South Africa has limited natural water resources. The country is characterised by few perennial rivers, no permanent snow pack, high evaporation rates, and an average annual rainfall of 497 mm - well below the world’s annual average of 860 mm. The annual average potential evaporation rate exceeds the annual average rainfall by approximately 360% and only eight percent (8%) of the rainfall is converted into useable runoff. The country is also characterised by a geographic mismatch between water availability and the demand for water as a result of historical human settlement patterns being located around mineral deposits rather than around water sources (Ashton & Haasbroek, 2002; DWAF, 2004a; Metcalf-Wallach, 2007).
The Upper Vaal Water Management Area (WMA) is part of the Vaal River system, which is known as the ‘workhorse’ of South Africa, as it flows through the economic heart of the country.
The WMA supplies water resources to major economic sectors such as mining, power generation and agriculture, and serves a population of approximately 12 million people. This WMA serves extensive developments and supplies water to the Crocodile West and Marico WMAs and has resulted in the full exploitation of the water resources for the entire region for more than three decades.
However, the WMA experiences water quality problems in the form of eutrophication and high levels of salinity. The reduction in water quality is caused by effluents from urban areas, mines, as well as the industries operating in the area. Even though the water quality of this WMA is described as being good, future developments may cause this situation to deteriorate (DWAF, 2004a; van Vuuren, 2008).
The Upper Vaal WMA is characterised mainly by sprawling urban and industrial developments, especially in the northern and western areas, which are historical mining areas. The major industries in the area include Sasol I at Sasolburg, Mittal Steel (previously known as ISCOR) near Vanderbijlpark, and Sappi and Sasol Synthetic Fuels near Secunda which are all important in terms of the country’s economy and in providing employment to the population.
There are three operational coal-fired power stations in the area, namely Lethabo, Tutuka and Majuba Power Stations. Eskom, South Africa’s main power utility, is currently constructing a new coal-powered power station, namely Kusile, near Standerton, Mpumalanga, which will be one of the largest in the world and will use approximately 70 million litres of water per day. This power station will have an adverse effect on the quantity of water in the Upper Vaal WMA since water from the Vaal River in Gauteng will be piped to Kusile, the reason being the poor quality and lack of usability of the water from the Olifants River, which runs through the area.
Upstream of the Vaal River Barrage, are mines producing coal, precious metals, especially gold and uranium, base metals, semi-precious stones and industrial minerals, which are making large demands on the water resources of this region. The planning of more mines in this region will exacerbate the water situation. Agriculture is practised upstream of the Vaal River Barrage in the Vereeniging district. It is characterised by dryland farming, with maize and wheat cultivation dominating (DWAF, 2004a; Groenewald, 2012).
Approximately 40% of South Africa’s agricultural production is based on agricultural activities in the wider Vaal Dam catchment area, with intensive cultivation, mixed farming and stock farming dominating. The main irrigated crops that are cultivated here are low-value crops including maize, wheat, vegetables, flowers, pasture crops and grass (Braune & Rogers, 1987;
Pitman et al., 2001; DWAF, 2004a). The application of fertilisers and pesticides, and feedlots in the case of livestock rearing, negatively impact upon the water, with an increase in salinity, turbidity, nutrient pollution and also pesticide pollution being some of the consequences (Pitman et al., 2001; DWAF, 2002; Avenant-Oldewage & Eddy, 2003; DWAF, 2004a).
The Upper Vaal WMA is also characterised by a negative water balance. Studies have indicated that the consumption of irrigation water in the area upstream of the Vaal Dam increased by nearly 100% between 1998 and 2005. The fact that consumption in this area is so high, namely about 240 million m3 per annum, and that most of the irrigation water in the Upper Vaal WMA is used illegally, will possibly impact upon the quality of the water in the WMA (DWAF, 2004a).
