The flood maps and your property

Property owners can take action to keep people safe and reduce flood damage. There are local flood guides for communities at risk of flooding. The guides can help you

  • improve your safety in a flood emergency, and
  • protect your property from flood impacts.

The guides include flood maps using the new strategic flood maps, along with information on local flood risks and how to prepare.  

Flood impacts on a property can differ depending on

  • the scale of the flood,
  • where the buildings on the site, and
  • the building’s construction.

Developing property that is mapped as being flood prone

Contact your local council for advice on

  • planning
  • development applications and
  • building controls.

Local governments use the Flood-Prone Area Hazard Code. This code sets requirements about development.

Flood insurance

Insurance companies use many different sources of information to assess risk. Much of the information they currently use is generated by the insurance company.

Understanding your level of risk can help you

  • decide what kind of insurance cover will best suit you, and
  • to prepare in other ways.

For example, you may make changes to your property that mean when a flood happens

  • there are fewer costs, and
  • you can recover quicker.

This can make your property safer and help to reduce your insurance costs.

When insurance companies decide whether to offer flood insurance, or how to price a flood insurance premium, they should consider:

  • if a building is at risk of flooding
  • the height of the building’s floor level
  • building construction type
  • roof type
  • property improvements
  • year of build, and
  • compliance with building codes.

For more information, see the Tasmanian Government’s Insurance Check-up online tool through the TasALERT website.

Questions you may have about the flood mapping and your property

I have lived in my property for 50 years and it has never flooded. Why is my property mapped as being flood prone?

Tasmanians need to prepare for flood events that may not happen often as well as the more minor flooding they may have experienced. Rainfall that causes flooding

  • varies in intensity from year to year, and
  • falls in different parts of the landscape.

The flood maps show a few different scales of flood events.

Some of the flood events mapped are like those seen more frequently. Some are large scale flood events that are rare. Tasmanians need to prepare for floods they may not have experienced.

The language used to describe the likelihood of flood events is ‘Annual Exceedance Probability’ or AEP. The AEP is the chance of a flood of a given size occurring in any one year. The 1% AEP has a 1% chance (that is a 1-in-100 chance) of occurring in any one year.

You may not have experienced a 1% AEP flood in the 50 years you have lived in your property but that does not mean it cannot happen.

Some parts of Australia have had more than one 1% AEP level flood recently. The Mersey River at Latrobe is one such area. Latrobe had damaging floods in 2011 and 2016. Some other areas have not had major floods in living memory, but it is still possible.

Will the flood mapping affect the value of my property?

There are many factors that can affect property values and the property market, such as

  • supply and demand
  • desirability of location
  • interest rates
  • the economy
  • the style and age of buildings.

It is difficult to figure out which factors influence property values. These factors can influence property values differently over time.

Being in a flood exposed area may impact property values, but the impact depends on many other factors.

  • The property has probably flooded in the past. This already affects its value, especially if there was
    • recent flooding, or
    • several floods in a short time span.
  • Insurance premiums can impact on property value. Insurance companies decide these premiums. They already use flood maps to inform their decisions.
  • Property values can recover over time after the release of improved flood information.
  • Flood maps often inform flood mitigation actions such as levee construction. This helps to reduce risk. Without this mapping, it is difficult to physically reduce flood risk.

I live on a hill. How can my property be flood-prone?

The flood maps show flooding from heavy rainfall especially when there is too much water for waterways. Water spreads over the landscape in locally low-lying areas, even in higher areas well away from the coast.

Living in higher places generally reduces the risk of flooding, as water naturally flows downhill. However, a property on a hill can still flood.

  • Heavy rainfall can cause localised flooding if there is poor drainage. Water can accumulate in low-lying places.  Blocked or overwhelmed drains can redirect water.
  • Intense rainfall can cause flash floods in steep or hilly areas. These floods occur quickly. Flash floods can impact properties that are safe from flooding from rivers.
  • Stormwater runoff can flood your property if there is very heavy rain.
  • Flood maps also consider factors such as
    • drainage patterns
    • infrastructure, and
    • extreme weather scenarios.

Even if your home does not flood, you still need an emergency plan for

  • isolation
  • power, telecommunications and other service cuts.

Get ready for emergencies

My house is built above the flood level so why do the Tasmanian Strategic Flood Maps show flooding on my property?

Flood maps show areas flooding could impact, not just properties at or below a specific flood level. Even if your house’s floor height is above the expected flood level, your property may still be mapped as flood prone as

  • other parts of your property could still be affected by flooding, such as
    • driveways
    • access roads, or
    • surrounding land.
  • This may mean you cannot safety leave your property during a flood event.
  • Flooding in surrounding areas means you may not be able to get to services you need. There may be cuts to power, water and internet.
  • While your building may not flood, the flood waters may surround you, you should still evacuate. Emergency services may not be able to reach you if needed during the flood.

The flood models have not considered individual house floor levels. The Tasmanian Strategic Flood Maps cover broad areas across the state. They are a strategic tool for understanding flood risks on a regional scale.

Flood maps help property owners to have the information needed to make informed decisions about

  • flood risk
  • flood preparedness
  • keeping safe during flood events
  • reducing damage from floods.

Council built a levee to protect my property from flood so why do the Tasmanian Strategic Flood Maps show flooding on my property?

The flood mapping provides essential information for understanding and managing flood risks, even in places with flood protection measures like levees.

  • While levees help protect properties from floods, they can fail. Flood waters can overtop or breach levees.
  • There may be flooding from other sources, such as
    • heavy local rainfall, or
    • drainage issues.
  • The flood mapping shows
    • the overall floodplain, and
    • potential flood behaviour in the region.
  • The flood maps consider broader flood risks that might still impact your property. 
  • In some areas, the maps do not include levees as there may not be enough detail to inform the maps.

Including properties behind levees in flood mapping helps ensure that all risks are considered when planning for

  • emergency response, and
  • land use.

Part of my property is mapped as being at risk of flooding. How does the flood mapping get updated?

Your property is included in an area mapped as flood-prone because the technical studies for your catchment have identified flood risk at your location. The flood mapping provides the best available flood hazard information for your location.

These maps

  • are created using standardised and objective data and
  • provide a comprehensive view of flood risks across a region.

See more information on the development of the flood maps.

SES updates the flood mapping periodically to reflect

  • changes in land use
  • climate patterns, and
  • other factors.

If new developments or data alters the flood risk in your area, future revisions of the flood maps may change the flood maps in your area. SES also recognises that there are limitations to flood maps.

If you have a question about the flood mapping, please email ses@ses.tas.gov.au.

What happens if I fill or raise part of my property, or build a levee?

Raising some of your property so it is above the flood level may seem like a solution to reducing flood risk, however

  • Changing the landscape could alter local drainage patterns. This could increase flood risks to your property or neighbouring properties. You may become legally responsible for flooding in neighbouring areas.
  • Filling or altering the land may need approval from your local council. It is important they carefully assess any changes to ensure the changes do not increase flood risk for others.
  • Your property may still be subject to
    • flood-related regulations or
    •  insurance requirements.
  • Flood maps show areas that are at risk of flooding under current conditions.
  • SES may periodically update the flood maps to reflect changes. Even if you raise part of your property, the maps may still show your property as being flood-prone depending on regional flood risks and modelling updates.
  • The flood maps are a strategic tool used to assess flood risks on a broader scale. Individual modifications may not change the regional flood risk or result in removing your property from areas marked as flood prone.

It is important to consult with local authorities and flood management experts before acting to

  • understand the potential impacts, and
  • requirements involved.