Horsham and Wartook Valley Flood Investigation Data Collation & Review December 2015 Wimmera CMA 4149-01R01v01 DOCUMENT STATUS Version Doc type Reviewed by Approved Distributed to Date issued by v01 Draft Ben Hughes Ben Hughes Paul Fennell 24/12/2015 v02 Final Ben Hughes Ben Hughes Paul Fennell 18/09/2018 PROJECT DETAILS Project Name 4149-01R01v01 Client Wimmera CMA Client Project Manager Paul Fennell Water Technology Project Manager Ben Hughes Report Authors Alison Miller, Ben Hughes Job Number 4149-01 Report Number R01 Document Name 4109-01R01v01.docx Cover Photo: Inundation at the corner of Hamilton Street and Firebrace Street during January 2011 (Wimmera Region Flood Report, January 2011) 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) 8526 0800 Fax (03) 9558 9365 ACN No. 093 377 283 ABN No. 60 093 377 283 4149-01 / R01 v01 - 24/12/2015 ii Wimmera CMA 4149-01R01v01 TABLE OF CONTENTS 1. Introduction .................................................................................................................. 7 2. Study Area ..................................................................................................................... 7 3. Flood Related Studies .................................................................................................... 9 3.1 Lower Wimmera River Flood Mapping .................................................................................... 9 3.2 Wartook to Zumsteins Walking Track ................................................................................... 11 3.2.1 Overview ................................................................................................................................ 11 3.2.2 Relevant Findings................................................................................................................... 11 3.3 East Horsham Flood Plan ....................................................................................................... 11 3.3.1 Overview ................................................................................................................................ 11 3.3.2 Relevant Findings................................................................................................................... 11 3.4 Wimmera CMA Flood Report – January 2011 ....................................................................... 12 3.4.1 Overview ................................................................................................................................ 12 3.4.2 Relevant Findings................................................................................................................... 13 3.5 Yarriambiack Creek Flows Study............................................................................................ 13 3.5.1 Overview ................................................................................................................................ 13 3.5.2 Relevant Findings................................................................................................................... 13 3.6 Horsham Bypass Hydrology and Hydraulic Investigation ...................................................... 13 3.6.1 Overview ................................................................................................................................ 13 3.6.2 Relevant Findings................................................................................................................... 14 3.7 Horsham Flood Study ............................................................................................................ 14 3.7.1 Overview ................................................................................................................................ 14 3.7.2 Relevant Findings................................................................................................................... 14 3.8 East Horsham Channel Decommissioning Modelling ............................................................ 14 3.8.1 Overview ................................................................................................................................ 14 3.8.2 Relevant Findings................................................................................................................... 14 4. Hydrological Data ........................................................................................................ 16 4.1 Streamflow ............................................................................................................................ 16 4.1.1 Wimmera River at Horsham (Walmer) .................................................................................. 17 4.1.2 Norton Creek at Lower Norton .............................................................................................. 21 4.1.3 MacKenzie River at Wartook Reservoir ................................................................................. 22 4.1.4 Burnt Creek at Wonwondah East .......................................................................................... 24 4.1.5 MacKenzie River at McKenzie Creek ..................................................................................... 24 4.1.6 Summary ................................................................................................................................ 24 4.2 Rainfall ................................................................................................................................... 24 4.3 Storages ................................................................................................................................. 27 5. Flood Records .............................................................................................................. 29 5.1 January 2011 .......................................................................................................................... 29 5.2 Observed peak flood heights and extents ............................................................................. 32 6. Physical Features ......................................................................................................... 32 6.1 Topographic survey ............................................................................................................... 32 6.2 Floor level and feature survey ............................................................................................... 35 7. Site Visit ...................................................................................................................... 37 4149-01 / R01 v01 - 24/12/2015 iii Wimmera CMA 4149-01R01v01 8. Data Gaps and Recommendations ................................................................................ 38 4149-01 / R01 v01 - 24/12/2015 iv Wimmera CMA 4149-01R01v01 LIST OF FIGURES Figure 2-1 Study area ..................................................................................................................... 8 Figure 3-1 Floor level survey captured as part of the East Horsham Flood Plan ......................... 12 Figure 3-2 Menadue Street/Peppertree Lane levee longsection survey ..................................... 10 Figure 3-3 Road and channel crest survey ................................................................................... 15 Figure 4-1 Streamflow gauges within the study area................................................................... 16 Figure 4-2 January 2011 hydrograph recorded at the Wimmera River at Horsham (Walmer) streamflow gauge ........................................................................................................ 19 Figure 4-3 Wimmera River at Horsham (Walmer) gauge and Western Highway January 2011 measurement locations............................................................................................... 20 Figure 4-4 Wimmera River at Horsham streamflow gauge rating curve and measurements ..... 21 Figure 4-5 Wimmera River at Horsham current and previous rating curves ............................... 21 Figure 4-6 Gauge record at Norton Creek at Lower Norton showing water level and limit of extrapolated section of the rating curve ..................................................................... 22 Figure 4-7 MacKenzie River maximum discharge flood frequency distribution (Log Normal) .... 23 Figure 4-8 Rainfall gauge locations with respect to the study area ............................................. 25 Figure 4-9 Inflow, outflow and level of Lake Wartook in January 2011 ....................................... 28 Figure 5-1 Riverside area showing inundation on the 18th January, 2011 ................................... 30 Figure 5-2 Peak flood heights surveyed by Wimmera CMA within the study area ..................... 31 Figure 5-3 Historic flood data capture ......................................................................................... 32 Figure 6-1 Available LiDAR ...........................................................................................................