CHAPTER
16
Glaciers of the Ragged Range,
Nahanni National Park Reserve,
Northwest Territories, Canada
Michael N. Demuth, Philip Wilson, and Dana Haggarty
ABSTRACT
A new glacier inventory was developed for the
Ragged Range, an area only recently added to
Nahanni National Park Reserve, Northwest Territories. Federal mapping from aerial photography in
1982 was compared with Landsat satellite imagery
from 2008. Glacier cover decreased in area by 30%
over that period; the greatest percentage loss was in
glaciers with areas between 1 and 10 km 2 , while the
largest number of disappearances was of glaciers
0.1–1 km 2 in area. The smallest glaciers less than
0.1 km 2 in area showed little loss to modest growth
in topographic niches protected from solar radiation. Recommendations for further work in this
environmentally significant frontier region are
provided.
16.1
INTRODUCTION
The glaciers of the Ragged Range were recently
delineated and described as part of a broader effort
to expand the boundaries of Nahanni National
Park Reserve (NNPR). The entire Ragged Range
was identified as a high conservation value region
within what is referred to as the Greater Nahanni
Ecosystem (GNE). In 2009, the expanded bound-
aries were agreed upon, and NNPR now includes,
amongst other lands, a significant portion of the
headwaters of the South Nahanni River and its
glaciers (Fig. 16.1). Prior to the expansion, only a
very small portion of glacier cover within the
Ragged Range was encompassed by the Park.
The general information available, including
glacier size and situation noted from 1:50,000-scale
NTS map sheets, and related hydrography, suggests
that the glaciers of the GNE represent significant
hydroecological value. Moreover, the glaciers of the
Ragged Range have long been considered a potential site for an expanded national glacier–climate
observing system (Demuth 1997, 1998, Agnew et
al. 2002), extending perspectives on surface energy
balance and hydrological inputs northward from
several observing sites in operation in the Rocky
Mountains. Specifically, monitoring glacier–climate
parameters in this region would provide an additional pinning point for understanding the north–
south variation of atmospheric circulation and
moisture advection into western Canada as modulated by the Pacific North American circulation
pattern and its strong influence on decadal variations in glacier nourishment, snowfall, and river
flow (e.g., Walters and Meier 1989, Moore and
McKendry 1996, Zhang et al. 1997, Spence 2002,
Demuth et al. 2008, Moore et al. 2009).
376
Glaciers of the Ragged Range, Nahanni National Park Reserve, Northwest Territories, Canada
Figure 16.1. Location of Nahanni National Park Reserve, the Greater Nahanni Ecosystem, and the Ragged Range
(adapted from Parks Canada, 2009).
16.2
GEOGRAPHIC, SOCIAL, AND
CLIMATIC CONTEXT
Nahanni National Park Reserve is located at ca.
61 30 0 N, 125 30 0 W in the northern section of the
cordilleran physiographic region, in the southwest
corner of Northwest Territories (NT), and extends
generally along the Yukon–NT border. Covering
an area of approximately 30,055 km 2 , and ranging
in elevation from 180 to 2,773 m asl, NNPR
includes in its northwestern extent the Ragged
Range, the Sunblood and Dall Ranges to the northeast, the Ram Plateau and Tlogotsho Range to the
East, and the northward-flowing source tributaries
of a portion of the Flat River to the South. After
leaving its alpine headwaters, the South Nahanni
River flows east-southeast through the broad gap
between the Ram Plateau and the Tlogotsho
Range, and empties into the Liard River near
Nahanni Butte. The Liard River joins the
Mackenzie River at Fort Simpson, eventually flowing through the Mackenzie Delta, and out into the
Beaufort Sea and the Arctic Ocean.
NNPR is considered an icon of Canadian wilderness with the South Nahanni River being central
to the Park. Receiving contributions from snowmelt, surface water runoff, glacier meltwater, and
groundwater from numerous mineral springs, the
river, along with its tributaries and lakes, provides
water for terrestrial wildlife, habitat for aquatic
wildlife, traditional travel routes for the regional
native Dene tribe’s harvesters (hunters, trappers,
and fishers), and a corridor for the more recent
explorers of the land. Difficult access, uncompromising beauty, and isolation add to the region’s
now well-known whitewater river travel opportunities and some of the world’s most celebrated
alpine rock climbing sites (e.g., Cirque of the
Regional synthesis 377
Unclimbables, a group of peaks in the Ragged
Range). Naha Dehé (South Nahanni River) figures
prominently in local oral history. Moreover,
protecting the South Nahanni River (specifically
Nai˛li˛cho, or Virginia Falls, and the spectacular canyons) from hydroelectric development was the catalyst for establishment of a national park reserve in
1976 (Parks Canada, 2009).
