Investigating solutions for Cape Town to ensure water security until 2040.

Transcription

1 Investigating solutions for Cape Town to ensure water security until Prepared by Sekonyela Tieho (SKNTIE001) for Professor Neil Armitage Submission date: 23 November 2015

2 i Plagiarism Declaration i) I know that plagiarism is wrong. Plagiarism is to use another s work and to pretend that it is one s own. ii) iii) iv) I have used the Harvard Convention for citation and referencing. Each significant contribution to and quotation in this report form the work or works of other people has been attributed and has been cited and referenced. This report is my own work I have not allowed and will not allow anyone to copy my work with the intension of passing it as his or her own work. Names Student number Signature Sekonyela Tieho SKNTIE001

3 ii ACKNOWLEDGEMENTS I would like to express my thanks the follow the following people, without them the completion of this research projection would not have been possible. My sincerest gratitude to Professor Neil Armitage, for his supervision, assistance and guidance throughout the whole project. To Dr Kirsty Carden, for guidance and providing me with contacts of my interviewees. To Lloyd Fisher-Jeffers, for helping me to refine my draft and for giving his time when I needed the consultations. To Nina Viljoen and Colin Mabudiro from the City of Cape Town for agreeing to have interviews with me. To Barry Wood who directed me to Nina Viljoen. Finally, to Dr Kevin Winter who gave me his time to interview him.

4 iii Abstract The City of Cape Town is expecting to experience a shortage of water by This is due to a rapid increase in potable water demand as a result of, amongst others, population growth and rising standard of living. In addition, Cape Town s annual yield from current water sources is expected to decrease due to the impact of climate change. Therefore, the City of Cape Town needs effective solutions to increase the current water supply and/or decrease the demand of potable water in order to prevent water shortage. The aim of this research was to investigate potential solutions that can be implemented by the City of Cape Town to prevent water deficits between 2015 and This was done by identifying interventions which have not yet been implemented to their full potential in Cape Town and quantifying the amount of water that can be saved or added to the system by further implementing those interventions. In this research, the adoption of water efficient devices (WED) in domestic sector and reduction of water losses were identified as the two interventions that have the most potential in reducing total demand of potable water in Cape Town. According to still et al. (2008), only 10% of the South African population is using water efficient devices, therefore, there is a high potential of saving a considerable amount of water through the use of these devices in Cape Town. The calculations of this research showed that about 20% of the total water demand could be saved annually if water WED could by adopted throughout Cape Town. The combined effects of water efficient and water loss reduction has a potential of reducing water demand by 22.8%. The implementation of these interventions will therefore postpone the occurrence of the predicted water shortage by 6 years from 2021 to The adoption of water efficient devices in domestic sector and reduction of water losses in Cape Town could not meet the goal of this research which was to ensure water security until Further interventions to decrease water demand could have been introduced, but climate change is causing a decrease in water quantity from current sources. Therefore, additional water sources that will increase the current water supply were investigated. After analysing all the potential the additional water sources which were reviewed in this research, seawater desalination, re-use of treated effluent and addition of more aquifers into the current system were considered to be the best solutions. These additional water sources will increase the current water supply by a total of 259Mm 3 /annum to 658Mm 3 /annum which will postponed water shortage due to unrestricted high water requirement growth by 15 years from 2021 to Although Cape Town is considered as a water-stress region, the results of this research showed that there are still potential interventions that can be implemented by the City of Cape Town to prevent a water shortage until the year Furthermore, the projected water balance of Cape Town for the year 2040 showed that, the demand will be 81Mm 3 lower than supply if the City of Cape Town can implement the suggested solutions in this research report. Therefore, the suggested solutions will ensure water security beyond the year In addition, the 2040 water

5 iv balance for Cape Town shows an improved water system which is more diversified as seawater, treated effluent, groundwater and surface water are used at one time. This will therefore shift a big dependence of water from surface water as it forms 98.5% of the City of Cape Town s water supply. As result, surface water will not be exhausted quickly. Finally, this research project has successfully achieved its goal of searching for potential solutions to ensure water security in Cape Town until In addition, the results of this research can be improved or used as the basis for similar research in the future.

6 v Table of content Abstract Table of contents List of Figures List of Tables iii v vii viii 1. Introduction Background Problem Statement Objectives of the project Research method Scope and limitations Plan of development Literature review Water scarcity in South Africa Sustainable urban water management Historical water demand in Cape Town Current situation of water Infrastructure leakage index Water Wastage Inefficient water use Water end use Water supply in Cape Town Water demand in Cape Town Future water requirements for the Cape Town General recommended solutions to water deficit User education and campaign initiatives Leak detection and repair Replacement of pipes Pressure management Water efficient devices Tariff increase Greywater harvest Rainwater harvesting Private boreholes/ wellpoints Groundwater 2-26

7 vi 2.18 Desalination Treated effluent Surface water development Procedure for wed calculations Results and discussion The situation of the city of Cape Town s water supply User education and campaign programs Results of water demand reduction Options for additional water supply Treat effluent Seawater desalination Groundwater Future projections of water demand Final results Conclusions and recommendations 5-1 References Appendices

8 vii List of Figures Figure 2-1: South African gap of water demand and supply 2-2 Figure 1.2: Historical water demand of Cape Town 2-4 Figure 1-3: Historical trend of Cape Town s infrastructure leakage index 2-5 Figure 1-4: International average water use per capita per day 2-7 Figure 1-5: Historical average consumption per capita per day in Cape Town 2-8 Figure 1-6: Household water use per end-use 2-10 Figure 1-7: Cape Town's sources of fresh water 2-11 Figure 1-8: Cape Town's sectoral water demand 2-12 Figure 1-9: Cape Town's water use cycle 2-13 Figure 1-10: Projected impacts of climate change on the available water supply 2-14 Figure 1.1: Projections for potable water demand 2-15 Figure 2-12: Example of the ways in which the City of Cape Town promotes awareness 2-17 Figure 2-13: Damage caused by a pipe burst 2-18 Figure 2-14: Existing and proposed sites for pressure 2-22 Figure 2-15: Historical tariff block for the City of Cape Town 2-24 Figure 2-16: Illustration of the geology for Table Mountain Group aquifer 2-27 Figure 2-17: Pipeline for distribution of treated effluent 2-29 Figure 1.2: Structure for chapter four 4-1 Figure 1.3: current water balance for Cape Town 4-2 Figure 1.4: Projections of Cape Town's water demand 4-3 Figure 1.5: Projections for high water requirements after water demand reduction 4-5 Figure 1.6: Projections for low water requirements after reducing water demand 4-7 Figure 4.6: Potential contribution by each additional water source 4-11 Figure 1.7: Projections of water demand after including additional sources 4-12 Figure 1.8: Final projections for high water requirements Figure 1.9: Final projections for low water requirements 4-14 Figure 1.10: Cape Town's 2040 water balance 4-16

9 viii List of Tables Table 1.1: Performance classification of NRW 2-6 Table 1-2: Historical average water use per capita per day in Cape Town 2-8 Table 2-3: Advantages and disadvantages of pressure management forms 2-20 Table 2-4: Pressure management savings from the previous projects 2-21 Table 2-5: Survey results on the use of WED in South Africa 2-23 Table 2-6: Potential amount of treated effluent per year 2-30 Table 1-1: volumes and frequencies for domestic end-uses 3-1 Table 1-2: Water volume used per event by end-uses 3-2 Table 1-3: Reduction coefficients for low income households in Cape Town 3-2 Table 1-4: Average reduction coefficients for high and medium saving devices 3-3 Table 1.2: Multi-criteria analysis table 4-9 Table 1.3: Ranking of the alternatives' positive impacts 4-10

10 ix Abbreviations CoCT RWH DWA FAVAD GWH NRW PM TE WC/WDM WED PRV City of Cape Town Rainwater Harvesting Department of Water Affairs Fixed and Variable Area Discharge Greywater Harvesting Non-Revenue Water Pressure Management Treated Effluent: potable water replacement through re-use Water Conservation / Water Demand Management Water Efficient Device Pressure Reducing Valve

11 Introduction 1.1 Background Water resources are nowadays threatened by a rapid population growth, economic growth and the rise in the standard of living. This is further exacerbated by a poor management of water and inefficient water use (DWA, 2013a). Since the last century, the population of the world has tripled, with the use of non-renewable energy being increased by a factor of 30 and the industrial production being increased by a factor of 50 (Fariborz, 2012). As a result, water demand has increased and resources with suitable quality are depleting due to urban, agricultural and industrial uses (ibid.). Climate change is one of the serious threats to water resources. It is caused by the emissions of greenhouse gases, and predicted to continue changing even if the greenhouse gas emissions are curtailed in accordance to Kyoto protocol (IPCC 2001; Mukeibir& Ziervogel, 2006). The impacts of climate change are associated with extreme weather events such as floods, droughts and heatwaves. In Cape Town, the impact of climate change is expected to be more evident by 2030, with an average atmospheric temperature increase ranging between 1.5 C and 2 C (ibid.). This will cause a reduction in water yield from current water sources due to high evaporation rate. As a result, Cape Town is expected to experience a shortage of water in 2020 if the increase in water demand follows high water requirements trend and climate change impacts occur (DWAF, 2013b). However, this water shortage will happen if the City of Cape Town cannot find alternative sources of water and if water demand growth remains unrestrained. There has been a considerable amount of work done to ensure water security for the City of Cape Town. Historically, it has been easy to meet the increasing water demand largely through the construction of new dams (DWA, 2013a). However, large augmentation schemes like dams are expensive to construct and lengthy. Furthermore, most of the economical viable sites to construct more dams are now developed and in use (DWA, 2013a). As a result, the focus has recently shifted to the demand management and efficient use of water (National Planning Commission, 2012). In 2001, the City of Cape Town developed Water Conservation and Water Demand Management (WC/WDM) policies and strategies to reconcile its limited water supply with the increasing demand (Melissa, 2015). In the period between 2011 and 2013, WC/WDM initiatives reduced water demand by 4.8% and the demand of water was expected to increase due to population growth (DWA, 2013b). This showed the potential of WC/WDM initiatives in decreasing water demand. 1.2 Problem Statement Climate change can be thought as a way of shifting climate variables such as temperature and precipitation from their average states (Mukeibir& Ziervogel, 2006). Climate models predict an increase in average atmospheric temperature and a decrease in the frequency of annual Chapter 1: Introduction

