36 votes

At least 158 people die in devastating flash floods in eastern Spain

13 comments

  1. [8]
    fefellama
    Link
    Wow, terrible. Hope the number doesn't climb too much higher. Interesting to me that there was a drought before this? Usually these freak flooding events that have happened in recent years are (in...

    Wow, terrible. Hope the number doesn't climb too much higher.

    Interesting to me that there was a drought before this? Usually these freak flooding events that have happened in recent years are (in part) caused by some excessive rain over a few days/weeks that saturates the ground, then a really strong storm that passes and drops a lot of water all at once (over the span of like 1-3 days). In those cases, the ground is too saturated with the previous couple weeks of rain, so all that excess water goes everywhere else, with devastating effect.

    But in this case there was apparently a drought before this event? That seems unusual for these flash flooding events but I'm not a meteorologist. I wonder if the drought helped at all (drier ground can absorb more water) or if there's some other phenomenon going on.

    5 votes
    1. [2]
      Englerdy
      Link Parent
      Drought usually makes floods worse. You can look up videos but slightly wet ground absorbs water substantially faster than completely bone dry. So saturated ground certainly create conditions for...

      Drought usually makes floods worse. You can look up videos but slightly wet ground absorbs water substantially faster than completely bone dry. So saturated ground certainly create conditions for a flood risk, but also completely dry ground. The two extremes are bad news unfortunately.

      15 votes
      1. fefellama
        Link Parent
        Wow I had no idea, thanks! In case anyone else is curious why this is the case, I found this helpful askscience thread on reddit with a good explanation:

        Wow I had no idea, thanks! In case anyone else is curious why this is the case, I found this helpful askscience thread on reddit with a good explanation:

        It's because of the high surface tension of water. Water in soil forms microscopic channels around/between the soil particles. The initial formation of these microscopic channels in dry soil must overcome the surface tension forces. Once the initial formation occurs, (wet soil) it is relatively easier to expand the channels to accommodate more water.

        7 votes
    2. [2]
      parsley
      Link Parent
      Dry soil does not stay put absorbing water, it gets pulled into the flood and makes things worse. These types of floods are not uncommon in that area but this one has been particularly strong....

      Dry soil does not stay put absorbing water, it gets pulled into the flood and makes things worse.

      These types of floods are not uncommon in that area but this one has been particularly strong. There has also been cuts in emergency services because... well... because.

      7 votes
      1. fefellama
        Link Parent
        I live in a much wetter climate so am unused to droughts and their relations to flooding, but that makes sense. Thanks. Fucking hell. Hope that doesn’t hamper rescue efforts too much.

        I live in a much wetter climate so am unused to droughts and their relations to flooding, but that makes sense. Thanks.

        There has also been cuts in emergency services because... well... because.

        Fucking hell. Hope that doesn’t hamper rescue efforts too much.

        4 votes
    3. [3]
      chocobean
      Link Parent
      To echo what's already been said, a very parched ground is way way worse for "sliding" water off the land instead of absorbing. You can experiment by using a dry towel to swipe a puddle off a...

      To echo what's already been said, a very parched ground is way way worse for "sliding" water off the land instead of absorbing. You can experiment by using a dry towel to swipe a puddle off a table vs using a wrung out slightly damp towel. If you let dry soil soak it'll eventually absorb but not right away like wet soil.

      Same thing with sandbags for floods: they work for a very short while to divert sudden water away if they're dry, but once they're soaked through they don't hardly do anything.

      7 votes
      1. [2]
        fefellama
        Link Parent
        Super interesting, thanks. I live in a very wet and very flat area, so the flooding here is usually a result of just soooo much rain that the ground can’t handle it anymore so the drainage systems...

        Super interesting, thanks. I live in a very wet and very flat area, so the flooding here is usually a result of just soooo much rain that the ground can’t handle it anymore so the drainage systems are forced to work overtime. Didn’t occur to me that extremely dry soil would also be a problem.

        5 votes
        1. jredd23
          Link Parent
          In the USA, we've are going through a really dry Sep/Oct time frame and in the past I've seen this in action. Really something to be concerned of, especially if you are living on a mountain side.

          In the USA, we've are going through a really dry Sep/Oct time frame and in the past I've seen this in action. Really something to be concerned of, especially if you are living on a mountain side.

          1 vote
  2. [2]
    nukeman
    Link
    When I was listening to Bloomberg this morning it was 51 dead. What an awful tragedy.

    When I was listening to Bloomberg this morning it was 51 dead. What an awful tragedy.

    3 votes
    1. AugustusFerdinand
      (edited )
      Link Parent
      Indeed. AP needed to, sadly, update their title, and I just did the same here. Another story with more updates as of this morning:...

      Indeed. AP needed to, sadly, update their title, and I just did the same here.

      Another story with more updates as of this morning: https://apnews.com/article/flash-floods-spain-valencia-climate-change-30c6ef59ddf27598c691c89d0ba41442

      EDIT: Updated the title of this link to match the updated totals of the link in this comment.

      3 votes