Water Use and Availability Assessment for the Western Bay of Plenty Prepared for Environment Bay of Plenty Report No. H05017/1 May 2007 Disclaimer: This report has been prepared solely for the benefit of Environment Bay of Plenty. No liability is accepted by Aqualinc Research Ltd or any employee or sub-consultant of this Company with respect to its use by any other person. This disclaimer shall apply notwithstanding that the report may be made available to other persons for an application for permission or approval or to fulfil a legal requirement. Quality Control Client: Environment Bay of Plenty Title: No: Report reference: Water Use and Availability Assessment for the Western Bay of Plenty H05017/1 Prepared by: Channa Rajanayaka Reviewed by: Bob Rout Approved for issue by: Bob Rout Date issued: May 2007 Project No: H05017 Document History Version: 1 Status: Draft, for Client’s review Author: C Rajanayaka Reviewer: B Rout H05017_Water Sustainability Date: 12-3-07 Doc ID: Typist: K Glentworth Approver: Strategy_rpt_Draft.doc Version: 2 Status: Final Author: C Rajanayaka Reviewer: B Rout H05017_Water Use and Availability Date: 7-6-07 Doc ID: Typist: K Glentworth Approver: B Rout WBOP_rpt.doc © All rights reserved. This publication may not be reproduced or copied in any form, without the permission of the Client. Such permission is to be given only in accordance with the terms of the Client’s contract with Aqualinc Research Ltd. 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TABLE OF CONTENTS Page List of Abbreviations........................................................................................................... 4 Acknowledgements.............................................................................................................. 5 Executive Summary ............................................................................................................ 6 1 Introduction ............................................................................................................. 13 1.1 Project Objectives............................................................................................. 14 1.2 Study Area........................................................................................................ 14 1.3 Information and Data Sources........................................................................... 15 1.4 Planning Horizon .............................................................................................. 16 1.5 Water Resource Zones ...................................................................................... 16 2 Land use Assessment................................................................................................ 19 3 Demand Assessment................................................................................................. 21 3.1 Approach and Parameters.................................................................................. 21 3.1.1 Water Demand Categories ..................................................................... 21 3.1.2 Demand Units........................................................................................ 22 3.2 Climate Change ................................................................................................ 22 3.3 Domestic Water Demand .................................................................................. 23 3.3.1 Population Growth................................................................................. 23 3.3.2 Domestic Water Demand....................................................................... 25 3.4 Agriculture Water Demand ............................................................................... 28 3.4.1 Livestock............................................................................................... 29 3.4.2 Irrigation Demand ................................................................................. 30 3.4.3 Horticulture........................................................................................... 31 3.4.4 Pastoral Irrigation.................................................................................. 32 3.4.5 Frost Protection ..................................................................................... 34 3.5 Industrial and Commercial Water Demand........................................................ 34 3.6 Forestry Water Demand .................................................................................... 37 3.7 Recreational Water Demand.............................................................................. 41 3.8 Rural Residential Water Demand ...................................................................... 41 3.9 Summary of Water Demand.............................................................................. 42 4 Resource Assessment ............................................................................................... 44 4.1 Surface Water ................................................................................................... 44 4.1.1 Run-of-stream ....................................................................................... 44 4.1.2 Dams..................................................................................................... 49 4.1.3 Harvesting Winter Flows....................................................................... 49 4.2 Groundwater..................................................................................................... 50 4.3 Rooftop Water Harvesting................................................................................. 52 4.4 Tankered Water Supply..................................................................................... 53 4.5 Wastewater Reuse............................................................................................. 54 4.6 Summary of Water Resources........................................................................... 54 5 Water Balance.......................................................................................................... 56 5.1.1 Global (WBOP) Water Balance ............................................................. 56 5.1.2 Water Balance by Water Resource Zones .............................................. 57 Water Use and Availability Assessment for the Western Bay of Plenty © Aqualinc Research Ltd Prepared for Environment Bay of Plenty (Report No. H05017/1, May 2007) Page i 5.1.3 Surface Water Balance .......................................................................... 58 5.1.4 Groundwater Balance ............................................................................ 60 5.1.5 Dams..................................................................................................... 61 5.2 Sensitivity Analysis .......................................................................................... 61 5.2.1 Surface Water........................................................................................ 63 6 Water Resource Sustainability for SmartGrowth Development............................ 67 6.1 Sustainability of Water Resources..................................................................... 67 6.1.1 Surface Water Takes.............................................................................. 68 6.1.2 Groundwater Takes ............................................................................... 69 6.1.3 Harvesting Winter Flows and Dams....................................................... 69 6.1.4 Domestic Use and Rooftop Water Harvesting ........................................ 69 6.2 Summary .......................................................................................................... 70 7 Conclusions and Recommendations ........................................................................ 71 References.......................................................................................................................... 76 List of Appendices: Appendix A: Summary of relevant water reports ........................................................ 78 Appendix B: Assumptions and parameters ................................................................. 80 Appendix C: Land use distribution ............................................................................. 83 Appendix D: Domestic water demand......................................................................... 86 Appendix E: Soil water balance model....................................................................... 90 Appendix F: Irrigation regimes, soils and crop factors................................................ 92 Appendix G: Parameters and assumptions for agricultural water demand.................... 95 Appendix H: Parameters and assumptions for agricultural land change....................... 97 Appendix I: Livestock water demand ........................................................................ 98 Appendix J: Area distribution of agricultural land use (Hectares) .............................. 99 Appendix K: Estimates of area distribution of irrigated land (Hectares).....................101 Appendix L: Estimated agricultural irrigation demand ..............................................102 Appendix M: Irrigation demand