12 1-2 precipitation with the intense rainfall when it happens (Altman & Spencer, 2010). As Cape Town s climate is expected to change, this will reduce the annual yield of dams due to high evaporation rates as a result of the increasing atmospheric temperatures. The demand of water, on the other hand, is continuing to increase due to population growth and the rising standard of living. These factors are therefore exhausting the available water in the current sources. The City of Cape Town currently depends mainly on surface water and most of the viable sites to construct more dams have already been developed. Therefore, alternative sources of additional water supply need to be found. Alternatively, effective water demand management strategies can be developed and implemented in order to reduce water demand. 1.3 Objectives of the project The main goal of this research project was to investigate solutions for the City of Cape Town in order to ensure water security until To achieve this, the following was done: The extent of the Cape Town s water crisis was investigated. Potential solutions to combat Cape Town s water crisis were investigated, and the best solutions were selected. The projections of Cape Town s water supply between 2015 and 2040 were carried out to check the effectiveness of the suggested solutions. Finally, Cape Town s water balance for 2040 was developed to show how Cape Town s water situation will look like in Research method This section outlines the method used to achieve the goal of this research. The following procedure was followed to carry out this project research: Firstly, a literature review was done to gain a better understanding of the extent of water crisis facing the City of Cape Town. In addition, future plans and the abilities of the City of Cape Town to combat this crisis were investigated through the literature. This was to avoid proposing the solutions that the City of Cape Town will not be able to implement or those that cannot be applicable to Cape Town. Moreover, the literature was studied to learn various methods of how to calculate water use reduction through the adoption of water efficient devices, since this is proposed as one of the best alternatives to save water. Several interviews with the professionals from the Department of Water and Sanitation in the City of Cape Town were conducted. The reason for this was to acquire information about the current water situation in Cape Town. This was to obtain the information that was missing in the literature. Furthermore, the purpose of these interviews was to acquire Chapter 1: Introduction

13 1-3 updated data to do calculations. In addition, some of the interviews or consultations were done with the academics from the University of Cape Town. With the data obtained from the City of Cape Town and literature, the amount of water use that can be reduced through the installation of water saving devices was calculated. Furthermore, this research used the already available data to carry out projections and calculations since the experiments and site measures were out of the scope of this research. The multi-criteria analysis approach formed big part of this research. Due to the large amount of information obtained in this research, multi-criteria analysis was used as a tool to make decision in choosing the best recommended solutions in this report. Finally, Microsoft excel was used to carry out all the calculations and generate graphs for interpretation and analysis of the results. 1.5 Scope and limitations This research is limited to the region of Cape Town. Whilst the impacts of climate change are expected to negatively affect the whole ecosystem in Cape Town, this research focused only on the impacts of climate change on water resources. Furthermore, although climate change will affect both quality and quantity of water resources in Cape Town, the research was focused only on identifying the potential solutions to water shortage and not to the quality. This research investigated the solutions to ensure water security until the year Attention was not given to the time beyond 2040, although some of the suggested solutions will have an effect on the water system after The calculations for water savings through the adoption of water efficient devices were limited to domestic sector. This is because potable water use in the domestic sector is about 47.6% of the total water demand, therefore there is a potential of realising high water saving by reducing water use in this sector. 1.6 Plan of development This introductory chapter introduces the topic and gives a motivation for the research. It also explains briefly how the research was conducted. Chapter 2 provides a literature review on the situation of water resources in Cape Town. It also reviews water supply crisis which is caused by the increasing water demand in Cape Town and provide the general recommended solutions to these situations. Chapter 3 explains the method used to calculate the amount of water that can be saved through the adoption of water efficient devices. Chapter 4 presents the findings of the research whilst the Chapter 5 gives conclusions and recommendations. Chapter 1: Introduction

14 Literature review In order to provide an effective solution to water crisis that is facing Cape Town, a literature review was first carried out to gain a better understanding of the extent of the problem. This chapter starts broadly by explaining the situation of water supply in South Africa. It continues by narrowing down to Cape Town, whereby history, current situation and future projections of potable water demand are discussed. Then, general recommended solutions to water crisis that is facing Cape Town are provided. 2.1 Water scarcity in South Africa South Africa has annual rainfall of approximately 450mm which is below the world s average annual rainfall of 860mm (DWAF, 2004). Most of the South African rain falls along the eastern and southern coasts. The driest (western) part of the country receives annual rainfall which is less than 200mm (ibid.). South Africa is therefore classified as a semi-arid country; currently ranked 30 th driest country in the world with less water available per capita when compared to some of the water-stressed countries such as Namibia and Botswana (DWA, 2013a). Whilst there is an expectation of water shortage in South Africa, this is not a unique problem to this country. It is predicted that 3.5 billion people, which is about 50% of the world s population, will face water scarcity around the world by 2025 (Governing Board Induction Manual, 2011). In South Africa, it is projected that water demand will exceed current potable water supply by 2025 if the usage trend remains the same (ibid). Listed below are some of the factors which are expected to place further pressure on water resources unless mitigation actions are put in place: Climate change: is expected to reduce the current annual water yield due to the increase in average atmospheric temperature, which will in turn increase evaporation rate of surface water. In addition, climate change is expected to decrease annual rainfall frequency. Economic growth: is expected to cause an increase in current water demand. Population growth: a number of people is related to the amount of water use, therefore population growth will also rise the current water demand. Standard of living: like economic and population growths, the rise in standard of living causes the increase in water demand and it is considered as the main driver of water demand growth. There has been a great concern about the growing water shortage in South Africa (Turpie et al., 2008). This is because the current policies of the Department of Water and Sanitation (DWS) are not adequate to effectively address the expected water crisis that is faced by the country (Hidden & Cillier, 2014). As a result, there is a gap between water demand and supply. This gap was modelled by Hidden & Cillier (2008), and the results of the model are show in Figure 2-1. Chapter 2: Literature review

15 2-2 Figure 2-1: South African gap of water demand and supply (Heden & Cilliers, 2014) Sustainable urban water management Sustainable Urban Water Management (SUWM) is a term that is used to describe sustainable water management in the wider sense (Brown et al., 2007). SUWM treats water cycle as an integrated system that needs to be managed in a way that does not compromise the needs of both people and the environment. The current water management approaches are considered not sustainable in the long term (Brown et al., 2007). As a result, there has been a growing interest in finding alternative water management approaches (Brown et al., 2007). Furthermore, most of these approaches adopt very similar philosophical methods but vary in the scale or extent of their application (Coulson, 2014). Some of the components of Sustainable Urban Water Management (SUWM) approach are: Water Sensitive Urban Design (WSUD) Total Water Cycle Management (TWCM) Integrated Urban Water Management (IUWM) Sustainable Urban Design System (SUDS) Water Conservation and Demand Management (WC and DM) Integrate Water Resource Management (IWRM) Low Impact Development (LID) Chapter 2: Literature review

16 2-3 According to the City of Cape Town s Long term water conservation and demand management intervention report (CoCT, 2007), all sustainable water management approaches have similar objectives, which are as follows: Reducing potable water demand, Increasing the number of alternative sources of water, Increasing infiltration to recharge groundwater and attenuate stormwater flows, Reducing wastewater discharge and lowering stormwater flows to mitigate environmental degradation of downstream waterways. In general, these objectives are concerned with efficiency and sustainability of water use. The conventional water management approach was water demand driven, which means a focus was only to increase water supply through the construction of new dams. Currently, most of the economically viable sites for dam constructions have now been developed. As a result, South Africa needs to adopt a new water management approach to combat its water crisis. 2.2 Historical water demand in Cape Town The historical water use of Cape Town is marked by three sharp declines which happened between 1976 and 1997, and again between 1995 and The last sharp decline happened between 1999 and In 2000, water demand reached 499Mm 3 /annum, whilst winter rainfall simultaneously fell below average. Shortfalls then were experienced and water restrictions were introduced to prevent the exhaustion of available water in the sources. These water restrictions resulted in a temporary decrease in water demand, which was then followed by a progressive return to a relatively high water usage of 476Mm 3 /annum in In the same year (2004), a severe drought was experienced and water restrictions were introduced again. In addition, further water restrictions were introduced again in 2006, and that resulted in the water demand drop to 465Mm 3 /annum (DWA, 2007a). Figure 2-2 shows the trend that was followed by potable water demand over the years between 1996 and It can be seen that over the period between 2001 and 2005 potable water demand did not return to the level it was before the implementation of water restrictions in The yellow arrows show that the increasing rate of water demand is slower than prior to It can then be concluded that water restrictions have a potential to change water users behaviour. To clarify Figure 2-2, the water demand reduction in the graph was caused by the combined effects of water tariff increase, user education and Water Demand Management (WDM) initiatives (DWA, 2007a). Chapter 2: Literature review

17 2-4 Figure 2.2: Historical water demand of Cape Town (DWA, 2007) 2.3 Current situation of water The City of Cape Town receives the bulk of water from winter rainfall with annual average of 464mm (Tadross & Peter, 2012). It relies mainly on dam and reservoir water storages to supply water throughout the year, and to meet high water demand during the dry summer months. The City of Cape Town s water sources consist of surface water and groundwater with proportions being approximately 98.5% and 1.5% respectively (Water Service Development Plan, 2013) Infrastructure leakage index Infrastructure Leakage Index (ILI) is defined as Current Annual Real Losses (CARL) divide by Unavoidable Annual Real Losses (UARL). Municipalities use infrastructure leakage index to assess their management of real water losses and the performance of their water distribution systems. A well-managed water reticulation system has a value of infrastructure leakage index equal to one. However, it is uneconomical to achieve this value in many countries (WCWDM Strategy, 2015). As a result, countries accept a value that is greater than one, and the internationally acceptable ratios of ILI range between 2 and 10 (ibid.). Figure 2-3 illustrates a trend of infrastructure leakage index and real water losses for Cape Town s water reticulation network. It can be seen that there has been a continuous decline in the levels of annual real losses between 2010 and 2013, while the expected unavoidable real losses Chapter 2: Literature review

