Riverine flooding information for the Huon River and minor tributaries

Version 1.0 August 2024

If the Huon River has a major flood, low lying areas along the river’s west side south of Huonville can be flooded, particularly if tides are high. The Huon Highway is likely to be impassable in several places.  There is likely to be flooding along the Franklin waterfront.

Parts of Castle Forbes Bay, Franklin and some other areas can also have flash flooding from local minor waterways that join the Huon River if there is heavy local rain. Flash flooding means there can be little specific warning beyond forecasts for heavy rain or severe weather.

The maps in this guide show the level of flooding that has a 1% chance of happening any year. You are likely to experience flooding such as that shown in the maps at least once in your lifetime.

Even if your home is not inundated, you should be prepared for isolation plus potential power and telecommunications outages. The Huon Highway may be cut at Huonville, Geeveston and some other places during a major flood event.  Travel in the area is likely to be difficult or impossible until roads are clear.  If you are safe at home or elsewhere, it is usually best you stay where you are until the flooding subsides, unless there is an emergency. If you need to evacuate, you should leave early, before flood waters rise.

Listen to ABC local radio 936AM for warnings and advice.

Are you at risk of flood?

The Huon River has a long history of flooding, with major flood events in 1901, 1947, 1958, 1960, 1975, 1996, 2016 and 2022. The area often has minor flooding.

Areas south of Huonville are exposed to weather systems from the West, South and East. The area often has heavy rain. Tasmanians need to be prepared for flood events that may not happen often, as well as the more minor flooding they may have experienced.

What should I do?

• Check the map to see whether your home or business could flood.
• Assess your home or business and prepare it to minimise possible flood damage.
• Check if you can safely get to your home, work, or school during a flood.
• Prepare a Home Emergency Plan.
• If you may be isolated and you must have access to services, you may need to evacuate early.

Avoid travel during floods.

Floods like the one shown in the map, or worse, will occur again. No two floods are the same.

If you live in a low-lying area or near a watercourse, your house may flood. Even if your home is safe, you may need to detour around flooded areas or your road access may be cut. Never drive into or enter flood waters. Roads and bridges may be washed out or unsafe.

Knowing what to do can save your life and help protect your property. Having a Home Emergency Plan is one of the best ways to prepare. Decide on weather and rainfall triggers for when to act.

Bureau of Meteorology Forecasts, Warnings, and Observations

The Bureau issues a Flood Warning, Severe Weather Warning and/or Thunderstorm Warning for heavy rainfall that may lead to flash flooding whenever heavy rain is expected in an area. The time between the warning and heavy rain occurring can vary from an hour to 24 hours or more.

Whenever rain that may lead to flooding along the Huon River is expected, the Bureau will issue:

• A Flood Watch – a “heads up” early advice of forecast weather that may lead to flooding
• A Flood Warning – giving a prediction of when flooding is likely to develop at gauge locations and possibly forecastng the likely peak river level.  Warnings are updated regularly.

SES and the Bureau will issue warnings when the Huon River reaches the following levels.

River gauges	Alert	Minor	Moderate	Major
Huon River at Harrison’s Opening	5.0	5.0	n/a	n/a
Huon River at Tahune Bridge		4.0	5.0	6.3
Huon River at Judbury	3.0	4.0	5.3	6.0
Huon River at Huonville	2.5	3.0	3.6	4.0

There are no formal warning levels for other waterways in the area as the river systems are too short.

Rainfall Observations at Hartz Mountain, Cannells Hill near Huonville, Grove and other nearby rain gauges can indicate possible flood risks. Given the very short warning times, you are encouraged to act on the predictive BoM warnings rather than wait for any flood alerts during rainfall.

The Mt Koonya Radar is useful to be aware in real-time where heavy rainfall is falling.  Radar Rainfall estimates can also fill in gaps in areas where there are no rainfall stations.

Understand the warnings and key information

Keep aware of what is happening around you. Check forecasts, observations and warnings regularly.

• TasALERT.com
• your local ABC radio station or
• the Bureau of Meteorology’s website.

Flood levels

While no two floods are the same, the following describes what you can expect at different flood levels around the area. Even if your property is not flooded, you need to think about access. Different levels of rainfall can cause flooding depending on its intensity, duration and how wet the ground is beforehand and where the rain falls.

Huon River major flooding

If there is major flooding along the Huon River, and depending on the tides, there may be flooding in low-lying areas close to the river particularly around Franklin. The Huon Highway may be inundated around north and south of Franklin, as well as areas further south, and/or

The Huon Highway may also be cut at Geeveston if there is major flooding Kermandie River.

A major flood on the Huon River means the river height is at least:

• 6 metres at Judbury and
• 4 metres at Huonville Bridge.

That level of flooding is approximately the level of the 2016 floods and there is about a 5-10% chance of such a flood happening any year.  Tasmanians need to be prepared for floods that have a 1% chance of happening every year.  In this level of flooding, the river height would be about:

• 9.5 meters at Judbury and
• 5.6 meters at Huonville Bridge.

Depending on where the rain falls and the tide level, this level of flooding is likely to

• Close the Huon Highway in several places including north of Franklin, near Garths Point plus near Doctor Dicks Drive and Hyndes Road at Port Huon.
• Flood some properties in low lying areas on the northern side of Franklin.
• Flood parts of Regatta Ground parklands and the wharf area.

Minor or Moderate flooding along the Huon River is unlikely to cause significant impacts in the lower areas of the river south of Huonville, unless there is a particularly high tide.

Flooding from other waterways

Minor flooding

A minor flood can inundate low lying paddocks, orchards and other farmland.  Stock should be moved for their safety.  There may also be some flooding across some minor roads and parkland areas.

