Small model dam failure.
As part of an open-day, school children made up a dam of sand and small stones. The ‘reservoir’ behind the dam was then slowly filled up with water, and through the sides of the perspex enclosure the water can be seen permeating through the sand.
Eventually once the moisture reaches the base at the opposite side of the dam the dam fails and the remaining relatively dry sand slides down the front.
Shows a typical failure of an embankment or earthen type dam.
Not good for those living down-stream of the construction!
A fun little experiment that shows that there is more to this sort of thing than just piling up sand and stone.