18 2-5 remained almost the same throughout this period. It can be concluded that there have been successive improvements in the water distribution network of Cape Town between 2010 and The International Water Association (IWA) consider Infrastructure Leakage Index (ILI) ratio which is below 2 as world class management (Delgado, 2008). The ILI ratio for the City of Cape Town is equal to 1.88 and according to IWA, Cape Town s water infrastructure is performing well. Figure 2-3: Historical trend of Cape Town s infrastructure leakage index (CoCT, 2015) Water Wastage The total water loss in Cape Town is currently estimated at 15.8% of the total potable water demand, which is equal to 58.3Mm 3 /annum. This amount includes bulk losses, reticulation losses and apparent losses excluding unbilled authorised water use. This amount has increased from 46.3Mm 3 /annum in 2013/2014 financial year, which means Cape Town s infrastructure leakage index has also increased over this short period. (CoCT, 2015) Chapter 2: Literature review

19 2-6 According to WCWDM Strategy report (2015), the minimum night flows where there are no industries are assumed to be water wastage as a result of: Leaks in the reticulation systems, Leaks within customers properties, Indiscriminate water wastage, And automatic flushing urinals. It is believed that leakage will always be available as a form of Unavoidable Annual Real Loss (UARL), but there is often an extra leakage that can be reduced (McKenzie, Siqalaba & Wegelin, 2012). In the case of Cape Town, currently the excess leakage is 0.8% of the total daily demand and that amounts to 7.51Mm 3 /day. The Reconciliation Strategy report (2007) for the City of Cape Town contains some of the initiatives which aim at eliminating extra leakage, which are as follows: User education and campaigns: with these initiatives, the City of Cape Town aims at making the community aware of water crisis and teaching users how to save water. These initiatives involves informative billing, media marketing, water user forums, outreach programmes and so on. Leakage detection and repair: the City of Cape Town believes that its unavoidable annual real losses (UARL) cannot be reduced economically to below 15% of the total water demand. The target is therefore the excess percentage of water loss above UARL. In addition, this initiative of leakage detection and repair is targeting low income household areas, because people in those areas cannot afford regular maintenance and repair. (WCWDM Strategy, 2015). Elimination of automatic flushing urinals: here the City of Cape Town is planning to replace all the automatic flushing urinals in public places with user-activated flushing urinals and waterless urinals. Classifications Table 2.1: Performance classification of NRW (McKenzie, 2012) Description < 15 % Low level of NRW, very good performance % Low level of NRW, good performance % Average level of NRW, average performance % High level of NRW, poor performance >50 % Very high level of NRW, very poor performance Non-Revenue Water (NRW) is defined as the amount of water supplied into the system that does not generate revenue. The City of Cape Town s NRW is currently 22.3%, and this is Chapter 2: Literature review

20 2-7 considerably better compare to average NRW of South Africa which is 36.8% (CoCT, 2015; McKenzie et al.,2012). The City of Cape Town s NRW is classified as good performance according to Table 2-1. Moreover, the City of Cape Town is hoping to improve and reduce its non-revenue water to 19% (ibid.) Inefficient water use In addition to water wastage, a significant amount of water is lost through inefficient water use (WCWDM, 2015). This is a volume of potable water that can be saved by installing Water Efficient Devices (WED) and/or through changing the users behaviour. WEDs are devices that use less water to perform the same function as the standard devices without altering the primary objective. For example, when a toilet is flushed, the objective is to clean the pan and facilitate the transportation of material to wastewater treatment works, and water efficient devices carry out this objective with less volume of water. It has been mentioned that South Africa is a semi-arid country. However, it has average water use of 235Ɩ/capita/day for domestic use, which is above the world s average of 173Ɩ/capita/day (Siqalaba et al.,2012). Figure 2-4 shows a comparison of countries average water use per capita per day. The horizontal red line represents world s average and the yellow bar is the average water use per capita per day in South Africa. It can be seen that most of the countries fall below world s average with the few including South Africa being above world s average water use. It can then be concluded that South Africa is using water inefficiently. Figure 2-4: International average water use per capita per day (Siqalaba et al., 2012) Chapter 2: Literature review

21 2-8 In Cape Town, water use per capita per day is calculated using equation 2.1. Water use (litres per capita per day) = (BAC Industrial water use)+auc Total population (2.1) Where: BAC : Billed authorized water use UAC : Unbilled authorized water use Table 2-2 presents the historical average water use per capita per day in Cape Town. It shows that water use has decreased continuously during the period between the years 2010 and 2014, and this can be seen clearly in Figure 2-5. The last recorded water use was in 2014, and it was 180Ɩ/capita/day which is below the country s average of 235Ɩ/capita/day but more than international average by 7Ɩ. From this information it can be concluded that there is amount of inefficient water use that can be saved from Cape Town. Table 2-2: Historical average water use per capita per day in Cape Town (CoCT, 2012) Sub sector % Indoor use Outdoor use Leaks Total Figure 2-5: Historical average consumption per capita per day in Cape Town (CoCT, 2012) Chapter 2: Literature review

22 2-9 The users behaviour has a big impact on the way water is used in urban areas (Hassell & Carry, 2007; Willis et al., 2007). The behaviour of water users can be changed by providing awareness, understanding and appreciation of water and the environment in which they live (Willis et al., 2007). The initiatives such as user education and water awareness campaigns can help to change users behaviour. The results of the water use survey which was conducted before the development of the Reconciliation Strategy Study (2008) indicated that 20% of the community changed their behaviour due to user education programs (DWA, 2009). Therefore, there is a potential of reducing inefficient water use through user education and campaign initiatives Water end use The amount of water that is used inefficiently for garden watering accounts for up to 40% of total demand (Jacobs et al.,2007). Since the amount of water use for garden watering varies all the time due to weather conditions such as rainfall, a conservative value of 20% is often used for inefficient water use (ibid.). According to Water Conservation and Water Demand Management (WCWDM) Strategy (2015), the efficiency of water use for garden watering can be improved significantly through Schedule 1 of Water Bylaw for the City of Cape Town, which is as follows: Irrigation scheduling states that no watering should take place between 10h00 and 16h00, Mulching should be encouraged, Plantation of indigenous plants should be encouraged, The use of grey water should be promoted to reduce the dependence on potable water for irrigation of plants, Replace grassed areas with alternative ground covers, And use pool covers to reduce evaporation. The City of Cape Town is currently in the process of conducting a household survey across all income households in order to have a better understanding of how water is used within the households (WCWDM, 2015). This will assist in finding an effective solution to water crisis that is facing Cape Town. The water end-uses that contribute the most in water demand turn to contribute more in water saving if they are being managed efficiently (Jacobs et al., 2007). Figure 2-6 shows a general breakdown of water use by household s end-uses. It can be seen that personal cleansing uses more water than other categories. Therefore, it can be concluded that there is a potential to realise a greater water saving from this category if it can be managed efficiently. Chapter 2: Literature review

23 2-10 Figure 2-6: Household water use per end-use (Jacobs et al., 2007) 2.4 Water supply in Cape Town Western Cape Water Supply System (WCWSS) currently allocates 399Mm 3 /annum of water to Cape Town at 90% level of assurance. The water is transported through a bulk conveyance pipe network which is 630km, and it serves over 1.1 million households with a population of over 3.8 million. (CoCT, 2015) According to the Water Services Departmental Sector Plan (2015), one of the City of Cape Town s goal is to make the provision of water services affordable to poor households. As a result, free basic water of 6kƖ is supplied to all residents every month. In addition, the first 4.2kƖ of sewerage is transported to the wastewater treatment works and treated free of charge for all users. The registered indigent households are provided with a free basic water of 10.5kƖ per month, and in Cape Town a total number of households qualifies for this free basic water (WSDP, 2015). Figure 2-7 shows the sources of Cape Town s raw water and how much each source is contributing to Western Cape Water Supply System (WCWSS). It can be seen that most of the raw water comes from the Department of Water Affairs water schemes which provides about 73% of the total supply. The City of Cape Town obtains the remaining 27% from its water sources. Chapter 2: Literature review

24 2-11 Figure 2-7: Cape Town's sources of fresh water (CoCT, 2015) 2.5 Water demand in Cape Town Currently Annual Average Daily Demand (AADD) for the City of Cape Town (CoCT) is 952.5MƖ (CoCT, 2015). Domestic sector s demand for potable water is 46.7 % of the City of Cape Town s total water demand (ibid.). It can be seen in Figure 2-8 that domestic sector s demand for potable water far outweighs that of the other sectors. Furthermore, domestic water use has decreased from 48.7 % in 2013/2015 financial year. As mentioned earlier, a decrease in domestic water use has a potential to realize a considerable water saving for the City of Cape Town. However, the total water demand has increased from 862MƖ to 952.5MƖ per day between 2014 and 2015, although domestic water use decreased (WCWDM Strategy, 2015; CoCT, 2015). Chapter 2: Literature review

25 2-12 Therefore, a decrease in domestic water use alone is not effective, as a result, the demands for other sectors need to be reduced. 14.8% 6.5% 8.1% 2.5% Commercial Industrial Domestic 11.0% 10.1% 47.1% Other Water supplied to external Water losses Unbilled Authorised Consumption Figure 2-8: Cape Town's sectoral water demand (CoCT, 2015) Water Conservation and Water Demand Management (WC/WDM) initiatives have been introduced to reduce the rapid increasing water demand in the City of Cape Town (CoCT). This shows that the City of Cape Town has moved from the conventional approach that was focusing on reconciling water demand by increasing the water supply alone to sustainable water demand management approach. During the period between 2011 and 2013, a big success of Water Conservation and Water Demand Management (WC/WDM) initiatives was realised. During that time the total water demand decreased by 4.8% when it was expected to increase because of the population growth of 2.9% per annum as result of childbirth and immigration (Ross, 2014). Water Conservation and Water Demand Management initiatives have a potential to reduce water demand significantly, but the City of Cape Town has not yet implemented these initiatives to their full potentials. To date the following initiatives of the Water Conservation and Water Demand Management (WC/WDM) initiatives have been implemented. In addition, these initiatives have resulted in a considerable savings based on the results of the previous projects. The amount of the savings of these initiatives are provided in Water Conservation and Water Demand Management Strategy report (2015). Chapter 2: Literature review

26 2-13 Pressure management Treated effluent Retrofit and leak repair Pipe replacement Leak detection and Meter replacement Repair on connections Figure 2-9 is an overview of the water use cycle within the City of Cape Town. The figure intends to graphically summarize this section on current water situation of Cape Town by showing how water is distributed. The estimations of water demand and water losses are provided in water balance diagram in Chapter 4. Figure 2-9: Cape Town's water use cycle (CoCT, 2015) 2.6 Future water requirements for the Cape Town The average atmospheric temperature is expected to rise by 1.5 C to 2 C by This will increase a rate of evaporation in open bodies of water, as a result, stored water will be lost through high evaporation rate (Mukeibir & Ziervogel, 2006). Precipitation is expected to decrease in Chapter 2: Literature review

