Geomorphology - 3

Question 1

Low intensity events …

Answer 1

Happen a lot but don’t do very much

Question 2

High intensity events …

Answer 2

Do a lot but don’t happen very much

Question 3

Leopold

Answer 3

1964

Question 4

Bank full discharge

Answer 4

Maximum discharge that can be contained in a channel without over topping its banks

Question 5

Dominant discharge

Answer 5

Single steady discharge that would produce the same morphology and dimensions as produced by the actual flow regime

Question 6

Effective discharge

Answer 6

Discharge or range of discharges that transports the largest proportion of sediment load over the long term

Question 7

Gumbel

Answer 7

Log distribution curve

Extreme events recorded in the landscape

Question 8

Static equilibrium

Answer 8

Inputs and outputs are balanced

Question 9

Stable equilibrium

Answer 9

If disturbed, landscape may recover back towards its original state

Question 10

Stable equilibrium example

Answer 10

Linear dunes by climatic fluctuations

Vegetating
Devegetating
Moving
Re vegetating

Question 11

Meta stable equilibrium

Answer 11

New recovery state/trend when thresholds are crossed

E.g stream transport in a landslide

Question 12

Steady state equilibrium

Answer 12

If the system constantly fluctuates around the mean equilibrium state

Question 13

Dynamic equilibrium

Answer 13

Mean variations around a definite trending change

Glacial Erosion

Question 14

Wainwright

Answer 14

2006

Question 15

Wainwright 2006

Answer 15

Is equilibrium just a metaphor ?

As equilibrium is untestable by process it functional geomorphology

Question 16

Threshold definitions (2)

Answer 16

1) BOUNDARY CONDITIONS - where geomorphic systems change from equilibrium to disequilibrium state
2) LIMIT OF STABILITY

Question 17

Threshold controlled by external factors

Answer 17

Extrinsic

Question 18

Intrinsic threshold

Answer 18

Gradual changes when external factors remain constant

Question 19

Geomorphic threshold

Answer 19

Stability of a landform itself, amount of slow accumulated change a landform can taken before it moves into a new system

Question 20

Lag time

Answer 20

Delay between controls changing and landscape responding

Question 21

Relict landform

Answer 21

Landforms created under previous climatic conditions

Question 22

Exceeding a particular threshold can lead to more than one geomorphic process responding

What is this?

Answer 22

COMPLEX RESPONSE

Question 23

Dominant landform events

Answer 23

Occur with moderate frequency and moderate magnitude

CONCEPT OF MAGNITUDE AND FREQUENCY

Question 24

Events control what the landscape looks like in between events: either recovery or adjustment

Answer 24

CONCEPT OF EQUILIBRIUM OR STEADY STATE

Question 25

Landscape response (form change) to process forcing varies

Answer 25

Notions of THRESHOLDS and equilibrium

Question 26

Recent changes in geomorphology technologies 5

Answer 26

1) improved technologies for remote sensing and surveying 2) important developments of absolute dating techniques 3) advent of personal and large scale computation 4) recognition that geomorphology is a system science 5) reintegration it tectonics into geomorphology, consideration of landscape history 6) increasing dominance of human agency in modification of Earths surface

Question 27

How can we stimulate the evolution of a topographic surface ?

Answer 27

By using a set of driving erosion and sedimentation processes

Question 28

Challenges in modelling landscape change 3

Answer 28

- need to extrapolate geomorphical information in a landscape - need to reconcile theories/ models with different scales - need to integrate human impacts into landscape evolution models

Question 29

Case study of human influences effecting models

Answer 29

1830 - 1928 200 years of extracting deposits to extract water from coal mines West Midlands

Question 30

Landscape Evolution Models

Answer 30

CYBEROSION Cells define local characteristics E.g. animal agents, human agents, soil properties

Question 31

Equifinality

Answer 31

Notion that the same landforms may be produced by more than one mechanism

Question 32

Implications of equifinality | 3

Answer 32

1) can’t work out history of landscape in its present state 2) can attempt to work out response if you understand the process CANT WORK OUT PROCESS FROM THE RESPONSE 3) LEMs are over simplified in dependency and condition to stop people’s own predictions

Question 33

Wolman and miller

Answer 33

1960 Relationship between rate of transport, applied stress and frequency of stress

Question 34

Wainwright 2006

Answer 34

Represent equilibrium as a metaphor as it is an untestable process or by functional geomorphology

Question 35

Schumm

Answer 35

1985 Limit of stability Boundary conditions at which geomorphic systems can change from equilibrium to disequilibrium state

Question 36

Wainwright 2010

Answer 36

Agent based models - over come limitations of existing approaches Grid based cellular model, identifies features that can vary through time and human interactions Helps to understand complex landscape responses and form policy related decisions