Wednesday, September 18, 2013

Some Boulder Flooding Links

Bad Dad and Meta Megan asked what I am posting about the Boulder floods.  I just don't feel very good about being right in What nesting articles don't tell you because some of the people affected by the floods didn't act irresponsibly.  That is, they took reasonable precautions based on past experience but the environment changed about them.

Both climate change and development around them changed  the distribution of rainfall and how much the ground absorbs (or doesn't absorb).  It's hard to make rational and economically-viable plans when so much that is out of your control is changing.

Ironically, the City of Boulder Flood Hazard Map was updated in 2013 to reflect changes in modeling and the built environment.  The results were submitted to FEMA in September 2013.
As a result of the proposed floodplain boundary changes, 106 buildings would no longer be affected by the 100-year floodplain, 76 buildings would be newly affected, and 565 buildings would remain in the floodplain. As the data is refined and public input is received, these numbers may change slightly, but the general trends will remain the same. Changes to the floodplain maps can affect flood insurance requirements.
The last week or so have been the ultimate model validation experiment.  As a modeler, I should be excited.  But I have no appetite for it right now.

Take a look at the soil in this slow-motion mudslide.  Boulder canyon, and its side canyons, also suffered from recent wildfires.  Not only was there no vegetation to hold the soil in place, but a blanket of ash prevented water from soaking into the ground.


Dr Rood mentioned the comparison with flooding in western Pakistan.  If you have gardened in Boulder, you will be familiar with clay soils.  That's also why the flooding in western Pakistan was so severe.  Due to AO, the Asian monsoon flow pattern has moved from areas with sandy soils that drain quickly to areas with clay soils that don't.  Unlike Boulder, the people in western Pakistan won't have insurance money (public or private) to rebuild.

Hermosa Beach's sister city of Loreto suffered the collapse of two bridges (including one major throughfare) in torrential rain this summer.

When I lived in Colorado, people who like to point out government incompetence often cited the statistic that Colorado spends more per mile on road maintenance than any other state.  I looked at the climate data and thought, of course.  Colorado used to be the only state where the daily average highs are above freezing while the daily average lows for 5-6 months of the year were below freezing.  Thus, Colorado infrastructure experiences more freeze and thaw cycles than those in any other state.

Who should pay for rebuilding and retro-fitting for climate change?  The people who live in harm's way?  Or the people who dumped the most carbon in the atmosphere?


  1. Thanks! I have been mentioning your blog a lot to people who say, "Well it will never happen again in our lifetime." I say, "It's a 1/100 chance, not a 1 in 100 years thing." As for rebuilding, we plan to rebuild in preparation for the next flood, not assuming it will never happen again. But that's just my family, and we are lucky to have savings and already got a check from FEMA. No flood insurance as we were not in the 500 or 100 year zone. If we were living paycheck to paycheck, we would just have half the square footage going forward, I guess. I am thankful to your for your post, because I have no interest in reading anything that isn't flood related, and I feel like we have already dropped off the news.

    1. @MM You are making the wiser choice. I am sorry that you were flooded. Please point people to Dr Rood's articles. You are fortunate to have more atmospheric scientists per capita than any other town in the world. OTOH, that means people use more jargon.

      You WILL be flooded again and again due to the melting ice caps. The circumpolar stratospheric jet, the jet stream about the poles, has gone from mostly circular to very wavy. That's due to the melting N polar ice cap. The waves in the jet stream mean that mid-latitudes will swing between drought and flood in the summer.

      I was almost going to be in Boulder this week, but some family work came up and I had to cancel my trip.

      Perhaps next time I am in Boulder we can meet up IRL?

  2. We have floods in Alexandria whenever there is a huge snowmelt or hurricanes; Old Town is built on reclaimed marshland that gets "reclaimed" back at those times. When we bought our house we bought on top of a hill, mostly because we had small children, and did not want to worry about them falling into the river. This was a fortuitous choice since we've had three hurricanes and the derecho since then. Don't we ALL pay for climate change, no matter who is most responsible? Isn't that why those most responsible deny it even exists? They don't want to pay.

  3. Thank you for this terrific post. I just read Mary Pipher's book, "The Green Boat." She is a therapist who tackles this sort of denial about climate change and also advises how to deal with the enormity of the challenge. You might enjoy her Psychology Today interview:

  4. Agreed - everyone pays for climate change, at least at this point through taxes that are funding FEMA. I'm already losing my resolve with the basement remodel. Polished concrete would be so much easier to deal with in the next flood, but carpet would be so much more comfortable. And I could use the savings to go towards regrading the yard. We'll see. Let me know when you are in Boulder!

    1. @MM Try what our friends in E Boulder did. They now use an area rug, which they roll and move upstairs before a major rain is predicted.


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