Investigating Solutions for Cape Town to Ensure Water Security Until 2040
Total Page：16
File Type：pdf, Size：1020Kb
Investigating solutions for Cape Town to ensure water security until 2040. Prepared by Sekonyela Tieho (SKNTIE001) for Professor Neil Armitage Submission date: 23 November 2015 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) 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. iii) This report is my own work iv) 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 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. iii Abstract The City of Cape Town is expecting to experience a shortage of water by 2021. 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 2040. 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 2027. 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 2040. 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 259Mm3/annum to 658Mm3/annum which will postponed water shortage due to unrestricted high water requirement growth by 15 years from 2021 to 2036. 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 2040. Furthermore, the projected water balance of Cape Town for the year 2040 showed that, the demand will be 81Mm3 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 2040. In addition, the 2040 water 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 2040. In addition, the results of this research can be improved or used as the basis for similar research in the future. v Table of content Abstract iii Table of contents v List of Figures vii List of Tables viii 1. Introduction 1-1 1.1 Background 1-1 1.2 Problem Statement 1-1 1.3 Objectives of the project 1-2 1.4 Research method 1-2 1.5 Scope and limitations 1-3 1.6 Plan of development 1-3 2. Literature review 2-1 2.1 Water scarcity in South Africa 2-1 2.1.1 Sustainable urban water management 2-2 2.2 Historical water demand in Cape Town 2-3 2.3 Current situation of water 2-4 2.3.1 Infrastructure leakage index 2-4 2.3.2 Water Wastage 2-5 2.3.3 Inefficient water use 2-7 2.3.4 Water end use 2-9 2.4 Water supply in Cape Town 2-10 2.5 Water demand in Cape Town 2-11 2.6 Future water requirements for the Cape Town 2-13 2.7 General recommended solutions to water deficit 2-15 2.8 User education and campaign initiatives 2-16 2.9 Leak detection and repair 2-17 2.10 Replacement of pipes 2-18 2.11 Pressure management 2-19 2.12 Water efficient devices 2-23 2.13 Tariff increase 2-24 2.14 Greywater harvest 2-25 2.15 Rainwater harvesting 2-25 2.16 Private boreholes/ wellpoints 2-26 2.17 Groundwater 2-26 vi 2.18 Desalination 2-28 2.19 Treated effluent 2-28 2.20 Surface water development 2-30 3. Procedure for wed calculations 3-1 4. Results and discussion 4-1 4.1 The situation of the city of Cape Town’s water supply 4-2 4.2 User education and campaign programs 4-4 4.3 Results of water demand reduction 4-5 4.4 Options for additional water supply 4-8 4.5 Treat effluent 4-10 4.6 Seawater desalination 4-10 4.7 Groundwater 4-11 4.8 Future projections of water demand 4-12 4.9 Final results 4-13 5. Conclusions and recommendations 5-1 References Appendices 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 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 ix Abbreviations CoCT City of Cape Town RWH Rainwater Harvesting DWA Department of Water Affairs FAVAD Fixed and Variable Area Discharge GWH Greywater Harvesting NRW Non-Revenue Water PM Pressure Management TE Treated Effluent: potable water replacement through re-use WC/WDM Water Conservation / Water Demand Management WED Water Efficient Device PRV Pressure Reducing Valve 1-1 1.