Rogue Valley Fire Prevention

Suppression Methodology

You may have some specific questions about wildland firefighting tactics, such as: what is a fireline, and how does it stop wildfires from spreading?  In this section, we will cover some fire basics, and in doing so, explain some of the reasoning behind certain firefighting tactics.

Fire needs three fundamental elements to occur:  Fuel, Oxygen, and Heat.

If you remove any one of these three elements, the fire will go out-- or fail to begin in the first place.

 

 

Fire behavior/movement is controlled by elements in the environment.  It is influenced by:

  • Available Fuel
  • Weather Factors (such as sun and wind)
  • Topography (slope, valleys, canyons, etc.)

Extreme warm temperatures will dry combustible fuels to extremely flammable (fire prone) levels.  When fire burns on steep slopes it preheats fuels above it, resulting in more combusitble fuel and therefore more intense flames.  Winds can cause fires, especially those on steep terrain, to move faster and with greater intensity than fires on flat terrain.

Altering the amount of available fuel in an area is often the most efficient method of combating forest fires (or fires in the wildland urban interface).  This is the key idea behind creating fireline.

Firefighters use scraping/chopping tools (such as pulaskis, hazel hoes, etc.) to create fireline, which is an area of ground cleared of burnable debris (such as duff, dead leaves, and ground cover) down to mineral soil.  The line's width depends on fire intensity, weather conditions, and the physical features of the immediate area.  A low intensity, smoldering fire will require a more narrow line than an intense grass fire burning on a steep slope (as fires on slopes will burn more quickly and with more intensity than fires on flat ground).  High winds add more intensity to flames and are also a consideration to be taken during line construction.

Sometimes, when fires become extremely intense, constructing  direct fireline (fireline in close proximity to the fire) ceases to be a viable option.  In these situations, indirect fireline can be constructed at greater distances from the flames, and/or firefighters can attempt aerial attacks with fire retardants and water drops.  

Retardant and water drops can somteimes fully extinguish fires, depending on the size of the drop and the intensity of the fire.  In other cases, retardant can act as a "wet line" of sorts-- preventing lower intensity ground fires from spreading to unburnt surface fuels.  Retardant/water drops are often used in conjunction with ground crews-- knocking down flames so that ground personnel (or bulldozers) can safely construct fireline.