Lecture 11-12 - Knickpoints

Question 1

What are knickpoints?

Answer 1

Steps on the river longitudinal profiles, a disturbance to the equilibrium that needs to be destroyed. Regulated by the stream power law.

Question 2

The equation for stream power law is i=kA^mS^n. What does it mean when m and n =1 and when m and n = <1?

Answer 2

• When m and n = 1 then incision rate is directly proportionate to stream power, parallel retreat
• When m and n <1 erosion rates are proportional to bed shear stress. The height and slope of knickpoints decrease, slope replacement

Question 3

What effects do normal faults have on topography?

Answer 3

• Facets will be created.
• Large facets = active faults
• Degraded facets = inactive faults

Question 4

What is drainage spacing and what happens to these in tectonically acitve and tectonically inactive areas?

Answer 4

• Drainage spacing is the ratio between the length of the river and the distance between two river mouths.
• Tectonically active: small catchment area, closesly spaced rivers
• Tectonically inactive: bigger catchment areas. widely spaced rivers

Question 5

What is sinuosity and what does it mean when this = 1 and what does it mean when it is >2?

Answer 5

• Sinuosity: ratio between the actual length of the mountain front and the straight length of the mountain front.
• When sinuosity = 1 then actively deforming, when >2 then inactive front.