27 Volume (Million m3) 2-14 frequency but increase in intensity when it happens (ibid.). An increase in evaporation rate and a drop in annual rainfall frequency will therefore reduce the City of Cape Town s annual yield for current water sources. Figure 2-10 illustrates the projected impact of climate change on the City of Cape Town s water quantity. The water yield of Cape Town from current sources is expected to decrease linearly. According to these projections, climate change will cause the City of Cape Town to lose approximately 20Mm 3 by Therefore, water yield for the City of Cape Town is expected to drop to 379Mm 3 in the year In order to prevent water shortage before 2040, additional water sources need to be found Yield drop by Years Water supply Climate impact Figure 2-10: Projected impacts of climate change on the available water supply (CoCT, 2015) High Water Requirement (HWR) growth and Low Water Requirement (LWR) growth for the City of Cape Town are estimated at 3.38% and 2% respectively. As water demand increases, climate change on the other hand is causing the quantity of the current water yield to decrease linearly as shown in Figure As a result, climate change shortens the time that will take the increasing water demand to reach the quantity of available water from current sources. Therefore, climate change mitigation and adaptation measures need to be implemented. Chapter 2: Literature review

28 2-15 Figure 2-11 shows the potable water demand projections for the City of Cape Town (CoCT). There would have been a water shortage in 2012 had water conservation and water demand management initiatives not been implemented before that year (2012). Water conservation and water demand management initiatives were further implemented to avoid projected water shortage in 2016, and that postponed water shortage by 4 years. Water demand is now expected to reach the current water yield by 2020 based on average water demand growth of 3.38% when 2013 is used as the baseline. As a result, new water augmentation schemes are needed by 2020 or water demand should be reduced in order to avoid the expected water deficit. Figure 2-1: Projections for potable water demand (WCWDM, 2015) 2.7 General recommended solutions to water deficit In this research, the solutions to prevent water deficit include reduction of potable water demand and improvement of water use efficiency. In addition, different augmentation schemes to increase and/or diversify water supply in order to have a range of supply options were also investigated. According to Flack (1981), four basic approaches to improve water use efficiency are as follows: Chapter 2: Literature review

29 2-16 Structural methods: are concerned with the improvement of the physical infrastructure for efficient water distribution. Examples for this approach include the use of water saving devices to reduce the amount of water use. Other example is the installation of pressurereducing valves to manage water pressure in the system and reduce leakages. The performance of this approach can be assessed by calculating the infrastructural leakage index. Operational methods: include operational interventions that aim at improving the efficiency of water distribution system. Leak detection and repair is a good example for this approach. For this method to be effective, operation and maintenance need to be proactive. Economic methods: involve the increase of tariffs to change the behaviour of customers towards water use. Socio-political methods: here user education and campaigns, as well as water laws and regulations are used to control the water usage. 2.8 User education and campaign initiatives User education and campaigns are initiatives which aim at encouraging voluntary water conservation, either by altering the behaviour of water users or by promoting the adoption of Water Efficient Devices (WED). Media marketing, water use forums, outreach programmes, school education programs and websites can be used to achieve the objectives of these initiatives. Furthermore, these initiatives are considered as the most important aspects of Water Demand Management (WDM) projects. According to McKenzie (2014), the well-designed projects often do not succeed because community may have not been included into the design process. Smith & Visser (2014) assessed the impact of spreading information about water saving tips to water users. A sample of low income households in Cape Town was used. Three aspects of this assessment were as follows: Increasing the understanding and awareness of households water use, Giving tips on how to save water, Providing water use comparisons to neighbours. A reduction of about 1% of water use was achieved from simply reporting water saving tips (ibid.). This percentage is equivalent to water demand of 3.3Ɩ/household/day. This shows that user education and campaign initiatives have a potential to contribute to the reduction of water use. Altering human behaviour is a continuous process, therefore user education and campaigns need to be invested in a long term and be kept interesting and relevant to the users (CoCT, 2007). In this way, both users and suppliers will not give up along the way and the objectives of the Chapter 2: Literature review

30 2-17 initiatives can be achieved. However, it is difficult to predict and measure the success of these initiatives. The informative billing is one of the tools that can be used to improve awareness and make the process interesting. This involves providing consumers with information of their water use for each month. Accompanied by this information, can be a trend of user water demand for a certain period, and an average water use of the municipality for comparison. Together with this information, tips on how to reduce water use can be included. By providing this information in a format that can be easily understood by water users, will improve awareness about the importance of saving water. Figure 2-12 shows one of the ways in which the City of Cape Town (CoCT) is promoting the awareness about the importance of saving water. The tips on how to save water are written on the wall, but there is no information on how to report water wastage, or enquire information about water usage. This shows that the City of Cape Town needs to improve the interaction with the community. Figure 2-12: Example of the ways in which the City of Cape Town promotes awareness (CoCT, 2015) 2.9 Leak detection and repair The reduction of water loss in a form of leakages can be achieved through structural and operational approaches. Firstly, the cause of this leakages need to be understood to effectively Chapter 2: Literature review

31 2-18 solve the problem of water loss. Listed below are some of the causes of leakages in Cape Town according to Mabudiro (2015): Aging of materials corrosion and condition Poor laying conditions Poor operations for example air in pipes Pressure surge faulty valves Failing joints Working pressure of pipes The study conducted by Couveils (2013), where on-site leakages were investigated in Cape Town, showed that 16.4% of 402 properties which were investigated had on-site leakages. Langa was found to have the highest occurrence of leakages (42.3%) and Mowbray with the lowest occurrence of leakages (3.8%). This difference in leakages is due to the income levels of the two areas with Mowbray being a middle income area and Langa being a low income area. Since Langa is a low income area, it can be assumed that residents are not able to afford regular maintenance and repair of pipes, and this resulted in the high amount of leakages. Therefore, domestic leak detection and repairs need to be implemented and focus mainly on low income households as planned in the Reconciliation Strategy (2007). A recent leak detection and repair programs which have been implemented were in Highbury and Wesbank, and together they saved 76 MƖ/annum (Water Conservation and Water Demand Management Strategy, 2015). The amount of water that can be saved through leak detection and repair programs depends on the extent to which these programs are implemented. As a result, many of these programs are required in order to increase the amount of water that can be saved Replacement of pipes Figure 2-13: Damage caused by a pipe burst (Mabudiro, 2015) Chapter 2: Literature review

32 2-19 Poor maintenance of pipes and aging of material contribute to water losses. According to the presentation by Mabudiro (2015), the City of Cape Town (CoCT) replaces pipes only when their collateral damages are severe, and on average 324 kɩ of water is lost per pipe burst. This approach that is used by the CoCT is costly and life threatening since poorly maintained mains can affect the surrounding environment. Therefore, a proactive operation and maintenance (O&M) of water infrastructure need to be implemented to reduce water losses. Figure 2-13 shows the damage that was caused by a pipe burst Pressure management There is a relationship between pressure and leakage rate. The amount of water lost through the leaks increases with the increase in pressure (Van Zyl & Clayton, 2007). The Fixed and Variable theory (FAVAD) is commonly used to explain the relationship between pressure and leakage rate (ibid.). The theory is explained as follows: A Fixed area discharge is that of an orifice in iron or steel pipe whereby the orifice s size does not change with the increase in pressure, as a result, a 100% increase in pressure will cause a 41% increase in leakage (McKenzie & Wegelin, 2010). A Variable area discharge is that whereby an orifice changes with an increase in pressure. The leakage increase by as much as 8 times the original value if orifice changes in size (ibid.). Therefore, a pipe material plays an important role in controlling the amount of leakage. During the periods of low water demand, mostly at night, the pressures in the water reticulation systems increase and contribute to the amount of leakage rate. According to McKenzie (2014), pressure management is one of the most important initiatives of Water Demand Management (WDM) which helps to reduce water losses. It is able to reduce the probabilities of new leaks development and pipe burst by 90% or more through the reduction of unnecessarily excess pressures (Lambert& Fantozzi, 2010). As a result, pressure management prolongs the lifespan of the reticulation systems and result in financial saving. Pressure management schemes are not effective at all areas they are being implemented (Meyer et al.,2009). Therefore, it is vital to take feasibility studies for each proposed pressure management project (ibid.). In addition, pressure management schemes need to be implemented as a part of a well-managed and well maintained reticulation systems in order to perform effectively (McKenzie, 2014). Listed below are aspects of an area that need to be taken into consideration before implementing pressure management programs according to Meyer et al. (2009): Elevation Low lying areas are likely to experience high pressure, as a result, the pressure management can be effective when applied to low lying areas. High minimum night flows Areas with high leakage will still have high water flow at night, therefore, there is a potential of high water savings in these areas. Size of an area Large areas usually have long mains and more connections, this often result in more leakage than small areas. Chapter 2: Literature review

33 2-20 Strategic facilities in areas where hospitals are present, pressure management should be avoided or a special form of pressure management should be implemented, so their pressure may be dependably constant. Currently there are three forms of pressure management, each with a unique application and advantages as well as disadvantages: Fixed outlet regulates maximum pressures entering the system using Pressure Reducing Valve (PRV). Time modulated operates the same as fixed outlet but it enables pressure to be further reduced during specified off-peak hours. Flow modulated here pressure can be controlled continuously since the live data is sent back to pressure controller at the inlet. Table 2-3: Advantages and disadvantages of pressure management forms (McKenzie&Wegelin, 2010) Form of pressure control Advantages Disadvantages Fixed outlet Simple to install and only requires PRV. The cheapest option to install Simple maintenance and operation. Pressure cannot be adjusted at different times of the day, and thus missing further saving opportunity. Time modulated Pressure can be reduced at specific, predefined times of the day. Electronic equipment is simpler and cheaper than that for flow modulated. Electronic controller is simple to set up and operate. More expertise required to operate and maintain than fixed outlet. Does not react to the demand for water and thus firefighting requirements can be a problem during the reduced pressure periods. Flow modulated Will provide the highest possible savings in the system. Can accommodate fire-fighting requirements. Installation is costly. Operation requires specialised technical skills. More opportunity for equipment to fail. Chapter 2: Literature review

