Why do flood waters stick around? Why do places stay flooded after things like hurricanes, tsunamis, etc?
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The space in the ground that water usually drains into after normal rain and stuff is already full so the newly arrived water just has to wait its turn.
Floodwaters stick around after hurricanes, tsunamis, and other storms because there’s often too much water for the land and drainage systems to handle at once. In flat areas, water has nowhere to flow, so it pools up and takes longer to evaporate or get absorbed. If the ground is already saturated from previous rain, it can’t soak up any more water, leaving the excess to linger on the surface. Additionally, debris from the storm can block drainage systems and rivers, slowing down the natural flow of water, which makes the flooding last even longer.
Imagine a regular size sink with a regular size drain at the bottom of it. This represents a piece of land and its ability to drain water. When you fill the sink up from the tap, unless you have a really slow drain, water can drain about as fast as it fills.
Now imagine instead of a tap filling up a sink of water, you blast it with a fire hose, filling it with several hundreds of times the amount of water a sink would normally hold in a short amount of time. The sink can’t hold all that water, and it can’t drain it away very quickly. What happens here is the sink overflows and the water splashes to whatever is next to the sink.
But in land, what is next to the sink is… another sink, with another sink next to it, and another sink next to *that,* and so on. These sinks are all stacked up next to each other with no gaps for water to drain through – except, of course, the actual drains. And in floods, *all* of these sinks each have their own firehose’s worth of water. So the water can’t overflow to the side – there’s just *more water* there – and it can’t go down the drain very quickly. So it just kind of sits there, until the sinks can drain enough of it away, which takes time.
This is why floods give homeowners a sinking feeling.
When you take the plug out of the bath does the water disappear instantly?
Water filtering can be slow. If the soil contains mud filtering can be as long as weeks. And storm surges can bring water to places that don’t have any outflow.
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