Bulletin of Glaciological Research ,2 (,*+*) ,1ῌ-,῍Japanese Society of Snow and Ice

27

Hot-water drilling at Glaciar Perito Moreno, Southern Patagonia Iceﬁeld
Shin SUGIYAMA+, Pedro SKVARCA,, Nozomu NAITO-, Kenta TONE+, Hiroyuki ENOMOTO.,
Kunio SHINBORI+, Sebastian MARINSEK, and Masamu ANIYA/+ Institute of Low Temperature Science, Hokkaido University, Nishi-2 Kitaῌ+3 Sapporo, *0*ῌ*2+3 Japan, Dirección Nacional del Antártico-Instituto Antártico Argentino, Cerrito +,.2, Buenos Aires, Argentina- Department of Global Environment Studies, Hiroshima Institute of Technology, ,ῌ+ῌ+, Miyake, Saeki-ku, Hiroshima, 1-+ῌ/+3Japan. Department of Civil Engineering, Kitami Institute of Technology, +0/, Koen-cho, Kitami, *3*ῌ2/*1 Japan/ Professor Emeritus, University of Tsukuba, Tsukuba, -*/ῌ2/1, Japan(Received November +*, ,*+*; Revised manuscript accepted December -, ,*+*)

Abstract
Glaciar Perito Moreno is one of the major freshwater calving glaciers in the Southern Patagonia
Iceﬁeld. Its fast-ﬂowing characteristic is probably due to high water pressure at the glacier bed,
however, subglacial conditions have never been observed in Patagonia until our recent undertaking.
To investigate the role of subglacial water pressure in the calving glacier dynamics, we performed
hot-water drilling at Glaciar Perito Moreno from February to March ,*+*. This study represents theﬁrst attempt ever at hot-water glacier drilling in Patagonia. Two boreholes were drilled to the bed at..1 km upglacier from the terminus, where the ice was revealed to be /+/῍/ m thick and the bed
located at about --* m below the proglacial lake level. The water levels in the boreholes were ῎+** mabove the lake level, which indicates that more than 3*ῌ of the ice overburden pressure was balancedout by the subglacial water pressure. Water in the boreholes had drained away before the drilling
reached the bed, suggesting the existence of an englacial drainage system. These results provide
crucial information for understanding the hydraulic and hydrological conditions of calving glaciers.
In order to drill a /** m deep glacier, an existing hot-water drilling system was adapted by increasing
the number of high-pressure hot-water machines. The drilling operation at Glaciar Perito Moreno
conﬁrmed the system’s capacity to drill a /**-m-deep borehole at a rate of /* m hῌ+ with fuelconsumption rates of +/.1 l hῌ+ for diesel and -.3 l hῌ+ for petrol.
Key words: calving glacier, hot water drilling, subglacial water pressure, borehole, Patagonia+.

Introduction

The close examination of physical conditions beneath a glacier (e.g., water pressure, drainage system,
unconsolidated sediment layer, bedrock roughness) is
important for understanding the role of basal processes in glacier motion. Subglacial conditions determine the speed of ice sliding over a bedrock as well as
the deformation of a subglacial sediment layer, causing substantial changes in glacier ﬂow speed. These
basal ice ﬂow processes are particularly important inoutlet glaciers in Patagonia Iceﬁelds since most ofthem terminate in lakes or the ocean (Warren andAniya, +333; Rignot et al., ,**-; Rivera et al., ,**1).
Calving glaciers ﬂow faster than land terminating
glaciers, particularly because the basal ﬂow processes
are enhanced by high water pressure generated by the

proglacial water body. Since a large amount of ice isdischarged from the fast-ﬂowing calving glaciers in
Patagonia (Naruse et al., +33,; Skvarca et al., +33/;
Warren et al., +33/a; Warren et al., +33/b; Rott et al.,+332), the dynamics of these glaciers plays a key rolein the recent ice mass loss of the Patagonia Iceﬁelds(Aniya et al., +331; Aniya, +333; Rignot et al., ,**-; Rivera
et al., ,**1). Nevertheless, detailed studies on glacier
dynamics are very scarce and subglacial measurements have never been carried out in Patagonia.
Glaciar Perito Moreno is a fast-ﬂowing freshwater
calving glacier in Patagonia. The glacier extends over-* km to the northeast from the Southern Patagonia
Iceﬁeld and covers an area of ,/2 km, (Aniya et al.,+331). The glacier front currently terminates in Brazo
Rico and Canal de los Témpanos (+2/ m a.s.l.) (Stuefer
et al., ,**1), forming a narrow water channel between
the glacier snout and Península Magallanes. (Fig. +a).

