CHAPTER 5: WATER RESOURCES CHAPTER 5 Water Resources CHAPTER 5: WATER RESOURCES CHAPTER 5: WATER RESOURCES Integrating Authors P. Hobbs1 and E. Day2 Contributing Authors P. Rosewarne3 S. Esterhuyse4, R. Schulze5, J. Day6, J. Ewart-Smith2,M. Kemp4, N. Rivers-Moore7, H. Coetzee8, D. Hohne9, A. Maherry1 Corresponding Authors M. Mosetsho8 1 Natural Resources and the Environment (NRE), Council for Scientific and Industrial Research (CSIR), Pretoria, 0001 2 Freshwater Consulting Group, Cape Town, 7800 3 Independent Consultant, Cape Town 4 Centre for Environmental Management, University of the Free State, Bloemfontein, 9300 5 Centre for Water Resources Research, University of KwaZulu-Natal, Scottsville, 3209 6 Institute for Water Studies, University of Western Cape, Bellville, 7535 7 Rivers-Moore Aquatics, Pietermaritzburg 8 Council for Geoscience, Pretoria, 0184 9 Department of Water and Sanitation, Northern Cape Regional Office, Upington, 8800 Recommended citation: Hobbs, P., Day, E., Rosewarne, P., Esterhuyse, S., Schulze, R., Day, J., Ewart-Smith, J., Kemp, M., Rivers-Moore, N., Coetzee, H., Hohne, D., Maherry, A. and Mosetsho, M. 2016. Water Resources. In Scholes, R., Lochner, P., Schreiner, G., Snyman-Van der Walt, L. and de Jager, M. (eds.). 2016. Shale Gas Development in the Central Karoo: A Scientific Assessment of the Opportunities and Risks. CSIR/IU/021MH/EXP/2016/003/A, ISBN 978-0-7988-5631-7, Pretoria: CSIR. Available at http://seasgd.csir.co.za/scientific-assessment-chapters/ Page 5-1 CHAPTER 5: WATER RESOURCES CONTENTS CHAPTER 5: WATER RESOURCES 5-9 5.1 Introduction and Scope 5-9 5.1.1 What is included in this topic? 5-10 5.2 Characterising features of the Karoo environment 5-13 5.2.1 Geology 5-13 5.2.2 Groundwater 5-15 5.2.2.1 Occurrence 5-15 5.2.2.2 Water quality 5-17 5.2.2.3 Contextual discussion 5-22 5.2.3 Surface water 5-25 5.2.3.1 Occurrence 5-25 5.2.3.2 Water quality 5-31 5.2.3.3 Aquatic ecosystems 5-34 5.2.3.4 Resource condition 5-39 5.2.4 Surface and groundwater interaction 5-41 5.3 Water resources 5-42 5.3.1 Availability and demand 5-42 5.3.2 Inter-catchment water transfers 5-46 5.3.3 Climate change and water resources 5-48 5.3.4 Summary of water resource availability for SGD 5-49 5.4 Relevant legislation, regulation and practice 5-50 5.4.1 International law 5-50 5.4.2 Constitution of the Republic of South Africa 5-51 5.4.3 Relevant South African laws 5-51 5.4.3.1 The National Water Act 5-51 5.4.3.2 The Water Services Act 5-53 5.4.3.3 The Mineral Petroleum Resources Development Act 5-53 5.4.3.4 The National Environmental Management Act 5-55 5.4.4 Regulatory water quality guidelines and standards 5-55 5.5 Key potential impacts and their mitigation 5-56 5.5.1 Groundwater issues 5-56 5.5.1.1 Exploration activities 5-60 5.5.1.2 Appraisal activities 5-60 5.5.1.3 Development and production activities 5-61 5.5.1.4 Post-development and -production activities 5-62 Page 5-2 CHAPTER 5: WATER RESOURCES 5.5.2 Indirect groundwater impacts 5-63 5.5.3 Surface water issues 5-63 5.5.3.1 Overview of issues 5-63 5.5.3.2 Assessment of likely impacts resulting from SGD activities 5-66 5.6 Risk Assessment 5-70 5.6.1 Identification of sensitive areas 5-70 5.6.2 How are risks measured? 5-71 5.6.3 Results of Risk Assessment 5-82 5.7 Best practice and mitigation guidelines 5-87 5.7.1 Overview of Best Practice Guidelines 5-87 5.7.2 Technologies and practices to mitigate SGD impacts on water resources 5-92 5.7.3 Potential setbacks 5-94 5.8 Monitoring framework and requirements 5-105 5.8.1 Monitoring frameworks 5-106 5.8.2 Water quality analyses 5-108 5.8.3 Quality assurance and quality control during water quality sampling 5-109 5.8.4 Data management 5-110 5.9 Gaps in knowledge 5-111 5.10 References 5-114 5.11 Digital Addenda 5A – 5F 5-123 Tables Table 5.1: Water requirement estimates for fracking in four Texas shale gas resources (from Cooley and Donnelly, 2012). 5-12 Table 5.2: Disposal of effluent from waste water treatment works in the study area 5-33 Table 5.3: Summary of water use by shale gas well type. 5-58 Table 5.4: Summary of water use per drill rig by type of shale gas campaign. 5-60 Table 5.5: Consequence levels developed for use in assignment of risk to water resources. 5-76 Table 5.6: Target water quality ranges for surface water use, with values taken from DWAF (1996a, b and c) unless otherwise specified. Concentrations are of dissolved, usually ionic, species of the elements listed. [ ] = concentration. 5-79 Table 5.7: Groundwater risk assessment 5-82 Table 5.8a: Surface water risk assessment of direct impacts. 