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Hillslopes - moving mass: creep,slides and flows Force balance - driving vs resisting forces Soil creep - slope dependent, diffusive processes Mass movements - landslides and rock falls Flows - of debris and mud. FORCE BALANCE. DRIVING VERSUS RESISTING. GRAVITY. SHEAR STRENGTH (FRICTION

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Hillslopes moving mass creep slides and flows force balance driving vs resisting forces

Hillslopes - moving mass: creep,slides and flows

Force balance - driving vs resisting forces

Soil creep - slope dependent, diffusive processes

Mass movements - landslides and rock falls

Flows - of debris and mud


Force balance
FORCE BALANCE

DRIVING VERSUS RESISTING

GRAVITY

SHEAR STRENGTH (FRICTION

AND COHESION or VISCOSITY)


Hillslopes moving mass creep slides and flows force balance driving vs resisting forces

http://ees.as.uky.edu/sites/default/files/elearning/module11swf.swfhttp://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf


Processes that move mass on slopes first consider infiltration rate
Processes that move mass on slopeshttp://ees.as.uky.edu/sites/default/files/elearning/module11swf.swffirst consider infiltration rate

  • Rainsplash (bare soil only)

  • Channels (ephemeral, permanent)

  • Creep (grab-bag, many processes)

  • Mass movement (landsliding = translational, rotational and rockfall)

  • Flowage (debris and mud)


Slope types connect to process
Slope types – connect to processhttp://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf


Rain splash

2http://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf

Rainsplash - splatering, downslope component

Rain splash


Where flow is thin rainsplash disturbance prevents channelization

2http://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf

Where flow is thin, rainsplash disturbance prevents channelization

Incision begins when shear stress exceeds strength


Hillslopes moving mass creep slides and flows force balance driving vs resisting forces

2http://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf

Critical Distance from drainage divide = channelization


Soil creep evidence

3http://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf

Soil Creep - evidence

Rate is a function of slope Q= ks

Marathon Basin, west Texas. J.S. Aber.

Which way is soil moving?


Other biotic effects vary by climate and location

3http://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf

Other biotic effects - vary by climate and location


Mammals gophers here

3http://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf

Mammals (gophers here)

NET DOWNSLOPE TRANSPORT


Rotational failure clay silt homogeneous material

Rotational failure - clay, silt, homogeneous materialhttp://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf


Hillslopes moving mass creep slides and flows force balance driving vs resisting forces

Bishop method of sliceshttp://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf

Rotational Failures


Hillslopes moving mass creep slides and flows force balance driving vs resisting forces
Importance of unique events/thresholdshttp://ees.as.uky.edu/sites/default/files/elearning/module11swf.swfDiscrete vs. continuous processesStormsDisturbanceLandslidesDebris Flows


Hillslopes moving mass creep slides and flows force balance driving vs resisting forces

The Ritterbush Recordhttp://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf

50 cm

2000

2600

Calendar Years BP

5900

6800

8200

9400


Hillslopes moving mass creep slides and flows force balance driving vs resisting forces

AMS http://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf14C Analysis


Hillslopes moving mass creep slides and flows force balance driving vs resisting forces

Storm Frequencyhttp://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf

2

4

6

8

10

12

0

Calendar kyr BP

• 4 maxima; currently increasing—observed?


Hillslopes moving mass creep slides and flows force balance driving vs resisting forces

Northhttp://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf

Atlantic

Climate

Storm

Freq.

Coolings

Storms

Floods

GISP2 ssNa

GISP2 nssK

0

2

4

6

8

10

12

Calendar kyr BP


Hillslope channel transition colluvial hollows
Hillslope- channel transition, colluvial hollowshttp://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf


Bank erosion
Bank erosion?http://ees.as.uky.edu/sites/default/files/elearning/module11swf.swf