Global Change Abstracts The Swiss Contribution - SCNAT

124 Global Change Abstracts – The Swiss Contribution | Cryosphere
08.1-227
Hazard assessment of potential periglacial
debris flows based on GIS- based spatial modelling
and geophysical field surveys: A case
study in the Swiss Alps
Kneisel C, Rothenbühler C, Keller F, Haeberli W
Germany, Switzerland
Cryology / Glaciology , Modelling , Geomorphology
Geology
Combined geomorphological and geophysical approaches
were used to perforrn a hazard assessment
of potential periglacial debris flow. Possible
debris flow initiation zones were identified within
a GIS- based model and located based on geomorphic
attributes which contribute the most to this
type of instability. In permafrost- affected alpine
environments, these include the extent and location
of ground ice and permafrost. In a potential
debris flow-starting zone in the Upper Engadine
(moraine/debris rock glacier complex Boval) twodimensional
electrical resistivity surveys were
used to detect the presence/absence of permafrost
and to estimate active- layer depth. The results
show that the moraine complex represents
a periglacial debris reservoir which consists of
frozen and unfrozen debris. The ice-bonded part
of the moraine is largely protected from sudden
destabilisation and retrogressive erosion can be
assumed to be limited. However, future degradation
or loss of permafrost in the lower parts of the
debris rock glacier would increase the amount of
erodible debris and generally reduce mechanical
stability.
Permafrost and Periglacial Processes, 2007, V18,
N3, JUL-SEP, pp 259-268.
08.1-228
Tracing glacier wastage in the Northern Tien
Shan (Kyrgyzstan/Central Asia) over the last
40 years
Niederer P, Bilenko V, Ershova N, Hurni H, Yerokhin
S, Maselli D
Switzerland, Kyrgyzstan
Cryology / Glaciology , Meteorology & Atmospheric
Sciences
The status and dynamics of glaciers are crucial
for agriculture in semiarid parts of Central Asia,
since river flow is characterized by major runoff in
spring and summer, supplied by glacier- and snowmelt.
Ideally, this coincides with the critical period
of water demand for irrigation. The present study
shows a clear trend in glacier retreat between 1963
and 2000 in the Sokoluk watershed, a catchment of
the Northern Tien Shan mountain range in Kyrgyzstan.
The overall area loss of 28% observed for the
period 1963-2000, and a clear acceleration of wast-
age since the 1980s, correlate with the results of
previous studies in other regions of the Tien Shan
as well as the Alps. In particular, glaciers smaller
than 0.5 km(2) have exhibited this phenomenon
most starkly. While they registered a medium decrease
of only 9.1% for 1963-1986, they lost 41.5% of
their surface area between 1986 and 2000. Furthermore,
a general increase in the minimum glacier
elevation of 78 m has been observed over the last
three decades. This corresponds to about one-third
of the entire retreat of the minimum glacier elevation
in the Northern Tien Shan since the Little Ice
Age maximum.
Climatic Change, 2008, V86, N1-2, JAN, pp
227-234.
08.1-229
Validation of the SNOWPACK model in five different
snow zones in Finland
Rasmus S, Gronholm T, Lehning M, Rasmus K,
Kulmala M
Finland, Switzerland
Cryology / Glaciology , Modelling
The performance of a snow pack structure model
SNOWPACK was studied in five locations around
Finland during two winters. Reasonable agreement
between modelled and observed snow depth
and snow pack structure evolution was found
in all other locations except in coastal Santala.
Agreement grew when going towards the north;
better agreements were obtained during the early
winter than during the melting period. Several
test runs with changed input data were done for
Hyytiala. Water equivalent, temperature, grain
form and grain size were the most sensitive of the
model output quantities to changes in the input
data. The use of measured precipitation instead
of snow depth for driving the mass balance or the
use of different radiation schemes had relatively
large effects on the model output. Model sensitivity
was high when many phase changes were involved
such as during the melting phase in spring
or in temperate climate zones.
Boreal Environment Research, 2007, V12, N4, AUG
27, pp 467-488.
08.1-230
Rockglacier activity studies on a regional scale:
comparison of geomorphological mapping and
photogrammetric monitoring
Roer I, Nyenhuis M
Switzerland, Germany
Geomorphology , Geology , Instruments & Instrumentation
, Cryology / Glaciology
In their spatial distribution as well as in their
different states of activity, rockglaciers imply