Moulamein Flood Study Stage 3 Report Prepared For Murray River Council September 2019 HydroSpatial Pty Ltd ABN: 23 624 304 070 Suite 10, Level 14, 70 Pitt Street, Sydney NSW 2000 Contact: Erika Taylor Email: [email protected] Mobile: 0423 624 696 COPYRIGHT NOTICE This document, Moulamein Flood Study 2019, is licensed under the Creative Commons Attribution 4.0 Licence, unless otherwise indicated. Please give attribution to: © Murray River Council 2019 We also request that you observe and retain any notices that may accompany this material as part of the attribution. Notice Identifying Other Material and/or Rights in this Publication: The author of this document has taken steps to both identify third-party material and secure permission for its reproduction and reuse. 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You should obtain professional advice before making decisions based upon the contents of this document. 18010_Moulamein_FS_Stage3_R03.docx Project Details Project Name Moulamein Flood Study, Floodplain Risk Management Study and Plan (C2017-2018/02) Client Murray River Council Author Tim Morrison, Erika Taylor, Michael Wyk Job Number 18010 Document Stage Stage3 Document Version R03 Document Name 18010_Moulamein_FS_Stage3_R03.docx Document Version Control Version Stage Release Author Reviewer Date R01 Stage 1 Submission Erika Taylor Tim Morrison 02/10/2019 R02 Stage 2 Submission Erika Taylor Tim Morrison 09/04/2019 R03 Stage 3 Submission Erika Taylor Michael Wyk 27/09/2019 Document Approval Erika Taylor Signature Director 18010_Moulamein_FS_Stage3_R03.docx Table of Contents Forward.................................................................................................................................. i Flood-Related Legislation, Policies and Guidelines ............................................................ i Terminology ...................................................................................................................... ii Executive Summary .............................................................................................................. iii 1 Introduction ................................................................................................................... 1 1.1 Overview ................................................................................................................. 1 1.2 Study Objectives ..................................................................................................... 1 1.3 Study Area Description ........................................................................................... 1 2 Study Methodology ........................................................................................................ 2 3 Consultation .................................................................................................................. 3 3.1 Floodplain Management Committee........................................................................ 3 3.2 Community Consultation ......................................................................................... 3 3.2.1 First Round ...................................................................................................... 3 4 Available Data ............................................................................................................... 5 4.1 Previous Studies ..................................................................................................... 5 4.1.1 Edward/Wakool Rivers Rural Floodplain Management Plan (Ref 11) ............... 5 4.1.2 Moulamein Levee Upgrade Flood Study (Ref 10) ............................................. 6 4.1.3 Edward River at Deniliquin Flood Study (Ref 12) ............................................. 7 4.2 Field Trips ............................................................................................................... 8 4.3 Topographic Data ................................................................................................... 9 4.3.1 Aerial-based Survey Data ................................................................................ 9 4.3.2 Ground-based Survey Data ........................................................................... 10 4.3.3 Verification of Aerial-based Survey Data with Ground-based Survey Data ..... 10 4.4 Historic Flood Data ............................................................................................... 10 4.4.1 SES Flood Intelligence Card .......................................................................... 10 4.4.2 Council Database .......................................................................................... 11 4.4.3 Old Court House and Library Archives ........................................................... 12 4.4.4 Landsat .......................................................................................................... 14 4.5 Historic Stream Data ............................................................................................. 14 4.5.1 Stream Gauges .............................................................................................. 14 4.6 Historic Rainfall Data ............................................................................................ 15 4.6.1 Rainfall Gauges ............................................................................................. 15 4.6.2 Analysis of Daily Rainfall Data ....................................................................... 16 4.6.3 Analysis of Pluviometer Rainfall Data............................................................. 18 5 Flood Frequency Analysis ........................................................................................... 19 5.1 Overview ............................................................................................................... 19 5.2 Annual Peak Heights............................................................................................. 19 5.3 Probability Distribution .......................................................................................... 20 18010_Moulamein_FS_Stage3_R03.docx 5.4 Results .................................................................................................................. 21 6 Hydraulic Model Development ..................................................................................... 23 6.1 Overview ............................................................................................................... 23 6.2 Digital Elevation Model ......................................................................................... 23 6.3 Hydraulic Roughness ............................................................................................ 23 6.4 Hydraulic Structures .............................................................................................. 24 6.4.1 Rural Levees.................................................................................................. 24 6.4.2 Town Levees ................................................................................................. 24 6.4.3 Edward River and Billabong Creek................................................................. 24 6.4.4 Tributaries and Divergences .......................................................................... 24 6.4.5 Bridges and Culverts ...................................................................................... 24 6.4.6 Buildings ........................................................................................................ 26 6.5 Initial Water Level Conditions ................................................................................ 26 6.6 Hydraulic Inflow and Outflow Conditions ............................................................... 26 6.6.1 Rural Model ................................................................................................... 26 6.6.2 Urban Model .................................................................................................. 27 7 Historical Flood Simulations ........................................................................................ 28 7.1 Overview ............................................................................................................... 28 7.2 Historic Event Selection .......................................................................................