Sulphate salts arising from emissions from power stations, Sasol, as well as other industries in the area, are deposited in the water and have been recognised as a major long-term threat to the salinity, as well as the acidity, of the water resources in the Upper Vaal WMA. Power stations
and other industries contribute to further degradation in the quality of the water through atmospheric deposition in the region so that the construction of future power stations in the region needs to be carefully considered before approval for them can be granted (Herold, 2009).
It is also estimated that the Vaal River water will be unfit for consumption in two years’ time as a result of the Acid Mine Drainage (AMD) that is occurring on the West Rand of Gauteng Province. At present, the polluted water is being neutralised through emergency water treatment measures and is being pumped into rivers connected to the Vaal River and into the western basin of the Witwatersrand. Even though the water is being neutralised through emergency water treatment measures and through the pumping of water into rivers flowing into the Vaal River, the sulphate concentrations remain high. It was estimated that the AMD would be decanting above the ground surface in the central and eastern basins of the Witwatersrand by July 2013 and that this would have major impacts on the region. This has however been averted but is still a looming threat which needs to be addressed accordingly through the construction of proper water treatment facilities.
As a long-term strategy, the Department of Water Affairs (DWA) is planning to build pumps in the central basin and is upgrading the Witwatersrand acid water treatment plant. Desalination plants need to be constructed to purify the water. However, construction was commenced only in July 2013 and they will take two years to complete. The Vaal Dam will be used as a short-term solution in that it dilutes the polluted water in the Vaal River. However, the Wilge River, which is a tributary flowing into the Vaal Dam, is also being polluted by acid water from the western and eastern basins of Gauteng Province.
South Africa is a water-stressed country. Should a drought occur in the area, water restrictions would have to be imposed upon the mines, as well as on consumers in Mpumalanga, Gauteng, the Free State, North-West and Northern Cape provinces. AMD will thus have an impact on the mines in that higher treatment costs and reduced production levels would be necessitated. These would also impact upon the consumers located in areas such as Klerksdorp in terms of health as the standard of dilution will affect the quality of the water negatively and make it unfit for human consumption and other uses (Blaine & Seccombe, 2012; Child, 2012).
AMD will increase the pressure on South Africa’s mining industry to increase production and justify the development of the proposed mines in the Upper Vaal WMA. This will have major negative impacts on the quality of the water, food security, the aquatic health of the rivers and the health of the population living in the region.
Already, the entire area of Ekangala grasslands, situated in the upper north-eastern corner of the WMA, is under application for prospecting rights for minerals. If the applications are granted, there will be numerous hydrological impacts since there are various water systems there which supply water to the rest of the country (Yende, 2012).
The future costs of water treatment will be enormous if the government, the private sector and the people of South Africa do not address the issues at hand and attempt to assess the pending impacts as soon as possible.
The Upper Vaal WMA is highly developed and is being significantly impacted upon with the full exploitation of all the water resources in the area. The tributaries are significantly affected through urban and industrial return flows from the northern regions. The intensive mining activities, as well as the re-opening and closure of mines, have had a large impact on the environment. The exact impact of AMD has not been fully established yet, however, as there are conflicting opinions.
The WMA is also characterised by water transfer schemes, which assist with the water requirements needed by the growing population and economy (DWAF, 2004a; NSTF, 2011). In order to ensure that future socio-economic growth is not inhibited and that the water in the WMA does not become unfit for consumption, a full investigation into the hydrological responses in terms of water quality of the WMA to land cover changes needs to be completed. In this way, effective planning and management for the future, as well as informed decision-making, will be ensured.
The anticipated contribution of this study is to quantify the hydrological responses of the Upper Vaal WMA in terms of its water quality, which is associated with particular land cover changes over the period, July 2000 to June 2012. By quantifying these relationships and making predictions accordingly, it will be possible to facilitate improvements in the planning and
management of water, with the main emphasis being on predicting possible impacts associated with future development scenarios or changes in the land cover or land use practices in the study area with the use of model equations. In turn, this will increase the cost-effectiveness and the sustainability of the Upper Vaal WMA and facilitate more informed decision-making as a whole.
