Document Actions

IJEGE-11_BS-Chiarle-et-alii

background image
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
45
DOI: 10.4408/IJEGE.2011-03.B-006
IMPACTS OF CLIMATE CHANGE ON DEBRIS FLOW OCCURRENCE IN
THE CORDILLERA OF WESTERN CANADA AND THE EUROPEAN ALPS
M. CHIARLE
(*)
, M. GEERTSEMA
(**)
, G. MORTARA
(*)
& J.J. CLAGUE
(***)
(*)
Consiglio Nazionale delle Ricerche - Istituto di Ricerca per la Protezione Idrogeologica U.O.S. Torino - Strada delle Cacce, 73 -
10135 Torino, Italy. E-mail: marta.chiarle@irpi.cnr.it – Tel. +39 011 3977 836
(**)
British Columbia Ministry of Forests and Range - 1011 4th Avenue - V2L 3H9 Prince George, B.C., Canada
(***)
Simon Fraser University - Department of Earth Sciences - 8888 University Drive - V5A 1S6 Burnaby, B.C., Canada
INTRODUCTION
Earth’s climate is likely to warm through the re-
mainder of the 21st century (IPCC, 2007), with sig-
nificant impacts on the amount, intensity, and spatial
distribution of precipitation. Evidence is mounting
that climate change will affect the stability of slopes,
although the full extent, time, and magnitude of the
response remain uncertain, in part because climate is
only one of the factors contributing to slope instabil-
ity (t
uRneR
& s
CHusteR
, 1996). The role played by
climate may be difficult to discern, both because of
sparse observational data through much of the historic
period and because the responses may be delayed or
non-linear over time (v
iles
& G
oudie
, 2003). Moreo-
ver, the effects of climate warming onregional and lo-
cal precipitation patterns are still uncertain.
In this paper we contribute to discussions within
the scientificcommunity of the impacts of climate
change on mountainenvironments by discussing con-
trols on debris flow occurrence inthe Cordillera of
western Canada and the European Alps. We usesever-
al debris flow case studies to illustrate these controls.
study areas
Our focus is the mountains of western Canada and
the European Alps. These two areas share many com-
mon features, but also have marked climatic, geolog-
ic, and physiographic differences that provide context
for a discussion of the processes affecting the world’s
mountains, the emphasis here being on debris flows.
ABSTRACT
In spite of a general agreement on present cli-
mate trends, actual impacts on terrestrial systems
are still very debated. Evidence is mounting that
climate change is affecting the stability of slopes,
although the full extent, time, and magnitude of the
response remain uncertain, in part because climate
is only one of the factors contributing to slope in-
stability. Moreover, at the regional and local scale
climate change patterns can be very different.
Mountain environment seems to respond promptly
to climate warming, in part because of the presence
of the cryosphere. The present paper contributes
to discussions within the scientific community by
discussing controls on debris flow occurrence in
the Cordillera of western Canada and the European
Alps. Several debris flow case studies illustrate
how cryosphere degradation can play a signifi-
cant role in debris flow occurrence in glacial and
periglacial margins, both on a short and on a long
time span. Processes responsible for debris flow
development under a warming climate include rock
falls and rockslides induced by glacier debuttress-
ing, thaw of alpine permafrost, sudden draining of
glacial lakes, and exposure of unconsolidated, un-
vegetated, and commonly ice-cored sediments due
to glacier recession.
K
ey
words
: debris flow, cryosphere, climate change, Cana-
dian Cordillera, European Alps
background image
M. CHIARLE, M. GEERTSEMA, G. MORTARA & J.J. CLAGUE
46
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
ice, some up to 1.6 km thick, filled valleys and flowed
out onto the plains north and south of the Alps. Today,
glaciers cover about 2000 km
2
of the Alp,s but the gla-
cierized area is rapidly decreasing (z
emP
et alii, 2007).
Permafrost is sporadic at elevations from 2000 up to
3200 m asl, and more continuous at higher elevations,
but even at high elevations ground temperatures are
close to 0°C (G
uGlielmin
, 2004).
The Alps are affected by four climate systems
(w
anneR
et alii, 1997): mild, moist air masses from
the Atlantic Ocean to the west; warm Mediterranean
air from the south; cold polar air from the north; and
continental air from the east. The range strongly influ-
ences its own climate, which ranges from maritime to
continental, and from temperate at low elevations to
alpine. The exact role of large-scale climate systems
on Alpine climate and, in particular, recent climatic
trends is still uncertain (a
GRawala
, 2007).
