I teach in East Austin and my students have had a lot to say about the ongoing wildfires around Texas. Our school is about 30 miles from the worst wildfire in Texas history in Bastrop. An estimated 1,386 homes were destroyed (Statesman news article). One of my students was absent until today and said that he was trapped for four days in Smithville because all the roads to leave were shut down. Here’s a dramatic video of the fire crossing one of those roads.
In addition to being sadden by the loss of homes and 35,000 acres of tall piney woods, I have a lot of questions about the fire.
Firstly, how many people were displaced? News reports have yet to give an estimate. Students used Wolfram Alpha’s US Census on Bastrop’s ZIP code data to discover that there are an average of 2.63 persons per household. At 1,386 homes, that’s about 3,650 people without homes. Sometimes big numbers are hard to grasp without a context. Our high school has 830 students so that would be the equivalent of about four of our school’s student population displaced!
So just how big is the fire? How many square miles or acres does it cover? What shape is it? A map shows that it’s a teardrop shape that covers about 38,000 acres or 60 square miles. I wondered how the perimeter of such a shape is measured.
What progress has been made in fighting the fire? Reports currently say that the fire is “30 percent contained”. I assumed that this means that 30% of the area of the fire has been put out. I was wrong. Instead it means that 30% of the fire’s 50 mile perimeter has a fire trench or barrier dug around it.
After seeing this footage of the fire, I wondered if “percent containment” really matters at all. Who cares if they have 15 miles of the 50 mile perimeter stopped if the rest of the border moves this fast?!
I’m learning more about the mathematics of wildfires by reading a guide on the math a firefighter should know. It’s awesome. (Algebra teachers should refer to this demo from Ch. 5 and see how slope effects that rate of spread of a fire.)
Lastly, I found hope in watching these planes filling up with water in Lake Travis. Tomorrow morning, firefighters will get a bigger helping hand in the form of a DC-10 jet airliner capable of dropping 12,000 gallons of fire retardant.