34 2-21 Table 2-3 summarises the advantages and disadvantages of each form of pressure management. The aim of this table is to assist in the selection of a desired pressure management form by comparing advantages and disadvantages of the types of pressure management. To quantify the water savings through pressure management schemes, the following information is required: Length of mains Number of residential and non-residential properties Identification of large non-residential users Number of connections Condition of the network (age, reported bursts, etc.) Population figures Pressure exponent (N1) Logging of Average Daily Demand (ADD) and Minimum Night Flow (MNF) flow rates The information listed above is used as the input in FAVAD equation below. L1 L0 = (P1 P0 )N1 (3.1) The logging results give current pressure (P0) which can be compared to the level of service requirements to obtain excess pressure that can be reduced to new lower pressure (P1).The pressure exponent (N1) determines the character of the system. L1 and L0 represent new leakage flow rate and old leakage flow rate respectively (Lambert et al.,2010). Leakage flow rate can be reduced by 111m 3 /h if the MNF is reduced from 158 m 3 /h to 47 m 3 /h (WRP, 2009). Table 2-4 shows the results of the previous years projects of pressure management. Table 2-4: Pressure management savings from the previous projects (Meyer et al., 2009) Area Year commissioned Water savings (Mm 3 / annum) Implementation cost (R million) Cost Savings ( R millions/ annum) Payback period (years) Khayelitsha Mfuleni Gugulethu Mitchell s plain Belhar Chapter 2: Literature review

35 2-22 Area Year commissioned Water savings (Mm 3 / annum) Implementation cost (R million) Cost Savings ( R millions/ annum) Payback period (years) Langa Eerste River Brentwood park Figure 2-14 illustrates the suitable sites which have been identified by the City of Cape Town (CoCT) for the implementation of pressure management schemes. Due to the limited time for this research, it was found impossible to obtain necessary data to calculate the amount of water that will be saved through the implementation of pressure management schemes at the proposed sites. This is because the CoCT has not yet installed the devices to log flow and pressure at proposed sites and it takes time to do so, therefore the required inputs for FAVAD equation were not available during the period of this research. Figure 2-14: Existing and proposed sites for pressure management (Ross, 2014) Although there was no data to calculate the potential savings by pressure management schemes, Table 2-4 showed that all the past schemes have all been successful in saving water. In addition, all schemes have paid back within a short period after being implemented with the Chapter 2: Literature review

36 2-23 longest being 3 years. Therefore, increasing pressure management schemes will increase the amount of water that can be saved Water efficient devices Water Efficient Devices (WED) are similar to standard alternatives except that they use less water to carry out the same function. According to Still et al. (2008), in Europe, Australia, and the USA, the use of WED such as aerated taps, dual flushing toilets, water efficient baths, showers and basins are becoming standard. Table 2-5 shows the results of the survey which was conducted by Still et al. (2008) on 1428 households in South Africa to investigate water use and the level of awareness about WED of water users. The results of the survey indicate that about 30% of the participants were interested in using Water Efficient Devices (WED), and only 10% is already using WED. Based on these results it can be concluded that at least 30 % of the population will adopt the use of water efficient devices in the future and at most 90% of the population will install water efficient devices in the long run. Table 2-5: Survey results on the use of WED in South Africa (Still et al., 2008) Water efficient device Percentage of participants who have device fitted Percentage of those who do not have device and would like to install one Aerated tap Low flow shower Toilet- low volume Toilet dual flush Cistern displacement device Average According to the study by Coulson (2014) on Liesbeek river catchment, the adoption of Water Efficient Devices (WED) is capable of reducing the total water use of the catchment by 37%. This shows that a considerable amount of water can be saved if water efficient devices can be adopted by the entire City of Cape Town. In this study, the potential water saving through the adoption of WED was compared with that of greywater harvesting (GWH) and rainwater Chapter 2: Literature review

37 2-24 harvesting (RWH) in the catchment. The amount of potable water that can be saved through the adoption of WED outweighed that of greywater harvesting (GWH) which was 12% and rainwater harvesting (RWH) which was 13%. Since water that can be saved by Water Efficient Devices (WED) is potable, that gives this option of reducing water demand an advantage over other alternatives. This is because potable water does not have any restrictions on usage, for example greywater and rainwater cannot be used for drinking, and a separate, expensive and complex water system is required for greywater and rainwater use Tariff increase Different countries use different structures of tariff blocks to control water demand (Still et al., 2008). The City of Cape Town (CoCT) uses a five-step tariff block and it was introduced in 2001 (DWA, 2007b). This structure was designed in such a way that it can accommodate 6kƖ/month of free basic water for each household in Cape Town (ibid.). Figure 2-15 illustrates historical tariff structure for Cape Town. It can be seen that tariffs have been increasing since 2008/2009 financial year, and in 2010 a proportion of block one was shifted to block two and proportion of block three was shifted to block four in order to reduce water demand. Furthermore, the increase in tariffs is higher across all blocks for both 2012/13 and 2013/14. Figure 2-15: Historical tariff block for the City of Cape Town (CoCT, 2014) Chapter 2: Literature review

38 2-25 The City of Cape Town has successfully used tariff increase to reduce water demand during periods of droughts. According to Reconciliation Strategy (2007), 30% of the tariff increase in Cape Town has a potential to reduce up to 6 % of the total water demand. The tariff increase has the greater impact on changing water users behaviour when compared with the adjustment of meters and credit control measures (DWA, 2007b). In addition, tariff increase can also be used to improve revenue, and use that money to fund new water schemes while the demand is being reduced Greywater harvest The study by Coulson (2014) on Liesbeeck River catchment showed that greywater can potentially supply 12% of the catchment s water demand. However, greywater can only be used for two end-uses at homes, namely flushing toilets and garden watering. This is because the level of human contact with water for toilet flushing and garden watering is very low. Therefore, health risks associated with human contact with greywater will be minimized. Greywater has a foul odour when it has been kept for a long time and this will be a challenge when it is used for flushing toilets. As a result, using greywater for garden watering only will be the best option. This will help to avoid a prolonged storage of greywater, in turn a foul odour will be avoided. In addition, the use of greywater will provide a constant supply for garden watering throughout the year at the cheaper cost than that of potable water. Although, the probabilities of humans coming into contact with grey water are very low when it is used for garden watering, there is still a need for a basic level of greywater treatment and trip irrigation will need to be used to further minimise health risks (Christovaboal et al., 1996;Jeppesen, 1996). The installation and management of greywater systems are complex, and its broad scale adoption by the City of Cape Town will become a challenge (Coulson, 2014). However, this challenge can be simplified by using greywater for large properties such as schools, business complexes and hospitals. Improper storage and use of greywater has serious health risks (Christovaboal et al., 1996;Jeppesen, 1996). Therefore, there will be a need for extra care when greywater is used by hospitals since there are more vulnerable people in hospitals Rainwater harvesting The use of rainwater has less health implications when compared to greywater. In addition, rainwater does not have a foul smell when it has been kept for long and it can be used for more end-uses than greywater, for example washing clothes. The past studies have shown that rainwater harvest has a potential to reduce demand for potable water by a considerable amount as it can be seen from the previous years studies listed below: Chapter 2: Literature review

39 2-26 The study conducted by Abdulla & Al-Shareef (2009) over twelve areas in Jordan, has shown that a potential reduction of the demand for potable water ranges between 0.29% to19.7%. The Study conducted by Coulson (2014) in Liesbeek River catchment, showed that a potential reduction of a demand for potable water can be up to 13 % of the total demand of the catchment. The study which was conducted by Ghisi, Montibeller & Schmidt (2006) over 62 cities in Brazil, has shown that a potential reduction of the demand for potable water ranges between 34% and 92%. Although the statements above proved that rainwater harvesting has a potential to reduce potable water demand, the City of Cape Town cannot adopt rainwater harvest since it is located in a winter rainfall region Private boreholes/ wellpoints Private boreholes and wellpoints are some of the potential solutions to increase water supply and reduce demand for potable water. Boreholes and wellpoints serve the same function, but the difference is that boreholes are deeper and more expensive than wellpoints. This presents an opportunity for low income and middle income residents, as they can install wellpoints instead of boreholes. Although private wellpoints have potential to improve water supply, they have consequences. One of the consequences of wellpoints is that an area will run at a risk of saline intrusion if a groundwater is over-extracted, especially in coastal areas (Mardini, 2010). Moreover, when boreholes are randomly drilled and water is collected from many points that will lead to a reduction in net flow of underground water and in turn affect water cycle (ibid.). The City of Cape Town will have to put laws and regulations in place to mitigate these consequences of using boreholes and wellpoints Groundwater Groundwater forms 1.5% of the total raw water allocated to the City of Cape Town (CoCT) by Western Cape Water Supply System (WCWSS) (WSDP, 2013). The City of Cape Town is currently using only two aquifers, namely Albion Springs and Atlantis Groundwater Scheme although there are at least nine aquifers in Cape Town. Seven aquifers which are currently not used by the City of Cape are listed below: Adamboerskraal Aquifer, Langebaan Road Aquifer, Elandsfontein Aquifer, Chapter 2: Literature review

40 2-27 Grootwater Aquifer, Table Mountain Group (TMG) Aquifer, Newlands Aquifer, Cape FlatsAquifer. The first four aquifers are referred to as the West Coast Aquifers, and their total annual yield is currently not known. The last three aquifers have been considered as the future water supply schemes in the City of Cape Town and their total annual yield is estimated at 68Mm 3 /annum (CoCT, 2015). Table Mountain Group Aquifer (TMG) contributes the most with the total annual yield of 48Mm 3. Although Table Mountain Group Aquifer (TMG) is expected to have the highest yield, its geological nature makes it challenging for the abstraction of water. There are faults which prevent a continuous flow of groundwater and that separates a body of water into small volumes. Figure 2-16 illustrates the geological nature of Table Mountain Group aquifer. Figure 2-16: Illustration of the geology for Table Mountain Group aquifer (Knowles et al., 2005) Conjunctive use is the scheme that involves injecting excess surface water into the aquifers in winter and using it in summer. It also involves pumping groundwater into the storage facilities of surface water to supplement supply when dam levels are low. According to the Reconciliation Chapter 2: Literature review