CLIMATIC FACTORS OF DEBRIS FLOW
INITIATION
Climate affects the stability of slopes in a variety
of ways and on different time scales. Debris flows, in
particular, have a close and immediate relationship
with climate and weather; most are triggered by heavy
or intense rainfall (s
andeRsen
et alii, 1996). Even so,
topographic and geologic factors, land-use, and veg-
etation are important in preconditioning slopes to de-
bris flow activity (t
RoPeano
& t
uRConi
, 2003; w
ieC
-
zoRek
& G
lade
, 2005).
Intense rainstorms and rapid melt of snow and
ice are the principal triggers of debris flows. Rapid
infiltration of water can saturate soil and elevate pore-
water pressures, reducing the strength of surficial ma-
terials and initiating shallow debris avalanches and
slides (i
veRson
, 2000) that evolve into debris flows.
In addition, channelized runoff may entrain sediment
and transform into debris flows. The critical rainfall
threshold for debris flow initiation is generally ex-
pressed as a combination of intensity and duration. It
can be used by emergency managers as part of warn-
ing systems (w
ilson
, 2005), although studies have
documented important regional differences (J
akob
&
w
eatHeRley
, 2003; G
uzzetti
et alii, 2008).
Antecedent rainfall and snow influence whether
debris flows are triggered during a rainstorm, earth-
quake, or volcanic eruption. Its role in debris flow
initiation, however, is still debated. In particular, there
THE CANADIAN CORDILLERA
The Cordillera of western Canada is part of the
great belt of mountains that forms the western margin
of the Americas. The population of the region is only 4
million people and most mountain valleys are remote
and uninhabited. The Canadian Cordillera is a region
of extremely diverse topography, geology, climate,
and vegetation. Rugged glacier-clad mountains that
receive more than 3000 mm of precipitation per year
are within sight of broad semiarid valleys. The general
form of the Cordillera resembles that of a great wall
flanking Canada’s Interior Plains (b
ostoCk
, 1948).
The high mountains of the Cordillera today support
valley glaciers and small ice caps. The total area of
glaciers in B.C. and Alberta is about 26,000 km
2
and the number of glaciers is approximately 15,000
(C
laGue
et alii, in press). During major Pleistocene
glaciations, glaciers covered a great part of the area
beneath as much as 2.5 km of ice. These glaciers re-
peatedly disrupted and rearranged the drainage of the
region, sculpted mountains, and left prodigious quan-
tities of sediment in valleys, plateaus, coastal low-
lands, and the seafloor (C
laGue
, 1989).
The climate of Canada’s western Cordillera is
controlled by three main factors: the proximity to
the Pacific Ocean, the presence of several mountain
ranges trending parallel to the Pacific coastline, ENSO
and its linked North Pacific Ocean state, the PDO (Pa-
cific Decadal Oscillation). Permafrost is continuous
in northern Yukon Territory and is common, although
discontinuous elsewhere in the Yukon (b
Rown
, 1967).
In British Columbia, permafrost has a patchy distribu-
tion above 1200 m asl in the north and above 2100 m
asl in the south (b
Rown
, 1967).
THE EUROPEAN ALPS
The Alps are a complex of mountain ranges that
form an arc across western Europe, and are home to
about 15 million people The highest peaks are be-
tween 4400 and 4800 m asl, and the average elevation
is about 2500 m asl. Alpine physiography is strongly
controlled by geology, which ranges from folded sedi-
mentary rocks in the low-lying pre-Alps that border
the main range everywhere except in northwestern It-
aly, to the crystalline massifs of the inner Alps, which
have the highest peaks. The Alps, like the Canadian
Cordillera, were strongly shaped by glaciers during
the Pleistocene (e
HleRs
& G
ibbaRd
, 2004). Tongues of
background image
IMPACTS OF CLIMATE CHANGE ON DEBRIS FLOW OCCURRENCE IN THE CORDILLERA OF WESTERN CANADA
AND THE EUROPEAN ALPS
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
47
century. Significant trends in northern British Columbia
range from +10.2 to +18.6 percent (e
GGinton
, 2005).
