Managing bushfire risk

Fuel is any grass, leaf litter, twigs, bark and other live vegetation which can burn.  Fuel builds up at different rates in different areas depending on how fast the vegetation grows compared to how fast it decomposes.

One of the major ways we manage bushfire risk in Victoria is to manage fuels.

Fuels are managed differently across different areas in Victoria. In areas close to towns, burns are more frequent to protect people and the things they value.

In other areas, burns can be managed to reduce the spread of bushfires across the landscape. The focus here is on maintaining and improving ecosystem resilience, as well as for fuel management. These areas are excluded from planned burning to protect areas that can’t tolerate fire.

Fuel management is conducted across four Fire Management Zones:

• Asset Protection Zone - Aim to reduce fuel through planned burning or other methods approximately every 5 to 7 years.
• Bushfire Moderation Zone - Aim to reduce fuel through planned burning or other methods approximately every 8 to 15 years. Length of time between planned burns in some areas can vary due to ecological considerations
• Landscape Management Zone - Planned burning will focus on maintaining and improving ecosystem resilience, and fuel management will also be undertaken for risk reduction.
• Prescribed Burning Exclusion Zone - No planned burning, mainly to protect particular areas that can’t tolerate fire.

The Fire Operations Plans outline a number of different methods we use to reduce the amount of fuel and bushfire risk in a landscape.  Importantly, these methods vary between Fire Management Zones.  Methods used include planned burning, slashing, mowing and clearing works, creating and maintaining fuel breaks and carrying out fire infrastructure maintenance (like fire dams and lookout towers).

There are four main types of planned burning:

• Fuel Reduction - to reduce fuel levels in a specified area
• Ecological – to achieve ecological objectives
• Regeneration Burn – to regenerate particular species or vegetation types
• Catchment Protection – to restrict the spread of bushfires in forested water catchments

We consider a number of factors when selecting the most suitable time to light a planned burn. These factors, or conditions, affect the way the fire behaves, the amount of fuel likely to be reduced and the impact on nearby communities and the local environment.

As conditions can change quickly, the final decision to go ahead is made on the morning of the proposed burn. Before the fire can be lit, the officer in charge checks the list of conditions on the day. If all conditions are suitable, the burn can proceed safely. If one or more conditions are unsuitable, we will postpone the burn.

Weather

Advice on seasonal weather conditions and long-range and daily weather forecasts from the Bureau of Meteorology help us understand how past and predicted weather can affect the planned burn program for the season. Long periods of dry weather with hot, windy days will result in fewer opportunities for safe burning. If the weather has been cool and wet for a long time, there may be little time when the fuel is dry enough to light or burn.

The weather both at the time of a burn and for several days afterwards, influences the decision whether to burn. A planned burn needs calm and mild weather – it will not go ahead if the weather is unsuitable or there is a sudden, unexpected change to hot, windy or stormy condition. For example, if the temperature is too high the burn could be too hot. If the weather is too windy the burn could spread beyond the control line or flare up several days later. If the fuel is moist because of heavy dew or recent rain it may not light.

Fuel and fuel moisture

When deciding to burn, we consider the amount and type of fuel, the fuel moisture (whether it is wet, damp or dry) and how it will burn. Dense coarse forest fuels, such as stumps and logs, may burn and smoulder over several days, while grass and other fine fuels ignite easily and burn quickly. A burn may be postponed if the fuel is too wet to light, or so dry that the fire could do damage or be hard to control.

Landscape

When carrying out planned burns, the type of landscape – hills, valleys and plains – is considered. In hilly country, the speed of a burn can change.  Generally, a burn will slow down as it goes downhill and speed up as the slope increases. Small fires called spot fires may be caused by sparks or embers lighting fuel outside the burn area.

The fuel on a north-facing slope will burn easily because it is dry and warm. Wind speed and direction can change suddenly on ridges and in gullies. Fuel may not burn in moist gullies.

Purpose

The reason for, and the intended impact of, the burn must also be considered. For example, if a burn is to provide protection for a town or settlement, the burn officer will use the list of conditions to assess the risk of burning and the effect of smoke on nearby communities.

Coverage

The intended burn coverage or percentage of fuel to be reduced is also important. A burn to protect a township is usually expected to reduce fuel across 90% of the burn area. If a burn cannot be carried out safely on the day, we may postpone the burn even though the day may be suitable to carry out other burns at other locations.

A planned burn involves many different actions and decisions, and depends on weather. Some of the issues involved in doing a burn, choosing when to burn, and managing the risk of escape are described below.

Planning the burn

Before a planned burn can go ahead, we compile detailed information about the burn and the area. This is called a burn plan and includes information drawn from months to years of planning. It includes the reason for the burn, the fire history of the area and any cultural sites or habitat to be protected from the fire.

As part of this planning process, we consult with and listen to key stakeholders and communities to understand their needs throughout the delivery of the planned burn.  The plan also covers notifications required, the likely impact of smoke on traffic and nearby communities, maps of the burn area and operational information. Key stakeholders that we have previously consulted throughout the planning process include community members, local councils, Melbourne Water, forest managers, CFA, wineries, tourism industry ,apiarists, flora and fauna specialists and any other parties who register their interest.

Planned burns vary in size and complexity. Simple burns need 20-30 people to manage the operation, but others, such as those in high-risk areas, may need more than 70 people. The CFA often provides extra people and equipment to assist us, particularly when planned burns are carried out near towns and settlements.

The range of equipment and vehicles includes drip torches to light the burn, four-wheel-drive vehicles with water tanks, large and small tankers, dozers and earthmovers. We may use a small or medium sized helicopter to light a large burn and a fixed-wing plane for observation or mapping. Refuelling crews and an airbase manager will be needed if aircraft are assisting at a burn.

