Monday, April 26, 2010

Boulder's 100 year flood

BY JAMES McGEADY
A problem in Boulder, which my geology 2 professor pointed out two semesters ago is the geographical location of the City of Boulder and it's propensity for flooding I read a great article on the topic, a little long but worth it if you are interested http://www.getboulder.com/visitors/articles_w05/flood-ready.html...

here is a little taste of one authors description of what the flood will look like if it happened today...

"a wall of water rages down Boulder Canyon, hurtling trees, cars and boulders the size of Volkswagens. Hitting the mouth of the canyon, the racing wall is carrying 30,000 cubic feet of water per second (cfs). Buildings are destroyed, bridges collapse and people are washed away, while those on high ground can do nothing but watch."

The last flood happened in the year 1894. It killed 144 people and cost 35.5 million dollars in damages. This happened at the bottom of local Thompson Canyon. However the real issue would be if the flood came out of the Boulder Canyon mouth instead. There is far more development, the Boulder Public Library, city buildings, Boulder High School, CU housing etc... an it is estimated that coming out of Boulder canyon, the destructive force would be around three times as powerful as the one that came out of Thompson, given the exact same variables.
The typical flow of the water coming out of the canyon is 10 cfs in December, in peak seasons it could run as high as 700 cfs. If the 100 year flood repeated, we would see a flow around 12,000 cfs. The scariest thing is that the 100 year flood is not even the biggest issue, it was just way to look at a perhaps near future problem. There is also a 500 year flood that is estimated to be far more destructive and there are over 5,000 private Boulderite properties within this zone.

So what should be done here? Better infrastructure, move housing and construction lines? Build a dam somewhere or create levee walls?

http://www.getboulder.com/visitors/articles_w05/flood-ready.html

14 comments:

  1. I don't think it is necessary to do anything to prepare for a flood. Everyone who lives in Boulder is well aware that it is in a flood zone, and those that choose to live near the creek understand the risk of living here. What people love about this town is the proximity to nature, and with that comes the risk of natural disaster such as a flood. To build a dam or walls, or move the housing would destroy what is so unique about Boulder to many people. The only thing that is necessary is to educate the residents of the risk, which many are already well informed on.

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  2. There has been much speculation as to when the next great flood will be in the Boulder Canyon. I think that people, for the most part, should not be worried about some "inevitable" 100 year flood. I guess they should keep renaming it every year that it doesn't happen. But, what we do need to worry about is how we treat the rivers, streams, and tributaries in and around Boulder. Our city is responsible for damaging the endocrine systems of many native fish species, specifically the white sucker fish. This may seem to have little impact on the overall health of our rivers, but the long term effects of these drastic changes in morphology can and probably will decrease the population of many otherwise healthy populations of fish species in the Boulder creek.

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  3. I think the flood is something that should be addressed in a more urgent manner. The flood could also bring with it the destruction of the barker dam which would be catastrophic. Every summer the city tests its warning sirens at the Boulder public library. Floods are quick and usually unpredictable and can kill thousands of people if they aren't prepared. The thought of of the people at risk is scary. People shouldn't be worried but they SHOULD be prepared and have a plan to evacuate to higher ground on short notice.

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  4. I think the main thing that should be done is to educate those who live in the flood zone. All actions that deal with construction will draw away from the aesthetic value of boulder and the creek running through it. Also instead of spending time and money on how to prevent it they should be concentrating on what to do when it does come.

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  5. I agree that education is important. Anyone moving into housing within the flood zone should obviously know about it. Any sort of construction to prevent a flood would require a great deal of money, which the people of Boulder would much rather spend on green initiatives, etc.

    College students must also be considered, as tubing down the creek is a significant recreational activity!

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  6. I also think that nothing should be done to prevent the flood. It is a ticking time bomb that most people in Boulder are aware of. I was also in a geology class that talked about the 100 year flood. We were shown a map of the area that would affected by the flood and I was surprised just how much of Boulder would be under some water. I was thinking about what kind of damage would occur if the 100 year flood did happen in the near future as I was sitting on my friends balcony overlooking Boulder Creek. There are so many apartment buildings and houses within yards of the creek. The damage would be amazing. I think people should just keep one eye toward the creek and be aware that this flood is very much possible. It is their choice to live in the flood plan so they should plan accordingly.

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  7. Yes, there needs to be more education and awareness, especially during the wet seasons about the potential danger of flooding in boulder. I would be up for a dam/ levee system (similar to the one in fort collins) but thats because their water system is great for the summer activities; and its better than swimming in boulder creek due to the sewage runoff!

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  8. This reminds me of a concept that we talk about in Astronomy occasionally, the long overdue "super extinction" of the Earth.

    The Earth has a probability of getting hit by a large asteroid every 10^8 years, roughly, but that doesn't mean it necessarily will happen every 10^8 years.

    The likelihood of this perfect storm to flood Boulder is probably calculated using a similar formula, only getting a very rough estimate at when this could happen.

    The best solution in this event is education. If we say the creek is going to flood within 25 years and build dams, we stand the chance to lose credibility if the flood doesn't happen for 125 years.

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  9. I agree that education and awareness should be the course of action, rather than the construction of a levee or dam. Along with the high cost of any such dam or levee construction process, it would also eliminate some of the aesthetic beauty of the creeks and rivers that run into Boulder. Other cities across the nation face a similar dilemma. St. Louis, Missouri lies in a bit of a valley, and is prone to a major flooding of the Mississippi every 50-100 years. Rather than building an unsightly concrete wall on the river shoreline, they choose to just prepare their residents for the possibility of flooding. I think that Boulder should have adopt a similar approach. Boulder residents should be warned and be prepared for the possibility of flooding, but I think the construction of a dam or levee for a flood that may or may not happen in the next 100 years is unnecessary.

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  10. Given the nature of Boulder Canyon, I doubt it would be possible to build an effective levee system even if you wanted to. When a "Hundred Year" type storm occurs, water is going to come down the canyon in a manner that can't be controlled unless you build a massive aqua duct right down the middle of town that would be dry 36499 out of 36500 days(not counting leap years). The reality of the situation is that occasional property loss due to flooding is inevitable. The real concern is to minimize human loss. Warning systems and education are important as well as having certain structures that people can escape to if they get caught out.

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  11. This reminds me of the "flood drills" we had when I attended Boulder High School where they corralled all of us onto the second and third stories. My generation has never been threatened by it but its importance is demonstrated in the fact that we were doing drills over 100 years later. I think it is impractical to prepare for a future impending disaster such as Boulder's situation. I can see the benefits in other places such as New Orleans but am not sure that a 100 year threat would garner much support.

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  12. I thought something had already been done in the form of building that dam up at the boulder creek's headwaters in Nederland. I think this dam would be effective in preventing something like this from ever occurring again.

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  13. I think that all options should be considered but that a good flood evacuation plan is a very important characteristic as well as possibly developing an early warning system i think that these things plus education are are a good place to start.

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  14. I dont think there is a whole lot we can do to avoid the hundred year flood. With many businesses and a large university located in Boulder no one is going anywhere soon. Damming the Canyon would never be passed with so many environmentalists living here so the only real option is to be prepared and wait. Boulder has already put in place a flood warning system much like many cities have tornado warning systems. The only other thing the city of Boulder can do is educate the public and have a well planned evacuation and rescue program in place.

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