When fighting fires there are many different techniques for each variety, from house fire, to grass fire, to forest fire, yet what doesn't change are the essentials. These essentials range from the behavior of fire itself, the way it moves, and how best to undermine its advance before being able to successfully extinguish it. In this case we will examine the various forest fire fighting techniques that are currently used, and potential ones yet to be tested.
The first essential of fire is that it is more like a wild animal than a random force of nature. This is important because very much like a living creature, it is as unpredictable as it is concrete in its habits. Despite the fact that it is herded in a direction based upon wind and fuel, it eats, breathes, grows, reproduces, and has defensive mechanisms in the form of intense light, heat, and smoke. To confront it without this understanding is asking to be beaten by it.
The next essential is that fire can only sustain a growing form so long as there is ample supply of nourishment in the form of dead plant and animal life, a type of hydrocarbon (including all fossil fuels, natural gases, and by-products, like plastics), or anything considered flammable. In a similar respect, if it is unable to 'breathe' then it will be unable to sustain as well. By depriving it of these two things, fires can be dwarfed and subdued by easier means.
The final essential mentioned is the understanding of how a fire moves. Just like growing, a fire needs to eat and breathe in order to advance, which if it doesn't do vertically, it does by the wind or what is available to eat. Just by simple observation one can tell that a fire grows from its base, using its heat to expel moisture from a potential meal, and that it likes to travel up, and not down. A lit matchstick will usually have a harder time burning down if the lit end is up and never if the base is damp. This is very important because the fastest way for a fire to work quickly through a forest is by burning trees and low brush from the bottom up.
Now that there is an understanding of the behavior of the fire, it is possible to examine the techniques used against it. One of these is the fire line, which is placed at a point somewhere in front of a forest fire's advance. These are made by knocking over trees, digging up the ground, and basically carving a line in the earth at a certain width, in hopes that it will halt the fire's advance by removing a steady source of nourishment from its path. If the ground is hosed down and the forest beyond is watered by hose or sky drop, then it will be more effective. This works very well, provided there is no wind pushing the heat and embers past the line, and igniting it on the other side.
Other techniques involve the water drops mentioned before, usually from plane or helicopter. This is done by the aircraft scooping or sucking water into a containment tank at a lake or other still body of water, and dropping the water load on the fire from above, usually on or behind the front line. If there is little wind, then dropping the water on the advancing line will halt it, letting additional drops contain it, if the water is dropped behind the line, then it is done with the intention of disrupting a stronger flame by cutting off a portion of its heat source.
Other techniques involve direct ground battling, where firefighters will attempt to stall a fire spreading by targeting its lesser expanse. This is done where the fire is creeping along against the wind, and is easily displaced by watering the ground beneath it. Serious fires are never good to approach directly from the front, or else those fighting the blaze may be simply over run. It is much better to eliminate the weaker side of a fire when they are able to, to prevent the spread if the wind shifts direction, while evacuating those caught in the fire's path.
A yet untried technique involves the use of an implosion device detonated behind the wall of a fire. The hope is that a strong enough backwards pull will eliminate a fire at its outer edges, while enabling firefighters to battle the weaker blaze in the middle. The fear is that the damages to the landscape, or the unintentional spreading of the blaze by pulling the embers high into the air, is just another worry. Getting a device that works well and is cost effective is another matter entirely.