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21 Φεβ 2014 (πριν από 3 χρόνια και 8 μήνες)

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Permafrost
-
Influenced
Geomorphic Processes

Torre Jorgenson

environmental research & services

Overview of Geomorphic Processes


Coasts


Storm surges, sedimentation, salinization, permafrost
degradation


Floodplains


Changing flooding, sedimentation,


Channel migration


Coastal Plain
-
Lowlands


Thermokarst lakes, waterbody creation


Lake expansion and shrinkage


Paludification, organic matter accumulation


Ice
-
wedge Degradation


Uplands


Loss of permafrost aquatard, drainage


Thaw slumps


Thermokarst Lakes in Extremely ice
-
rich loess (yedoma)


Mountains


Slope Failure



North Slope Ecological Profile

C
o
a
s
t
a
l

W
a
t
e
r
C
o
a
s
t
l
i
n
e
Jago Coastal Plain
F
l
o
o
d
p
l
a
i
n
U
p
l
a
n
d
s
Glaciated
Uplands
Icy
Coast
Coastal Plain
Okpilak
Mountains
Sadlerochit Uplands
Lakes
Lowland s
Dwarf Shrub
edge-
Lacustrine Wet
S eadow
edge M
Upland Tussock
Tundra
Coastal Wet
Sedge Tundra
Coastal Grass
and Dwarf
Shrub Tundra
Mesic shurbby
tussock tundra
Upland Low birch-
Willow shrub
Upland Tall
Alder Shrub
River
Riverine Barrens
Riverine low
willow shrub
Riverine Dryas
Riverine Wet
Sedge Meadow
Alpine acid
barrens
Alpine Dryas
Dwarf Shrub
Intrusive,
felsic
Quaternary,
glacial
Sedimentary
,
Noncarbonate
Quaternary
,
alluvial-marine
Quaternary,
marine
H
u
l
a
h
u
l
a

M
o
u
n
t
a
i
n
s
Beaufort
Coastal Plain
Brooks
Foothills
Beaufort
Coast
0
500
1000
1500
2000
2500
3000
E
l
e
v
a
t
i
o
n

(
m
)
Brooks
Range
Intrusive
Felsic
Quaternary
,
Alluvial

Coastal
Ecosystems



Sedimentation (up to 10 cm in big year)


Storm Surges (1970 to 2 m)


Salinization (up to 15 km inland)


Sea Level Rise (3 mm/yr)

Barrier Island and
Lagoon Ecosystems
Tundra Cliff and
Sandy Shore
Ecosystems
Delta
Ecosystems
Summer
DON
DOC
NO
3
Thermokarst
S
h
o
r
e
l
i
n
e

E
r
o
s
i
o
n
Salinity
Temperature
Wind
O
r
g
a
n
i
c

M
a
t
Ground ice
PO
4
Active
Dunes
Inactive
Dunes
Tidal
Flats
Precipitation
C
o
a
s
t
a
l

W
e
t

M
e
a
d
o
w
s
Sea Level
S
h
o
r
e
l
i
n
e

E
r
o
s
i
o
n
Wave
Energy
Sea
Sediment
Discharge
Winter
OCEANOGRAPHIC
­
­
¯
­
­
Sea Level
Storm surges
Sea Ice
Fetch Length
Wave Energy
GEOMORPHIC
Shoreline Erosion
Barrier Island Migration
Marine Sedi. Transport
Land Sediment Deposit.
Dune Formation/Scouring
Thermokarst
­
D
D
D
D
­
CHANGE
Coastal Geomorphic Processes

October 2002

Storm at Barrow

2000 Beaufort Lagoon
-1.0
-0.5
0.0
0.5
1.0
1.5
7/13/2000
7/23/2000
8/2/2000
8/12/2000
8/22/2000
9/1/2000
9/11/2000
9/21/2000
DATE
WATER LEVEL (m)
Mininum
Maximum
Mean tidal range = 0.31 m
1.0 m on 11-12 August
Storm Surges

Coastal
Erosion

Deltaic Environments

Salinization: Salt
-
killed tundra


FLUVIAL PROCESSES

Changing flooding, sedimentation,

Channel migration

Changes over Time:

