Information

Councils — Flood maps (Tasmania)

Practical guidance for using the Tasmanian Strategic Flood Maps (TSFM) to assess riverine flood risk, including how to view layers in LISTmap, what hazard and Annual Exceedance Probability (AEP) scenarios are shown, limits of the maps, and actions to take before relying on mapping for property decisions or emergency planning.

By Our Tasmania Editorial

Memorial stones commemorate Mayor Henry Cook and the Hobart Town Corporation Waterworks erected in 1861. In 1960 floods wiped out much of the scenery and surviving tourist facilities at the Fern Tree Bower. Cook’s monument was salvaged and reinstated at the Bower entrance and a plaque unveiled in 1961 commemorates its rehabilitation Plaque reads : Fern Tree Bower These Inscribed Stones Were Salvaged From The Original Water Tower Erected In 1861 And Destroyed By The Great Flood Of 23rd April 1960 This Tablet Is Erected By The Hobart City Council To Commemorate Its Rehabilitation In 1961Xavier Lahey, CC BY-SA 4.0, Wikimedia Commons

What the Tasmanian Strategic Flood Maps present

The Tasmanian Strategic Flood Maps (TSFM) are a statewide modelling product that shows where riverine flooding is likely to occur under a range of flood scenarios. The maps display flood extent and water depth as a default, plus options for velocity and water level. They also include a derived hazard rating that combines depth and velocity into levels that describe how dangerous flooding could be at a site.

Flood scenarios and hazard classes to check

Mapped flood scenarios include several Annual Exceedance Probability (AEP) levels: a 2% AEP (about a 1 in 50-year event), a 1% AEP (about a 1 in 100-year event), a 0.5% AEP (about a 1 in 200-year event) and a 1% AEP projected for a future climate around 2100. Hazard is reported in six classes (H1 to H6). H1 indicates conditions generally safe for vehicles, people and buildings; H6 indicates conditions where all building types are considered vulnerable to failure. When you inspect a property, note both depth and velocity values and the hazard class for the scenario you care about.

How to access and layer the data

You can view the TSFM for free through LISTmap, the Tasmanian government mapping application. In LISTmap use the Layers button, choose Add layer and search for TSFM to add the available TSFM layers. A practical starting layer is the 1.0% AEP Depth. Local community flood guides published for specific areas also include the flood mapping. The mapping is being staged into other emergency information tools and can be exported for use in desktop GIS packages such as ArcGIS, QGIS or MapInfo if you need to analyse data offline.

What the maps do not cover and how they can vary

The TSFM focus primarily on riverine flooding. Local flash flooding from intense local storms and stormwater run-off is only partially represented. The maps cannot precisely predict any single future flood event. Flood extents can differ because rainfall can be uneven across a catchment, river levels and soil moisture vary before a storm, snow melt can add volume, and tidal conditions may influence inundation near estuaries. A small number of municipal areas are known to need more modelling information; these include parts of the West Coast, Circular Head, Huon Valley, Derwent Valley, Central Highlands, Waratah-Wynyard, Flinders Island and King Island. The responsible agency is working to extend coverage.

When to check local council studies

Where an up-to-date local council flood study exists for your specific area, that study can provide more detailed, locally specific information than the statewide TSFM. Local studies often use finer-resolution data and different assumptions tailored to a town or catchment. Not every council area has a recent local study, and some local studies may be dated or use different methodology. Before relying on mapping for buying property or for development decisions, contact the local council to confirm whether a more detailed local study or guidance applies.

Suitability: who should use the maps and for what

The TSFM are intended for households, communities, businesses, farmers, local government and state agencies. Use them to make informed decisions about property purchase, to reduce exposure when making changes to land, and to guide land use planning or emergency response planning. They are also useful for people preparing a household emergency plan, for insurers and for infrastructure managers assessing asset exposure.

Practical checks and safety steps before and during flood season

If the mapping shows your home could flood, include clear triggers in your household emergency plan that state when and how you will leave for safety. Even if your home is unlikely to flood, plan for the possibility that access routes to and from your property could be cut. Review the local community flood guide for advice tailored to your area. If you use the mapping to plan work on land or buildings, verify which AEP scenario and hazard class are relevant to your regulatory or insurance requirements.

Technical notes for GIS users and planners

If you intend to use TSFM data in GIS, the mapping can be downloaded in formats compatible with common desktop packages. When adding TSFM layers in LISTmap, turn layers on and off to compare depth, velocity and hazard outputs. For many planning questions, the 1% AEP depth layer is a common reference point; include the 1% AEP projected climate scenario if you need to account for longer-term climate change effects.

Final checks before acting on the maps

Treat the TSFM as a state-scale tool that identifies likely flood-prone areas and supports preparedness. For site-specific decisions you should combine TSFM outputs with local flood studies where available, and seek confirmation from local council or qualified flood engineers where a detailed assessment is required. Check the local guides and incorporate access-route considerations into evacuation planning.

Sources and further reading

The Tasmanian Strategic Flood Maps · Tasmania State Emergency Service (SES)
About the LIST (Land Information System Tasmania) and LISTmap · Land Information System Tasmania (the LIST) — Tasmanian Government

Before you go

Practical information

How to view TSFM in LISTmap: Open LISTmap, click Layers, choose Add layer, search for 'TSFM' and add the desired layers. A suggested starting layer is 1.0% AEP Depth.
Cost to access: Free to view via LISTmap and local community flood guides.
Data for GIS: TSFM data can be downloaded for use in desktop GIS packages such as ArcGIS, QGIS or MapInfo.
When to contact local council: Contact council to find out if a local flood study exists, and whether it supersedes statewide mapping for your site.
Emergency planning check: If your property could flood, include when and how you will leave in your emergency plan; remember access routes may be cut.
When to include climate projection: Use the 1% AEP projected climate (2100) layer when assessing longer-term exposure or future land-use decisions.

Developer: Tasmania State Emergency Service (SES)
Primary viewing platform: LISTmap (Land Information System Tasmania)
Mapped scenarios: 2% AEP, 1% AEP, 0.5% AEP and 1% AEP projected for circa 2100
Main focus: Riverine flooding (flooding from river rises); local stormwater run-off partially covered
Hazard classification: Six levels H1 to H6 describing increasing depth and velocity risk
Coverage note: Most of Tasmania is mapped, but some areas require more information (including parts of West Coast, Circular Head, Huon Valley, Derwent Valley, Central Highlands, Waratah-Wynyard, Flinders Island and King Island)
Intended users: Households, communities, businesses, farmers, local and state government, planners and emergency services
Limitations: Maps cannot precisely predict any single flood event; extents vary with rainfall distribution, antecedent conditions, snow melt and tide