41 2-28 Strategy Study (2007), opportunities for conjunctive use exists primarily in the West Coast aquifers and the Breede River Valley alluvium. As previously mentioned, climate change is expected to reduce the frequency of precipitation and cause an intense rainfall when it occurs. In addition, evaporation rate is expected to increase as the temperature rises. Therefore, conjunctive use schemes will come in handy when these conditions are experienced. This is because aquifers will be used as extra storage for excess surface water from intense precipitations. Moreover, water loss through evaporation can be reduced by storing water underground in the aquifers Desalination Desalination is the process of removing salt from seawater or brackish water to produce fresh water. Seawater desalination is now hailed as the solution by some countries to the problem of water shortage. However, desalination is more expensive relative to other alternatives such as reuse of treated effluent (Koschikowski, 2011). Although desalination is more expensive compared to other options, seawater is an unlimited and reliable water resource. Despite the high cost to desalinate seawater, the City of Cape Town (CoCT) has considered it as one of the future sources of water supply in Cape Town (CoCT, 2015). Since Cape Town is located next to the sea, it will be easy to obtain seawater. According to Mabudiro presentation (2015), the City of Cape Town is hoping to desalinate up to 160Mm 3 /annum in the future. This will be a significant augmentation to the current water yield. Desalination requires a large amount of energy. As a result, an extensive development of desalination will increase the dependence on fossil fuel, hence increase emissions of greenhouse gases (Kendrick, 2011). This will worsen the situation of climate change, therefore the use of seawater should be limited to mitigate the impacts of climate change Treated effluent The City of Cape Town (CoCT) has a total of 27 wastewater treatment plants, of which 9 have the facilities to extract treated wastewater before it is released into the rivers, wetlands and sea. This treated wastewater is further cleaned to produce treated effluent, and then transported to the customer for irrigation. The use of treated effluent in Cape Town was introduced in 2004 (Water Sustainable Development Plan, 2013). The distribution network for treated effluent consists of orange pipelines, and that makes it unique from the other water distribution networks. Figure 2-17 shows a pipeline for treated effluent. Chapter 2: Literature review

42 2-29 Figure 2-17: Pipeline for distribution of treated effluent (WSDP, 2011) There are number of benefits of using treated effluent for both the City of Cape Town (CoCT) and water users: The demand for potable water can be reduced by substituting potable water with treated effluent for certain water uses, for example irrigation. The City of Cape Town can increase its revenue by selling more treated effluent, rather than discharging treated wastewater into the sea, Irrigation with treated wastewater is not limited during water restriction periods, therefore this will benefit water uses, Treated effluent is cheaper than potable water and this is a benefit to water users, The use of treated effluent promotes diversification of water supply hence prevent exhaustion of fresh water. Treated effluent can be used for garden watering and flushing toilets in the domestic sector. However, like greywater, it requires a complex system which is difficult to manage and implement. Furthermore, a human contact with treated effluent has serious health risks and this is one of the issues that will make the use of treated effluent challenging. Besides using treated effluent for irrigation and indusrtial use, it can be treated further to the standard of potable water and then augment the supply of potable water. This will facilitate the use of treated effluent without restrictions of use, for example, it will be used for drinking and cooking. Furthermore, a separate infrastructure to distribute this water will not be required and there will be no health risks associated with this option. Chapter 2: Literature review

43 2-30 Table 2-6 presents the potential amounts of wastewater that can be treated from some of the Cape Town s wastewater treatement plant in one year. In total, Mm 3 of wastewater can be treated by the City of Cape (CoCT) in one year according to Mabudiro (2015). Table 2-6: Potential amount of treated effluent per year (CoCT, 2015) Wastewater treatment works (WWTW) Total existing summer reuse (Mm 3 /d) Potential expansion of summer reuse (Mm 3 /d) Total potential reuse (Mm 3 /d) % of Total dry weather effluent treated Total potential annual reuse (Mm 3 ) Athlone Bellville Borcherds quarry Cape Flats Gordonsbay Kraaifonteen Macassar Melkbos Strand Mitchell s Plain Parrow Potsdam Scottsdene Wesflur(Atlantis) Weldevoelvlei Zandvleit Marine outfalls Total Surface water development According to the Reconciliation Strategy Study (2007), there is a number of options to increase water supply through the development of surface water. This includes construction of new dams, river diversions and raising of dam levels. Listed below is a list of future projects that have been considered by the City of Cape Town to increase water supply. Raising Lower Steenbras Dam Construction of new Dam (Upper Campanula dam) Chapter 2: Literature review

44 2-31 Lourens River Diversion Eerste River Diversion Voelvlei Augmentation Construction of new dam at Misverstand Construction of Twenty-four Rivers Dams Construction of Waterval River Dam Michell s Pass Diversion Raising Theewaterskloof Dam Construction of Lower Wit River Dam Wemmershoek Dam and pipeline Upper Molenaars Diversion Brandvlei to Theewaterskloof transfer Refer to Appendix F for the descriptions of the future projects listed above. However, these projects are expensive and lengthy. According to the water demand projections based on high water requirements (HWR), the City of Cape Town will have a shortage of water by 2020 if nothing is done, either lowering the water demand or increase the supply of water. Therefore, a quick solution to prevent the expected water shortage is needed and this research focused on the projects which can provide quick solutions. Chapter 2: Literature review

45 Procedure for WED calculations The chapter presents the results for low income households. The results for middle and high income house households can be found in Appendix B. The procedure described in this chapter for low income household was used to do calculations for middle and high income households. The topic of water savings through the adoption of water efficient devices is often subjective, for example when a 9Ɩ normal flush toilet is compared with an old 13Ɩ flush toilet, a 9Ɩ toilet will be considered efficient. However, this cannot be the most efficient option since there are some specialized flush toilets that can use as little as 1.5Ɩ per flush (Schlunke et al.,2008). To solve this issue, water efficient devices for the end-uses were categorized into two groups namely, high saving devices and medium saving devices. In order to calculate the potential water savings through the adoption of water efficient devices, average frequencies of water use and volumes required per event for each domestic enduse were obtained from the results of the survey which was conducted by Jacobs & Haarhoff (2004) in South Africa. These results are presented in Table 3-1. Table 3-1: volumes and frequencies for domestic end-uses (Jacobs & Haarhoff, 2004) Water devices Low water use Volume (Ɩ/ event) Typical water use High water use Frequency (per event per person/day) Low water use Typical water use High water use Bath Bathroom basin Dishwasher Kitchen sink Shower Toilet normal Toilet dual flush large Toilet dual flush small Washing machine Chapter 3: Procedure for WED calculations

46 3-2 Then, data of the amount of water use by different water efficient devices (WED) was obtained from the results of the survey which was conducted by Still et al. (2008) and Jacobs & Haarhoff (2004). This data is tabulated in Table 3-2. Table 3-2: Water volume used per event by end-uses (Jacobs&Haarhoff, 2004; Still et al., 2008) Volume per event (Ɩ / use) Water efficient devices High saving device Medium saving device Standard device Time (min) Bath Bathroom basin 2.4 l/min 6 l/min 9 l/min 0.4 Dishwasher Kitchen sink 2.4 l/min 6 l/min 12 l/min 0.6 Shower 7 l/min 10 l/min 15 l/min 4 Toilet-normal Toilet- dual flush large Toilet- dual flush small Washing machine Table 3-3: Reduction coefficients for low income households in Cape Town Water efficient devices Frequency (use/p/d) Standard device Device (l/use) Demand (l/p.d) High Saving device Device (l/use) Demand (l/p.d) Medium Saving device Device (l/use) Demand (l/p.d) Bath Bathroom basin Dishwasher Kitchen sink Shower Toilet-normal Toilet- dual flush large Toilet- dual flush small Chapter 3: Procedure for WED calculations

47 3-3 Water efficient devices Frequency (use/p/d) Standard device Device (l/use) Demand (l/p.d) High Saving device Device (l/use) Demand (l/p.d) Medium Saving device Device (l/use) Demand (l/p.d) Washing machine Total Coefficients The reduction coefficients for inefficient water use in domestic sector were then calculated using the information in Table 3-1 and Table 3-2. In this research it was assumed that residents in low income areas do not have dishwashers, showers and washing machines. Therefore, frequencies for these devices were equated to zero. To calculate reduction coefficients, the frequency of use for each water device was multiplied by a volume required per event to get a daily demand. This calculation was done for standard, high saving and medium water saving devices. The total demand for high and medium water saving devices were each divided by the total demand of standard devices to get reduction coefficients. Table 3-3 presents the reduction coefficients for low incomes household in Cape Town. The same calculations were also done for middle and high income households, and the tables for these calculations can be found in Appendix B. Table 3-4 presents a summary of the calculated reduction coefficients for low, middle and high income households. The average coefficients for high and medium water efficient devices was then calculated. Table 3-4: Average reduction coefficients for high and medium saving devices Household income level High saving device Medium saving device High income Middle income Low income Average The average coefficients were then used to determine the annual reduction of water for the City of Cape Town at three adoption rates of water efficient devices. First adoption rate was when 30% of the Cape Town s population have water efficient, second adoption rate was when 50% of the population installed water saving devices and the last one was when the whole community of Cape Town have water efficient devices. These adoption rates were chosen based on the findings of the survey conducted by Still et al. (2008) which were discussed in Chapter 2. Chapter 3: Procedure for WED calculations

48 3-4 Finally, an estimation of the amount of water reduction was obtained by multiplying the annual domestic water demand for Cape Town by a reduction coefficient and the percentage of people using devices (high and medium saving devices). For example, if the average water use for a particular low income household was 6kƖ/month and medium saving devices were adopted, then water use would reduce to 4.1kƖ/month. Chapter 3: Procedure for WED calculations

49 Results and discussion This chapter presents the findings of the research. It starts off by providing an overview of the current situation of the City of Cape Town regarding potable water supply. Then, it continues by providing the results of the proposed solutions. The proposed solutions are grouped into two categories, namely water demand reduction and water supply increase. Finally, the results of the combined effects of the two solutions are provided. Figure 4.1 is a graphical summary of how this chapter is structured. The situation of water supply in the City of Cape Town The current water balance. Future projections of water demand and supply. Impacts on the City of Cape Town s water supply. What needs to be done to solve the City of Cape Town s water crisis? Solutions Reducing water demand How can this be achieved? How much water can be saved? Results after implementing water reduction measures. Increasing potable water supply How can this be achieved? By how much potable water needs to be increased to ensure sufficient supply in 2040? Results after increasing water supply. Combined results of water demand reduction and water supply increase. Figure 4.1: Structure for chapter four Chapter 4: Results and Discussion