Increasing height,

Decreasing flooding
frequency,

Decreasing sedimentation,

Increasing organics,

Decreasing thaw depths,

Decreasing water depths

Decreasing pH

Increasing ground ice,

Increasing susceptibility to
thermokarst,

GEOMORPHIC PROCESSES ON RIVER FLOODPLAINS

Upland
Sandy Low
Scrub

Upland
Barrens

Riverine
Barrens

Riverine
Low and
Tall Scrub

Riverine
Wet
Meadow

Lowland
Wet
Meadow

Lowland
Deep
Lake

Riverine
Wet
Meadows

Riverine
Lake
-

Connected

Riverine
Marsh

1000
-
2000 years

for development

Low
Water

1
-
2 yr

3
-
4 yr

5
-
25 yr

25
-
200 yr

Massive or Crossbedded Sand

Rippled sands/fines, with detrital organics

Layered fines

Masssive
organics

Layered fines w/ clay

Layered Organics

Ecotypes

Decreasing Flooding and
Sedimentation

River

Riverbed/
Riverbars

Active
-
floodplain
Cover Deposit

Inactive
-
floodplain
Cover Deposit

Abandoned
-

floodplain

Nuiqsut


Eroded Riverbed/Sandbar


Riverbed/Sandbar Deposition


Unchanged Riverbed/Sandbar


Thaw Basin Drainage/Deposition


Other Eroded Terrain


Unchanged Terrain


Lake
-
level Change


Unchanged Water


In
-
field Facilities


Pipelines

N

0

SCALE IN MILES

Proposed Project

Areas of Erosion and Deposition

1

2

Area (%)

1.3

2.6

7.6

1.8

1.0

58.8

0.9

26.1

Landscape Change from 1955 to 1992,

Central Colville River Delta

8.2% of area changed over 37 yr

2.3% of land eroded

At current rate it would take about 1700
years to rework entire delta

Erosion and Deposition

Lowland and Lacustrine Ecosystems

Lowland Hydrology:

8
-
11 ka surface

Poorly integrated surface

Snow
-
melt recharge

Summer Draw
-
down

Coastal Plain Geomorphic Model

Eolian Sand

Loess

Thaw Lake

Coastal Plain with
Moist/ Dry Tundra

Ice
-
rich Thaw Basin
with Wet Tundra

Ice
-
poor Thaw Basin
with Wet Tundra

1992
Jun
Aug
Jul
1991
Jun
Aug
Jul
-500
-400
-300
-200
-100
0
100
200
1990
Jun
Aug
Jul
Class A Pan
Evaporation
Net Water Balance
Precipitation
NET WATER BALANCE (mm)

Shoreline Erosion and
Lake Basin Development

0.7% of land was eroded over 45
-
56 year period, 0.01%/yr

At this rate it would take 8400 years to rework the surface.