Climate also warmed in the European Alps during
the 20th century and the early years of the present cen-
tury, with accelerated warming since the early 1990s
(Casty et al., 2005, 2007). Surface temperatures rose
1.2°C in the 20th century (a
ueR
et alii, 2007), almost
double the global average of 0.74°C (1906-2005; IPCC,
2007). As a consequence, glacier cover in the Alps has
decreased about 50% in the past 150 years (z
emP
et alii,
2007). The rate of ice loss has increased over the past
three decades. Warming of permafrost, although spa-
tially variable, is typically 0.5-2°C at the depth of zero
annual change (b
Rown
& R
omanovsky
, 2008).
Precipitation patterns in the Alps have been more
variable than temperature, both spatially and season-
ally. In the hydrographic basins of the European Alps,
well-defined meteorological configurations of several
consecutive days duration give rise to extraordinary
rainfall events (n
iGRelli
et alii, 2009). a
ueR
et alii
(2007), however, reported an increase in precipitation
north of the Alps of 9 percent during the 20th century
and an equivalent decrease south of the Alps, enhanc-
ing the polarity in climate across the orogen. b
Runetti
et alii (2004) found that the decrease in precipitation
south of the Alps is the result in fewer wet days – pre-
cipitation intensity has increased. This finding is con-
sistent with observed increases in extreme precipitation
events, for example 1-in-50 year storms (IPCC, 2007)
INITIATION MECHANISMS RELATED
TO CLIMATE CHANGE IN THE STUDY
AREAS
Debris flow initiation depends on both debris
and water availability (m
aRCHi
et alii, 2002). Climate
change influences both debris abundance and the hy-
drological cycle, and thus can alter the spatial and
temporal distribution of debris flows. The effects of
climate change are most evident in glacial and per-
iglacial environments, where geomorphic processes
are particularly sensitive to temperature changes.
A consequence of climate warming is that debris
availability in proglacial and periglacial areas is in-
creasing: glacier retreat has exposed large quantities of
glacial sediment and increased instability of formerly
glacier-buttressed rock walls and glacial deposits en-
hanced. Instability has been excacerbated by thaw of
alpine permafrost. Large quantities of unconsolidated,
is little agreement on the duration of significant ante-
cedent rainfall necessary to trigger debris flows. Ante-
cedent soil moisture can vary significantly with slope
morphology and aspect, and the geologic and climatic
setting of an area (w
ieCzoRek
& G
lade
, 2005). Yet,
several studies have illustrated the importance of soil
moisture conditions in initiating debris flows at times
of earthquakes and volcanic eruptions (P
ieRson
et alii,
1990, m
aRtinez
et alii, 1999).
Climate also affects geomorphic processes that
supply sediment to slopes susceptible to debris flow
activity, such as solifluction, freeze-thaw activity, and
glaciation. Sediment supply can be a limiting factor in
debris flow initiation (b
ovis
& J
akob
, 1999).
Warm and dry weather can also predispose slopes
to debris flows. Wildfires under such conditions can
lead to fires that remove vegetation and produce sur-
face hydrophobic ashy layers in soils (C
annon
, 2001).
CLIMATIC TRENDS IN THE STUDY ARE-
AS AND RELATED CHANGES IN THE
CRYOSPHERE
Tree-ring research has provided temperature re-
constructions for the Cordillera of western North
America for the past millennium. The reconstructions
show generally cooler climate during the Little Ice
Age and pronounced warming late in the 19
th
century,
between the 1920s and 1940s, and after about 1980
(b
Radley
& J
ones
, 1993; J
ones
& m
obeRG
, 2003;
k
oCH
et alii, 2009). Surface temperatures rose, on
average, 0.6° in the 20th century, but high latitudes
experienced higher increases (IPCC, 2007). The most
significant warming has occurred since the 1990s:
most of the warmest years on record in North America
have been in this period, including 1998, the warmest
year of the 20th century (IPCC, 2007).
Most glaciers in western North America have fluc-
tuated in tandem with climate on a decadal timescale,
with large ice losses in the 20th century. Most glaciers
have lost more than 25 percent of their mass in the
20th century, and many small glaciers have shrunk by
more than 50 percent (l
uCkman
& k
avanaGH
, 2000;
IPCC, 2007). Over the same period, the lower limit of
alpine permafrost has rise on average 100-200 m
Precipitation patterns during the 20th century
have been more spatially and seasonally variable than
temperature. Much of British Columbia, however, ex-
perienced an increase in precipitation during the 20th
background image
M. CHIARLE, M. GEERTSEMA, G. MORTARA & J.J. CLAGUE
48
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
retreat in the Italian Alps has been proportionately great-
er due to the concurrent reduction of precipitation.
