"We Didn't Start The Fire!" A Hillside Fire in Anchorage
When most people think of wildfires in Alaska, they usually can be found in the Interior near Fairbanks, or on the Kenai Peninsula. They don't think of Anchorage, the biggest city in the region.
I remember the summer of 2019. It was on average 90 degrees. For Anchorage that was very hot. Normally we get about 60-70 degrees Fahrenheit in the summer, with occasional rises into the 80's. With climate change, the temperatures have been steadily increasing. The birch trees went into overdrive as the heat cranked up, pumping out pollen. I barely could breath. Then the fires began. The smoke was unbearable for an asthmatic like me. I had to wear an N95 mask. This was several months before the coronavirus pandemic made it normal. Everyone looked at me funny.
When I was getting my allergy shots for birch pollen, I had some overreactions and had to stay at the local hospital. As I was looking out, someone pointed to the cloud of smoke after receiving a text notification. It was chilling. I was a bit paralyzed wondering, "Is my home going to burn down?" I went home later, after it had all calmed down, and I found out what had happened from the Anchorage Daily News. A local trailer park, with streets named after Polynesian islands and culture, had been evacuated by the Fire Department. Despite the difficulties for the National Guard fighting the Swan Lake Fire (the one in the Kenai Peninsula), and the fires in the Interior, they managed to send a helicopter with fire retardant in the way of the fire. The fire was repeating a historical precedent, in following a burn pattern up the Hillside. If it hadn't been stopped, the Hillside would have been in a lot of trouble with the strong winds, warm sun, uphill slope, and dry dead beetle killed spruce.
Who are we going to call?! Not the GhostBusters, kid. We will call the Anchorage Fire Department, the State Division of Homeland Security, and the Air National Guard--the people who are most likely to respond.
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This an overview map.
This map above shows a map of all the roads, the rivers and lakes (possible sources of water), speedbumps, fire stations, elevation and high schools (best water resupply source during an emergency) in the region. It is a lot of detail, and needs some refinement. I haven't included a legend yet, but I will shortly.
Also take a look at the Anchorage Water and Wastewater Utility (AWWU, the local water and sewer utility) Service Areas below. They correspond with the map of fire hydrants following it. Take a look to see where your home or the home of a friend belong in terms of service.
Here is a map of all the hydrants in Anchorage. This is the first and most important part of my model, finding places without public water supply.
This is a map of all the water hydrants in Anchorage with what is known as a "buffer". These are all the locations within 200 meters of a fire hydrant that can be served by a firetruck attached within two hose-lengths of the hydrant. You can see that the Hillside has many places running on wells. This is not conducive to fighting a wildfire in this region. While helicopters can reach it, and while fire trucks can access it, the lack of easy access to fire hydrants hinders a fast and effective response. Making this buffer helps me find the streets that I need to focus on the most. By using the erase by mask tool, I was able to erase the streets I didn't need to focus on. Some of the empty spaces on the Hillside are surrounding the three local schools: South High School, Service High, and Goldenview Middle School. In the middle of a fire, the Anchorage Fire Department would shuttle water from tankers to the firefighting apparatuses because it is easier to pump water from the relatively unencumbered six fire hydrants at each of the schools than to hook up to a hydrant that has never been used before, and may or may not work.
You can see how many streets are now missing after the erase by mask, due to the prevalence of hydrants in most parts of Anchorage. The exceptions are the HIllside, and another similarly exposed mountaintop neighborhood called Stuckagain Heights (Yes you can get stuck there very easily.) But we still have a problem: There are many neighborhoods that are well within a 5-10 minute response time for a fire response. So begs the question: which ones are in the most danger?
We've already determined what roads lack public water. We now move on to the slope of the roads.
The differing classes of green streets reflect differing levels of road grade. 0 is road grade percentage from 0%-6% percent, while 1 is 6%-30%, and 2 is 30%-60%, and 3 is 60%-90% percent grade. Unfortunately, all the roads in my analysis show up as green despite my best efforts to code roads so I can find which roads are at risk. It seems that almost all roads in the Hillside are at risk because of the original code of road grade as "6 ft per 100 ft" as the slope that starts giving fire apparatuses such as fire trucks difficulties in traversing distances to houses. There are obviously places such as the road up to Flattop and the Bear Valley that have the greatest and most difficult slopes, and those are the darkest road slopes on the maps.
Here is the road to Bear Valley. The slope is long, hard, and dark green.
