From atmospheric rivers… to rivers of debris.

Gordon Grant PNW Research Station

USDA Forest Service

Anne Nolin, Lauren Parker, Beth Copeland

Stephen Lancaster, Jonathan Ellinger

Oregon State University

Paul Kennard, Erin Tainer Ian Delaney

Mt Rainier National Park Whitman College

Coupling extreme precipitation events, glacial retreat, debris flows and channel changes on Mount Rainier, Washington

November 6, 2006

November 7, 2006

was a dark, stormy,

and very wet night...

Pineapple Express /

Atmospheric River

NASA Earth Observatory

Oct 31-Nov 7, 2006

Mount Rainier

> 100yr Flood

Tahoma Creek, Washington

Hwy 35

Mount Hood Debris Flows

Eliot Creek

West Fork Middle Fork Hood

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1947 1952 1957 1962 1967 1972 1977 1982 1987 1992 1997 2002 2007

# o

f d

eb

ris

flo

ws

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1947 1952 1957 1962 1967 1972 1977 1982 1987 1992 1997 2002 2007

# o

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Debris flow data from Driedger, Walder, Kennard

Mount Hood

Mount Rainier

Cascadian Periglacial Debris Flow Project

1) Atmospheric

rivers 2) Initiation

of debris

flows

3) Downstream

consequences Climate

Change?

Are debris flows correlated with Pineapple Express and

Atmospheric River (PE/AR) events?

PE/AR = Lots of rain

Pineapple Express event of November 5 and 6, 2006

+ High Freezing levels

Rainier

Hood

Mountain peak elevations

Mount Rainier Freezing Altitudes Mt Rainier

peak elevation

Associated with strong southwest flow

Dettinger, 2004

A debris flow was considered PE/AR related if a PE/AR event occurred

on the same day as a debris flow, or on the day prior.

PE/AR event non PE/AR event

Pineapple Express (PE) events (Dettinger, 2004) and Atmospheric Rivers (AR) (Neiman et al., 2008); Debris flow data from Driedger, Walder, Kennard

Mount Hood

Mount Rainier

Classification of storms proceeding debris flows

Classification of storms proceeding debris flows

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10/26/86

10/15/8811/8/89

10/2/9011/4/91

9/7/929/19/92

10/19/039/28/05

11/5/06

One Day Prior to Debris Flow Event Date

SW

E (

mm

)

Mount Rainier

Antecedent SWE

…and 3) Little snow cover

Iverson, pers comm.

RAIN

SNOW DEPTH

Geomorphic factors associated with debris flow

initiation All recent initiation sites are:

• In areas exposed by recent (5-10 year) glacier retreat

• Near glacier termini or debris-mantled stagnant ice

• At heads of steep-walled gullies flanked by steep debris-mantled slopes

2001-2006

debris flow

initiation sites

1913

Glacier Extent

2008

Ellinger, 2010

• water concentrated in sub- or supra-glacial channels.

• flow directed toward unstable, sediment mantled slopes below/adjacent to glaciers.

Fire Hose Effect?

Photo: NPS

Source areas • Moraines • Ice-cored debris • Debris mantled

slopes

Runout Zone

Deposition in larger channels

Downstream channel response?

0.1

1.0

10.0

100.0

1000.0

0.1 1.0 10.0 100.0 1000.0

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cen

t A

ggra

dat

aio

n R

ate

s (c

m/y

r)

Long term (1910-2006) Aggradation Rates (cm/yr)

1997-2006 2006

Aggradation rates within Mount Rainier National Park

Lower Van

Trump

Longmire

Sunshine

Point

White

River

1) Evidence for

widespread

aggradation

(not incision)

2) Higher than

long-term

average in last

decade

1951

1989

1960

1978

Tahoma Creek

post 2006 storm

Christopher Magirl, USGS

Aggradation rates downstream of Mount Rainier National Park

Effects of climate change?

• Change in

intensity/frequency of

PE/AR events

• Continued

glacial

retreat / fragmentation

• Increased

length of

snow free

period

• Downstream

signal?

No smoking gun yet… • Atmospheric events producing

debris flows come in different flavors

• Apparent recent increase in debris flows, but record is incomplete and potentially biased

• Consistent pattern of aggradation within Mt Rainier National park itself

• No consistent aggradation in larger rivers