The exact role played by cryosphere degradation
in debris flows is poorly known, but recent events
from western Canada and Europe, summarized in the
following sections show how climate warming con-
tributes to debris flow occurrence.
ROCk SLOPE INSTABILITY
Glaciers steepen valley walls; when glaciers re-
treat, valleyside slopes are debuttressed and exposed to
weathering and gravitational forces. At the same time,
melt of snow and ice increases the input of water to
slopes, increasing the possibility of landslide and debris
flow inception. This ensemble of processes is well illus-
trated by the case of recent landslides at Mount Meager,
in the southern Coast Mountains of British Columbia
On July 29, 1998, a 550,000 m
3
debris slide re-
leased from upper Capricorn Creek basin in the Mount
Meager Volcanic Complex, triggering a debris flow
which ran 6 km down Capricorn Creek (b
ovis
& J
akob
,
2000). The debris slide that triggered the debris flow
originated from a thick blanket of poorly consolidated
colluvium on the south flank of Mount Meager vol-
cano. The slide was initiated by accelerated snowmelt
during a record-breaking heat wave in late July 1998.
Approximately 1.2 × 10
6
m
3
of material were delivered
to the Meager Creek confluence, creating a landslide
dam. A much larger rock-slope failure occurred at the
same site on August 6, 2010, again in fair hot weather
(Fig. 2). The failed rock rapidly transformed into a large
debris flow that traveled down. Capricorn and Meager
creeks into the Lillooet River valley.
Large amounts of water were present with the
rock mass that failed, likely due to infiltration of
snowmelt and precipitation.
EXPOSURE OF GLACIAL SEDIMENT AND
CHANGES IN THE HYDROLOGICAL CYCLE
Glacier retreat is exposing large amounts of loose
unvegetated sediment that can potentially feed debris
flows. As glaciers thin and retreat, they are less able
to retard rainfall-induced runoff. Coincidentally, the
elevation marking the transition from rain to snow
is rising. An exemplary event illustrating the conse-
quences of these processes occurred on September 7,
2008, in the Castelfranco watershed, at Monte Rosa in
the western Italian Alps. During a period of only mod-
unvegetated, and, in some instances ice-cored debris
are available for transportation and can be easily mo-
bilized by heavy rainfall, enhanced snow and ice melt,
and outburst floods (Fig. 1; C
HiaRle
et alii, 2007)
Climate change is also affecting the hydrological
cycle in glacial and periglacial areas. The ratio of rain-
fall to snowfall is increasing and more water is supplied
by melting snow and glacier. Unstable, ephemeral ice-
dammed lakes are developing due to glacier retreat and
downwasting. Sudden draining of these lakes produce
catastrophic floods and debris flows (C
laGue
& e
vans
,
2000). Melt of massive ground ice in glacial and col-
luvial deposits can destabilize moraine dams and lateral
and terminal moraines, producing unexpected floods
and debris flows.
The impacts of climate change in the glacial and
periglacial environments of the Canadian Cordillera and
European Alps are similar, as temperature is the domi-
nant driving process in both orogens. However, glacier
Fig.1 - Heavy rainfalls on 24 July 1996 started a par
oxysmal erosion activity on the fore field of the
Ormelune Glacier (Aosta Valley, Nw Italy). Note
the extensive flooding of the distal fan portion and
valley bottom
Fig. 2 - Path and deposit of the 2010 Capricorn Creek
debris flow. The debris flow travelled down Capri-
corn Creek (top center) and Meager Creek (mid-
center),before coming to a rest in Lillooet River
valley (bottom center). (J.J.Clague)
background image
IMPACTS OF CLIMATE CHANGE ON DEBRIS FLOW OCCURRENCE IN THE CORDILLERA OF WESTERN CANADA
AND THE EUROPEAN ALPS
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
49
snow on the stagnant terminus of Castelfranco Glacier
played a critical role in the initiation and dynamics
of the event, temporarily damming the flow (Fig. 3).
The deadly debris flow generated by the Kolka-
Karmadon rockice avalanche in the Caucasus in 2002
showed the extreme size and travel distance of flows
that can result from such combinations of processes
(H
aebeRli
et alii, 2004).
GLACIAL LAkE OUTBURST FLOODS
Many new glacial lakes are forming in depressions
left by glacier retreat or on the surface of downwasting
glaciers. Lakes dammed by ice or moraines are suscep-
tible to sudden empting due to failure of their dams.