Bulletin of Glaciological Research

28

Figure +. (a) Satellite image of Glaciar Perito Moreno
with the drilling site indicated by (῎). Drilling
equipment was transported by a helicopter fromthe site indicated by (ῌ). The image was taken
on ,1 March ,**, (image courtesy of the Image
Science & Analysis Laboratory, NASA Johnson
Space Center). (b) Longitudinal cross section of
Glaciar Perito Moreno along the central ﬂowline.
The bed proﬁle is drawn by interpolation ofobservational data points (῎) (Stuefer et al., ,**1).
The lake water level and ice ﬂotation level are
indicated by the dot-dashed and dotted lines.

Unlike the other glaciers in Patagonia, no signiﬁcantretreat is being observed in Glaciar Perito Moreno(Aniya and Skvarca, +33,; Skvarca and Naruse, +331;
Stuefer, +333; Stuefer et al., ,**1). Its front position
has oscillated within several hundred meters since theearly ,*th century (Skvarca and Naruse, +331). The
glacier ﬂows at a rate of .**ῌ2** m a῍+ in the region
extending several kilometers from the calving front(Rott et al., +332; Michel and Rignot, +333; Floricioiu etal., ,**2; Ciappa et al., ,*+*). According to seismic
soundings performed by Stuefer et al. (,**1), the glacier bed elevation is +/*ῌ.** m below the lake levelwithin the reach of +* km from the terminus (Fig. +b).
The glacier bed is thus expected to be at high waterpressure under the inﬂuence of the proglacial lakes.
A substantial part of ice overburden pressure is balanced out by the subglacial water pressure, which is apreferable condition for the basal ice ﬂow processes(e.g., Bindschadler, +32-). Annual ﬂow speed variations are relatively small (Stuefer et al., ,**1), whereasa clear seasonal ﬂow speed change has been observed
by a recent study using satellite data (Ciappa et al.,,*+*). Naruse et al. (+33/) reported diurnal ﬂow speed
variations at a few hundred meters from the side

margins.
In the ,**2/,**3 austral summer season, we carried out high-frequency ice ﬂow measurements on
Glaciar Perito Moreno and found clear diurnal ﬂow
speed variations in the central region of the glacier at
about / km from the terminus (Sugiyama et al., ,**3).
The ﬂow speed was closely correlated to air temperature, suggesting that meltwater production is controlling the basal ice ﬂow by swiftly changing subglacial
water pressure. The ﬂow speed was very sensitive tothe meltwater input, probably because the relationship between the water pressure and ﬂow speed ishighly nonlinear when the pressure rises close to the
overburden pressure (Bindschadler, +32-; Tru#er and
Iken, +332; Sugiyama and Gudmundsson, ,**.). To
test this hypothesis, we drilled Glaciar Perito Moreno
using a hot-water drilling technique to measure subglacial water pressure. This was the ﬁrst attempt inPatagonia to drill through a glacier for the purpose of
conducting subglacial observations. The aim of thispaper is to describe the hot-water drilling system used
for this project and report the drilling ﬁeld campaign
carried out in early ,*+*.

,.

