loskop Dam that depend on water usage for their livelihood. (1) Developing a modified pollution index for the Loskop Dam, Mpumalanga Province using bioindicator algae species in relationship with water column physico-chemical parameters and national water guidelines as indication of pollution. (2) Analysing the threat of cyanobacteria, microsystin contaminations to crops irrigating by water from the Loskop Dam irrigation canals. (3) Discussing the social economic implication of water pollution on the Loskop Irrigation scheme and its stakeholders.
Using geostatistical-hydrogeological approach to develop groundwater monitoring system in South Western Karoo, South Africa
(University of the Western Cape, 2017) Gaffoor, Zaheed; Kanyerere, Thokozani
Groundwater in the South Western Karoo plays a vital role in the overall water supply in the region. However, this resource is vulnerable to impacts from anthropogenic and natural activities. Mitigating the impacts on groundwater quality and quantity depends on the information provided by groundwater monitoring networks. The information provided by groundwater monitoring networks allow for timely and effective intervention to take place before widespread degradation occurs. In recent times, there has been interest in exploiting potentially vast natural resources of shale gas in the South Western Karoo. However, studies have highlighted links between shale gas development and groundwater contamination. There are concerns that these issues of groundwater contamination and overexploitation can occur in the South Western Karoo during shale gas development. One of the key features that need addressing is the lack of a statistically sound baseline that can inform on the natural conditions of the groundwater system, before development of shale gas exploitation.
Assessing Rural domestic water demand and use for local groundwater governance during drought, Halambani area, South Africa
(University of the Western Cape, 2017) Lebese, Ally Hanyani; Kanyerere, T
Groundwater demand (abstraction) and use during drought continues to be a vital aspect in rural areas. However, the lack of systematic data to assess the availability, demand and use of such resource in addition to lack of having appropriate implementation plan for governing such resources at local scale especially in unmetered areas remain a problem. The argument in this study was that designing appropriate implementation plan that considers local context, informs the basis for implementing local groundwater good governance practice that would sustain utilisation and management of groundwater resources. The Ha-Lambani Village in Limpopo Province of South Africa was used as case study. The aim of this study was to assess rural domestic water demand and use that would inform a basis for designing an appropriate implementation plan for local groundwater good governance as an intervention during drought in rural unmetered areas. To achieve such an aim, i), physiographic factors that influence groundwater availability were explained to establish availability of groundwater; ii), rural domestic water demand and use were assessed to showcase the procedure of generating quantitative data on groundwater abstraction and consumption; iii), factors that determine rural domestic water demand and use were established; iv), appropriate implementation plan for local groundwater governance was designed with evaluation indicators built in. The capability, resilience and sustainable livelihoods approaches were applied as theoretical and conceptual frameworks for the study which informed better understanding of coping strategies during drought.
Analysis of monthly MOD16 evapotranspiration rates at sites with different climatic characteristics; Heuningnes and Letaba catchments in South Africa
(University of the Western Cape, 2017) Ndara, Nolusindiso; Mazvimavi D.; Jovanovic, N.
Evapotranspiration (ET) is an important component of the water cycle that is estimated to return about 60% of precipitation back to the atmosphere. Actual ET can be estimated using remote sensing techniques and ground-based measurements. In recent years, a remote sensing product MOD 16 ET has been developed. The limited validation of this product done in South Africa showed that ET was underestimated at some sites. A comprehensive analysis of historic and seasonal trends in MOD 16 ET data in different climatic regions of South Africa has not been done. This study has the objective of evaluating if MOD 16 evapotranspiration estimates realistically represent the seasonal variations of ET on different land cover types in two different climatic regions; Mediterranean (Heuningnes catchment in Western Cape) and Sub-tropical (Letaba catchment in Limpopo) regions. Monthly MOD 16 ET maps for 2000-2012 for the Letaba catchment and Heuningnes catchment were created using ArcGIS. The results suggested that during the 2000 - 2012 period, ET was 438 - 753 mm/ year in the Letaba catchment and 432 - 458 mm/year in the Heuningnes catchment. The accuracy of MOD 16 ET was evaluated using estimates of actual ET from scintillometer data in Elandsberg (Western Cape) and flux tower data in Malopeni (Limpopo) and Skukuza (Limpopo). Monthly ET estimated using scintillometer and flux tower were calculated to coincide with the monthly MOD 16 ET data for a period of 1 year from Nov 2012- Oct 2013 in Elandsberg, 1 year 1 month from Mar 2009- Mar 2010 in Malopeni and 13 years from 2000- 2012 in Skukuza. In Elandsberg, the results showed that MOD 16 underestimated ET (R2 = 0.16, RMSE = 28.30 mm/month). In Malopeni, the results suggested that there is a strong relationship between ET estimated from flux tower data and MOD 16 ET (R2 = 0.77), but MOD 16 slightly overestimate ET (RMSE = 8.6 mm/month). MODIS ET estimates for Elandsberg had a poorer comparison with the results obtained at Malopeni and Skukuza.