The floods and, in some cases, the debris flows spawned
by the escaping waters are a major threat because of
the large volumes involved, the long travel distances,
and their unpredictability. Klattasine Lake, a moraine-
dammed lake in British Columbia, catastrophically
drained sometime between June 1971 and September
1973, releasing about 1.7 × 10
6
m
3
of water (Fig. 4).
The escaping waters trenched the moraine and mo-
bilized large quantities of sediment along the channel
and valley margins, and the flood rapidly evolved in a
debris flow that travelled 8 km downstream (C
laGue
et alii, 1985). Scour of the valley floor by the debris
flow locally destabilized adjacent valley slopes, caus-
ing secondary slope failures. Two glacial lakes in the
European Alps – Roche Melon Glacier lake (French
Alps) and the Effimero Lake on Belvedere Glacier
(Monte Rosa) – created emergencies when they rap-
idly expanded due to thermokarst processes. Authori-
ties drained the lakes because of the threat they posed
to downvalley villages (b
essans
& m
aCuGnaGa
). An
earlier outburst flood from the Locce Lake in 1979
had triggered a debris flood, heightening concerns
(J
obaRd
, 2005, m
oRtaRa
& t
ambuRini
, 2009).
Outbursts of water from cavities within glaciers
can be insidious because the water pockets are dif-
ficult to detect. An englacial water pocket with a vol-
ume of 65,000 m
3
was recently identified with Tête-
Rousse Glacier on Mont Blanc. Local authorities,
concerned about the threat an outburst posed to sev-
eral villages in the valley below, decided to drain the
water through vertical holes drilled into the glacier.
Such a disaster happened in the area in 1892, when a
water pocket of about 200,000 m
3
drained, triggering
an 800,000 m
3
debris flow. The flow, which devastat-
erate rainfall (39 mm in 22 hrs), a debris flow initiated
at an elevation of 3600 m asl, which is unusually high
for the Alps. The debris flow continued as a series of
pulses several hours after the end of the rainfall. Upon
reaching the margin of Belvedere Glacier, the flows
continued in tunnels beneath the ice. Avalanched
Fig. 3 - Castelfranco catchment (Monte Rosa, Italian Alps).
The remnants of the Castelfranco Glacier, along with
snow avalanche accumulations, are thought to have
played a critical role in the initiation and dynamics of
the debris flow started close to the watershed ridge
(3600 m a.s.l., see the white stars)
Fig. 4 - klattasine Creek debris flow. The debris flow was
was triggered by the sudden draining of moraine-
dammed klattasine Lake, had a volume of nearly
2 million cubic metres, and temporarily blocked
Homathko River. (J.J.Clague)
background image
M. CHIARLE, M. GEERTSEMA, G. MORTARA & J.J. CLAGUE
50
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
ed the village of Saint Gervais and killed 175 people,
is one of the worst glacier-caused disasters in Europe
(v
inCent
et alii, 2010).
MELTING OF GROUND ICE
Ground ice and buried dead glacier ice are
common in high mountains in western Canada and
Europe. Such ice may persist, even though it is no
longer in equilibrium with climate, due to the in-
sulating effect of the debris cover and to the low
permeability of some glacial deposits. In a warm-
ing climate, the ice slowly melts, contributing water
to already wet sediments, in some cases leading to
debris flows. The flows may be triggered by rainfall,
but some occur in fair warm weather, simply due to
melting of the ice. Icerich debris and ice lenses have
been observed in many debris flow initiation scars
(C
HiaRle
et alii, 2007), but the exact role played
by ground ice is uncertain in most cases. The role
played by the melt of ground ice is illustrated by
a debris flow on July 29, 2005, in Val di Fosse in
the eastern Italian Alps. Melt of a buried ice mass,
exposed in a 20-m-long detachment zone at 3000
m asl, triggered her a debris flow (15,000 m
3
) that
travelled downslope for over 1 hour, cutting off a
popular hiking trail (Fig. 5).
Melt of ground ice is expected to significantly
decrease the stability of sediments in proglacial and
periglacial areas in coming years, although the main
effects may be delayed because of the complex inter-
play of factors and the lack of direct contact of the ice
with the atmosphere (k
ääb
et alii, 2007).
CONCLUDING REMARKS
Debris flows, like other natural hazards, repre-
sent disequilibria in the natural landscape. Climate
change, by altering important factors governing
geomorphic evolution, introduces new instability
in the Earth system. Mountain environments are be-
ing affected by climate change for several reasons:
a) geomorphic processes in mountains operate at a
high rate because of the high relief; b) processes in
high mountains are intimately linked to the cryo-
sphere, which is sensitive to climate change; and c)
climate is warming faster in mountains than in mid-
latitude lowlands. A consequence of these amplified
effects is that debris flows are likely to increase in
frequency as climate continues to warm.
