Understanding Colorado Flooding

The Poudre River in Fort Collins drains more than 500 square miles of mountains and empties through a narrow canyon.

ScreenHunter_573 Sep. 14 10.30

The Big Thompson River in Loveland drains more than 500 square miles of mountains and empties through a narrow canyon.

ScreenHunter_572 Sep. 14 10.30

The St. Vrain River, Lefthand Creek and Boulder Creek drain more than 500 square miles of mountains and empty through narrow canyons.

ScreenHunter_571 Sep. 14 10.29

Upslope winds force humid air from the plains up into the mountains. The air expands, cools and drops below its dew point. Rain falls and floods occur.

In 1976, the Big Thompson drainage received 14 inches of rain in four hours and produced one of America’s most deadly floods. This week’s rains have been nowhere near that intense.

In 1997, Spring Creek in Fort Collins received 10 inches of rain in four hours, and produced a flood with killed five people. Again, that rainfall was much more intense than this week.

In 1965, the South Platte River drainage received 15 inches of rain in 14 hours, and produced a flood with killed twenty-one people. Rainfall was much more intense than this week.

In 1921, a similar rain killed 1,200 people in Pueblo, Colorado.

People talking about biblical or 1,000 year rainfall have absolutely no idea what they are talking about. These floods can be expected somewhere along the Front Range every couple of decades.

About Tony Heller

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13 Responses to Understanding Colorado Flooding

  1. lance says:

    Very good description Steve, this same thing happened this June in Southern Alberta. Big rain in the mountains, and just to east, on the flood plains, they got flooded. Move forward in time….repeat….

  2. TD Vann says:

    Loved your list of “Great” Colorado floods. However I did not see the 1965 Platte River Flash Flood (all Colorado floods are Flash Floods due to the topography) which was one of the most expensive and led to the construction of Chatfield Dam. Which once constructed, the Platte has never had a Flash Flood below the Dam. Go figure. Of course that was back when the Army Corp of Engineers was really the Army and really used real Engineers to design flood control dams.

    • Lynn Clark says:

      I think the Cherry Creek dam was designed and built for the same reason as the Chatfield dam, but in 1950. The magnitude of the height of the top of the dam above the normal water level is awe-inspiring. LIke the Chatfield dam, the Cherry Creek dam is about 100 feet higher than the normal lake level. Yet another reason the South Platte River hasn’t had a flash flood in the Denver area since it was built.

  3. Colorado Wellington says:

    Middle school geomorphology and sedimentology but it won’t do.

    Because climate change.

  4. Duby says:

    Maybe some of this water will make it to Texas–

  5. cbdakota says:

    Reblogged this on Climate Change Sanity and commented:
    Can not improve on this one. Once again the “extreme” weather brigade are ill-informed or purposely deceptive. Your guess.
    cbdakota

  6. Mike says:

    Reblogged this on This Got My Attention and commented:
    Torrential rains and flooding aren’t new to Colorado and the South Platte River.

  7. rogerthesurf says:

    AGW might be deservedly on its knees but it is but a smoke screen.

    The real danger is Agenda 21 which wants to institute all the things that AGW threatened us with and more. The only thing is that its more subtle – it is creeping into our society as we speak.

    In my country it is in our legislation, local government and education.
    Take a look at my blog which shows how our government has very kindly used the devastating earthquakes which hit my city as an excuse to dispossess people of their homes and property in order to build an Agenda21 compliant city where our proud city once stood. http://www.thedemiseofchristchurch.com

    But its not just my country, its world wide! Try searching your local government’s website for the words “Agenda 21” and “ICLEI” and tell me I’m not wrong.

    Cheers

    Roger

    http://www.thedemiseofchristchurch.com

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