HARDEN SHIRE COUNCIL JUGIONG FLOODPLAIN MANAGEMENT STUDY AND PLAN FINAL REPORT AUGUST 2011 Jugiong F loodplain Risk Management St udy and Plan – FINAL Level 2, 160 Clarence Street Sydney, NSW, 2000 Tel: 9299 2855 Fax: 9262 6208 Email: [email protected] Web: www.wmawat er.com.au JUGIONG - FLOODPLAIN MANAGEMENT STUDY AND PLAN FINAL REPORT SEPTEMBER 2011 Project Project Number Jugiong Floodplain Manage me nt Stud y and Plan 1100 09 Client Client’s Representativ e Harden Shire Council Mark Crisp/Sha ron Langman Author Prepared b y Ste phen Gra y Date Verified by 1 SEPTEMBER 20 11 Revis ion Desc ription Date 3 FINAL REPORT AUG-11 2 DRAFT FINAL REPO RT FEB-11 1 PRELIMINARY DRAFT F INAL REPORT NOV-10 WMAwater 29030:110009_FPMS&P_v6.docx:1 September 2011 i Jugiong F loodplain Risk Management St udy and Plan – FINAL TABLE OF CONTENTS PAGE FOREWORD .............................................................................................................................. v 1. INTRODUCTION ................................................................................................................. 1 1.1. Background ...................................................................................................... 1 1.2. Study Goals ...................................................................................................... 1 1.3. Contents of Report ........................................................................................... 1 1.4. Available Data .................................................................................................. 2 1.4.1. Introduction ................................................................................................. 2 1.4.2. Topography ................................................................................................ 2 1.4.3. GIS Layers ................................................................................................. 3 1.4.4. Gauged Data .............................................................................................. 3 1.4.5. Previous Studies ......................................................................................... 3 1.4.6. Verification Data ......................................................................................... 5 2. STUDY AREA ..................................................................................................................... 6 2.1. Introduction ...................................................................................................... 6 2.2. Features of note with respect to flood liability ................................................... 6 2.3. Land Use on the Floodplain .............................................................................. 7 3. COMMUNITY CONSULTATION ......................................................................................... 8 3.1. Community Consultation .................................................................................. 8 4. EXISTING FLOOD ENVIRONMENT ................................................................................. 10 4.1. Introduction .................................................................................................... 10 4.2. Design Flood Information ............................................................................... 10 4.2.1. Summary of results ................................................................................... 10 4.2.2. Issues impacting design flood assessment at Jugiong .............................. 11 4.2.3. Inundated Buildings .................................................................................. 13 4.2.4. Hazard and Hydraulic Categories ............................................................. 15 4.2.5. Hydraulic Classification ............................................................................. 16 4.3. Social Impacts of Flooding.............................................................................. 16 WMAwater 29030:110009_FPMS&P_v6.docx:1 September 2011 ii Jugiong F loodplain Risk Management St udy and Plan – FINAL 4.4. Environmental Impacts of Flooding ................................................................. 17 4.5. Flood Emergency Response Classification ..................................................... 17 4.6. Flood Damages .............................................................................................. 18 5. JUGIONG’S FLOOD RISK ................................................................................................ 19 5.1. Existing........................................................................................................... 19 5.2. Proposed zoning changes .............................................................................. 19 6. FLOODPLAIN RISK MITIGATION .................................................................................... 20 6.1. Introduction .................................................................................................... 20 6.2. Existing Policy and Emergency Management Measures ................................ 20 6.2.1. Policy ........................................................................................................ 20 6.2.2. Emergency Response .............................................................................. 21 6.3. Identified Gaps ............................................................................................... 21 6.3.1. Policy ........................................................................................................ 21 6.3.2. Works ....................................................................................................... 22 6.3.3. Emergency Response .............................................................................. 22 6.4. Measures Proposed ....................................................................................... 22 6.4.1. Policy ........................................................................................................ 22 6.4.2. Potential Works ........................................................................................ 23 6.4.3. Emergency Response .............................................................................. 23 6.5. Flood Risk Mitigation Measures Recommended ............................................. 24 7. DRAFT JUGIONG FLOODPLAIN RISK MANAGEMENT PLAN ...................................... 28 7.1. Introduction .................................................................................................... 28 7.2. Floodplain Risk Management Measures Considered ...................................... 29 7.3. Proposed Floodplain Risk Management Measures in Plan ............................. 29 8. ACKNOWLEDGEMENTS ................................................................................................. 32 9. REFERENCES .................................................................................................................. 33 APPENDIX D - MAPPING / FLOOD SURFACING .................................................................... 1 Introduction ................................................................................................................ 1 Process Summary ...................................................................................................... 1 Mapping Domain ........................................................................................................ 1 Verification Work ........................................................................................................ 1 Verification Results ................................................................................................. 2 Deriving Design Flow Estimates – Flood Frequency Analysis .................................... 2 WMAwater 29030:110009_FPMS&P_v6.docx:1 September 2011 iii Jugiong F loodplain Risk Management St udy and Plan – FINAL Deriving Design Flow Flood Levels ............................................................................ 3 Deriving Flood Slope .................................................................................................. 3 Surface Creation ........................................................................................................ 4 LIST OF APPENDICES Appendix A: Glossary Appendix B: Community Consultation Mail outs and correspondence Appendix C: Communications issued by WMAwater on behalf of the Committee Appendix D: Details on the Design Flood Mapping Process Appendix E: Public Exhibition - Submissions and Responses LIST OF TABLES Table 1: Peak Flood Levels for Various Historical and Design Events – Bundarbo Road 10 Table 2: Over floor flooding in Jugiong 14 Table 3: Hazard Classification 15 LIST OF FIGURES Figure 1: Study Area Location Figure 2: Study Area Figure 3: House ID’s Figure 4: Digital Elevation Model Figure 5: Water Resources Commission Inundation Map for Village of Jugiong Figure 6: Cross-section locations Figure 7: Jugiong Flood Frequency Curve Figure 8: Stage versus ARI Plot Figure 9: Peak Flood Levels for Historical and Design events at Dowling St Cross-section Figure 10: Profiles used in surfaces Figure 11: 1974 Peak Flood Level Contours and Extent Figure 12: 1925 Peak Flood Level Contours and Extent Figure 13: Flood Planning Area and Levels Figure 14: 1% AEP – Low and High Hazard Zones Figure 15: 1% AEP – Hydraulic Categories Figure 16: 0.5% AEP Peak Flood Level Contours and Extent Figure 17: 0.2% AEP Peak Flood Level Contours and Extent Figure