5-85 Table 5.8b: Surface water risk assessment of indirect impacts. 5-87 Page 5-3 CHAPTER 5: WATER RESOURCES Table 5.9: Candidate technologies and practices to reduce the impacts of SGD on water resources (data from Mauter et al., 2013). Scale of benefit: scale(s) at which environmental benefits of technology are most applicable; Adoption: prevalence of technology (legally required in some places, widely used and/or emerging); Type: T = discrete technologies, M = shifts in management decisions, R = feasible regulatory intervention points. 5-89 Table 5.10: Recommended setback distances which were used to develop the sensitivity map. Specified separately for (1) stimulation well activities and (2) ancillary activities including stratigraphic wells, horizontal wells and the establishment of roads, wellpads, waste stores and other activities. 5-97 Table 5.11: Important water chemistry constituents to be measured in SGD monitoring programmes. Note: analytes indicated in bold (Murray et al., 2015, Miller et al., 2015) have been identified in South African shales; analytes indicated in italics have been identified in produced water from gas shales internationally (Orem et al., 2014). 5-109 Figures Figure 5.1: Co-efficient of variation (CV) as % of annual rainfall in the study area. The figure illustrates year-to-year rainfall assurance, as follows: the CV is a relative index of variability, expressed as a percentage (Std Dev/Mean*100), allowing a comparison of rainfall CV to streamflow CV. The higher the CV; the more variable and unreliable the year-to-year rainfall. The study area has amongst the highest CV’s in SA, particularly in the western two- thirds of the site. Original data sources: Schulze et al. (2010) and Schulze (2012). 5-11 Figure 5.2: Utilisable Groundwater Exploitation Potential. The figure shows the subdivision of the study area into four subareas identified as W (western), C (central), E (eastern) and S (southern) distinguished on the basis of lithological, hydrogeological and morphological factors; boundaries are gradational (adapted from Rosewarne et al., 2013): base map shows the utilisable groundwater exploitation potential in the study area with inset map for national context (after DWAF, 2005). 5-14 Figure 5.3: Groundwater occurrence in the study area (after RSA, 1997a; 2002a and 2002b). 5-18 Figure 5.4: Characterisation of shallow groundwater chemical composition between the four subareas recognised in the study area compared to ‘deep’ groundwater as reflected in a Piper diagram; southern subarea analysis excludes groundwater from the basal Dwyka Group, which varies considerably from fresh to brack. 5-21 Figure 5.5: Shallow groundwater vulnerability rating (from Esterhuyse et al., 2014). 5-24 Figure 5.6: Intermediate and deep groundwater vulnerability rating (Rosewarne, 2015). 5-25 Figure 5.7: Catchment context of the study area, with Primary and Secondary catchments and Water Management Areas (WMAs) indicated: river data from Nel et al. (2011). 5-26 Figure 5.8: Mean annual accumulated streamflow. Data at quinary level. Daily runoff values were generated with the ACRU daily time-step physical-conceptual, multi-soil level and multi- purpose hydrological model (Schulze, 1995 and updates). Streamflow at Quinary exit is the runoff generated within that specific Quinary plus the accumulated runoff of all upstream Quinaries. Note that from the darker coloration one can clearly see how, for the bigger rivers, the streamflow gets larger and larger as one cascades downstream. Original data source Schulze (2012). 5-27 Page 5-4 CHAPTER 5: WATER RESOURCES Figure 5.9: Coefficient of variation (CV) of annual accumulated streamflows CVs in the range 50‒ 250% show high inter-annual variability in streamflows. Original data source Schulze (2012). 5-28 Figure 5.10: Spate conditions in the ephemeral (seasonal) Theekloof River north-east of Beaufort West in January 2016 (photo courtesy D. Hohne, source unknown). 5-29 Figure 5.11: Aerial view showing wide spread of flows in the episodic Renoster River in the north- western part of the study area (Orange River WMA) in April 2016 (photo courtesy D. van Rooyen). 5-29 Figure 5.12: Ratio of the 1:50 to 1:10 year extreme 3 day streamflow. These data indicate areas prone to rare but highly damaging floods. Original data source Schulze (2012). 5-30 Figure 5.13: Areas of perennial, ephemeral (or seasonal) and episodic flows. Data shown as effective runoff (i.e. runoff generated minus channel flow losses to evaporation) from individual Quinaries. Information source new unpublished research by Schulze and Schütte (2016).