Yet few statistical studies of debris flow activ-
ity have been carried out in recent years in western
Canada and the European Alps, and to date no clear
trend of increasing activity has emerged in either re-
gion. The lack of a clear cause-and-effect outcome
may partly be explained by local differences in cli-
mate trends, especially for precipitation patterns.
Moreover, the factors that predispose slopes to de-
bris flows, and those that trigger debris flows, vary
across the landscape.
At present, in our warming world, cryosphere
degradation is the dominant driver of instability in
high mountains. Debris flows are occurring in re-
sponse to the greater availability of water and debris
caused by glacier melt and permafrost thaw, to slope
instability caused glacier debuttressing and perma-
frost thaw, and to outbursts of water from glacier-
and moraine-dammed lakes.
At lower elevations in mountains, changes in
seasonal frost activity and snow melt, and rain-on-
snow events can change the frequency of debris
flows. Changes in total annual rainfall and rainfall
intensity can either increase or decrease debris flow
occurrence at these lower elevations. Hazard as-
sessment procedures for debris flows in glacial and
periglacial environments during a time of rapid cli-
mate warming cannot be based entirely on experi-
ence gained in ice-free environments. Our study also
demonstrates the necessity of integrating observa-
tions and data from different areas of the world with
a variety of climatic and physiographic settings.
Only in this way will it be possible to paint a reli-
able picture of impacts of climate change on debris
flow initiation and development, and to accurately
predict other impacts of climate change.
Fig. 5 - Val di Fosse (Eastern Italian Alps). A buried ice
mass, exposed in a 20-m long detachment zone at
3000 m a.s.l. was responsible for the trigger of an
unexpected debris flow (Photo courtesy of Public
works Service, Bolzano Province)
background image
IMPACTS OF CLIMATE CHANGE ON DEBRIS FLOW OCCURRENCE IN THE CORDILLERA OF WESTERN CANADA
AND THE EUROPEAN ALPS
Italian Journal of Engineering Geology and Environment - Book www.ijege.uniroma1.it © 2011 Casa Editrice Università La Sapienza
51
REFERENCES
a
GRawala
s. (2007, Ed.) - Climate change in the European Alps; Adapting winter tourism and natural hazards management. Or-
ganization ofEconomic Cooperation and Development (OECD), Paris, 128 pp.
a
ueR
i. et alii., (2007) - HISTALP – historical instrumental climatological surface time series of the Greater Alpine Region. Inter-
national Journal of Climatology, 27: 17–46.
b
ostoCk
H.s. (1948) - Physiography of the Canadian Cordillera, with special reference to the area north of the fifty-fifth parallel.
Geological Survey of Canada Memoir 247, 106 pp.
b
ovis
m.J. & J
akob
m. (1999) - The role of debris supply conditions in predicting debris flow activity. Earth. Surf. Process. Landf.,
24: 1039- 1054.
b
ovis
m.J. & J
akob
m. (2000) - The July, 1998 debris flow and landslide dam at Capricorn Creek, southwestern B.C. Canadian
Journal of Earth Sciences, 37: 1321-1334.
b
Radley
R.s. & J
ones
P.d. (1993) . ‘Little Ice Age’ summer temperature variations: Their nature and relevance to recent global
warming trends. The Holocene, 3: 367-376.
b
Rown
R.J.e. (1967) - Permafrost in Canada. Geological Survey of Canada Map 1246A.
Brown R.J.E. & Romanovsky V. (2008) - Report from the International Permafrost Association: State of permafrost in the first
decade of the 21st century. Permafrost and Periglacial Processes, 19: 255–260.
b
Runetti
m., m
auGeRi
m., m
onti
f. & n
anni
t. (2004). Changes in daily precipitation frequency and distribution in Italy over the
last 120 years. Journal of Geophysical Research, 109.
C
annon
s.H. (2001) - Debris-flow generation from recently burned watersheds. Environmental and Engineering Geoscience, 7:
321–341.
C
asty
C., R
aible
C.C., s
toCkeR
t.f., w
anneR
H., & l
uteRbaCHeR
, J. (2007). A European pattern climatology 1766–2000. Climatol-
ogy Dynamics, 29: 791–805.
