Streams carry sediment, like pebbles, in their flows. The pebbles can be in a variety of locations in the flow, depending on it's size, the balance between the upwards velocity on the pebble (drag and lift forces), and it's settling velocity.
Work=f.d
Work=100*50 = 500
Power = work/time = 500/4
=125 watt
The 2nd has the most porosity
Infiltration
That's all I can answer for you. Hope it helps