This study could serve as a blueprint for the future planning and management of water which will subsequently benefit the environmental, social and economic spheres of the region and the country.
A statement of the research problem now follows:
The inefficient management of water has developed as a worldwide trend with an overall deterioration in the quality of water being a serious consequence (Ashton & Haasbroek, 2002).
Even though water is described as a vital resource in maintaining life and sustaining agriculture, manufacturing, transportation and other economic activities, it is the most poorly managed resource in the world (Ashton & Haasbroek, 2002; Helmschrot & Flugel, 2002; DEAT, 2005;
Kadewa et al., 2005; King et al., 2009; Usali & Ismail, 2010). Almost every country worldwide is facing a growing challenge to meet the rapidly increasing demand for water that is being driven by their growing populations, industrial pollution, a lack of adequate sanitation and climate change (Ashton & Haasbroek, 2002; Curry, 2010).
Given the current and anticipated future growth rates of the population and trends in socio-economic development, it has been estimated that South Africa’s freshwater resources will be unable to sustain the current patterns of water-usage and discharge (Ashton et al., 2008). South Africa could experience a water crisis in the not-too-distant future if the situation is not addressed properly. At present, numerous water management areas are experiencing a water deficit, the natural ecosystems and the country’s freshwater resources are being put under immense pressure by various sectors and consumers, and the quality of the water resources in question is declining (Ashton et al., 2008).
The DWA has developed several guidelines in order to ensure that, depending on water usage, the quality of the water is of the correct and an acceptable standard. Even though the government
security crisis, it is apparently resistant to accepting or implementing any suggestions from outsiders (Ndaba, 2010). South Africa needs to improve her management and maintenance of her water resources in order to improve the availability of water.
The Upper Vaal WMA is considered to be of prime importance in this respect in that the economic activities here contribute nearly 20% to the Gross Domestic Product of South Africa.
Of the nineteen WMAs of the country, the Upper Vaal is the second-largest contributor to the national wealth. The future economic growth of this WMA remains promising as most of the growth is attracted to the already strong urban and industrial areas of the Johannesburg-Vereeniging-Vanderbijlpark-Complex (DWAF, 2004a). Important to note, however, is that the local surface water resources of all three of the Vaal WMAs had already been fully exploited three decades ago. The fact that water quality is currently declining might inhibit the future economic growth of the region and the country as long as the water resources are not effectively managed in terms of water quality and quantity.
It is thus of great importance that effective water planning and management strategies should be in place to ensure that the WMA continues to grow sustainably. This study proposes that a historical progression in terms of the hydrological responses, specifically changes in water quality, towards land cover changes be completed for the Upper Vaal WMA for the period, July 2000 to June 2012 to allow for the quantification and prediction of hydrological changes or concentrations of the selected water quality parameters, linked to specific land cover change scenarios for the future. This will improve the management of water and planning in the WMA and in turn ensure sustainable future development in the Upper Vaal WMA.
The aim of this study is thus to quantify and predict future hydrological responses, in terms of water quality, towards land cover changes in the case of the Upper Vaal WMA for the period, July 2000 to June 2012. In so doing, model equations can be formulated and predictions can be made for future hydrological changes in terms of future concentrations of the selected water quality parameters linked to specific land cover change scenarios. In achieving this particular aim, this study incorporates the following themes with their relevant objectives:
Review of Literature
Describe the study area, namely the Upper Vaal WMA, in terms of its geographical characteristics such as climate and topography, as well as the quality and quantity of its water and the type of land cover and use.
Discuss the current issues of water quantity and quality in the global, national and regional contexts respectively.
Discuss the possible impacts of rainfall, evaporation and water flow on water quality.
Discuss the concept of land cover and land use changes and their possible impacts on water quality.
