What is the relationship between the size and speed of river and the sediment it can carry?

Answer 1

cookie monster

Answer 2

For a given mass of stream water, its kinetic energy is proportional to the speed of flow squared. So, for example, if we double the speed of the stream its kinetic energy will increase by four fold. And kinetic energy can be found from the average force acting on some mass (e.g., those "particles") over a distance.

So one can conclude that a faster moving stream can exert more force on the stones and debris in that stream. Which means the faster moving stream is more likely to be able to actually lift and carry larger heavier particles than the slower stream can. NOTE: This discounts particles that can float in a static stream, like wood chips, as they are carried without the stream flowing.

Answer 3

The larger and faster a river is, the more sediment it can carry. Think of sediment as a canoe - will a canoe travel further on the mighty Mississippi, or a tiny ditch-sized creek? Speed keeps sediment in suspension, large flow obviously moves more than small flow.

Answer 4

As a grain increases in size it's settling velocity increases.

The velocity of a settling grain in a fluid is controlled by a number of factors including the density of the particle, the density of the fluid, the fluid viscosity and the particles radius. This is derived from "Stokes' Law" - See the related link.

The terminal velocity (Vs) can be found using the following equation:

VS = (2 x r2(DP - DF)g) / (9 x VF)

Where:

r = Particle radius (m)

DP = Particle density (kgm-3)

DF = Fluid density (kgm-3)

g = Gravitational acceleration (ms-2)

VF = Fluid viscosity (Pa S)

From the above it should be clear that as the radius of the particle increases, the velocity at which it sinks will significantly increase (due to the square term).

Please see the related links for more information.

Answer 5

Generally, larger rivers with faster speeds can carry more sediment due to their increased energy and capacity. Higher flow velocities help to transport larger and heavier sediment particles, while larger rivers have more volume to transport sediment. However, there are other factors like sediment size, shape, and availability that can also influence the amount of sediment a river can carry.

Answer 6

Water flows faster through particles of larger size, because the spaces between them are larger.

Answer 7

As the water velocity increases, the size of the particles that the water can transport also increases.