Why have we not had such severe floods since 1967?
After the flood, and due to the Flood Acts of 68, money was available for the Chena River Lakes Flood Control Project which displaces water to the Tanana River when water rises. The Tanana River uses dikes to help protect Fairbanks.
Briefly describe at least one positive outcome that emerged as a result of the flood damage and losses.
Anytime something like this occurs, the resilience of a community is tested. Those who can weather the storm, come out more prepared in the future. Citizens raised money to assists local business, and they also helped fund the Fairbanks Memorial Hospital. The citizens took it upon themselves mostly to get back on their feet, which makes them better prepared in the future. This is always a plus.
I guess it’s time to do a EOTW closer to home (although I know some of you are all over the country!). The 1967 flood happened on the Chena River in Fairbanks during Augustin 1967. During July 1967, the Fairbanks area received almost twice the normal amount of rain as 3.32 inches fell. During August, the rain did not let up and another 3.42 inches fell within a 24 hour period between August 11 and 13. In total August 1967 experienced 6.2 inches of rain – almost triple the normal amount for August. As a result, the Chena River received far more water than usual and passed its flood stage. At the time, there was no stream gauging equipment on the Chena upstream of Fairbanks so the people and scientists did not know how bad the flooding would be. Flooding by August 14th was bad and many people evacuated. About 7,000 to 8,000 sheltered at UAF, which given its elevation was out of the flood waters.
Although Fairbanks is situated in a flood plain, we have not experienced flooding of this magnitude since. Read the following articles, and answer the questions below:
1) How much water was released during the dam failure?
12.6 billion gallons of water was released into the canyon.
2) How were people downstream warned of the coming flood, once people realized what was happening?
Phone operators phoned communities in the path and highway patrol members rode around with sirens.
3) Take a little tour in Google Earth in the region, by searching for St Francis Dam. From your search, can you figure out how the water is now stored in this region to serve LA?
From living in CA I know a majority of water comes from the Colorado. The bypass of the Saltan Sea near Indio is one reason the “sea” is drying up. I noticed various aqueducts around LA, but as far as storing the quantity of water they need I did not find a location so I googled it. The LADWP website lists water coming from the Colorado, California Aqueduct from NorCal and ground water, but I could not find an actual answer as to storage. The LADWP does list Lake Oroville in NorCal but that seems to be to far away for storage considering it takes 16 days for water to travel the length of the aqueduct.
Describe one new thing you learned from this article that shows that we are working in our country to improve our resilience
Development of measures to help make structures more resilient have been made instead of only ways of protecting people in order to make it easier for communities to bounce back from a disaster situation.
2. Can you take what you learned and think of one way that your own community might be able to increase its resilience to a likely future disaster?
The first thing that comes to mind that would affect the Fairbanks community would be wildfires. I’m not sure what steps can be taken to mitigate such disasters as a community.
The biggest thing that I learned was that San Diego and Tijuana are working together for resilience in handling 6.9+ magnitude earthquakes. I found this to be interesting. We do not hear much about national cooperation between the US and Mexico, especially when it comes to disasters. Mexico is not a country that I would look at as being ahead of us in earthquake detection, until reading about how Mexico has early warning systems and we do not. Just goes to show that the US is not as advanced as we think we are.
The biggest issue my community has is dealing with snow and wind storms as of recently, and of course wildfires. In 2015 we had a wind storm that took out power for dozens of residents for weeks. The storm also took out numerous trees, and actually killed some residents. One thing the community could do is take a more proactive approach to eliminating hazard trees, and developing better plans to handle power outages. When it comes to wildfires, fuel mitigation would greatly assist the area, however, it seems that funding is always an issue.
For this week, we are going to explore a human+geology caused disaster to bring awareness to the issues we can have when dealing with large-scale infrastructure as well.
On March 12th 1928 at approximately 11:58 PM, the St Francis dam om California failed, resulting in a ~5.5 hour-long flood through the Santa Paula-Ventura area in California. More than 400 people died during the resulting flood. The St Francis dam was built in San Francisquito canyon to hold water that was running through the California Aqueduct from the Owens Valley. The dam was approximately 205 feet high and spanned 1225 feet along its crest and 150 feet at its base across a narrow spot in the valley and canyon. The dam was 160 feet thick. The dam construction was overseen by William Mullholland, who at the time was one of the architects of the massive growth of Los Angeles – made possible in large measure by the piping of water from the Owens Valley and other parts of California, to the growing and thirsty town. While he had worked on another dam (Mulholland dam), Mulholland was essentially a “self-taught” civil engineer. The dam failure is considered one of the worst civil-engineering disasters in US history. The failure was originally thought to have resulted from issues with the dam’s foundation. More recent work indicates that the ground beneath the dam also played a role, in the form of water-saturation re-mobilizing an old landslide structure (see quote below for more details*).
*”Although opinions vary, more recent and more thorough investigations assign the ultimate failure mode to weakening of the left abutment foundation rock due to the saturated condition created by the reservoir which essentially re-activated a large landslide that combined with a destabilizing uplift force on the main dam caused failure to initiate at the dam’s left end. In quick succession as catastrophic failure was occurring at the left end, the maximum height section tilted and rotated which destabilized the right end of the main dam causing catastrophic failure at the right end as well.” (http://damfailures.org/case-study/st-francis-dam-california-1928/)
Additional Resources and Sources of information for the post:
The EOTW for this week is not so much an event, but a tool to get you all thinking beyond your Case Studies for what comes next in the course. Units 7 and 8 will focus on societal implications and issues and preparedness. One of the key parts of being a prepared community is resilience. Resilience is really a mitigation tool. Once a community recognizes which areas it has that are vulnerable to a particular disaster or disasters, it can make the decision to reduce the risk by increasing resilience. The word resilience means to be “able to withstand or recover quickly from difficult conditions.” (from the google dictionary). The two parts to this equation are to be able to withstand a disaster, as well as be able to recover quickly. It turns out that the National Institute of Standards and Techonology (NIST) has a program to help communities develop resilience to disasters. To get our brains thinking beyond the disasters we studied for Units 5 and 6, read the article by NIST and answer the questions below:
1) What are atmospheric rivers? About how often do megafloods impact the California and western states regions?
Long regions in the atmosphere that transport large amounts of vapor, a “river in the sky”. 30-50% of annual precipitation is brought on by these events. According to Ingram, geologic evidence shows a “mega flood” every 100-200 years, although the last one was in 1861.
2) Approximately how extensive was the 1861-62 event in terms of geography? (ie which states and countries were impacted)?
LA received 66 in of rainfall, flooding and creating lakes throughout the Mojave Desert area. Anaheim, and the Santa Ana river flooded. The Sierra Nevada’s received up to 15 in of snow. The Feather, American and Yuba rivers flooded. American river levees failed and flooded Sacramento. “They were the worst in recorded history over much of the American West, including northern Mexico, Oregon, Washington State and into British Columbia, as well as reaching inland into Nevada, Utah and Arizona.” (Ingram)
3) How well do you think the public is aware of the mega flood hazard, compared with earthquake hazards, in California and other western states?
Originally coming from California, I would say that they are oblivious to massive flooding. Growing up and in school I cannot recall ever hearing about this great flooding, or even atmospheric rivers. Earthquakes were the big talk when I was growing up. Coming from the Mojave Desert we knew there was flooding, because any time we had a serious rainfall our town would flood. That was never attributed to extreme weather or anything like that, just the fact that our town was no built to handle that much rainfall. This was a great assignment and it is sad that I am just hearing about this having come from California.