50 The situation of the city of Cape Town s water supply Figure 4.2: current water balance for Cape Town Chapter 4: Results and Discussion

51 Annual Water Volume (Mm 3 ) 4-3 Figure 4.2 illustrates the current water balance for the City of Cape Town (CoCT). The Western Cape Water Supply System (WCWSS) currently provides the City of Cape Town with 399Mm 3 of potable water per annum at 90% level of water supply assurance. This water is distributed to different water use sectors as shown in Figure 4.2. Then, about 62.5% is discarded into the sewage system as wastewater and then transported to nearby wastewater treatment works (WWT). This wastewater is then treated before released into the environment from the wastewater treatment works, to reduce harm to the environment. About 13.6% of the treated wastewater is further treated to become treated effluent, and then used for irrigation. The remaining 37.5% of the supplied potable water that is not discarded as wastewater, it is used outdoors, and some of it is lost into the atmosphere as a result of evapotranspiration. The rest of the other water percentage infiltrates into the soil due to pipe leakages and recharge groundwater. (Water Conservation and Water Demand Management Strategy, 2015) Years Water suppy to CoCT by WCWSS Actual trend in the previous years Impact of climate change Projected trend for high water requirement Projected trend for low water requirement Figure 4.3: Projections of Cape Town's water demand Chapter 4: Results and Discussion

52 4-4 The City of Cape Town uses water demand growth rates of 2% and 3.38% per annum to make projections for Low Water Requirements (LWR) and High Water Requirements (HWR) respectively. These growth rates were used in this research to make water demand projections from 2014 to 2040, and the results are shown in Figure 4.3. The figure shows that Cape Town will experience a shortage of water in 2021 if water demand follows HWR trend (yellow line), but if water demand follows LWR trend (green line), Cape Town will experience water shortage in However, it was shown in Figure 2-11 that the City of Cape Town is expecting a shortage of water to occur in 2020 based on HWR trend. This difference in years of water shortage occurrence is because the City of Cape Town used the year 2013 as the baseline for the projections, and in this research 2014 was used as the baseline. The reason for using the year 2014 as the baseline is because that is the year in which the last actual water demand was measured by the City of Cape Town. To be more accurate, the City of Cape Town should expect water shortage by 2021 not 2020, only if nothing is done on high water requirements. This research has found that although population growth and economic growth contribute to water demand increase, the biggest driver of water demand growth is the rise in the standard of living. This is because people tend to consume more stuff when their standard of living goes up (Parkin et al., 2008). Therefore, water demand was decided to be reduced by decreasing water losses and the total amount of inefficient water use. As mentioned in Chapter 2, the total water loss currently accounts for 15.8% of the total water demand for the City of Cape Town (CoCT). The Unavoidable Annul Real Loss (UARL) for the Cape Town is 15% of the total water demand. Therefore, the City of Cape Town can economically reduce the total water loss by 0.8% of the total water demand. This can be achieved through the implementation of the Water Demand Management strategies which were mentioned and discussed in chapter 2. Since the rising standard of living leads to a higher water usage, Water Demand Management (WDM) strategies need to be implemented to reduce the growth of water demand. For the purpose of this research, the amount of inefficient water use that can be reduced through the adoption of Water Efficient Devices (WED) in the City of Cape Town was modelled. The inefficient water use was considered only in the domestic sector, as it accounts for 47.6% of the total water demand. This is because a large percentage of water saving can be realised by reducing inefficient water use in the domestic sector. 4.2 User education and campaign programs It was found that user education programs play a very important role in reducing water demand. This is because, often the well-designed projects for reducing water demand do not succeed because community may have not been included into the process (McKenzie, 2014). These programs help to teach people about and make them aware of the new strategies of saving water. For example, according to Still et al. (2008), about 60% of the South African population is not Chapter 4: Results and Discussion

53 Annual Water volume (Mm 3 ) 4-5 aware of the water efficient devices. This is one of the reasons the adoption rate of water efficient devices is low in South Africa, with only 10% of the population using the devices. Education programs need to be expanded and lead the implementation of the new strategies. This will help to change human behaviour regarding water usage, and increase awareness of the importance of saving water in the community. Furthermore, this will increase the knowledge of the community on how to save water, because people cannot be able to save water if they do not see the importance and know to save water. 4.3 Results of water demand reduction Years Water supplied to CoCT by WCWSS Actual trend in the previous years Impact of climate change Projected trend of high water requirements 30% WED adoption 50% WED adoption 90% WED adoption Final results Figure 4.4: Projections for high water requirements after water demand reduction Chapter 4: Results and Discussion

54 4-6 Figure 4.4 shows the results of high water demand after the adoption of water saving devices and reduction of real water loss. The dotted-lines show the trends that will be followed by unrestricted growth in water demand. When the results of water saving devices were modelled, it was assumed that it will not be possible for all residents in Cape Town to install the devices at the same time. Therefore, three adoption rates namely 30%, 50% and 90% were used over time. According to the assumptions of this research, it can take 3 years to install water saving devices to 30% of the Cape Town s population, if the City of Cape Town can be committed to this idea. It was further assumed that the whole population will have water saving devices by 2023, which is 8 years from now. Furthermore, it was assumed that by 2025 water distribution network will be losing only 15% of the total water demand which is unavoidable water loss for the City of Cape Town. It can be seen in Figure 4.4 that the current amount of available potable water supply is decreasing constantly due to the impacts of climate change. This is represented by a red dash line, and the predictions of this trend were made by the City of Cape Town based on the assumption that climate change will reduce the current system s yield by 5% in 25 years. The impacts of climate change include, inter alia, high rate of evaporation due to the increase in average temperature and a decrease in rainfall frequency. This decline in the total yield from the current water sources will shortened the time that will take the increasing water demand to reach the available supply by a year. In contrast to the climate change projections shown in Figure 4.4, some research has indicated that the impacts of climate change on the system yield is not a steady decline but rather a fluctuating trend (Reconciliation Study, 2011). Therefore, in order to provide a more accurate predictions of the impact of climate change on the available fresh water resources, a detailed modelling is required, and that is beyond the scope of this research. Figure 4.4 shows the same water demand of approximately 350Mm 3 /annum in 2017 and 2025 after the implementation of demand reducing strategies. During the period between these years, there is a fluctuation of water demand. This is because water efficient devices reduce a certain amount of inefficient water use after the installation while there is continuous increase in water demand. According to the projections in Figure 4.4, the adoption of water saving devices and reduction of non-revenue water will prevent water demand growth between 2017 and In turn, the need for additional water supply source will be extended by 7 years, from 2021 to Based on the new projections, water demand is now expected to be 577Mm 3 in 2040, which is 178Mm 3 above the total water yield from the current water sources. This water demand can be reduced further by expanding the adoption of water inefficient devices to other sectors such as industrial and commercial sectors, and not limiting water efficient devices to indoor use. The solutions that have been provided in this report so far, have the potential to decrease water demand in 2040 from 747Mm 3 to 577Mm 3, and this will result in a water saving of 170Mm 3. Chapter 4: Results and Discussion

55 Water volume (Mm 3 ) 4-7 As it can be seen in Figure 4.4, there will now be a water deficit after 2028, therefore additional water sources that can ensure water security until 2040 were investigated instead of decreasing water demand by implementing more demand reducing interventions. This is because climate change, on the other hand, is causing a decline in the available amount of fresh water resources. As a result, even if water demand remains constant the change in climate will cause a water shortage. The result of additional water sources are provided in the following section. The population of South Africa is expected to start declining in the early 2030s, mainly due to lower fertility rate and the impact of AIDS epidemic (CoCT, 2010). This will in turn result in a decline of water demand growth rate in the City of Cape Town. This is because the growth rate of water demand depends on the rising standard of living and population growth. Therefore, the results that are shown in Figure 4.4 might change around the year 2030 when the growth rate of water demand decreases Years Water supplied to CoCT by WCWSS Actual trend in the previous years Impact after 30% WED adoption rate Impact after 90% WED adoption rate Impact of climate change Projected trend of low water requirents Impact after 50% adoption rate Final results Figure 4.5: Projections for low water requirements after reducing water demand Chapter 4: Results and Discussion

56 4-8 Figure 4.5 shows the projections of low water requirements trend. The City of Cape Town uses 2% per annum as the growth rate for the projections of low water requirements. The 2% per annum growth rate was therefore used in this research. The same procedure which was explained above for the projections of high water requirements in Figure 4.4, was used to make the predictions shown in Figure 4.5 for low water requirements. This represents the lower bound of water demand projections for the City of Cape Town. Household s water efficient devices were assumed to first be adopted in 2017 by 30% of the population in Cape Town. Then, 50% and 90% of the population were assumed to install the devices by 2019 and 2023 respectively. Furthermore, by 2025, it was assumed that 100% of the Cape Town s population will have household s water efficient devices and the City of Cape Town will have achieved the reduction of water loss to 15% of the total demand. This is the reason Figure 4.5 shows a fluctuation of water demand between 2017 and 2025, then the water demand continues to increase after the fluctuation. Between the year 2017 and 2025, there is a total decrease in water demand, which is the amount of inefficient water use. The new projections after reducing inefficient water use show that water deficit will now be experienced in 2036 instead of This postpones the need for additional water sources by a period of 10 years. However, water deficit would be required by 2039 in the absence of climate change. As a result, climate change has shortened the time to experience water deficit with about 3 years. Moreover, in the year 2040, water demand will be 320Mm 3 above the expected water yield of that year. Further water demand reduction measures will need to take place or additional water sources will need to be found by Options for additional water supply A number of potential options to increase the total water yield of the City of Cape Town were investigated, and discussed in Chapter 2. The pros and cons of these options were evaluated, and the approach of multi-criteria analysis was used to choose the best three options in this chapter. The potential options to increase water yield of the current water sources that were considered in this research are listed below, and each option was assigned a number which represented it in the multi-criteria analysis table. 1. Greywater harvesting 2. Rainwater harvesting 3. Reuse treated effluent 4. Treat effluent to the standard of potable water 5. Add more aquifers to the system 6. Promote the use of boreholes/well-points 7. Desalinate sea water Chapter 4: Results and Discussion

