The document summarizes the Hjulstrom curve, which is a graph used by hydrologists to determine if a river will erode, transport, or deposit sediment. The curve shows the relationship between river velocity and the particle sizes that can be transported. It displays the minimum velocity needed for erosion of a given particle size and the velocity at which deposition will occur. The x-axis represents particle size in mm and the y-axis is river velocity in cm/s. The curve contains lines for critical erosion velocity and settling velocity to illustrate the conditions required for transporting materials of different sizes.

1. Kamrul Islam Karim
Reg: 2013135023
Hjulstrom curve

2. Terms:
• 1. Capacity: largest amount (weight) of debris that the river can carry.
• 2. Competence: diameter of the largest particles (size) that can be carried.
• 3. Critical erosion velocity: lowest velocity at which grain of a given size
can be moved.
• 4. Settling/fall velocity: velocity falls below certain level particle (fall
velocity) will be deposited.
Hjulstrom Curve

3. • The Hjulstrøm curve is a graph used by hydrologists to
determine whether a river will erode, transport, or deposit
sediment.
• The Hjulstrom curve is a graph that shows the relationship
between the velocity of a river and the particle sizes that may be
transported.
• It shows the velocity needed to pick up material of a certain size
(velocity needed for erosion to take place), and the settling
velocity when deposition will occur.
Hjulstrom Curve

4. • Interpretation of the Hjulstrom curve/graph.
• The x-axis shows the size of the particles in mm.
• The y-axis shows the velocity of the river in cm/s.
• Hjulstrom graph shows relationship between stream velocity and
ability to transport materials of varying sizes. (i.e. finest
• particles; clay & silt to largest boulders)
• There are two curves lines drawn in a Hjulstrom curve; critical
erosion velocity and settling or fall velocity.
Hjulstrom Curve

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