What role do streams play in transporting weathered materials?

Question

What will be an ideal response?

Answer 1

Answer: There are two sources of stream water. These are groundwater and overland flow. When rain falls on the land surface, most of it infiltrates, or soaks into the soil, where it may drain to streams or to groundwater. Most of the water flowing into streams is supplied not by rainfall directly, but by groundwater.

If rain falls intensely, the soil may not be able to absorb it as fast as it falls. When water flows across the land, either on a hillslope or in a channel, it carries small particles of rock with it. Smaller particles are mixed with the water making it look muddy; larger particles may roll or bounce along the bottom of the flow.

This movement of material in a stream is called sediment transport. The amount of sediment a stream carries increases as the amount of flowing water increases, so larger streams typically carry more sediment than do smaller ones. The amount of sediment carried when a river is in flood may be hundreds or thousands of times more than the amount carried at ordinary flow levels. Sediment transport also tends to be greater on steep slopes than on gentle ones.