Mitigating Natural Hazards through Land Use Planning and Building Control Coastal Hazards Technical Report 1 December 2016 Department of Premier and Cabinet Contents Glossary of terms and acronyms..................................................................................................................................................................... 1 Executive Summary ............................................................................................................................................................................................... 5 Access to the coastal inundation and erosion mapping ..................................................................................................... 5 1 Introduction .................................................................................................................................................................................................... 7 1.1 Background ............................................................................................................................................................ 7 1.2 Purpose and scope ................................................................................................................................................ 7 1.3 Report structure .................................................................................................................................................... 8 2 Coastal hazards in Tasmania .................................................................................................................................................................. 9 2.1 What are coastal hazards? .................................................................................................................................... 9 2.1.1 What is coastal erosion? ................................................................................................................................... 9 2.1.2 What is coastal inundation? ............................................................................................................................ 10 2.1.3 Sea level rise planning allowance .................................................................................................................... 10 2.1.4 Coastal hazard exposure in Tasmania ............................................................................................................. 11 3 Regulatory and policy context ............................................................................................................................................................ 12 3.1 Resource management and planning system ...................................................................................................... 12 3.2 State Coastal Policy 1996 ..................................................................................................................................... 12 3.3 Regional strategies and planning ......................................................................................................................... 13 3.4 Local government planning ................................................................................................................................. 14 3.4.1 Pre interim planning schemes ......................................................................................................................... 14 3.4.2 Interim planning schemes ............................................................................................................................... 15 3.4.3 Tasmanian Planning Scheme ........................................................................................................................... 16 3.5 Building Act 2000 ................................................................................................................................................. 16 3.6 How other states have responded to coastal hazards ........................................................................................ 18 4 Methodology ............................................................................................................................................................................................... 20 4.1 The MNHLUP Framework .................................................................................................................................... 20 4.2 Hazard treatment approach ................................................................................................................................ 23 5 Assessment of public risk and coastal hazards ............................................................................................................................ 24 5.1 Nature of public risk ............................................................................................................................................ 24 5.2 Public risk: development types ............................................................................................................................ 26 5.3 Assessment of public risk..................................................................................................................................... 27 6 Coastal erosion hazard assessment ................................................................................................................................................. 31 6.1 Understanding coastal erosion planning bands evidence: identifying the hazard .............................................. 31 6.1.1 Soft sediment category ................................................................................................................................... 32 6.1.2 Soft-rock category ........................................................................................................................................... 33 6.1.3 Hard-rock shoreline category .......................................................................................................................... 33 6.1.4 Defining the Coastal Erosion Mapping Components ...................................................................................... 34 6.2 Defining coastal erosion hazard planning bands: analysing the hazard .............................................................. 36 6.2.1 Pairwise assessment........................................................................................................................................ 36 6.2.2 Coastal Erosion Hazard Bands ......................................................................................................................... 39 6.2.3 Coastal erosion investigation area .................................................................................................................. 42 6.2.4 Analysis of the coastal erosion planning boundaries ...................................................................................... 43 6.3 Coastal erosion hazard planning matrix – evaluation and treatment of hazard ................................................. 45 6.3.1 Coastal erosion – high hazard band ................................................................................................................ 46 6.3.2 Coastal erosion – medium hazard band .......................................................................................................... 49 6.3.3 Coastal erosion – low hazard band ................................................................................................................. 50 6.3.4 Coastal erosion – acceptable hazard band ...................................................................................................... 52 6.3.5 Coastal erosion - investigation area ................................................................................................................ 52 7 Coastal Inundation Hazard Assessment ........................................................................................................................................ 54 7.1 Understanding coastal inundation planning bands evidence: identifying the hazard ........................................ 54 7.1.1 Storm surge and tides ..................................................................................................................................... 54 7.1.2 Sea level rise planning allowance .................................................................................................................... 56 7.1.3 Contributing factors not considered in this study ........................................................................................... 56 7.1.4 Digital Elevation Model ................................................................................................................................... 57 7.2 Defining coastal inundation hazard planning bands: analysing the hazard ........................................................ 58 7.2.1 Coastal Inundation Hazard Bands ................................................................................................................... 59 7.2.2 Analysis of the coastal inundation planning boundaries ................................................................................ 61 7.3 Coastal inundation hazard planning matrix – evaluation and treatment of hazard ............................................ 63 7.3.1 Coastal Inundation High hazard Band ............................................................................................................