Slopes and Mass Wasting (Nov 9)

Question 1

What is a catena?

Answer 1

2D representation of a slope
ie a cross section

Question 2

In a slope, the break between the foot and the toe is where the slope nears ____

Answer 2

horizontal (should be able to picture this)

Question 3

Headward migration=

Answer 3

erosion into the headslope

Question 4

Interfluve=

Answer 4

(summit)
= topographic high between adjacent valleys

Question 5

What are the 2 types of material transport on slopes? Give examples of each

Answer 5

1. Advective transport: transport concentrated in one area (eg gullies and channels)
2. Diffuse transport: transport spread across a wide area (eg. soil creep, rain splash)

Question 6

There are 5 fundamental controls on transport on slopes. What’s the acronym and what are these 5 controls?

Answer 6

ClORPT

CLIMATE (rain, temp, wind)
ORGANISMS (vegetation)
RELIEF (aspect/ steepness)
PARENT MATERIAL (structural geology- grain size etc)
TIME (for processes to act/ occurence of catastrophic events)

Question 7

What is the role of vegetation in slope hydrology?
- list 3

Answer 7

• intercepts precipitation
• delays infiltration into surface
• removes water by evapotranspiration

ie. controls the amount, rate, and location of water input to slope

Question 8

What happens when the rate of precipitation exceeds the rate of infiltration? What is this called?

Answer 8

runoff! because no more water can soak into the ground

= Infiltration excess flow

Question 9

Describe the transition of runoff on a slope in terms of erosion

Answer 9

Runoff starts as sheet flow (diffuse) when the ground is saturated and infiltration stops. As it flows, very small channels may start to naturally form at the surface, called rills. The water erodes these channels into gullies, which are deep channels (more permanent)

Question 10

mass wasting=

Answer 10

downslope movement of rock and soil in response to gravity

Question 11

What are the 2 main forces at play in mass wastings?

Answer 11

1. shear stress: promotes susceptibility to movement
2. shear strength (resists susceptibility to movement)

have to evaluate the balance of shear stress/ strength