There are 70,000 forest fires on Earth every single year. In 2021, forest fires alone were the cause of 1.76 billion tonnes of carbon emissions. Economically, this amounts to 16.5 billion dollars for the United States alone. This horrendous disaster is a cause of concern for human beings and even for flora and fauna residing in forests. It can cause anything from heavy exposure to pollutants to destruction of natural habitat and even result in their death by being caught in the blaze. Forest fires are either artificial or natural, both being equally destructive. Any random fire in a forest cannot be referred to as a forest fire. Forest fires require precise conditions. For instance, dried plants will catch & spread fire faster. In contrast, a fire on lush greenery will be easier to contain since the fuel also has some quantity of extinguisher in the form of water mixed.
What are the causes of forest fires:
1. Human activities such as bonfires, cigarette butts and arson.
2. Natural phenomenon: Lightning is the most significant natural cause which works best on dry fuel and conditions. In very few cases, these fires may be initiated by volcanic activity or spontaneous combustion of vegetation.
The conditions for a forest fire are: -
Rainfall causes more forest fires. Although this is counter-intuitive, more rainfall results in a higher floral population, resulting in more fuel. This is true only for the pre-fire season.
High temperature in pre-fire season destroys flora, thus lesser fuel. So is the case with soil moisture, the more of it in the pre-fire season more fuel there is. Humidity is also a decisive factor. More the humidity less the chance of a forest fire.
Winds are a decisive factor in the spread of a wildfire. Wind speed and direction determine the direction of the spread of fire and the rate at which the fire spreads.
Height is also a significant factor. The more the altitude, the moister the climate is because warm air rises and its moisture; therefore, we see snow on mountaintops(high humidity and low temperature). Terrain features determine the spread of the fire on a mountain or elevated and undulating terrain. Which one do you think the fire will spread farther from, the top of the mountain or the bottom?
The answer is bottom because fire like heat tends to go upwards and not downwards.
Let us summarize all we have discussed in a table:
Factor | Pre-fire conditions | Just pre-Fire conditions |
Rainfall | More rainfall, more fuel in form of plants | Rainfall only increases humidity, thus slowing down the fire but cannot stop it. |
Temperature | Higher the temperature, the lesser the fuel(plants) | Higher the temperature drier the fuel, so fire spreads easily. |
Soil Moisture | More soil moisture, better flora, and thus more fuel for the fire. | Generally, soil automatically dries out before the start of a fire. |
Humidity | High humidity slows down plant growth, thus lesser fuel | High humidity will slow down the spread of fire. |
Winds | No relation | The windier it is, the greater the rate of spread of fire. |
Altitude | The higher the altitude, the wetter the conditions are | Low altitudes have more dry fuel than high altitudes, thus having the capacity of a more extensive fire. |
Slope | The slope will determine the amount of flora. | If the fire starts at the bottom of a slope, it will spread faster. |
For instance, let us understand the damage caused by the forest in the case of Uttarakhand Forest fires in 2016.
Below are the analyzed images that give an idea of the amount of forest burnt by the fire.
The image on the top is just before the forest fire, and the one below is just after the forest fire. The severity of the forest fire is indicated by the areas marked by the colour red.
Earth observation can not only be used to analyze the damage post-fire but to predict the possibility as well.
Although forest fires cannot be prevented and we cannot pinpoint the exact origin, we can predict a rough point of origin, and a buffer zone can be set up to prevent the spread. This is achieved by monitoring rainfall, vegetation, terrain, humidity, soil moisture, altitude and slope. These, coupled with the general wind speed and direction, can be useful to predict a point of origin that will be accurate to a few kilometers.
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