Fluvial Storm

Fluvial Storm
In “Fluvial Storm,” swirling water sculpts fine sand into an elaborate pattern of underwater dunes. Rotate the large globe filled with clear water and sand to see a demonstration of sediment and fluid flow that normally occurs in nature. On land or under water, sand dunes and ripples form when small bumps make the wind or water passing by undulate, carving hills and valleys into the sand. If you spin the globe quickly for about ten seconds, and then stop it suddenly, you’ll see ripples form and march slowly around the bottom edge of the globe. Desert sand dunes also “walk” in this way, pushed by wind instead of water.

The “Fluvial Storm” exhibit was designed by Exploratorium artist and exhibit designer, Ned Kahn. The idea came to him while he was watching a stream meander over a beach, towards the sea. He was intrigued by the flowing water and what it did to the sand below it.

In his own words: “Fresh water slicing down through very uniform sand would build up into underwater dunes that would keep building up, steeper and steeper, moving backwards against the current and getting steeper, until there would be a rush and they would just dissolve into turbulence and be completely annihilated. Then they would slowly start to build up again. I watched for hours, thinking of how could I create a system that would behave like that. The result was a glass vessel about twenty inches in diameter filled with water and sand that viewers could spin and see a similar process.”

Questions to Answer

Why are the underwater dunes similar to wind-driven sand dunes?

Does all of the dune material move at the same rate?

What size of particles are easiest to be moved?

What happens when the particles settle out as the current stops?

Does the sand surface affect the currents in the water?

Relevant Arkansas Science Frameworks

ESS.9.3.1, ESS.9.4.1, ESS.8.8.5, ESS.8.8.8, ESS.9.8.2, ESS.9.8.1

"Mini-Vibe" — An activity to do at home or in the classroom