Soil Slope Relations

1
Soil- Slope Relations
2
Soil Genesis- The Relief Factor

• How are soils and landforms related?
• How does sediment move on slopes?
• How does water move on slopes?
• What is the CATENA concept?
• How does relief affect soil climate?

3
Soil-Landscape Systems

• Register interrelations between soil development
  and geomorphology
• The systems approach
• Inputs vs outputs
• Equilibrium vs dynamic change

4
Denudational Balance

• Regolith weathered bedrock
• Thickness of (regolith soil)
• f (rate of soil formation rate of deposition)
• A accumulation of slope material (GAIN)
• S slopewash/ deflation (LOSS)
• M mass movements (Loss or Gain)

5
Slope Status

• A slope is
• Weathering limited if
• Transport exceeds weathering
• EROSION and DEPOSITION
• Transport limited if
• Weathering exceeds transport
• SOIL FORMATION

6
Uh Slope

• Key components
• Interfluve
• Convex slope
• Concave slope
• Colluvial footslope
• Alluvial Toeslope

7
Uh Slope

• Interfluve
• Maximum pedogenesis
• Minimal erosion

8
Uh Slope

• Convex slope
• Soil creep
• Some erosion
• Possible balance between
• erosion - pedogenesis

9
Uh Slope

• Concave slope
• Erosional removal
• Mass movements
• Minimal pedogenesis

10
Uh Slope

• Colluvial footslope
• Colluvial deposition
• Alluvial fans
• Cumulic soils

11
Uh Slope

• Alluvial Toeslope
• Alluvial deposition
• Pedogenesis conditioned by alluvial deposition

12
Slope Stability

• Slope angle
• Slope shape
• Microrelief
• Slope length
• Vegetation
• Texture

13
Slope Stability

• Slope shape
• HI straight/convex
• LO concave
• Microrelief
• Roughness reduces
• erosional potential

14
Slope Stability

• Slope angle
• Erosion
• from 1 x S to S2

15
Slope Stability

• Slope length
• Erosion L1/2

16
Gravity and Slope Stability

• Mass movements
• Soil creep
• Structural controls

17
Creepy Soils
18
Textural Control on Erosion

• Clay content increases resistance to erosion

19
Water Movement on Slopes

• Key Processes
• Infiltration
• Overland flow
• Throughflow
• Deep Percolation

20
Water Movement on Slopes

• Key Processes
• Infiltration
• Promotes solution
• Maximum at
• Interfluves
• toeslopes

21
Water Movement on Slopes

• Key Processes
• Overland flow
• Horton (unsaturated)
• Convex and steep slopes
• Saturated
• Lower slopes
• Dissolved load

22
Water Movement on Slopes

• Key Processes
• Throughflow
• Unsaturated
• Saturated
• Deep Percolation
• Mainly along interfluves

23
Water Movement on Slopes

• Key Processes
• Piping
• Requires aquitard
• Seasonal climate
• Precedes gullying

24
Solution Transport on Slopes

• May exceed mechanical loss
• Rainfall intensity-frequency
• High solubility minerals
• HI intensity - HI frequency
• Low solubility minerals
• HI intensity - LO frequency

25
Soils on Slopes

• The Catena Concept
• (Toposequences)

26
Soils on Slopes

• The Catena Concept
• (Toposequences)

Jenny 1941
27
Soils on Slopes

• The Catena Concept
• (Toposequences)

Jenny 1941
28
Soil Morphology on Slopes

• Solum thickness
• Horizonation
• Oxidation-Reduction
• Organic Matter
• Erosional losses
• Depositional Gains

29
Soil Morphology on Slopes

• Solum thickness
• Horizonation
• Oxidation-Reduction
• Organic Matter
• Erosional losses
• Depositional Gains

30
(No Transcript)
31

• Catena-Climate
• Note
• Horizonation
• Clay mineralogy
• Gleyed settings
• Ions lost

32

• Slope Aspect Effects

33
Soil Morphology on Slopes

• Solum thickness
• Horizonation
• Oxidation-Reduction
• Organic Matter
• Erosional losses
• Depositional Gains

34
(No Transcript)