George Rebane
Kudos to Yubanet.com for being the most heads up and informative website for wildfire information. At the same time, government falls short of its function as is apparent to anyone visiting mynevadacounty.com. Starting yesterday (4aug21) afternoon, all of us in western Nevada County have been on tenterhooks watching the River Fire started by someone at the Bear River Campground near Colfax.
For Jo Ann and me this kind of annual firewatch and evacuation preparedness has been a way of life ever since we moved to Simi Valley in 1968, and then into the Santa Monica Mountains in 1978, and here to Nevada County in 2002. Every year it’s the same ol’ same ol’ – are we going to lose our home this year? And frankly, after over fifty years of this and at our age, we’re starting to get a little tired of being puckered up every summer and fall.
Today some of our family also lives in Nevada County, and their houses are between us and the flames. More aggravation and worry. So, we’re all glued to the TV, internet, and radio trying figure out the location and progress of the fire. Which brings me to how such disasters are reported to the public. Bottom line, being keenly aware of wildfire reporting on the media for all these decades, and looking at it through the perspective of an engineer and a former forward observer (we’re the supposed map experts), the media on the whole gets no better than a D for their sophomoric efforts. Although I do admit that ever so slowly, they have been getting better at passing on information instead of just missing or mangling it. As I said, up here Yubanet is the closest thing we have to a gold standard in such reporting.
The basic questions an endangered individual wants to know is (1) where is the fire, its actual extent, and how is it spreading, and (2) what and when are my prospects for having to evacuate? Secondary information items are things like number of persons and resources on the fire line, percent containment, and when is it going to be over. The problem comes with how much credibility do such media information displays have. Because when a media outlet’s report is grossly inconsistent, time late, and missing critical items, it’s hard to believe the information they do put out that might be useful.
Back in the old days in LA County, when the fires burned, reporters and camera crews were dispatched, and the result was always confusion. Why? No TV producer understood the information items that their viewers needed, and the fielded reporters never knew from where they were reporting, or what their telephoto lens were looking at from some remote mountain top. So, the copy transmitted was mostly time late pabulum – human interest evacuation stories – and the video was always of close-up pictures of flames – totally information free reporting, no big picture of what was going on.
Today Yubanet shows you the latest contour of the fire area superimposed on boundaries of evacuated areas and areas under evacuation warning. In addition, they show us anecdotal verbiage on the nature of the fire and how crews/aircraft are fighting it. All this is accompanied by data items such as acreage burned, current containment, and when 100% is expected. There remain some humorous inconsistencies like currently ‘0% containment’, but the fire will be completely contained by ’14 August 2021’. Also, not all the items are time-tagged, so it’s hard to tell the time late of what you’re looking at.
And true to form, MyNevadaCounty.com is not only deficient in the information items shown, but also not consistent with Yubanet on the evacuation areas. Finally, the anxious citizen has no idea of the location and extent of the fire, and NOTHING is time tagged. Our county’s Office of Emergency Services is strictly a junior high school operation when it comes to keeping citizens informed during emergencies.
Let me end with some envelope calcs on making sense of the reported area of a fire. We recall that the important part of a wildfire from where it spreads is its perimeter. Other than high value structures inside the perimeter that need defending, almost all firefighting resources are expended on the perimeter. And therefore, it’s the lengthening perimeter that needs to be contained and doused, because that’s where the action is. That makes thinking about a fire in the form of a burning loop of rope, and the length of the rope, not the area it contains really communicates the ‘size’ of the fire.
Our River fire is now (1450hrs, 5aug21) about six miles long and two miles at its widest. It is reported to be a 2,400 acre fire. Recall that at 640 ac/sqmi, 1,000 acres is about 1.5 sqmi. So, our fire is about 3.6 sqmi. Were it really a square, it would be about 1.9 miles on a side, or with a minimum perimeter of about 7.6 miles. (I’m asking the geometrically astute to give us a little slack here. It’s easier to take one square root than to go from a circle’s area to its circumference, i.e. calculating C = 2*sqrt(Area*pi).)
So the shape of the fire’s area suggests that its perimeter is somewhere less than 14 miles = 2*6 + 2 (for the bulge in the middle). So this gives you a rough rule of thumb for figuring out the real size of the fire, it’s between the perimeter of a square and two times the length of the square’s perimeter. The firefighters have to manage this length of fire line of a 0% contained fire.
A fire is ‘contained’ to the extent that a “any physical barrier that stops the fire from passing a certain point” has been put around the fire line (i.e. perimeter). So, a fire is 50% contained if such a physical barrier has been created or encountered (i.e. coming to a sufficiently wide river) along half of its perimeter. Of course, a fire can be 90% contained, and a devilish wind can subsequently induce a breakout, and we’re off to the races again.
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