C
asty
C., w
anneR
H., l
uteRbaCHeR
J., e
sPeR
J. & b
öHm
, R. (2005). Temperature and precipitation variability in the European Alps
since 1500. International Journal of Climatology, 25: 1855–1880.
C
HiaRle
m., i
annotti
s., m
oRtaRa
G., d
eline
P. (2007) - Recent debris flow occurrences associated with glaciers in the Alps. Global
and Planetary Change Special Issue on "Climate Change Impacts on Mountain Glaciers and Permafrost", 56: 123-136.
C
laGue
J.J., e
vans
s.G., b
lown
i.G. (1985) - A debris flow triggered by the breaching of a moraine-dammed lake, kattlasine Creek,
British Columbia. Canadian Journal of Earth Sciences, 22: 1492-1502.
C
laGue
J.J. (1989) - Quaternary geology of the Canadian Cordillera. Chapter 1 in Fulton, R.J. (Ed.), Quaternary Geology of
Canada and Greenland. Geological Survey of Canada, Geology of Canada No. 1: 15-96.
C
laGue
J.J., e
vans
s.G. (2000) - A review of catastrophic drainage of moraine-dammed lakes in British Columbia. Quaternary
Science Reviews, 19: 1763-1783.
C
laGue
J.J., m
enounos
b. & w
Heate
R. (in press) - Canadian Rockies and Coast Mountains of Canada. In: Singh V.P., Singh P. &
Haritashya U. K. (Eds.) - Encyclopedia of Snow, Ice and Glaciers, Springer-Verlag.
e
GGinton
v.n. (2005) - Historical climate variability from the instrumental record in northern British Columbia and its influence
on slope stability. M.Sc. thesis, Simon Fraser University, Burnaby, BC.
e
HleRs
J. & G
ibbaRd
P.l. (2004) - Quaternary glaciations - extent and chronology. Part I: Europe. Developments in Quaternary
Science, no. 2. Elsevier, Amsterdam, 488 pp.
G
uGlielmin
m. (2004) - Observations on permafrost ground thermal regimes from Antarctica and the Italian Alps, and their rel-
evance to global climate change. Global and Planetary Change, 40: 159–167.
G
uzzetti
f., P
eRuCCaCCi
s., R
ossi
m. & s
taRk
C.P. (2008) - The rainfall intensity–duration control of shallow landslides and debris
flows: An update. Landslides, 5: 3–17.
H
aebeRli
w., H
uGGel
C., k
ääb
a., z
GRaGGen
-o
swald
s., P
olkvoJ
a., G
alusHkin
i., z
otikov
i. & o
sokin
n. (2004) - The kolka-
karmadon rock/ice slide of 20 September 2002: An extraordinary event of historical dimensions in North Ossetia, Russian
Caucasus. Journal of Glaciology, 50: 533–546.
IPCC (International Panel on Climate Change), 2007. Climate change 2007. 4th assessment report. Working Group I report «The
Physical Science Basis», 987 pp.
i
veRson
R.m. (2000) - Landslide triggering by rain infiltration. water Resour. Res., 36: 1897–1910.
background image
M. CHIARLE, M. GEERTSEMA, G. MORTARA & J.J. CLAGUE
52
5th International Conference on Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assessment Padua, Italy - 14-17 June 2011
J
akob
m. & w
eatHeRly
H. (2003) - A hydroclimatic threshold for landslide initiation on the north shore mountains of Vancouver,
British Columbia. Geomorphology, 54 (3-4): 137–156.
J
omelli
v., b
Runstein
d., G
RanCHeR
d. & P
eCH
, P. (2007) - Is the response of hill slope debris flows to recent climate change univo-
cal? A case study in the Massif des Ecrins (French Alps). Climatic Change, 85: 119–137.
J
ones
P.d. & m
obeRG
a. (2003) - Hemispheric and large-scale surface air temperature variations: An extensive revision and an
update to 2001. Journal of Climate, 16: 206-223.
k
oCH
J., m
enounos
, b. & C
laGue
J.J. (2009) - Glacier change in Garibaldi Provincial Park, southern Coast Mountains, British
Columbia, since the Little Ice Age. Global Change, 66: 161-178.
l
uCkman
b.H. & k
avanaGH
t.a. (2000) - Impact of climate fluctuations on mountain environments in the Canadian Rockies.
Ambio, 29: 371– 380.
m
aRCHi
l., a
Rattano
m., & d
eGanutti
a.m. (2002) - Ten years of debris-flow monitoring in the Moscardo Torrent (Italian Alps).
