Severe Drought effects on Fireline Safety

IV International Conference on Forest Fire Research and 2002 Wildland Fire Safety Summit
Gary Dakin (FERIC)

Note:
This presentation is for discussion at the 2002 Safety Summit in Protugal.
It is part of a round Table discussion on Fire Fighter Safety.
Round Table on Fire Safety - On the 20th of November a panel of invited speakers will participate in a Round Table on Fire Safety with the objective of discussing relevant topics to fire safety. The panelists will be:
G. Xanthopoulos, from the National Agriculture Research Foundation of Greece, Moderator
Gary Dakin, Forest Engineering Research Institute of Canada,
Leslie Anderson, USDA Forest Service, Missoula Technology and Development Center
Marc Castellnou, Spanish Fire Brigade Service
Commissioner Phil Koperberg, NSW Rural Fire Service, Australia

Temperatures June 2002
Temperatures were up to 7 degrees above normal in the Forest Protection area in the Province of Alberta, Canada
Note: Alberta has been experiencing drought conditions in some part of the province for the last several years. This graph is for June of 2002 and shows some of the effects.

Precipitation June 2002
The Protection area experienced up to 40% below normal precipitation for the month of June
Note: A large portion of the Province has been lacking in moisture and the accumulated effects of several years of drought have resulted in one the severest fire season with the largest fire been the House River Fire at 248,000 Hectares. A total of 1280 fires to October 21, 2002 as compared to 934 for all of 2001


Note: The graph demonstrates that since 1997 to 2002 there were more years below normal than above normal showing a buildup of drying conditions.

Sudden Flare-ups
Firefighters must constantly be aware that the fire may suddenly flare-up. They MUST have established safety zones and marked escape routes.
Note: Severe drought conditions mean the Firefighter will be exposed more often to sudden flare ups. It demonstrates that the Firefighter MUST work from anchor points and have safety zones and escape route clearly marked.

Extreme fire behavior
During severe drought conditions firefighters are often faced with violent and extreme fire behavior.	Chisholm Fire 2001 Build up Index = 123 Duff moisture code = 101 Drought Code = 388
Note: Extreme and violent fire behavior are trademarks of drought conditions. Fires run as fast at night as they do during the peak burning periods. Extreme caution must be used when deploying Firefighters on the line. These firefighters must always work from an anchor point and have escape routes and safety zones clearly marked. All safety briefings must give the Firefighter the expected worst case fire behavior expected for the day and they in turn must fully understand the consequences in failing to follow the guidelines and rules they were trained in. Each Wildland Fire agency has the thresholds in fire indices that indicate when extreme fire behavior can be exceeded.

Severe drought can put more values at risk
More values can be threatened in severe drought conditions. This exposes the wildland firefighter to more unfamiliar dangers and risks.
Note: The introduction of values at risk into the already complicated job of wildland fire fighting will add to the dangers faced by Firefighters. These value can pressure the Wildland Firefighter into dangerous situations just because a structure or value is involved. Unnecessary chances may be taken because of the public exposure during fires involving structures.

Camp burns by wind borne embers
Despite this camp been situated in an old burn; during severe drought conditions old burn areas may reburn. This camp is on fire due to air borne embers from the main fire 2 km away.
Note: In years of severe drought some of the areas used as safety zones no longer apply as shown by this camp that burnt in a 1998 fire area. This camp was 2 km away from fire front but was brunt as a result of air borne embers that ignited the fuels left in the old burn site. During high drought seasons all aspects of fire have to be considered and reconsidered. Do not take anything that worked in the pass for granted.

Aspen Stand Burn over
Aspen stands are often used as safety zones. However, during seasons of severe drought, even these areas suffer burn over.
Note: Aspen stands in “normal” years are used as a safety zone and fire barriers except for early spring and late fall, However in years of severe drought these havens do not exist and can result in burn over.

Deep ground fire
During severe drought, ground fires can burn deep.This creates another hazard for the unwary fire fighter.
Note: Deep fires covered large areas become a concern of the Firefighter, Do not fall into this pit; be careful as much of the fire remains unseen.

Fire intensity initiates indirect attack
The intensity of the fire forces more use of indirect attack where fire fighters must work from anchor points to be safe on the fire line.
Note: Indirect attack can mean working away from the fire line. This can create all types of dangers for the Firefighter. Anchor points escape routes and safety zones here will assist the firefighter in working safety and returning to base after a day on the line.

Travel rates versus fire spread
Independent of fuel type, dropping the pack and exiting through an improved escape route condition was significantly quicker than all other travel conditions (up to 200%).
Note: Data analyses demonstrated that independent of the fuel type firefighters were traveling through, dropping their pack significantly improved travel time in both the natural and improved conditions. The fastest escape, independent of fuel type was through an improved escape route without the pack (68s). This finding was ?19% faster than carrying the pack through an improved escape route (82s). Similarly, through a natural escape route dropping the pack also increased escape time by ?20% (137s vs. 110s with and without pack, respectively). These findings clearly demonstrate that from a purely speed of escape perspective, dropping the pack would considerably improve travel time from any fuel type, through improved or natural exits. Moreover, through a natural escape 27s could be a crucial amount of time! It was found from these analysis that in every test performed mean heart rate was approximately 95% (range 94.0 – 98.0%) of maximal heart rate, which is impressive considering the short duration of these trials (usually less than 2 minutes). Therefore, it appears that the subjects gave a maximal effort on each test and were unlikely to be able to go any faster. In drought conditions fire will travel faster however the firefighter cannot go any faster than what he is capable of under normal conditions.

Working wildfire in severe drought conditions can challenge even the most seasoned firefighter.
Note: Some of the old tried and true rules of thumb get challenged during periods of drought like 1. Camp in the black 2. Fire does not burn as well at night 3. Aspen stands make good fire guards and safety zones 4. Fires do not burn as well downhill as they do uphill

Download Video (4 MB MPG)

Note:
Severe drought can create extremes in fire behavior as demonstrated by this short video of a fire whorl created by the amount of dry fuels available for the fire to consume. This whorl sent spikes of fire approximately 300 meters high.

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Note:
This is what you would see if a crown fire burnt over you.This was taken by video cameras housed in specially designed boxes at the International Crown Fire modeling Experiment in the Northwest Territories of Canada.