Moderate flooding

There is more extensive flooding of agricultural land and some buildings may be impacted to above floor height. Some properties may be isolated for a few hours as more minor roads become flooded.

Major flooding

There is at least a 2% chance in any year of major flooding along smaller waterways that can flood homes and other buildings in parts of Franklin, Castle Forbes Bay and surrounding areas. 

This level of flooding could be as a result of about 50mm of rain over 6 hours, around Cannells Hill, south of Huonville, for example. Flash flooding can close the Huon Highway at several locations plus impact low lying properties in areas such as:

• Swamp Road
• Franklin near Church Street
• Murrells Road
• Castle Forbes Road and Harwoods Road

Know your risk, get ready, reduce risk where you can, connect with others, stay alert and act safe.

Before a flood

1. Know your risk

Flooding often happens in Tasmania and can cause widespread and significant damage. In the past 200 years there have been 78 flood related deaths in Tasmania. This guide is to help you understand flood risk in your area.

2. Prepare your household

Have an emergency plan that covers storms and floods

Thinking about what you would do in a storm or flood means you are more prepared and everyone is safer. Have an emergency plan that everyone in your household understands. There are checklists to help you think through your plan – see the SES website or Red Cross Rediplan.
Check your plan regularly and test it by everyone in the household thinking through a flooding scenario that may affect your household.

Prepare an Emergency Kit

Regularly test batteries in radios and torches.

3. Reduce your risk from flooding where you can

• Think about storms, flooding and other hazards when buying, maintaining or developing property.
• Trim or remove trees and branches overhanging your home, business or near powerlines on your property.
• Keep your gutters and drains clear.

4. Connect with others

Know your neighbours and get involved in your community.  A connected community is a safer and more resilient community in an emergency and can help everyone recover better afterwards. Check that family and neighbours are safe and aware of what’s happening.

See for example the Huon Valley Good Neighbour project.

During

5. Keep up to date

Keep aware of what is happening around you. Check forecasts, observations and warnings regularly. 

• TasALERT 
• your local ABC radio station or
• the Bureau of Meteorology’s website.

6. Act Safe

• Supervise children.
• Prepare for possible power, water or internet outages.
• Check your emergency kit is ready to go.
• Keep clear of flooded areas such as drains. NEVER walk, play, ride or drive in floodwater. You can’t always see what is under the water or how deep or fast-moving the water is. It is easy to be swept away and drown in as little as 20cm of fast-moving water. Flood water can be dangerous.

When your home may be flooded

• Put household items up high to minimise possible damage.
• Turn off the electricity and gas if it is safe to do so. 
• A great way to stop sewerage flowing back into your home is to place sandbags inside plastic bags and use them to block toilets and cover drains and sinks.
• Leave while you can get out safely.

If you need to evacuate

• Follow the advice from SES / Tasmania Police.  
• Take your emergency kit. 
• Go to friends or family in a safer place or an evacuation centre. 
• Let others know where you have gone.

Look after your animals

You are responsible for your animals in an emergency. If you have pets and other animals it will take you longer to evacuate in a flood or other emergency. Move livestock from flood prone areas well before flood waters may rise.  For more information see

• RSPCA’s guidance on preparing for animals in an emergency
• Huon Valley Council’s advice on preparing an emergency pet plan
• the Primary producer farm flood readiness toolkit.

Avoid travelling during storms and after storms

• Do not go sightseeing. Sightseers delay emergency services and cause accidents.
• Watch out for hazards such as
  • water over roads
  • damaged powerlines
  • landslides
  • damaged roads
  • falling trees or roofing iron.
• Never drive through flood waters. Most deaths and rescues in floods are from people driving through flood waters.
• Drive slowly and turn your headlights on roads not affected by flood waters.

After

• Keep listening for ABC Local Radio updates, road re-openings, community meetings, etc.
• If you left your home, do not return home until SES or Tasmania Police tell you it is safe to do so.
• Be aware of road hazards, such as mud or debris on the road, damaged roads/bridges and crews working on clean-up and repairs.

If your home has been damaged

• Stay at ground level while checking for damage. Be careful of fallen trees, broken glass, loose roofing or other hazards.
• Wear strong boots, gloves and protective clothes. 
• Use a torch, never use matches or candles inside flood affected buildings. 
• Boil all drinking water until you are told the tap water is safe again.
• Do not turn on it is tested by a licensed electrician or gas fitter for safety.
• If your home is damaged and you need to stay somewhere else, take your emergency kit and pets with you
• Take photos of any damage if safe for you to do so and contact your insurance company.
• Supervise children.
• Check neighbours are okay.

For further information go to www.ses.tas.gov.au

Staying informed and further information

Current warnings (TasAlerts) alerts.tas.gov.au

Bureau of Meteorology (BoM)

Emergency Broadcasters ABC 936AM

TASSES Social Media

• facebook.com/sestasmania
• twitter.com/sestasmania

Preparing for Flood Emergencies ses.tas.gov.au/plan-prepare/flood 

Huon Valley Council huonvalley.tas.gov.au 6264 0300

National Relay Service (NRS) relayservice.gov.au

Disclaimer

The maps show potential flooding risks from consistent levels of rainfall across catchments, such as a 1% Annual Exceedance Probability (AEP).  In flooding events, rainfall is likely to be more inconsistent across a catchment, so these flood maps should be considered indicative only.  The mapped areas of flood risk show higher probability of inundation. Other areas have lower probability of flooding, but in severe and rare events (rarer than 1%AEP), other lower areas may be also at risk of inundation.

The information in this guide is current at the date of publication. While every effort has been taken to ensure the validity and accuracy of the data presented, the State Emergency Service does not take responsibility for data error or omission. Please see the standard Tasmanian Government’s Copyright and Disclaimer Statement for more details.