What is the effect of a flowing stream on the land?

Students investigated this question in science yesterday. They bulldozed their land into a 20x5cm block and used a cup with a small hole in the bottom to represent the source of the stream. Two liters of water were poured at a constant rate to simulate the flowing stream.

Students then observed what effects the stream had on the land. Notice the gravel now showing, and the beach (delta) at the end of he streams. We are wondering why the gravel did not make it into the delta.

Each group also collected run-off from their stream tables. We will be collecting more from other investigations and comparing how much soil is  moved as we change the force of the water.