Suchergebnisse

Abstract. Four large drainages from glacial lakes occurred during
2006–2014 in the western Teskey Range, Kyrgyzstan. These floods caused
extensive damage, killing people and livestock as well as destroying
property and crops. Using satellite data analysis and field surveys of this
area, we find that the water volume that drained at Kashkasuu glacial lake in
2006 was 194 000  m3, at western Zyndan lake in 2008 was
437 000 m3, at Jeruy lake in 2013 was 182 000 m3, and
at Karateke lake in 2014 was 123 000 m3. Due to their subsurface
outlet, we refer to these short-lived glacial lakes as the "tunnel-type", a
type that drastically grows and drains over a few months. From spring to
early summer, these lakes either appear, or in some cases, significantly
expand from an existing lake (but non-stationary), and then drain during
summer. Our field surveys show that the short-lived lakes form when an ice
tunnel through a debris landform gets blocked. The blocking is caused either
by the freezing of stored water inside the tunnel during winter or by the
collapse of ice and debris around the ice tunnel. The draining then occurs
through an opened ice tunnel during summer. The growth–drain cycle can
repeat when the ice-tunnel closure behaves like that of typical supraglacial
lakes on debris-covered glaciers. We argue here that the geomorphological
characteristics under which such short-lived glacial lakes appear are (i) a
debris landform containing ice (ice-cored moraine complex), (ii) a depression
with water supply on a debris landform as a potential lake basin, and (iii)
no visible surface outflow channel from the depression, indicating the
existence of an ice tunnel. Applying these characteristics, we examine 60
depressions (> 0.01 km2) in the study region and identify
here 53 of them that may become short-lived glacial lakes, with 34 of these
having a potential drainage exceeding 10 m3 s−1 at peak discharge.