57 4-9 Table 4.1 presents the results of the multi-criteria analysis. To carry out the analysis, negative impacts of each option were scaled out of 10. The higher the scale value the more negative impact an option has. The important issues that should be considered before the implementation of each option were also investigated, and they are presented in the Table 4.1. Furthermore, each considered issue was assigned a level of importance between 0-10 based on the judgement and knowledge of the researcher. Table 4.1: Multi-criteria analysis table Issues Alternatives Level of importance Environment/health risks Options with low annual yield Complexity to implement Option that are expensive to implement Negative impacts: Impact*importance The positivity of each option was calculated by subtracting the total negative impact of each option from 400, which is the maximum negativity an option can have. The costs of the alternatives were regarded as negativity; the more expensive the alternative is, the more negative impact it has. The positivity values for all options are presented in Table 4.2 together with the rankings. The first three options with the highest positivity values, were considered as the best options to supplement the total water yield in order to avoid the expected water shortage in Cape Town. Chapter 4: Results and Discussion

58 4-10 Table 4.2: Ranking of the alternatives' positive impacts Alternatives Positivity Ranks Greywater harvesting th Rainwater harvesting th Reuse treated effluent th Treat effluent to potable water st Use more aquifers nd Wellpoints/boreholes th Seawater desalination rd 4.5 Treat effluent The City of Cape Town treats about 214Mm 3 of wastewater per annum. Most of the treated wastewater is discharged into the sea while about 13.5% of the treated effluent is used for groundwater recharge and irrigation, mostly golf courses. In addition, it was found that the City of Cape Town has the potential to increase the amount of treated effluent reuse by 31Mm 3 per annum. This additional amount of treated effluent can be used to offset the need of potable water, or it can be treated to the standard of treated potable water, and supplement the total water yield. The results of multi-criteria analysis indicated that it will be more economical to treated wastewater to the standard of potable water than reusing treated effluent. The water will be able to use the existing potable water infrastructure for distribution, and hence save additional costs of constructing separate infrastructure for transportation and safe irrigation systems. Moreover, this will significantly reduce health risks. This research therefore suggests that the City of Cape Town upgrades its wastewater treatment plants, and reuse 31Mm 3 of the treated effluent as potable water per year. This will help to save the costs and prevent water deficit. 4.6 Seawater desalination Desalinating seawater is expensive compare to the purification of fresh water and wastewater. However, the results of multi-criteria analysis ranked seawater desalination as the third best option compared to the other potential options which were considered in this research. Furthermore, it was mentioned in chapter 2 that the City of Cape Town is aiming at desalinating 160Mm 3 per annum of seawater in the future. This amount will increase the current total water Chapter 4: Results and Discussion

59 Volume (Mm3 per annum) 4-11 yield of Cape Town by 47% to 599Mm 3 per annum. This will substantially improve the water supply of the City of Cape Town. Some of the benefits of desalinating seawater is that there are no health risks posed to the users, and desalinated water can be distributed through the existing infrastructure of potable water. In addition, seawater is a reliable and unlimited water resource. This will ensure that the City of Cape Town will not be affected during drought periods, since climate change is expected to cause droughts in the future. However, some researchers claim that the use of seawater will exacerbate the situation of climate change because that will increase the use of fossil fuel. 4.7 Groundwater Aquifers Desalinated seawater Reuse treated effuent 31 Proposed options Figure 4.6: Potential contribution by each additional water source The results of multi-criteria analysis show that Table Mountain Group aquifer, Newlands aquifer and the Cape Flats aquifer have a high potential to improve the City of Cape Town s water supply. Furthermore, the use of these aquifers is regarded as the second best option compare to the other options that were considered in this research. Currently the City of Cape Town uses two aquifers, namely, Albion Springs and Atlantis Groundwater Scheme. These aquifers account for 1.5% of the potable water supplied to the City of Cape Town (WSDP, 2013). The Table Mountain Group aquifer, Newlands aquifer and Cape Chapter 4: Results and Discussion

60 Water volume (Mm 3 ) 4-12 Flats aquifer will therefore increase the use of groundwater in the Cape Town. The total potential annual yield of these three aquifers is estimated at 68Mm 3 per annum. These aquifers will increase the current annual water yield by 17% to 467Mm 3 per year. The Table Mountain Group (TMG) aquifer has a considerably higher annual yield compare to the other two aquifers. Its annual yield is estimated at 40Mm 3. However, the abstraction of groundwater for TMG aquifer is not easy. This is due to the geological nature of the area in which it is located. This area is still under the investigations to optimize the abstraction from the Table Mountain Group aquifer. Lastly, it was found that there are four more west coast aquifers which are not being used by the City of Cape Town. The annual yield volumes of these aquifers are currently not known. They are located close to the rivers, and this rise the opportunity for conjunctive use. Conjunctive use is a process of transferring water between the aquifers and dams. This will help to provide extra storage of water during winter when there is a high rainfall. The water stored in these aquifers will then be transferred back to supplement dams during dry months of summer. Figure 4.6 shows the breakdown of the water contributed by each proposed option to the current water system. The total volume of these options is the solution to increase water Cape Town s annual water yield. 4.8 Future projections of water demand Years Water supplied to CoCT by WCWSS Impact of climate change Actual trend in the previous years Projected trend of high water requirements Projected trend of low water requirents Aquifers Seawater desalination Reuse treated effluent Figure 4.6: Projections of water demand after including additional sources Chapter 4: Results and Discussion

61 Water volume (Mm 3 ) 4-13 Figure 4.7 shows the projections of unrestricted low water requirements and high water requirements with an increased annual water yield. The total water supplied to the City of Cape Town has been increased by 259Mm 3 per annum. However, if the increase in water demand follows high water requirement s trend, there will be a shortage of water by the year 2036; but if the increasing water demand follows the trend of low water requirement, water deficit will be experienced after the year To ensure water security in the City of Cape Town until 2040, water demand should be controlled to follow low water requirements trend. This can be achieved by implementing Water Demand Management (WDM) strategies, to reduce the amount of water use. If low water requirements cannot be maintained, the City of Cape Town will need more water sources by 2036 as shown in Figure 4.7. The projected high water requirement will be 747Mm3 per annum in 2040, and that is 112Mm3 greater than the proposed water supply increase. Therefore, to avoid water shortage before 2040 by increasing water supply, the City of Cape Town needs find additional water sources that can supply 371Mm3 per annum unless the demand decreases. 4.9 Final results Years Water supplied to CoCT by WCWSS Impact of climate change Actual trend in the previous years Projected trend of high water requirements 30% WED adoption 50% WED adoption 90% WED adoption Final results Aquifers Seawater desalination Reuse treated effluent Figure 4.7: Final projections for high water requirements Chapter 4: Results and Discussion

62 Water volume (Mm 3 ) 4-14 Figure 4.8 illustrates the final high water requirements projections after increasing total water supply and reducing inefficient water use in Cape Town. These projections were carried out to check the situation of water supply in 2040 after implementing the suggested solutions which intended to ensure water security by It can be seen that the projected water demand is lower than the total water supply in 2040, therefore, if the proposed solutions are implemented, the City of Cape Town will not experience water crisis by the year When the projections were done, the time required to put each proposed solutions into effect was taken into consideration. The estimations of the time required to implement each solution were given by Mr Colin Mabudiro (Head of Water Demand Management and Operations for the City of Cape Town) during the interview. As it can be seen in Figure 4.8, it was assumed that additional aquifers will be used by 2027, which is 12 years from now. In addition, more water will come from treated effluent which is assumed to happen in 16 years from now. Lastly, the facilities to desalinate seawater of about 160Mm 3 per annum are assumed to be completed by the year 2034, which is 19 years from In overall, the City of Cape Town is assumed to have additional water supply of 259Mm 3 per annum in 19 years time. The water demand is projected to be 747Mm 3 per year in 2040 for unrestricted water demand growth. The implementation of the suggested solutions to reduce the amount of inefficient water use will help to decrease water demand in 2040 to 577Mm 3. In addition, the implementation of these solutions will postpone the time of water shortage by 7 years, and this will enable additional water sources projects to be completed before the City of Cape Town experience water deficit. Lastly, after the implementations of all the proposed solutions, a shortage of water will now be expected to happen in the year The proposed solutions will therefore help to extend water supply of the City of Cape Town by 32 years Years Water supplied to CoCT by WCWSS Actual trend in the previous years Impact after 30% WED adoption rate Impact after 90% WED adoption rate Aquifers Impact of climate change Projected trend of low water requirents Impact after 50% adoption rate Final results Figure 4.8: Final projections for low water requirements Chapter 4: Results and Discussion

63 4-15 Figure 4.9 illustrates the projections of low water requirements after reducing the amount of inefficient water use and increasing water supply. The trend of low water requirements shows that, a first water deficit will be experienced in 2036 if only water use reduction measures are implemented. Furthermore, in 2040, water demand will be 32Mm 3 greater than the available supply. As a result, additional water sources had to be added into the system to increase the supply. The additional sources consists of only aquifers namely, Table Mountain Group, Newlands and Cape flats aquifers. The seawater desalination and treated effluent were not considered here since the demand is low, and water security can be achieved through the use of ground water alone. The reason for choosing aquifers over seawater desalination and effluent reuse is the costs associated with water purification. In additional, new big infrastructures are not required for using groundwater as compared to the other two options. As a result, the City of Cape Town will save money by choosing groundwater. Since the water demand is still increasing, seawater desalination and reusing treated effluent will be needed in the future, if no better alternatives have been found. Furthermore, by comparing the results of high water requirements (HWR) and low water requirements (LWR), it can be seen that a lot of effort will be needed if water demand follows HWR trend. Therefore, this can be avoided by ensuring that water demand follows LWR trend by further implementing water demand management strategies. The water balance of the City of Cape Town for the year 2040 was done for only high water requirements, which is the worst-case scenario. Figure 4.10 illustrates the predicted 2040 water balance after the implementation of the suggested water solutions. From the figure, it can be seen that only 79Mm 3 of the desalinated seawater will be needed to supplement water supply, if all the other proposed solutions are used to their full potential. This will save the costs of desalinating extra 81Mm 3 per annum. In addition, water supply in the City of Cape Town will be diversified. This will ensure that water supply in Cape Town is sustainable and resilient since there will be alternative supplies. Finally, the 2040 water balances show that Cape Town will be water secured if the proposed solutions can be implemented by the City of Cape Town. Chapter 4: Results and Discussion

64 4-16 Figure 4.9: Cape Town's 2040 water balance Chapter 4: Results and Discussion