Review literature sources regarding previous established relationships between water quality and land cover or land use changes.
Objectives
1. Determine water quality temporal trends from July 2000 to June 2012 by analysing water quality data from all of the available sampling sites in the particular study area, i.e. the Upper Vaal WMA.
2. Evaluate important or significant variations in the selected water quality parameters.
3. Determine rainfall, evaporation and water flow temporal trends for the study area over the specified time period. These variables need to be included as they could influence the water quality data.
4. Determine temporal trends in land cover change in the particular study area over the specified time period with the aid of land cover data for 1994, 2000, 2005 and 2009 respectively.
5. Complete a Principle Component Analysis and Partial Least Squares Correlation and Regression Analysis to determine trends, relationships and responses for the variables in
the above-mentioned time periods to determine whether the land cover and the changes in it affect the selected water quality parameters.
6. Discuss significant relationships related to the hydrological responses, in terms of water quality, of the study area to land cover changes over the specified time period, and the consequences thereof.
7. Formulate model equations according to the established relationships between the selected water quality parameters and land cover.
8. Simulate future concentrations of the selected water quality parameters according to the formulated model equations in terms of future land cover change scenarios.
9. Evaluate the areas of concern associated with these scenarios in terms of the environmental, social and economic impacts.
Conclusions and Recommendations
Synthesise significant results.
Supply recommendations accordingly in terms of steps which need to be taken within the study area as well as future research.
By quantifying the hydrological responses related to the land cover changes characterising the study area, it is possible to improve the planning and management of water resources. This can be done with the formulation of model equations which will in turn enable the prediction of the possible impacts associated with future developments or changes in the Upper Vaal WMA. The afore-mentioned will in turn increase the cost-effectiveness and the sustainability of the Upper Vaal WMA as a whole.
This thesis is divided into five parts to present a logical sequence of steps to ultimately reach a final conclusion. (Refer to Figure 1.1 for the schematic flow-chart). The background to the study in terms of geographical features and attributes, as well as in terms of water quality and the nature of the land cover or type of land use, now follows.
PART 1: ORIENTATION
Chapter 1: Introduction and Problem Statement Chapter 2: Background to Study Area
PART 2: LITERATURE STUDY Chapter 3: Review of Literature
PART 3: DATA COLLECTION AND ANALYSIS Chapter 4: Methodology and Data Collection
PART 5: SYNTHESIS
Chapter 9: Recommendations and Conclusions PART 4: RESULTS AND DISCUSSION
Chapter 5: Water Quality Status of the Upper Vaal WMA
Chapter 6: Trends in and the Respective Relationships between Rainfall, Evaporation, Water Flow and Water Quality
Chapter 7: Land Cover across the Upper Vaal WMA
Chapter 8: Quantifying and Predicting Hydrological Responses associated with Land Cover Changes
The quantification and prediction of hydrological responses in terms of water quality in the event of land cover change is therefore essential within the Upper Vaal WMA as this WMA forms the basis and core water supply for numerous major economic sectors and serves a population of approximately 12 million people. The degradation of this WMA will therefore be accompanied with widespread negative effects on the environment but also lead to socio-economic losses and possible human health impacts within the region.
The WMA is faced with numerous water problems in terms of availability and quality which will place immense pressure on the environment as the region tries to achieve further socio-economic growth within the region but also for the country. The WMA is already under immense pressure in terms of water availability and supplying water to the various major economic sectors and the region’s population. The degradation of the WMA’s already limited water resources will increase these pressures and exacerbate the already problematic water situation within the region and lead to multiple negative effects on the environment and the region and country’s future economic growth and developments. The importance of good quality water within the Upper Vaal WMA can therefore not be overlooked as the degradation thereof will be accompanied with significant negative environmental, economic and social consequences.
This research will therefore serve as a blueprint for the future planning and management of water
This research will therefore serve as a blueprint for the future planning and management of water