Geomorphology - 3 Flashcards

1
Q

Low intensity events …

A

Happen a lot but don’t do very much

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2
Q

High intensity events …

A

Do a lot but don’t happen very much

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3
Q

Leopold

A

1964

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4
Q

Bank full discharge

A

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

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5
Q

Dominant discharge

A

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

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6
Q

Effective discharge

A

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

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7
Q

Gumbel

A

Log distribution curve

Extreme events recorded in the landscape

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8
Q

Static equilibrium

A

Inputs and outputs are balanced

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9
Q

Stable equilibrium

A

If disturbed, landscape may recover back towards its original state

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10
Q

Stable equilibrium example

A

Linear dunes by climatic fluctuations

Vegetating
Devegetating
Moving
Re vegetating

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11
Q

Meta stable equilibrium

A

New recovery state/trend when thresholds are crossed

E.g stream transport in a landslide

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12
Q

Steady state equilibrium

A

If the system constantly fluctuates around the mean equilibrium state

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13
Q

Dynamic equilibrium

A

Mean variations around a definite trending change

Glacial Erosion

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14
Q

Wainwright

A

2006

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15
Q

Wainwright 2006

A

Is equilibrium just a metaphor ?

As equilibrium is untestable by process it functional geomorphology

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16
Q

Threshold definitions (2)

A

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

17
Q

Threshold controlled by external factors

A

Extrinsic

18
Q

Intrinsic threshold

A

Gradual changes when external factors remain constant

19
Q

Geomorphic threshold

A

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

20
Q

Lag time

A

Delay between controls changing and landscape responding

21
Q

Relict landform

A

Landforms created under previous climatic conditions

22
Q

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

What is this?

A

COMPLEX RESPONSE

23
Q

Dominant landform events

A

Occur with moderate frequency and moderate magnitude

CONCEPT OF MAGNITUDE AND FREQUENCY

24
Q

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

A

CONCEPT OF EQUILIBRIUM OR STEADY STATE

25
Q

Landscape response (form change) to process forcing varies

A

Notions of THRESHOLDS and equilibrium

26
Q

Recent changes in geomorphology technologies

5

A

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

27
Q

How can we stimulate the evolution of a topographic surface ?

A

By using a set of driving erosion and sedimentation processes

28
Q

Challenges in modelling landscape change

3

A
  • 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
29
Q

Case study of human influences effecting models

A

1830 - 1928

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

30
Q

Landscape Evolution Models

A

CYBEROSION

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

31
Q

Equifinality

A

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

32
Q

Implications of equifinality

3

A

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

33
Q

Wolman and miller

A

1960

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

34
Q

Wainwright 2006

A

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

35
Q

Schumm

A

1985

Limit of stability

Boundary conditions at which geomorphic systems can change from equilibrium to disequilibrium state

36
Q

Wainwright 2010

A

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