Assessment of the contributions of water allocation reforms to achieving equitable access to water by smallholder emerging farmers in the Breede-Gouritz catchment management agency
(University of the Western Cape, 2018) Mnyaka, Sinazo; Mazvimavi, Dominic
The National Water Act of (1998) of South Africa has a goal of achieving equitable access to water resources, as well as achieving environmental sustainability and efficient use of water. Consequently, water resources management is being reformed to ensure the achievement of these principles. Allocation of water through granting of licenses for abstraction and storage of water has been implemented to ensure that historically disadvantaged individuals (HDIs) have access to water and to promote sustainable, efficient and beneficial use of water resources for the whole country. The Water Allocation Reform Policy is a tool that is used to implement the goal of the National Water Act and it is guided by the set objectives, which are to allocate 30% of all water to previously disadvantaged individuals by 2014, 45% by 2019 and 60% by 2025. Despite these efforts, there is evidence that smallholder emerging farmers who are part of the disadvantaged groups do not have access to water for productive use. Many studies conducted so far have shown that equitable, sustainable and efficient water allocation has not been achieved in South Africa. It is not very clear why this trend is continuing despite all efforts to the contrary. The aim of the study was to assess the contribution of the reforms of water allocation systems towards increasing access to water by historically disadvantaged groups in Barrydale area in the Western Cape Province, South Africa. Interviews were conducted to determine how the reforms have influenced access to water for productive use by smallholder emerging farmers. Document review was undertaken to determine the progress in the implementation of the water allocation reform by the Breede-Overberg Catchment Management Agency (BGCMA). The results indicated that small-scale farmers do not have access to water for agricultural activities in Barrydale due to lack of components, which include financial funding, access to farming infrastructure and skills. The BGCMA has not completed the implementation of the Water Allocation Reform and as a result, mechanisms initiated by the BGCMA have not resulted in improved access to water by HDIs. The outcome of the study indicated a lack of implementation of the water allocation reforms by the BGCMA, hence there is still no increase to water access for agricultural use by HDIs.
Conceptualization of urban hydrogeology within the context of water sensitive urban design: case study of Cape Flats Aquifer
(University of the Western Cape, 2018) Gxokwe, Siyamthanda; Xu, Yongxin; Kanyerere, Thokozani
Urban hydrogeology can be used to facilitate a decision-making process regarding the implementation of water sensitive urban design (WSUD) to manage water systems of periurban cities. This thesis was aimed at providing explanation of how that approach can be applied in Cape Town using Cape Flats Aquifer as a case study. To achieve this main objective, three specific objectives were set, namely, objective 1 which focused on estimating aquifer parameters using Theis analytical flow solution, in order to identify areas for implementation of managed aquifer recharge (MAR) suggested by WSUD principles; Objective 2 focused on conceptualizing groundwater flow system of Cape Flats Aquifer using the Finite Difference Method (FDM), in order to predict aquifer behaviour under stresses caused by the implementation of WSUD; Objective 3 focused on assessing gw-sw interaction using Principal Aquifer Setting, environmental isotope, and hydrochemical analysis, in-order to identify where and when groundwater surface water interaction is occurring, and thus informing the prevention strategies of the negative effluence of such exchanges on WSUD. The analysis of data collected through pumping test approach which were conducted in March, October 2015 and June 2016, showed that average transmissivity ranged from 15.08m2/d to 2525.59m2/d, with Phillipi Borehole (BG00153) having the highest and Westridge borehole 1 (G32961) having the lowest transmissivity values based on Theis solution by Aqua test analysis. Theis solution by excel spreadsheet analysis showed that average transmissivity ranged from 11.30m2/d to 387.10m2/d with Phill (BG00153) having the highest transmissivity and Bellville 2 (BG46052) having the lowest transmissivity. Storativity values ranged from 10-3 to 10-1 with Phillipi borehole (BG00153) having the highest storativity and Lenteguer borehole 1(BG00139) having the lowest values from both analysis. Average transmissivity visual maps showed that highest transmissivity values within the Cape Flats Aquifer can be obtained around the Phillipi area towards the southern part of the aquifer. Storativity maps also showed that the greatest storativity values can be obtained around Phillipi and Lenteguer area. These findings reveal that MAR would be feasible to implement around the Phillipi and Lenteguer area, where aquifer storage and discharge rates are higher.