Hot-water Drilling System

The hot-water drilling system was prepared byadapting an existing system developed at the Institute of Low Temperature Science, Hokkaido University (Sugiyama et al., ,**2; Tsutaki and Sugiyama,,**3). The original system was designed for drillingas deep as ,** m, thus it was necessary to increase thedrilling capacity to drill through Glaciar Perito Moreno
with expected thickness of ./*ῌ//* m at our study site.
We installed an additional high-pressure hot-watermachine (Kärcher HDS+***BE) and constructed piping to bring together hot water from two machines(Fig. ,a). The length of the drilling hose was extended to //* m. An electrically powered winch system (Fig. ,b) was developed to lower down and lift up
the hose in a borehole, as the hose is too heavy tohandle by man power alone during deep drilling.
The winch was controlled by hand using a handle
connected to a gear system as observed in Figure ,b.
Electric power from a generator was used only towind up the hose after the completion of drilling.
The winch was equipped with a brake system (lower
right in Fig. ,b) designed and constructed at the workshop of the Institute of Low Temperature Science.
This brake keeps the hose tightly wound around thewinch drum, so that the necessary friction was generated at the interface between hose and drum.
The hot water machines draw water with petroldriven pumps from a water basin or supraglacial water source. The water is warmed up with a heater
which uses diesel as fuel. Hot water ﬂowed through+,.1 mm inner diameter high pressure hoses (Bridges-

SUGIYAMA et al.

29

Figure -. Flow rate (ῑ) and water jet temperature (ΐ)
of the hot-water drilling system obtained using
water jet nozzles with di#erent diameters. The
closed circles and squares (ῒ, ῔) are ﬂow rate andtemperature reported for the old system, whichuses one hot-water machine (Tsutaki and Sugiyama,,**3).

l hrῌ+ and a pressure of +* MPa (Fig. -). The watertemperature and the ﬂow rate show that the new
system generates approximately 2*ῌ more power(heat in a unit time) than the original system (Fig. -)(Tsutaki and Sugiyama, ,**3).

-.

Figure ,. Photographs showing hot-water drilling on
Glaciar Perito Moreno. (a) High-pressure hot-watermachines. The machines discharge hot water
through the black hoses, which are combined into
one by means of the piping. (b) Winch systemwith a brake in the lower right. (c) The hot-water
drilling system set up on the glacier. The borehole is at the middle left.

tone WAR*2, outer diameter is +3.2 mm) before it emitted a narrow water jet from a -.* mm diameter nozzle(Katorigumi Inc. K-+2). The nozzle was mounted ona --m-long metal pipe, which provided a load tostraighten the hanging hoses for drilling a verticalborehole. For drilling of shallow boreholes, a tripod
and pulley system was used instead of the winch.
The weight of all the drilling equipment was approximately 0** kg, excluding fuel.
The drilling system was tested before the campaign at the Institute of Low Temperature Science
using a water basin ﬁlled with water from a tap. The
temperature of the water jet was measured with atemperature logger (HIOKI -0--) following a method
described in Tsutaki and Sugiyama (,**3). The system generated hot water at about 0/ῐ at a rate of +0**

Overview of Field Campaign

The ﬁeld campaign began on ,. February ,*+*.
It was ascertained that the location of the drilling site
fulﬁlled the requisite conditions such as: availabilityof water, relatively ﬂat surface for drilling and helicopter operations, proximity to the ,**2/*3 GPS measurement sites, and ice thickness not greater than thehose length. After a reconnaissance visit on ,. February,
the drilling site was chosen at S/*῍ ,3῎ ,1.,῏, W1-῍ /῎-3./῏ (Fig. +a). The site was ..1 km from the terminus
and several hundred meters o# the central ﬂowline.
The ice thickness was estimated as ./*ῌ//* m, basedon the seismic data (Stuefer et al., ,**1). Water wasavailable in a nearby supraglacial pond. The drilling
equipment and fuel (.** l of diesel for the heaters and+/* l of petrol for the pumps and generator) weretransported on ,/ February by a helicopter of the
Gendarmería Nacional from Puerto Bajo de las Sombras located at 1./ km east of the drilling site (Fig. +a).
The system was set up immediately upon arrival at
the site, and drilling began on ,0 February. As thedrilling site was a two-hour walk from our camp, thedaily activity on the glacier was limited to +***ῌ+3** h.
Drilling operations continued until March / and theequipment was evacuated by helicopter from the glacier on the following day.

Bulletin of Glaciological Research

30..

