River Processes and the Hjulstrom Curve

Silt and Sand are picked up at velocities of 20cm/sec?

• True

• False

What happens when velocity is 10cm/sec

• Boulders are transported

• Pebbles are transported

• Gravel is transported

• Sand is transported

Which particles are entrained at 1000 cm/sec?

• Just clay

• Silt and sand only

• All types of sediment

• Only boulders

What is settling velocity of gravel

• approximately 900 cm/sec

• approximately 20 cm/sec

• Approximately 1 cm/sec

• Approximately 0.2 cm/sec

Why is the entrainment velocity higher for particles like clay compared to silt and sand?

• Clay and silt particles are larger therefore require more energy to entrain.

• The mean settling velocity is slower than the critical erosion velocity

• Clay particles form stronger bonds than sand particles

• Sand is very sticky

Channel load...

• increases downstream

• decreases downstream

• stays the same downstream

• is most expensive when bought in duty free (don't fall for it)

Which is the correct order of increasing size?

• Sand, silt, clay, boulders, cobbles, pebbles

• pebbles, boulders...... where is Hjulstrom from anyway?

• Clay, silt, sand, pebbles, cobbles, Boulders

• Boulders, cobbles, pebbles, sand, silt, clay

Name the type of sediment that requires the lowest velocity to be eroded.

• Clay

• Silt

• Sand

• Really small particles

The line that separates each drainage basin is called?

• Tributaries

• the source

• A watershed

• a floodplain

Poll: which statement is true for you?

• I find the Hjulstrom Curve easy to understand

• The Hjulstrom Curve makes sense, but I would need to see it to answer any questions on it.

• I have found the Hjulstrom Curve difficult to understand

• What is the Hjulstrom Curve?