ELI5: Why does water make roads crack and break during a flood??

Imagine your favorite cookie! It's nice and strong when it's dry.

Now, imagine you dunk that cookie in milk for a long time. What happens? It gets soft and crumbly, right?

Roads are kind of like that cookie! They're made of stuff like asphalt and concrete, which are strong when they're dry. But water, especially lots of it like in a flood, can sneak into tiny cracks and spaces within the road.

Here's why that's bad:

• Water weakens the "glue": The materials that hold the road together, like the "glue" in your cookie, get weaker when they're soaked in water. This makes the road easier to break apart.

• Water expands when it freezes: If the flood water freezes (like in winter), it turns into ice. Ice takes up more space than water. Imagine your cookie getting bigger inside! This puts pressure on the road, making the cracks bigger and causing more damage.

• Water washes things away: The water rushing during a flood can also wash away the soil underneath the road. Think of it like the table your cookie is sitting on disappearing! Without support underneath, the road is more likely to collapse and break.