Los Angeles firefighters were left empty-handed this week. They emptied three reservoirs and the state of California asked citizens to limit their water consumption. But could we put the water of the Pacific to use?
Published at 5:00 a.m.
Why aren’t we using salt water to fight wildfires in Los Angeles?
In fact, water is drawn from the Pacific Ocean to fight the forest fires ravaging the City of Angels. This is the case, among others, of the two Canadair CL-415 aircraft, each equipped with a tank with a capacity of 6000 liters. These two planes and their pilots report to the government of Quebec, but are assigned to California each fall, under an agreement with the American authorities. The two planes are currently refueling with water in the Pacific Ocean, confirms The Press the Society for the Protection of Forests against Fire (SOPFEU).
In this context, with so much water at the disposal of the authorities, shouldn’t we quickly put out these fires?
It’s not as simple as it seems. The Canadair CL-415 are unique devices in the world, recalls Stéphane Caron, prevention and communications coordinator at SOPFEU. And, currently, there are only two planes assigned to fighting fires in Los Angeles, although two more are expected to be added next week, says Mr. Caron. They were designed to respond to the Canadian context, where there is no shortage of lakes and rivers to supply water. “Salt water will make devices more vulnerable to corrosion,” explains Mr. Caron. Every day, it takes a complete cleaning of the devices and tanks. » The body of water must also be relatively calm to allow the device to land there to fill its tank, which is easier to do on a lake than in the ocean, adds the expert.
Are these planes still able to put out fires?
“A water tanker is not going to put out a fire. It will contain it, reduce it to allow firefighters on the ground to put it out. To really extinguish it, you have to go deep,” explains Stéphane Caron. Devices like the CL-415 work in pairs. For an effective strategy against fire, they must empty their tank every 10 minutes. “While one plane is dropping its water, the other is fetching water. There is like a chain to strike the fire, it must be continuous to be effective,” adds Mr. Caron.
Why don’t we pump water directly into the ocean to supply ground teams?
Again, seawater poses several challenges. One option would be to pump water from the Pacific Ocean into the Los Angeles aqueduct network: there would be no shortage of water to fight fires, but that would cause a major problem, says Pascal Caron, lecturer. and engineer specializing in fire protection. “The problem is that if you put salt water into the drinking water network, you have just created another water contamination problem. You have to clean everything and it becomes almost impossible, because you have to chlorinate it, and you have to take samples, and you never end it…”
The solution is also not ideal for firefighters, who could fill their truck’s tanks with salt water. But several parts of the tanks and other firefighters’ equipment are made of metal and would have poor resistance to corrosion caused by salt, explains the American site Technology.org, specializing in science and technology.
Are there any other disadvantages to using seawater to fight fires?
According to scientists, salt water has a less significant cooling effect than fresh water. “The cooling effect of seawater is slightly less than that of fresh water, and it decreases with increasing salt concentrations in seawater,” concluded a study published in the specialist journal International Journal of Refrigerationin 2021.
“From an environmental point of view, dropping salt water on vegetation is not ideal,” underlines Stéphane Caron, from SOPFEU. Such quantities can particularly affect the soil and harm plant regeneration. This is an option used as a last resort. In Quebec, SOPFEU supplies itself with sea water to fight fires in Gaspésie, for example, when there are no other options, adds Mr. Caron.
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