The morphodynamic characteristics of erosional headcuts in Palmiet (Prionium serratum) wetlands
(University of the Western Cape, 2018) Williams, Afeefah; Grenfell, Michael C.
Gully erosion and headcut migration has been at the crux of wetland degradation in South Africa. The resulting erosion and draining effect has seen more than 50% of wetlands in the country degraded. This study investigated the degradation of indigenous Palmiet, peat forming, wetlands through headcut erosion. This was done by exploring the relationship between headcut migration rate and morphodynamic characteristics through the use of multiple regression analysis. Wetlands investigated in this study occurred in the Kromme River catchment and Nuwejaars River catchment, in the Eastern Cape and Western Cape respectively. Morphodynamic characteristics assessed include headcut dimensions, gully characteristics, soil characteristics and drainage basin characteristics. These parameters were determined either through infield assessment, image analysis or laboratory analysis. Three headcut migration rate types were calculated through a combination of infield measurements and image analysis techniques executed within ArcGIS. These migration rate types include apex advancement (m/a), gully expansion (m2/a) and volume erosion (m3/a). Statistical analysis revealed significant relationships between morphodynamic characteristics and both volume erosion and gully expansion. Morphodynamic characteristics such as drop height, apex width, gully width, drainage rate and sand content were found to have a direct relationship with migration rates, whereas characteristics such as average drainage basin slope, clay content, silt content, SOM content and soil saturation were found to have an indirect relationship with headcut migration rates. Results provide insight into the headcut migration process, its influencing factors and the potential for headcut migration rate prediction. An evaluation of these results using WET-Health found that the wetland management tool captures wetland geomorphic controls to an accuracy of 68% and 70%. Furthermore, the influence of morphodynamic characteristics on migration rates contributes to the wetland rehabilitation process as it allows for the identification of headcut sites most susceptible to erosion. This will then allow for timely wetland rehabilitation, decreasing the rate of net wetland degradation and improving the management and efficiency of wetland restoration.
An assessment of the contribution of surface and subsurface flows to river flows of the Sandspruit in the Berg River Catchment, South Africa.
(University of the Western Cape, 2018) Damons, Matthew; Mazvimavi, D
Studies have shown that the primary origin of salinity in river flows of the Sandspruit in the Berg Catchment located in the Western Cape Province of South Africa was mainly a result of atmospheric deposition of salts. The salts are transported to rivers through surface runoff and subsurface flow (i.e. through flow and groundwater flow). The purpose of this study was to determine the contributions of subsurface and surface flows to the total flows in the Sandspruit, Berg Catchment. Three rain events were studied. Water samples for two rain events were analysed for environmental tracers ?18O, Silica or Silicon dioxide (SiO2), Calcium (Ca2+) and Magnesium (Mg2+). Tracers used for two component hydrograph separation were ?18O and SiO2. The tracers, Ca2+ and Mg2+, revealed inconsistent contributions of both subsurface flow and surface flow. Two component hydrograph separations indicated is that groundwater is the dominant contributor to flow, while surface runoff mainly contributes during the onset of the storm event. Groundwater response to precipitation input indicated that boreholes near the river have a quicker response than boreholes further away from the river. Boreholes nearer to the river also indicate higher water levels in response to precipitation, in comparison to boreholes further from the river.

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