Landscape Shaping Processes

Question 1

What is mass conservation?

Answer 1

The notion that mass (landscapes) cannot be created nor destroyed through the balance between uplift/subsidence and sediment supply/removal balance only changed

Question 2

How do you calculate changes in land surface elevation?

Answer 2

Amount of uplift/subsidence + balance between sediment supply/removal

Question 3

How do you calculate sediment supply/removal balance?

Answer 3

[Input quantity per year - output quantity per year (m^3)]/ Landscape Area (m^2)

Question 4

What does it mean if a system is in landscape equilibrium?

Answer 4

The change in land surface elevation is 0. In other words denudation = uplift

Question 5

What is important to remember when applying landscape equilibrium?

Answer 5

That you need to specify both the time and spatial scale you are measuring

Question 6

What does WM Davis’ model of landscape evolution ‘cycle of erosion’ suggest about landscape equilibrium?

Answer 6

That the landscape is never in equilibrium instead it is constantly changing. Even the transition from uplift to denudation is instantaneous.

Question 7

What is the evidence in New Zealand that disproves WM Davis’ idea that landscape equilibrium does not exist?

Answer 7

Along the Alpine Fault there is a change in the amount of uplift being forced upon different parts of the range. As you move down through the range there are mountains experiencing a balance between the uplift and denudation. Equilibrium

Question 8

What is Hack’s concept of static equilibrium?

Answer 8

Over a very short geological period (month) there is very little change relative to landscape and is therefore argued to be in a static equilibrium. However, no change rarely occur.

Question 9

What is Hack’s concept of steady-state equilibrium?

Answer 9

Over a medium length geological period (Century) the landscape is steadily alternating between states.

Question 10

What is Hack’s concept of dynamic equilibrium?

Answer 10

Over long term geological periods (millenniums) the landscape fluctuates steadily around an average which is gradually changing. It is dynamic but equilibrated along this average

Question 11

What is Gilbert’s process-form feedback?

Answer 11

Affecting the distribution of water
Affects the transportation method for sediment
Affects the location of erosion and deposition within the channel
Affects the shape of the river
which affects the distribution of water (start)

Question 12

How do you describe Gilbert’s process form feedbacks?

Answer 12

Dynamic feedback

Question 13

What did the quantitative revolution change within the study of fluvial systems?

Answer 13

A transition from conceptual models towards trying to quantity and explain processes through data then seeing if laws are applicable.

Question 14

What were the notable laws that were first created in this new study of fluvial systems?

Answer 14

Power Laws - Laws that would describe the relationship/correlation between two variables. The result they created would create a logarithmic relationship

Question 15

What were among the first power laws used for fluvial systems?

Answer 15

Sediment Transport Laws:
Diffusive - How slope affected sediment movement
Advective - How sediment is moved by either water or air processes.

Question 16

What are process-form feedbacks?

Answer 16

They describe the relationship between a disturbance and an affected variable that can either amplify or dampen initital disturbances

Question 17

What are positive process-form feedbacks?

Answer 17

Amplification of initial disturbances

Question 18

What are negative process-form feedbacks?

Answer 18

Dampening of initial disturbances

Question 19

What type of process-form feedback is topographic erosion and why?

Answer 19

Negative: If you remove some of the slope then you reduce its potential energy and thus potential to cause the same amount of erosional damage during future events.

Question 20

What process-form feedback occurs following a landslide in to a river that generates a large amount of sediment?

Answer 20

If the channel receives a large pile of sediment then its form is changed. On the lower side of the channel past the sediment pile the gradient of the channel is steeper and so there is more potential for erosion. Over time this cuts back to equilibrate the channel bed back to original level. This is a negative-form feedback

Question 21

What sort of processes are the top of convexo-concave hillslopes dominated by?

Answer 21

Diffusive processes. At the top of the hillslopes there is little water supply so the movement is dictated more by land movements such as landslides.

Question 22

What sort of processes are the middle of convexo-concave hillslopes dominated by, why?

Answer 22

Advective processes. the water supply and flow increases allowing for more efficient erosion and transportation.

Question 23

What sort of processes are the bottom of convexo-concave characterised by?

Answer 23

There is an accumulation of sediment but also discharge increase which assists with the movement of this extra sediment.