Next we converted the rasters equal to a 2, 3, or 4 (all numbers greater than 6% grade elevation), and we converted them to polygons so we could see what roads had the greatest increase in slope. We also did it for ease of use. We then made a buffer of 6,400 feet so we could eliminate the insignificant small spots of elevation gain nearest the fire stations so that we could focus on the steeper, and more dangerous roads. However, in this analysis, some of the steeper roads, such as the one contained near the right hand edge of this buffer in this second photo are probably just as dangerous but they are close enough it should not be a problem. The ones I am looking for are outside of the 6,400 foot radius, and are extensively long, sinuous, and therefore dangerous. Again, the Bear Valley, the areas by Flattop, and farther south on the mountains are the most dangerous places according to this analysis.
Great, we have found the roads most likely to slow a ground based fire apparatus's response to a wildfire on the Hillside based on slope and access to public water! While this is great, we now need to consider the factors that make wildfires more dangerous such as southerly aspect, slope of the hill, and vegetation. We also need to consider the question, "Will speedbumps get in the way of said response?"
First off, lets focus on Aspect. Aspect is the direction that a slope faces, particularly in a cardinal direction such as North, South, East, or West. It also can face any degree of Northwest, Southeast, and all the other cardinal directions in between. Aspect is important for wildfire modeling because the slopes that tend to burn the most are found on the South, Southeast, and Southwest. This is due to the sun having more time to dry up vegetation on the south facing slopes and cause a fire. In this map, I managed to take the three southern aspects, and combine them into one. They are the yellow slopes. The blue slopes are all other slopes.
We can see that many of the roads that we have discussed not only lack the public water supply, have steep road grade, and have a south facing slope, all of which do not bode well for firefighting efforts. The black is raster polyline, and the orange is a 100 foot buffer to make it easier to see on the blue and yellow map, yellow being the south facing sides. They certainly remind me of ice worms in the ice at Portage Glacier.
So now we use the Raster Calculator to combine the Slope and the Aspect model we have just made above. We will put the slope at 45 degrees and above, and the Aspect for the Southern directions.
We can now see the vulnerable, too steep of grade roads, the butternut locations of less danger, with the purple indicating an increased risk, (slope and aspect) facing south, and a 3 or turquoise blue showing the steepest slopes (sheer 90 degrees, of which there is none) facing south. We now have a basic, landcover-less model for modeling wildfire risk on the Hillside in Anchorage, Alaska.
What stuff am I not considering?
I am not considering aerial firefighting response time. I am not considering network analysis. I am only focusing on the places with the greatest risk of a delayed response by a ground-based firefighting apparatus due to the steepness of the roads, best slope for a wildfire, lack of public water access, and a southerly aspect.
What are the limits of the data?
There is nothing in the attribute table for the streets dataset that allows me to determine if a road has two or more lanes, also known as secondary access. There are roads in Anchorage that don't have secondary access, and this is critical because if thirty cars are evacuating the Bear Valley on the one road out, then the fire engines can't get up to fight the fire. A more sophisticated analysis would rely on data being able to tell me what roads do and do not have secondary access so that we can plot out traffic and network analysis for a future wildfire. It would be further helpful to have a dataset on FireReady homes in the area so that we can target our interventions for those people who are in need of some extra help in preparing for a wildfire.
Policy Recommendation:
Build a secondary access road in front of Fire Station #10. Put gates on it, like the ones that barricade JBER, the local military base in the area, so that people can't use it unless there is a severe emergency. This would be done so that the residents who oppose said road do not have people driving all night long at inappropriate hours.
For more information about wildfire preparedness and prevention, please visit the following websites:
https://www.ready.gov/wildfires
Works Cited
Anchorage Water and Wastewater Utility (AWWU). “Public Information Map.” AWWU Service Areas, 31 Oct. 2019, awwu.maps.arcgis.com/apps/PublicInformation/index.html?appid=b46c3d08299d49119608edd7262ea0fd. Accessed 30 Mar. 2021. This map displays the Anchorage Water Utility and Anchorage Wastewater Utility certificated areas. ESRI online interactive map.
Brooks, James. “As Climate Change Increases Alaska’s Wildfire Risk, Power Companies Say California-Style Blackouts Could Arrive in Alaska.” Anchorage Daily News, 28 Mar. 2021, www.adn.com/politics/alaska-legislature/2021/03/28/as-climate-change-increases-alaskas-wildfire-risk-power-companies-warn-that-california-style-blackouts-could-arrive-in-alaska/. Accessed 30 Mar. 2021.
Municipality of Anchorage GIS Data. “Downloadable Data.” Moa-Muniorg.hub.arcgis.com, Municipality of Anchorage, 2021, moa-muniorg.hub.arcgis.com/pages/data. Accessed 22 Mar. 2021.
Paul. “Fire Station 10 Preparedness for a Hillside Wildfire.” OneNote Notebooks, 5 Mar. 2021. Engineer for station that would be most responsible for a Hillside wildfire.
Rodman, Susanne U., et al. Community Wildfire Protection Plan Municipality of Anchorage. Anchorage Fire Department, 8 Jan. 2008. Wildlife Mitigation.