Drilling

Drilling did not progress e$ciently until ,2 February because one of the pumps needed to be repaired
and the winch system had to be tested. The ﬁrst
borehole (BH+) reached the glacier bed on , March
after the consumption of ,-/ l of diesel and 3* l of
petrol. The total duration of the hot-water system
operation was ,+ hours, including time spent for testing the devices. The total fuel consumption rates
were ++., l hῌ+ for diesel and ..- l hῌ+ for petrol. The
diesel consumption rate was lower than the normal
value of the system because one of the two hot watermachines was out of order during the ﬁrst half of thedrilling. The second borehole (BH,) was drilled approximately / m downglacier from BH+. Drilling began on . March and completed the next day after +*./
hours of operation. The diesel and petrol consumption rates were +/.1 and -.3 l hῌ+, respectively.
Figure . shows drilling depth as a function ofdrilling duration. The depth was known from thehose length plus its extension due to the own weight.
The extension was calculated from the extension rate
(1.+῎+*ῌ/ Nῌ+) and hose weight (*.,/ kg mῌ+) reportedby the manufacturer (Bridgestone Co.). The drillingrate for BH+ was not uniform because we began drilling by hand with the tripod and pulley system andthen the system was replaced by the winch at thedepth of +31 m. Hand drilling is generally more e$cient unless the hose in a borehole is too heavy tohandle. The winch system was used for the entire
part of BH, to avoid an interruption due to the exchange of the systems. Drilling rates from the surface to the bed were .2 and /* m hῌ+ for BH+ and BH,,
respectively. The drilling speed and fuel consumption rates are summarized in Table +.
In order to detect the glacier bed during drilling,
the weight of the drilling hose hanging in the borehole was measured every / to ,* m (Fig. /). A rope
was twisted around the hose to hang it under a hookof a spring scale. Sudden increases in the load wereobserved at hose lengths of -.. m in BH+ and -1/ m in
BH,. These clear changes occurred because of waterdrainage from the borehole as described later in thissection. At hose lengths between /*0ῌ/+, m (BH+)
and /*.ῌ/+, m (BH,), the load suddenly dropped anddecreased progressively as we continued the drilling.
Detailed measurements in BH+ showed that thechange could be reproduced by lowering and lifting
the hose at this depth (Fig. / inset). These were clear
indications that the drilling nozzle hit the bed. The
load decreased because the nozzle came into contact
with the bed and the hose leaned on the borehole wall.
Based on these observations, we conclude that the ice
thickness at the drilling site was /*.ῌ/+, m plus stretching of the hose (1῍*./ m) and ambiguities in the hose

Figure .. Drilling depth v.s. duration for the drillingof BH+ (black) and BH, (bold gray).

Table +. Depth of the boreholes, drilling speed andfuel consumption rates of the hot water system.

Figure /. Weight of the drilling hose measured during
the drilling of BH+ (῏) and BH, (ῐ). The dashedlines are weight of the hose estimated for theindicated water levels (relative to the surface).
The inset shows details near the bed in BH+.

length (῍*./), which equals to /+/῍/ m. This result
is consistent with the seismic data (Stuefer et al., ,**1),
although detailed comparison is not possible as theseismic measurements were performed several hundred meters upglacier from our drilling site.
Boreholes are usually ﬁlled with water during
hot-water drilling. The water often drains awaywhen a borehole reaches the bed, but drainage canalso occur beforehand, within the glacier. These drainage events provide important information on subglacial and englacial hydrological connections. Water in BH+ ﬁrst drained at +10 m from the surface.

SUGIYAMA et al.

Figure 0. Drilling nozzles (a) before the drilling and(b) after the drilling of BH+ and (c) BH,.