The geology of NNPR was influenced by three
major events: (i) the deposition of some 6,000 m of
sedimentary rock during the Paleozoic era, 250–500
million years ago—consisting of sandstones, mudstones, and shales from continental rivers, and limestones and dolomites from dissolved minerals and
marine animal skeletons; (ii) the deformation and
uplift of sedimentary rocks by continental drift to
form mountain ranges (ca. 200 million years ago),
followed by additional mountain building ca. 110
million years ago, when molten volcanic rock
intruded to within 3,000 m of the surface. The result
was an uplifting and doming of the sedimentary
rock above and around the intrusion, creating the
mountain ranges that surround the Nahanni River;
and (iii) glaciation, which first occurred between 2
and 8 million years ago (Bostock 1948, Parks
Canada 2002).
Since then, the landscape has been influenced
primarily by continental erosion, with shorter episodes of glacial action interspersed with longer
periods of river erosion. The last major glaciation,
which ended ca. 10,000 years ago, had only covered
the far eastern and far western reaches of the Park.
It is in the western reaches of the Park where one
finds the Ragged Range—named after its spectacular granite peaks. Horvath (1975) noted that
several mountain groups in the NT have glaciers,
and specifically they mentioned those lying in the
Hess and Wernecke Mountains, the Ogilvie Mountains, and the Backbone and Canyon Ranges of the
Mackenzie Mountains. Notably, only scarce mention of the existence of glaciers in the Ragged Range
(of the Logan and Selwyn Mountains) appears in
the literature (Bostock 1948, pp. 53–55; Demuth
1998, Williams and Ferrigno 2002, p. J20).
a digital elevation model (DEM) for the GNE
(Sawada 2005). The NTDB thematic information
is for the most part uniformly based on 1982
(August 2) vertical aerial photography with exceptions noted in the inventory database for the study
region. An orthophoto mosaic was created to perform a check on the PSI theme, with adjustments
made as required. Contemporary glacier inventories
were constructed using Landsat 5 TM data for
August 5, 2008 (Fig. 16.2 and Online Supplements
16.1A and 16.1B); this terrain-corrected (Level 1T)
imagery was obtained from the USGS Earth
Resources Observation and Science Center (EROS)
website. Two scenes—Path 055: Rows 016 and
017—cover the study region.
Glacier extents were delineated—at a scale
between 1:5,000 and 1:15,000—using on-screen
digitizing techniques that made use of: (i) a falsecolor composite image (bands 5, 4, 3); (ii) a normalized difference snow index representation (bands 2
and 5); and (iii) DEM-based hillshading representations. A sample inventory map is depicted in Fig.
16.3 and shown in detail in Online Supplement 16.2.
A full presentation of the methodology and error
considerations is provided in Online Supplement
16.3 for a similar effort by Demuth et al. (2008)
in the Rocky Mountain headwaters of the North
and South Saskatchewan River basins.
Delineated features are associated with an attribute table containing the hydrological basin designation (after Ommanney et al. 1970); a point ID;
geographic coordinates of the feature centroid;
area, perimeter, maximum, mean, and minimum
elevation; mean aspect; mean slope; major flowline
length; and details regarding area fragmentation.
Change detection maps and relational data representations are then easily constructed.
Rock glaciers, misclassified features, and features
confounded by spectral ambiguity (e.g., cloud,
shadow, debris cover) were parsed and, for the
purposes herein, resulted in a final comparative
dataset of 263 glaciers for change detection.
16.4
16.3
GLACIER INVENTORY AND
MORPHOMETRY
Glacier dimensions and other morphometric
measures were retrieved for some 271 features using
Canada’s National Topographic Data Base
(NTDB) perennial snow and ice (PSI) theme and
REGIONAL SYNTHESIS
In 2008 the majority of GNE glaciers (n ¼ 127)
occupy a size class 0.1 < A < 1.0 km 2 but represent
only ca. 20% of the total glacier area (Table 16.1).
54 glaciers in size class 1.0 < A < 10 km 2 provide
65% of the cover, while two large outlet glaciers
emanating from the ‘‘Brintnell–Bologna Icefield’’
378
Glaciers of the Ragged Range, Nahanni National Park Reserve, Northwest Territories, Canada
Figure 16.2. (Top) False-color composite of the Ragged Range, Landsat 5 TM bands 543 from August 5, 2008,
and (bottom) a view of the Brintnell Creek Glacier, looking west (see Fig. 16.4 for glacier location); photo by
Margaret Demuth, August 2006. Figure can also be viewed in higher resolution as Online Supplements 16.1A and
16.1B.
Regional synthesis 379
Figure 16.3. Sample glacier inventory map for the Ragged Range, 2008. Figure can also be viewed in higher
resolution as Online Supplement 16.2.
Table 16.1. Ragged Range glacier area (A) and count
(n) by area class.
