Remote-sensing-based monitoring the dynamics of Kyagar Glacial Lake in
the upstream of Yarkant River, north Karakoram
Abstract
Long-term monitoring of ice-dammed lake development are important for
understanding the process of lake storage and outburst. Based on remote
sensing observations for the period 1972-2020, we obtained so far the
most detailed reconstruction of the filling and drain of Kyagar lake, a
typical annually ice-dammed lake in the north Karakoram. We show that
annually repeated lake filling-drains were detected by satellite
observations during two periods:1996 to 2009 and 2015 to 2020, while
between 2009 and 2015 none obvious outburst occurred. These two
intermitted periods with regular annual cycles of lake outburst were
likely related to the long-term cycle of glacier surge dynamics, which
show two remarkable surge-induced terminus accelerations during
1995-1997 and 2014-2016. Following each surge, the maximum lake areas
were decreased by about 33% from 1996-2009 and by about 88% from
2015-2020. With climate warming and the thinning of the ice-dam, the
storage capacity of glacial lake will likely continue decrease in the
future, and the risk of lake outburst flood thus somehow decrease.
Repeated drainage following filling exacer-bates the depletion of
material at the glacier terminal, leading to the cessation of storage
and creating the conditions for the next glacial surge to occur, thus
creating a long-term cycling process. Together with the uncertainty and
intensified climate changes, it suggests that a close monitoring of the
glacial lake development and glacier dynamics would be still important.