Glacier flow characteristics in the ablation
are of Koryto glacier in summer 2000
SUGIYAMA Shin*, YAMAGUCHI Satoru, MATSUMOTO
Takane and NARUSE Renji
Institute of Low Temperature Science, Hokkaido
University
Surface flow and basal sliding of ice were
observed in the ablation area of Koryto glacier
during the late ablation season in 2000.
From the beginning of August to the middle
of September, surface flow velocity decreased
by 20% near the terminus. This change could
be attributed to the change in basal sliding
velocity which was directly measured at a
contact of basal ice and rock on the lateral
side of the glacier. In the meantime flow
velocity due to plastic deformation of ice
which was calculated by subtraction of basal
sliding velocity from surface flow velocity
maintained almost constant value throughout
the period. Daily variation of the basal
sliding velocity was significant until the
middle of August and it had a correlation
with discharge of the stream from the glacier.
In the latter half of the observation, however,
the velocity was rather steady and not sensitive
to the discharge. This result suggests that
the basal sliding is ruled by basal water
during the high ablation season but by the
intrinsic conditions of glacier base (normal
and shear stresses, basal rock, subglacial
till etc.) when water input is insufficient.