Before the burn

We carry out a range on-ground of preparation works in the weeks before the burn to make the planned area ready to be ignited when the weather and other conditions are right. Planned burn preparation is essential for the safety of fire crews and the community.

In the days leading up to a burn, trained firefighters finalise the preparation of the control lines that form the outside edge of the burn. The officer in charge of the burn makes sure that the correct approvals are in place. Weather conditions are monitored regularly, and safety checks are carried out.

Preparation works may include raking around trees to protect habitat trees, removing hazardous trees to make the burn safer for fire crews, grading the existing roads and tracks to improve access and reduce the risk of the burn escaping.

On the day of the burn

On the day of the burn, the burn officer checks the weather, wind, fuel moisture and other conditions. If everything is suitable authorisation is requested and the public is then notified through a range of channels. If traffic control is necessary, signs are put in place on local roads and tracks. Weather, fuel and other factors that we consider when choosing the most suitable time to light a planned burn are described below.

At the burn site

Burn officers lead briefings for trained firefighters at the burn site. These cover the burn tasks, any likely hazards, special consideration for protection of important natural or cultural values and contingency plans.

The burn is then lit according to a special lighting plan or pattern to achieve the planned coverage. Lighting may take three to four hours for a small burn or two or more days for a very large burn. For smaller burns lighting occurs using ground crews, while for larger burns helicopters may be used to light the burn from the air.

After the burn

After the burn, trained firefighters patrol and monitor the area putting out or removing smouldering material around the edge, until the burn is eventually declared safe. Depending on the size of the burn, this monitoring period may range from a few hours to many months.

We understand that planned burns can cause some anxiety for people who live near a burn or who may worry when they see smoke. Carrying out a planned burn is a complex and difficult process so we take precautions to ensure the safety of local communities, firefighters and the environment.  Although we make every effort to reduce the chances of a planned burn escaping, a very small percentage do escape.

To reduce the risk of a burn escaping, trained firefighters and other fire support staff conduct planned burns when the fire danger is low, the weather is expected to be stable for several days and all other conditions are suitable. Each burn has a plan that describes the conditions that must be met before a burn can go ahead. Once a burn has been completed, trained firefighters patrol the burn area for several days or weeks until a burn is declared safe.

Burn escapes

Research data over a twenty-year period indicates that very few burns escape. Nine bushfires out of a yearly average of 584 bushfires on public land are as a result of escaped planned burns. Burn escapes amount to about two percent of all fires and about five percent of the total area burnt.

If a burn escapes

Unexpected or rapidly changing conditions can lead to burns spreading beyond control lines, even though we have taken every step to keep the risks to a minimum as detailed previously. If this happens, firefighters respond quickly to contain the burn.

If a burn spreads significantly we will declare and manage the burn as a fire, keeping the community informed. We will also investigate how and why the escape happened. The Victorian Government may be able to help landholders if a burn damages fences.

We consider a number of factors when selecting the most suitable time to light a planned burn. These factors, or conditions, affect the way the fire behaves, the amount of fuel likely to be reduced and the impact on nearby communities and the local environment.

As conditions can change quickly, the final decision to go ahead is made on the morning of the proposed burn. Before the fire can be lit, the officer in charge checks the list of conditions on the day. If all conditions are suitable, the burn can proceed safely. If one or more conditions are unsuitable, we will postpone the burn. Weather, fuel and other conditions that affect the decision are described below.

Weather

Advice on seasonal weather conditions and long-range and daily weather forecasts from the Bureau of Meteorology help us understand how past and predicted weather can affect the planned burn program for the season.

Long periods of dry weather with hot, windy days will result in fewer opportunities for safe burning. If the weather has been cool and wet for a long time, there may be little time when the fuel is dry enough to light or burn.

The weather both at the time of a burn and for several days afterwards, influences the decision whether to burn. A planned burn needs calm and mild weather – it will not go ahead if the weather is unsuitable or there is a sudden, unexpected change to hot, windy or stormy condition. For example, if the temperature is too high the burn could be too hot. If the weather is too windy the burn could spread beyond the control line or flare up several days later. If the fuel is moist because of heavy dew or recent rain it may not light.

Fuel and fuel moisture

When deciding to burn, we consider the amount and type of fuel, the fuel moisture (whether it is wet, damp or dry) and how it will burn. Dense coarse forest fuels, such as stumps and logs, may burn and smoulder over several days, while grass and other fine fuels ignite easily and burn quickly. A burn may be postponed if the fuel is too wet to light, or so dry that the fire could do damage or be hard to control.

Landscape

When carrying out planned burns, the type of landscape – hills, valleys and plains – is considered. In hilly country, the speed of a burn can change. Generally, a burn will slow down as it goes downhill and speed up as the slope increases. Small fires called spot fires may be caused by sparks or embers lighting fuel outside the burn area.

The fuel on a north-facing slope will burn easily because it is dry and warm. Wind speed and direction can change suddenly on ridges and in gullies. Fuel may not burn in moist gullies.

Purpose

The reason for, and the intended impact of, the burn must also be considered. For example, if a burn is to provide protection for a town or settlement, the burn officer will use the list of conditions to assess the risk of burning and the effect of smoke on nearby communities.

Coverage

The intended burn coverage or percentage of fuel to be reduced is also important. A burn to protect a township is usually expected to reduce fuel across 90% of the burn area. If a burn cannot be carried out safely on the day, we may postpone the burn even though the day may be suitable to carry out other burns at other locations.