Geomorphology, 46: 1-17.
m
oRtaRa
G. & t
ambuRini
a. (2009, Eds.) - Il Ghiacciaio del Belvedere e l’Emergenza del Lago Effimero. SMS.
m
aRtinez
J., a
vila
G., a
Gudelo
a., s
CHusteR
R.l., C
asadevall
t.J., & s
Cott
k.m. (1999) - Landslides and debris flows triggered
by the 6 June 1994 Paez earthquake, southwestern Colombia. Landslide News, 9: 13-15.
n
iGRelli
G. & a
udisio
C. (2009) - The May 2008 extreme rain event in the Germanasca Valley (Italian western Alps): processes and
effects observed along the hydrographic network and valley slopes. Geografia Fisica e Dinamica Quaternaria, 32 (2): 157-166.
P
ieRson
t.C., J
anda
R.J., t
HouRet
J.C. & b
oRReRo
C.a. (1990). Perturbation and melting of snow and ice by the 13 November 1985
eruption of Nevado del Ruiz, Colombia, and consequent mobilization, flow, and deposition of lahars. Journal of Volcanology
and Geothermal Research, 41: 17-66.
R
ebetez
m., l
uGon
R. & b
aeRiswyl
P.a. (1997) - Climatic change and debris flows in high mountain regions: The case study of the
Ritigraben Torrent (Swiss Alps). Climate Change, 36: 371-389.
s
andeRsen
f., b
akkeHøi
s., H
estnes
e. & l
ied
k. (1996) - The influence of meteorological factors on the initiation of debris flows,
rockfalls, rockslides and rockmass stability. In: s
enneset
k. (ed.). Landslides: 97-114, A.A. Balkema, Rotterdam.
s
toffel
m., l
ièvRe
i., C
onus
d., G
RiCHtinG
m., R
aetzo
H., G
äRtneR
H. & m
onbaRon
m. (2005). 400 years of debris flow activity
and triggering weather conditions. Ritigraben VS, Switzerland. Arctic, Antarctic, and Alpine Research, 37: 387-395.
t
RoPeano
d. & t
uRConi
l. (2003) - Geomorphic classification of alpine catchments for debris-flow hazard reduction. In: R
iCk
-
enmann
d. & C
Hen
C.L. (2003,
eds
.) - Debris-Flow Hazards Mitigation: Mechanics, Prediction and Assesment: 1221-1232,
Millpress, Rotterdam.
t
uRneR
a.k. & s
CHusteR
R.l. (1996, Eds.) - Landslides: Investigation and mitigation. Transportation Research Board and National
Research Council, Special Report 247. National Academy Press, Washington, DC, 673 pp.
v
iles
H.a. & G
oudie
a.s. (2003) - Interannual, decadal, and multidecadal scale climatic variability and geomorphology. Earth-
Science Reviews, 61: 105–131.
v
inCent
C. G
aRambois
s., t
HibeRt
e., l
efebvRe
e., l
e
m
euR
e. & s
ix
d. (2010) - Origin of the outburst flood from Glacier de Tête
Rousse in 1892 (Mont Blanc area, France). Journal of Glaciology, 56: 688-698.
w
anneR
H., R
iCkli
R., s
alvisbeRG
e., s
CHmutz
C. & s
CHuePP
m. (1997) - Global climate change and variability and its influence
on Alpine climate - Concepts and observations. Theoretical and Applied Climatology, 58: 221–243.
w
ieCzoRek
G.f. & G
lade
t. (2005). Climatic factors influencing occurrence of debris flows. In: J
akob
m. & H
unGR
o. (
eds
.) - De-
bris flow Hazards and Related Phenomena: 325-362, Springer, Berlin Heidelberg.
w
ilson
R.C. (2005) - The rise and fall of debris-flow warning system for the San Francisco Bay region, California. In: T. Glade, M.
Anderson & M.J. Crozier (Eds.) - Landslide Hazard and Risk: 493–516, West Sussex, United Kingdom, John Wiley & Sons.
z
emP
m., P
aul
f., H
oelzle
m. & H
aebeRli
w. (2007) - Glacier fluctuations in the European Alps 1850–2000: an overview and
spatio-temporal analysis of available data. In: o
Rlove
b., w
ieGandt
e. & l
uCkman
b. (e
ds
.) - The Darkening Peaks: Glacial
Retreat in Scientific and Social Context: 152–167, University of California Press, Berkeley, CA.
Statistics