Area class
(km 2 )
A1982
(km 2 )
n1982
A2008
(km 2 )
n2008
0.01 < A < 0.1
1.90
23
1.50
20
0.1 < A < 1
63.8
173
33.5
127
1 < A < 10
167
65
121
54
0 < A < 100
29.9
2
28.5
2
Total
262
263
184
203
(Fig. 16.2) represent ca. 30 km 2 or 15% of the GNE
total. The remaining <1% is made up of 20 glaciers
in the 0.01 < A < 0.1 km 2 size class.
Between 1982 and 2008 (26 years) the glaciercovered area in the GNE contracted by approximately 30% (from 262 to 184 km 2 ). Small-glacier
diminution appears to characterize regional glacier
cover change during this interval. Fractional area
change (FAC) relative to A1982 is shown in Fig. 16.5.
While smaller glaciers underwent greater fractional
percent losses than larger glaciers generally, scatter
in the FAC data increases significantly as size (area)
decreases (see error discussion in Demuth et al.
2008 and Online Supplement 16.3).
380
Glaciers of the Ragged Range, Nahanni National Park Reserve, Northwest Territories, Canada
Figure 16.4. Ragged Range glacier perimeter and major flowline length–area relationships.
Recommendations for further work 381
Figure 16.5. Ragged Range glacier fractional area change (FAC) 1982–2008 as a function of 1982 glacier area.
Individual observations and area class means and single standard deviations are shown.
Several glaciers show little to modest growth.
These were confined to the smaller size classes
and were found in areas of the GNE landscape
where topographic niches provided reliable nourishment in the form of drift snow, and protected
them from solar radiation. These glaciers, and those
of the same size classes exhibiting relatively little
contraction, were also perched at higher elevations
and exhibited a lower elevation range.
In addition to developing perspectives on landscape change, surface mass balance measurements
were initiated on the Bologna Creek Glacier in
2007. Net balance has averaged (2007–2009) ca.
1,300 mm w.e., with a corresponding equilibrium
line altitude (ELA) of 2,280 m asl and an accumulation area ratio (AAR) of 0.23. The long-term ELA
(e.g., as defined by the ‘‘Hess’’ altitude; see Cogley
and McIntyre 2003) is estimated from glacier geometry to be ca. 2,050 m, while the maximum height of
the Neoglacial lateral moraines suggests a minimum
ELA height (i.e., moraine building) of ca. 2,095 m.
Lapse rate considerations suggest then that the
present climate may be 1.5–2 C warmer than that
which characterized Neoglacial expansion for the
region.
16.5
RECOMMENDATIONS FOR
FURTHER WORK
The glaciers of the GNE have only recently been
delineated in sufficient detail to initiate comprehensive glaciological, climatic, and hydroecological
study. The study of their variation now contributes
to a national glacier–climate observing system,1
1
State and Evolution of Canada’s Glaciers, http://
pathways.geosemantica.net
382
Glaciers of the Ragged Range, Nahanni National Park Reserve, Northwest Territories, Canada
extending perspectives on surface energy balance
and hydrological inputs northward from several
observing sites in operation in the Rocky Mountains, and inland from those in the Coast
Mountains.
Further data collection and analysis is required to
better define ecosystem integrity condition relative
to the influences that glaciers exert on other variables pertinent to, for instance, aquatic resources.
Specifically this should include more comprehensive
mass balance measurements, mapping of regional
ELAs and AARs, the dating of previous recession
and end moraines, the establishment of former
glacier cover configurations, subsequent hydrological modeling and estimated future glacier cover
configurations, isotope hydrology studies, and the
establishment of water quality measurements along
the glacio–rithral2 (glacier and snow-fed) stream
segments of the GNE (e.g., Petts et al., 2006).
16.6
ACKNOWLEDGMENTS
Danielle Finckling, Veronique Pinard, and Mark
Ednie for GIS support in the GSC’s Glaciology
Remote Sensing/Modeling Lab; from the NNPR
Fort Simpson base, Steve Catto, Doug Tate, Lisa
Moore, Scott Cameron, Kim Schlosser, and Chuck
Blyth for support, all manner of good advice, and
conservation perspectives; Herb Norwegian,
Dehcho First Nations for a conversation on ecological values; the Aurora Research Institute, for
connecting us with the communities and their
elders; Dan McCarthy, Brock University for perspectives on where we might go with this; Matt
Beedle, Steve Bertollo, Margie Demuth, Susan
Henry, and Troy Searson for field support; Colin
Munro, Great Slave Helicopters for friendly and
competent aviation support; Atkinson Fellowship
recipient and author Ed Struzik for telling our
stories.
16.7
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2
Rithral headwaters: fed mainly by snowmelt and rainfall,
hydrograph typically with two peaks (one in June and one
in November), high biodiversity, but less specialized
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