The Hjulstrom Curve

Question 1

What is the hjulstrom curve used for and what is its 2 key ideas

Answer 1

To determine wether a river will erode, transport, or deposit sediment depending on low velocity

Two key ideas:
Larger particle- more energy to erode or transport
Erosion needs more energy than transport

Question 2

TWO KEY IDEAS NOT TRUE FOR SMALLER SEDIMENT: what causes this anomaly?

Answer 2

-Clay particles COHESIVE- need more energy to separate- then easily transported
-Clay particles form smooth surface when packed together= less turbulent flow= so fewer EDDIES in water that could scour off particles from the surface. Sand sized + larger encourage these EDDIES

Question 3

What is the capacity and the competence of a river

Answer 3

Capacity- maximum volume of load a river can carry

Competence- biggest size particle a river can carry

Question 4

What are the 2 curves on the Hjulstrom curve

Answer 4

Critical erosion- shows minimum velocity needed to pick up, transport and erode a particle

Mean settling- shows minimum speed that particles of different sizes will be deposited by the river

Shaded areas between curves= different transport processes that will be taking place eg traction and suspension