A - River Discharge Flashcards
What does discharge refer to in a river?
Volume of water passing a point per unit of time.
How is discharge typically measured?
In cubic meters per second (cumecs).
What does Bradshaw’s model illustrate?
Changes to channel characteristics downstream in a river.
According to Bradshaw’s model, what increases downstream?
Water velocity and discharge.
What decreases downstream according to Bradshaw’s model?
Channel bed roughness and load particle size.
Define abrasion in the context of river erosion.
Wearing away of the bed and bank by the load carried by a river.
What is attrition?
Wearing away of the river’s load, creating smaller, rounder particles.
What is hydraulic action in river processes?
Force of air and water on river sides and cracks.
Define solution (or corrosion) in river erosion.
Removal of chemical ions, causing rocks to dissolve.
How does load affect erosion in rivers?
Heavier and sharper loads increase erosion potential.
What effect do velocity and discharge have on erosion?
Greater velocity and discharge increase erosion.
How does gradient impact erosion?
Higher gradient increases erosion rate.
How does geology affect erosion in rivers?
Soft, unconsolidated rocks are easily eroded.
How does pH affect river erosion?
More acidic water increases rates of solution.
What human impacts increase erosion in rivers?
Deforestation, dams, and bridges.
What is suspension in river transportation?
Small particles held up by turbulent flow.
Define saltation in river transportation.
Heavier particles bounced along the river bed.
What is solution in river transportation?
Chemical load dissolved in the water.
What does traction refer to?
Heaviest material dragged along the river bed.
What is floatation in river transportation?
Leaves and twigs carried on the river surface.
Define stream capacity.
Largest amount of debris a stream can carry.
What is stream competence?
Diameter of the largest particle a stream can carry.
What is critical erosion velocity?
Lowest velocity at which grains of a given size can be moved.
According to Hjulström curves, what particles require high velocities to lift?
The smallest and largest particles.
What is needed for entrainment compared to transport according to Hjulström curves?
Higher velocities for entrainment than for transport.
What happens to particles when river velocity falls below a certain level?
Particles are deposited (settling velocity).