In
-
filling of Lake Margins


1945

Wetting location

Drying location

Time Series: Beaufort Coastal Plain


1982

Pond shifts

Pond develops

2001

Pond drains

Pond develops

Ponds drains


1982

2001

Micro
-
topographic Effects of Ice
-
wedge Degradation

Alluvial
-
marine Deposit
(gently rolling)
Ice
-
poor
Thaw Basin
Ice
-
rich Thaw
Basin Margin
Before Disturbance
Thermokarst After Disturbance
Shallow
Water
Deep and
Shallow
Water
Wet Tundra, Deep and
Shallow Water
Before Disturbance
Active Layer (m)
Segregated Ice (%
vol
)
Wedge ice(%
vol
)
After Disturbance
Active Layer (%)
Mound Settlement (m)
Trough
Settement
(m)
Drainage
0.3
0.4
0.3
0.4
0.4
71
64
64
64
60
20
15
20
15
0
0.8
0.8
0.8
0.8
0.8
0.6
±
0.3
0.4±0.3
0.3±0.1
0.4±0.3
0.4±0.3
1
-
2
1
-
2
1
-
3
1
-
2
0
partial
none
none/partial
none
none
Water
Active Layer
Ice Wedges
Ice
-
rich Thaw
Basin Center
Ice
-
rich Thaw
Basin Margin
Deep and
Shallow
Water
Deep
Water
Alluvial
-
marine Deposit
(gently rolling)
Ice
-
poor
Thaw Basin
Ice
-
rich Thaw
Basin Margin
Before Disturbance
Thermokarst After Disturbance
Shallow
Water
Deep and
Shallow
Water
Wet Tundra, Deep and
Shallow Water
Before Disturbance
Active Layer (m)
Segregated Ice (%
vol
)
Wedge ice(%
vol
)
After Disturbance
Active Layer (%)
Mound Settlement (m)
Trough
Settement
(m)
Drainage
0.3
0.4
0.3
0.4
0.4
71
64
64
64
60
20
15
20
15
0
0.8
0.8
0.8
0.8
0.8
0.6
±
0.3
0.4±0.3
0.3±0.1
0.4±0.3
0.4±0.3
1
-
2
1
-
2
1
-
3
1
-
2
0
partial
none
none/partial
none
none
Water
Active Layer
Ice Wedges
Water
Active Layer
Ice Wedges
Ice
-
rich Thaw
Basin Center
Ice
-
rich Thaw
Basin Margin
Deep and
Shallow
Water
Deep
Water
Stable Permafrost
Degrading Permafrost
Alluvial
-
marine Deposit
(gently rolling)
Ice
-
poor
Thaw Basin
Ice
-
rich Thaw
Basin Margin
Before Disturbance
Thermokarst After Disturbance
Shallow
Water
Deep and
Shallow
Water
Wet Tundra, Deep and
Shallow Water
Before Disturbance
Active Layer (m)
Segregated Ice (%
vol
)
Wedge ice(%
vol
)
After Disturbance
Active Layer (%)
Mound Settlement (m)
Trough
Settement
(m)
Drainage
0.3
0.4
0.3
0.4
0.4
71
64
64
64
60
20
15
20
15
0
0.8
0.8
0.8
0.8
0.8
0.6
±
0.3
0.4±0.3
0.3±0.1
0.4±0.3
0.4±0.3
1
-
2
1
-
2
1
-
3
1
-
2
0
partial
none
none/partial
none
none
Water
Active Layer
Ice Wedges
Ice
-
rich Thaw
Basin Center
Ice
-
rich Thaw
Basin Margin
Deep and
Shallow
Water
Deep
Water
Alluvial
-
marine Deposit
(gently rolling)
Ice
-
poor
Thaw Basin
Ice
-
rich Thaw
Basin Margin
Before Disturbance
Thermokarst After Disturbance
Shallow
Water
Deep and
Shallow
Water
Wet Tundra, Deep and
Shallow Water
Before Disturbance
Active Layer (m)
Segregated Ice (%
vol
)
Wedge ice(%
vol
)
After Disturbance
Active Layer (%)
Mound Settlement (m)
Trough
Settement
(m)
Drainage
0.3
0.4
0.3
0.4
0.4
71
64
64
64
60
20
15
20
15
0
0.8
0.8
0.8
0.8
0.8
0.6
±
0.3
0.4±0.3
0.3±0.1
0.4±0.3
0.4±0.3
1
-
2
1
-
2
1
-
3
1
-
2
0
partial
none
none/partial
none
none
Water
Active Layer
Ice Wedges
Water
Active Layer
Ice Wedges
Ice
-
rich Thaw
Basin Center
Ice
-
rich Thaw
Basin Margin
Deep and
Shallow
Water
Deep
Water
Stable Permafrost
Degrading Permafrost

Water
-
tracks

Hillslope Geomorphic Processes

Increased drainage, south
-
facing slopes

Thaw slumps

Thermokarst Lakes in extremely ice
-
rich
loess (yedoma)


Foothills Model


Precipitation
-

Leaching
Gradient


Snow Phenology

Spring

Fall

Thermokarst Gullies and Water Tracks, Healy

Thaw Slumps


Photo by Andrew Balser

Deep Thermokarst Lakes



Seward Peninsula

CONCLUSIONS


Regional Factors


Cold climate leading to permafrost development


Coastal Processes (16% of Coastal Plain including
Lagoons, 5% land)


Sediment deposition, salinization, thermokarst


Spread of halophytic vegetation, salt
-
killed tundra


Fluvial Processes (9% of area)


Flooding leading to sediment deposition


Channel migration, erosion, and thaw lakes


Feedback from ice aggradation of flooding regime


Willow thickets, legumes, productive wet sedge


Lacustrine Processes


(14% areas in lakes, 39% in basins)


Differential sediment deposition


Shoreline Erosion (0.1%/yr)


Lake Drainage (3% of landscape over 100’s yrs)


Carbonate inputs, strong pH gradients

Thermokarst

Ice Wedge Degradation (>3%, up to 20%)

Tussock loss, wet sedge increase, redistribution

of water

Hillside Processes

Deeper Drainage,

Gully formation,

Thaw slumps

Deep Thermokarst Lakes

CONCLUSIONS