Murray Downs Floodplain Risk Management Study and Plan Final Report
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Murray River Council Murray Downs Floodplain Risk Management Study and Plan Final Report January 2017 This report: has been prepared by GHD for Murray River Council and may only be used and relied on by Murray River Council for the purpose agreed between GHD and the Murray River Council as set out in Section 1 of this report. GHD otherwise disclaims responsibility to any person other than Murray River Council arising in connection with this report. GHD also excludes implied warranties and conditions, to the extent legally permissible. The services undertaken by GHD in connection with preparing this report were limited to those specifically detailed in the report and are subject to the scope limitations set out in the report. The opinions, conclusions and any recommendations in this report are based on conditions encountered and information reviewed at the date of preparation of the report. GHD has no responsibility or obligation to update this report to account for events or changes occurring subsequent to the date that the report was prepared. The opinions, conclusions and any recommendations in this report are based on assumptions made by GHD described in this report. GHD disclaims liability arising from any of the assumptions being incorrect. Cover photograph: View looking downstream from Moulamein Road at Murray Downs. GHD | Report for Murray River Council - Murray Downs Floodplain Risk Management Study and Plan, 31/32610 | i Preface The NSW State Government’s Flood Policy aims to provide solutions to existing flooding problems and ensure that new development within flood prone areas is compatible with the prevailing flood risk and does not create additional flooding problems in other areas. Under the Policy, the management of flood liable land is the responsibility of local government. State government subsidises flood mitigation works to alleviate existing problems and provide specialist technical advice to assist councils in the discharge of their floodplain management responsibilities. The Policy provides for technical and financial support by the State Government during the following four sequential stages: Flood Study – determines the nature and extent of the flooding problem. Floodplain Risk Management Study – evaluates management options for the floodplain in respect of both existing and proposed development. Floodplain Risk Management Plan – the formal plan adopted by Council for the management of the floodplain. Plan Implementation – implementation of the various structural and non-structural measures proposed by the Plan. This report documents the above second and third stages in the process (Floodplain Risk Management Study and Floodplain Risk Management Plan). It follows the completion of the Murray Downs Flood Study in 2014. The Murray River Council has prepared this document with financial assistance from the NSW and Commonwealth Governments through the Natural Disaster Resilience Program. This document does not necessarily represent the opinions of the NSW or Commonwealth Governments. The Murray River Council was formed on the 12 May 2016 as a result of the merger of the Wakool Shire Council and the Murray Shire Council. Murray Downs is located within the previous Wakool Shire Council area. ii | GHD | Report for Murray River Council - Murray Downs Floodplain Risk Management Study and Plan, 31/32610 Table of Contents 1. Introduction .................................................................................................................................... 1 2. Community Consultation ................................................................................................................ 3 2.1 Overview .............................................................................................................................. 3 2.2 Floodplain Risk Management Committee ............................................................................ 3 2.3 Other Stakeholders .............................................................................................................. 3 2.4 Community Consultation Activities ...................................................................................... 4 2.5 Public Exhibition of the Draft FRMS&P Report .................................................................... 5 3. Flood Study Summary .................................................................................................................... 6 3.1 Overview of 2014 Flood Study ............................................................................................. 6 3.2 Catchment Description ........................................................................................................ 6 3.3 Floodplain Description ......................................................................................................... 6 3.4 Flooding Conditions ............................................................................................................. 8 4. Flooding Impacts .......................................................................................................................... 11 4.1 Approach ............................................................................................................................ 11 4.2 Above Floor Flooding ......................................................................................................... 12 4.3 Flood Damages .................................................................................................................. 12 4.4 Summary of Flooding Impacts ........................................................................................... 13 5. Preliminary Assessment of Mitigation Options ............................................................................ 14 5.1 Overview of Types of Measures ........................................................................................ 14 5.2 Property Modification Measures ........................................................................................ 15 5.3 Response Modification Measures ...................................................................................... 17 5.4 Flood Modification Measures ............................................................................................. 20 5.5 Summary and Recommendations ..................................................................................... 21 6. Property Modification Options - Detailed Assessment ................................................................. 23 6.1 LEP and DCP ..................................................................................................................... 23 6.2 Development Control FPLs ................................................................................................ 23 6.3 FPA .................................................................................................................................... 25 6.4 True Flood Hazard ............................................................................................................. 25 6.5 Local Flood Policy .............................................................................................................. 26 7. Response Modification Options - Detailed Assessment .............................................................. 27 7.1 Swan Hill Flood Warning Station ....................................................................................... 27 7.2 Flooding Duration ............................................................................................................... 28 7.3 Local Flood Plan ................................................................................................................ 30 7.4 SES Flood Data Outputs ................................................................................................... 31 7.5 Flood Response Discussion .............................................................................................. 32 7.6 Flood Data ......................................................................................................................... 33 7.7 Community Awareness Measures ..................................................................................... 33 GHD | Report for Murray River Council - Murray Downs Floodplain Risk Management Study and Plan, 31/32610 | iii 8. Flood Modification Options - Detailed Assessment ..................................................................... 35 8.1 Existing Levees .................................................................................................................. 35 8.2 Murray Downs Creek ......................................................................................................... 39 8.3 Future Development .......................................................................................................... 45 9. Floodplain Risk Management Plan .............................................................................................. 47 9.1 Overview ............................................................................................................................ 47 9.2 Recommended Mitigation Measures ................................................................................. 48 9.3 Implementation/Funding .................................................................................................... 51 10. Acknowledgements .....................................................................................................................