Warracknabeal and Brim Flood Investigation - Flood Intelligence Report September 2016 ISO 9001 QEC22878 SAI Global Wimmera CMA Warracknabeal and Brim – Flood Intelligence Report DOCUMENT STATUS Version Doc type Reviewed by Approved by Date issued v01 Draft Ben Tate Ben Tate 08/12/2015 v02 Final Ben Hughes Ben Hughes 08/09/2016 PROJECT DETAILS Project Name Warracknabeal and Brim – Flood Intelligence Report Client Wimmera CMA Client Project Manager Clare Wilson Water Technology Project Manager Ben Hughes Report Authors Ben Hughes Job Number 3532-01 Report Number R03 Document Name 3532-01R03v02_Flood_Intel.docx Cover Photo: Aerial imagery of the flooding on 20th January 2011 in Warracknabeal, Wimmera CMA. Copyright Water Technology Pty Ltd has produced this document in accordance with instructions from Wimmera CMA for their use only. The concepts and information contained in this document are the copyright of Water Technology Pty Ltd. Use or copying of this document in whole or in part without written permission of Water Technology Pty Ltd constitutes an infringement of copyright. Water Technology Pty Ltd does not warrant this document is definitive nor free from error and does not accept liability for any loss caused, or arising from, reliance upon the information provided herein. 15 Business Park Drive Notting Hill VIC 3168 Telephone (03) 9558 9366 Fax (03) 9558 9365 ACN No. 093 377 283 ABN No. 60 093 377 283 3532-01 / R03 v01 - 08/12/2015 ii Wimmera CMA Warracknabeal and Brim – Flood Intelligence Report TABLE OF CONTENTS 1. Introduction .................................................................................................................. 5 1.1 Project Scope and Objectives .................................................................................................. 5 1.2 Project Area ............................................................................................................................. 5 1.3 General .................................................................................................................................... 7 1.4 Historic Floods ......................................................................................................................... 7 1.4.1 January 2011 ............................................................................................................................ 7 1.5 Description of Major Waterways and Drains ........................................................................ 12 1.5.1 Riverine Flooding ................................................................................................................... 12 1.5.2 Stormwater Flooding ............................................................................................................. 12 1.6 Dam Failure............................................................................................................................ 17 1.7 Other Infrastructure .............................................................................................................. 17 1.7.1 Levees .................................................................................................................................... 17 1.7.2 Channels ................................................................................................................................ 21 1.7.3 Roads ..................................................................................................................................... 21 2. Typical Flood Peak Travel Times (Appendix B) ............................................................... 24 3. Yarriambiack Creek Flood Emergency Plan – Including Jung, Kellalac, Warracknabeal, Lah and Brim (Appendix C) ............................................................................................ 29 3.1 Overview of Flooding Consequences .................................................................................... 29 3.1.1 Wimmera Highway to Horsham Minyip Road ....................................................................... 30 3.1.2 Horsham Minyip Road to Warracknabeal ............................................................................. 31 3.1.3 Warracknabeal (Dumbouy Road to Rainbow Road) .............................................................. 31 3.1.4 Warracknabeal to Brim .......................................................................................................... 31 3.1.5 Brim ....................................................................................................................................... 31 3.1.6 Brim to Galaquil Road East .................................................................................................... 32 3.2 Flood Mitigation .................................................................................................................... 32 3.3 Flood Impacts and Required Actions ..................................................................................... 32 3.4 Flood Intelligence Card and Property Inundation List ........................................................... 33 3.4.1 Introduction ........................................................................................................................... 33 3.5 Streamflow Gauges ............................................................................................................... 70 3.5.1 Overview ................................................................................................................................ 70 3.5.2 Storm water and rainfall gauging .......................................................................................... 70 3.5.3 Key Streamflow Gauges ......................................................................................................... 71 3.5.4 Additional Streamflow Gauges .............................................................................................. 72 4. Flood Warning Systems (Appendix E) ........................................................................... 74 4.1 Flood Warning ....................................................................................................................... 74 4.2 Flood Bulletins ....................................................................................................................... 74 4.3 Local Flood Warning System Arrangements ......................................................................... 74 5. Maps (Appendix F) ....................................................................................................... 75 LIST OF FIGURES Figure 1-1 Observed January 2011 extent (data provided by the Wimmera CMA) ....................... 6 3532-01 / R03 v01 - 08/12/2015 iii Wimmera CMA Warracknabeal and Brim – Flood Intelligence Report Figure 1-2 Warracknabeal Museum daily rainfall records (1st – 31st January 2011) ...................... 8 Figure 1-3 Warracknabeal – January 2011 stormwater inundation .............................................. 9 Figure 1-5 Warracknabeal – January 2011 flood inundation and mitigation ............................... 10 Figure 1-6 Brim – January 2011 flood inundation ........................................................................ 11 Figure 1-6 Interaction between the Wimmera River, Yarriambiack Creek and Two Mile Creek . 13 Figure 1-7 Streamflow gauge locations ........................................................................................ 14 Figure 1-8 Warracknabeal – Stormwater impacted areas ........................................................... 15 Figure 1-9 Brim – Stormwater impacted areas ............................................................................ 16 Figure 1-10 Remnant sections of levee (Water Technology) ......................................................... 17 Figure 1-11 Warracknabeal Remnant Levees ................................................................................. 18 Figure 1-12 Brim Remnant Levees (not required up to a 0.5% AEP event).................................... 19 Figure 1-13 Warracknabeal design levee alignment ...................................................................... 20 Figure 2-1 January 2011 - Gauged water levels and travel times ................................................ 25 Figure 2-2 September 2010 - Gauged water levels and travel times ........................................... 26 LIST OF TABLES Table 1-3 Water storages along Yarriambiack Creek .................................................................. 17 Table 3-1 Timing of peak flow on the Wimmera River for historic events – Timing beginning ae the Wimmera River at Eversley streamflow gauge ..................................................... 28 Table 3-1 Summary of flood affected properties along Yarriambiack Creek .............................. 29 Table 4-2 Yarriambiack Creek Flood Intelligence Card ............................................................... 34 Table 3-3 Wimmera River flows at Glenorchy ............................................................................ 45 Table 3-4 Yarriambiack Creek flows at Murtoa (Wimmera Highway) ........................................ 45 Table 3-5 Detailed List of Properties Flooded ............................................................................. 46 3532-01 / R03 v01 - 08/12/2015 iv Wimmera CMA Warracknabeal and Brim – Flood Intelligence Report 1. INTRODUCTION 1.1 Project Scope and Objectives The Warracknabeal and Brim Flood Investigation included several major mapping