0 10/2016 Glacier Field Course in Switzerland 2016 Hydrological and meteorological observations at the proglacial lake of Rhonegletscher Roisu Yamasaki 1 , Eva de Andrés Marruedo 2 , Cayetana Recio Blitz 2 1 Graduate school of environmental science, Hokkaido University. 2 Numerical Simulation in Science and Engineering (GSNCI) ETSI de Telecomunicación. Universidad Politécnica de Madrid.
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Hydrological and meteorological observations at the ... · A) Metrological observation (Vaisala WXT510) Vaisala Weather Transmitter WXT510 (Figure 5) is a multi-sensor instrument
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10/2016
Glacier Field Course in Switzerland 2016
Hydrological and meteorological observations
at the proglacial lake of Rhonegletscher
Roisu Yamasaki1,
Eva de Andrés Marruedo2,
Cayetana Recio Blitz2
1 Graduate school of environmental science, Hokkaido University.
2 Numerical Simulation in Science and Engineering (GSNCI) ETSI de Telecomunicación.
Universidad Politécnica de Madrid.
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1. Introduction
Rhonegletscher is a glacier of the Swiss Alps, in the canton of Obergoms VS (Figure
1). It has been very popular for visitors due to mainly two reasons. First, it is the water
source of one of Europe's largest river; the Rhone river. Second, it is easily accessible
from the Furka pass road, situated at about 2300 m a.s.l. From 1874 to 1915, one of the
most complete surveys was carried out in Rhonegletscher, and the first detailed
topographic map of a glacier was accomplished (Mercanton, 1916). The results of these
efforts, this glacier gains world-wide reputation in the glaciological community.
Figure 1: Map of Rhonegletscher location. (Omoto and Ohmura, 2015)
Recently, due to global warming, Rhonegletscher is retreated and made glacial lake
(proglacial lake) at the front of Rhonegletscher (Figure 2). Proglacial lake accelerates
ablation of glacier and it has a risk as the lake bursts by increasing water level, in case a
large ice block collapses into water (Tsutaki et al., 2011).
Figure 2: Rhonegletscher and proglacial lake (September, 2016).
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As shown in Figure 3, over the last 150 years, Rhonegletcsher has retreated from
Gletsch to Belvèdere, and some studies suggested 30% of mass lost (Huss et al., 2008a).
Figure 3: Plane figure showing the retreat of the Rhone Glacier between 1602 and 2014.
Red line indicates shoreline of Rhonesee observed in September, 2014. (Omoto and
Ohmura, 2015)
Currently, this glacier is located at an altitude between 2300 to 3500 m a.s.l., with the
highest part oriented northward and limited by Eckstock peak; the mountain reaches
3557 meter. Also, this glacier is enclosed in a valley formed by Gästenhörner at the
western side and Galestorn at the east. The glacier surface covers almost 16 km2, with a
total volume estimated in 2.063 km3 (2007) and the value is smaller recently. (Table 1)
Table 1: Surface area and ice volume of Rhonegletscher for different years for which a
digital elevation model of the glacier surface exists (Farinotti et al., submitted).
There is a proglacial lake placed at the terminus and it was produced by ice melting
water filling a basin in front of the glacier. From bed topography studies, this lake is
expected to grow, reaching a potential lake volume amounts of 10.2 × 106 m
3 of water,
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with an averaged depth of 22 m and a maximum of 71 m (Zanho, 2004).
What will lead to change the configuration and the recession of Rhonegletscher? For
example, we can think that its retreat may be somewhat related with the global warming
trend, since the higher atmospheric temperatures, the more melting would be expected.
Another circumstance which encourages ice melting would be the change of snowfall,
i.e., decrease snowfall causes less accumulation. But, have these questions already been
studied in Rhonegletscher? Some numerical models have been run under different
scenarios, trying to answer this kind of questions and trying to reveal the estimations of
Rhonegletscher retreat rates (Sugiyama et al., 2007) as well as the drift in the seasonal
runoff peak, which is supposed to vary from July-August to May-June (Huss et al.,
2008b). As we have seen, Rhonegletscher is a very well-studied and monitored glacier,
with a big dataset that allows us the opportunity to keep going further in order to
understand important and crucial aspects of alpine glacier behavior and trends.
Our fieldwork has been carried out for several days in September, every year since
2007. Therefore, our motivation becomes from the aspects that follows daily
fluctuations. Although many parameters have been surveyed on the glacier – such as
albedo, elevation of GPS-referenced points, and pH of surface melt waters, etc. –, we
focus on measurements of the proglacial lake and atmospheric environments, in order to
give a more comprehensive perspective. Apart from keeping increase the dataset, the
aims of this study relay on approximating lake-glacier dynamics in terms of: (1)
identifying daily variations in height of lake-level surface; (2) determining circulation
patterns by observing iceberg movement; (3) co-relating parameters in order to reveal
possible triggers.
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2. Method
We did three observations (metrological observation, logging of glacial lake
variability, photogrammetry).The setting point of each observation is shown in
Figure 4. All of the observations were logged from about 9/2 18; 00 to 9/4 10; 00.
The detail of each observation is following.
Figure 4: The setting point of each observation.
A) Metrological observation (Vaisala WXT510)
Vaisala Weather Transmitter WXT510 (Figure 5) is a multi-sensor instrument that
measures six weather parameters. This equipment consists of the sensors, and by
connecting it to a data logger, it allows us to obtain continuous measure of climatic
components listed below (Field manual for Swiss glacier course, 2006). We set this
equipment on the land at east side of the glacier.
Wind speed and direction (horizontal)
Wind speed and direction are measured using the array of three equally
spaced ultrasonic transducers (three small poles) on the top of the instrument.
Liquid precipitation
The precipitation is by the sensor under the metal plate that covers the top of
the instrument, detecting the impact of individual raindrops.
Barometric pressure and Temperature and relative humidity
Barometric pressure, temperature and humidity measurements are done by the
sensor module in the inner part of the instrument, behind the radiation shield.
Logging of
proglacial lake
Photogrammetry
Metrological observation
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B) Logging of lake variability.
We used HOBO U20 (Figure 6) water level and water temperature logger for
recoding water pressure, water temperature and air temperature. The measurement
was 5 min intervals. The logger for measuring water pressure and temperature was
fixed to a bar (Not to move in water) and it was set at lake shore (Figure 7, 8). The
logger for measure of air parameters was set on the land near the water logger
(Figure 8).
Figure 6: HOBO U20 water level and water temperature logger. One used for
recoding water pressure, another used for recoding air pressure.
Figure 7: Logger for water parameters was fixed to a bar.