• Legge@lemmy.world
      link
      fedilink
      arrow-up
      24
      ·
      edit-2
      2 months ago

      If a 400 sq mi area gets 2 ft of rain and there’s a low valley area surrounded mostly by mountains, the water will drain down the mountainsides to the valley. It’s like a big bowl. The water that settles in the valley will be more than 2 ft because of the rest of the runoff from even higher elevations

      • HappycamperNZ@lemmy.world
        link
        fedilink
        arrow-up
        1
        ·
        2 months ago

        Yes, but that valley usually has an outflow at its low point in the form of a river. I can understand it getting that deep, but not it staying there.

        • Sludgeyy@lemmy.world
          link
          fedilink
          arrow-up
          19
          ·
          2 months ago

          What happens if you turn your kitchen sink on? Your drain shouldn’t have a problem draining the amount of water.

          Now take a large 5 gallon bucket of water. Dump the whole thing in your sink.

          Not only is the amount of water too much for the drain but the volume of water makes it hard for the drain to even function properly.

          How long is there going to be water filling in the sink? Eventually, it will all find its way out, but that takes time

        • Legge@lemmy.world
          link
          fedilink
          arrow-up
          12
          ·
          2 months ago

          That’s right: usually. Sometimes no. Or sometimes the volume of water only slowly drains away (like some rivers move extremely slowly and it’s almost as if it’s not moving at all). If it takes 3 days for the water in the normally filled river to move 1 mile, even if it takes 2 days with the flooded valley to drain instead of 3, that’s still 2 days of floods.

          Imagine you drop a bunched up shirt onto the floor. If you look, you’ll see that there are lower spots surrounded on all sides of high spots. Terrain irl is not so different from that in spots. Hope this helps explain :)

          • GraniteM@lemmy.world
            link
            fedilink
            arrow-up
            4
            ·
            2 months ago

            And don’t forget that quite a lot of the rivers are likely clogged with downed trees, landslides, and other debris, further showing the draining process.