The sudden increase in the hose weight at the depth-.. m (Fig. /) implies that water drained again andbuoyancy force acting on the hose decreased. Judging from the weight of the hose hanging in the borehole estimated for di#erent water levels (dashed lines
in Fig. /), the level dropped from ,* to /* m below theice surface at the second drainage. In BH,, drainage
occurred at -1/ m depth, as did the increase in weight(Fig. /). The change in the weight by +1./ kg implies
that the water level dropped approximately 0* m.
These observations suggest the existence of an englacial drainage system in Glaciar Perito Moreno. According to our visual observation of the water level inthe boreholes, the drainage rate was in the range of+*ῌ,ῌ+*ῌ+ m- minῌ+. This rate was relatively lower
than those of subglacial and englacial drainage that
we encountered in the Alps.
The inspection of the hot-water jet nozzles after
the drilling provided a clue to glacier bed conditions.
The surface of the brass nozzle often became heavily
scratched or scraped when it hit bedrock (Sugiyama
et al., ,**2). However, the nozzle used for BH+ had
only small scratch marks and the one used in BH,
bore no evidence of contact with rocks (Figure 0).
Therefore, it is likely that the glacier is underlain by
an unconsolidated layer composed of sediment andgravels at the drilling site. The di#erence in thedamage to the nozzles used in the two boreholes may
be due to the fact that we moved the drill up anddown at the bottom of BH+, whereas we stopped thedrilling in BH, as soon as reached the bed.
After drilling was completed, water-pressure sensors (Geokon ./**S and HOBO U,*) were installed in
the two boreholes to measure the respective waterlevels. The measurements showed that the waterlevels in BH+ and BH, correlated with one another.
They ﬂuctuated in a diurnal manner within a level
between .,/ῌ.0* m from the bed, which corresponded
to more than 3*ῌ of the ice ﬂotation level at the site.
The pressure variations were correlated to surface
ﬂow speed and air temperature, implying that our
hypothesis was correct. Detailed analyses of the water level variations together with ice ﬂow speed andair temperature data will be presented elsewhere.

/.

Conclusion
A hot-water drilling technique was employed to31

drill through Glaciar Perito Moreno, a freshwater calving glacier in the Southern Patagonia Iceﬁeld, forsubglacial observations. We drilled two boreholes to
the glacier bed at ..1 km from the terminus. The
drilling revealed the ice thickness at the drilling site
to be /+/῍/ m. The completion of the drilling to the
bed was clearly detected by changes in the weight of
the hose hanging in the boreholes. Water in the boreholes drained before the drilling reached the bed, indicating the existence of an englacial drainage system.
According to inspections of hot water nozzles after
the drilling, the glacier is probably underlain by unconsolidated sediments and gravels. The water levelin boreholes after the drilling was more than 3*ῌ ofthe ice ﬂotation level, which strongly suggests that ice
ﬂow of Glaciar Perito Moreno is inﬂuenced by a highsubglacial water pressure and its variations.
In order to drill a glacier to a depth of more than/** m, two high-pressure hot-water machines were assembled together and a winch system was newly constructed. The drilling speed from the surface to the
bed was /* m hῌ+ when the system was running properly. The rates of fuel consumption were +/.1 l hrῌ+for diesel and -.3 l hrῌ+ for petrol.

Acknowledgments
We thank the members of GRPP (GlaciologicalResearch Project in Patagonia) for their help in theﬁeld and for preparation of the drilling system. T.
Wyder provided necessary information for the construction of the winch and T. Shiraiwa loaned us thewinch drum. The drilling equipment was transported to the glacier by a helicopter operated by
Gendarmeria Nacional Argentina. Hielo y Aventura
S. A. o#ered logistic support during the ﬁeld activity
and Toshin S. A. organized the transport of materials
in Argentina. Kärcher Inc., Bridgestone Co. and Nakamura Service Co. Ltd. assisted in the construction of
the drilling system. The hose-stretching experimentcarried out by Bridgestone Co. is greatly appreciated.
S. Tsutaki and S. Matoba helped with preparation andshipment of the drilling equipment. We thank ananonymous referee for helpful comments and the scientiﬁc editor S. Matoba for handling the paper. The
English was corrected by S. Braun-Clarke. This research was funded by the Japanese Ministry of Education, Science, Sports and Culture, Grant-in-Aid for
Scientiﬁc Research (A), +2,/+**,, ,**0-,**3 and by afunding program of the Institute of Low Temperature
Science. This support is gratefully acknowledged.

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