Glacier Lake Outburst Floods (GLOFs)—Mapping the Hazard of a Threat to High Asia and Beyond - Impact of Global Changes on Mountains: Responses and Adaptation - page 335

Hazard Probability
of Ice Avalanches

4 Kilometer 0 1 2 3 4 Kilometer

0 1 2 3

Glacier

Lake with ID and
Hazard Potential

High
Low

Hazard Probability of
Flashflood

Glacier
Settlement
Road
Vegetation

Level I
Level II
Level III
Level IV

Debris Flow

high
low

high
low

Figure 14.5. Examples from the fl ow modelling. Left: probability of an area affected by ice
avalanches, right: probability of an area affected by fl ash fl oods and mudfl ows (Bolch et al.
2011a, Peters 2009).

Color image of this figure appears in the color plate section at the end of the topic.

In order to obtain some indications whether a moraine dam is
currently within the permafrost zone and could be affected by thawing,
permafrost may be modelled using a simple empirical model, e.g., based
on Permakart (Keller 1992). This model is based on empirical fi ndings of
the permafrost distribution as well as geomorphometric parameters, Mean
Annual Air Temperature (MAAT), which can be computed using a DTM,
and additional data. Bolch et al. (2011a) extended this model and included
the solar radiation as additional information. The limits of the permafrost
distribution are geographically strongly differing, and frequently small-scale
variability (e.g., caused by the land cover) cannot not be captured. Climate
change also has an impact on the permafrost distribution, and the global
permafrost area diminished during the last 130 years (cf. i.a. Marchenko et
al. 2007). It can be assumed that a dam may become unstable if it is located
outside the continuous permafrost.
Although being a rough estimate, especially when taking into account
that the blocky moraine material itself may retard thawing (Gorbunov et al.
2004) this approach provides a relatively quick evaluation of the possible
current existence and condition of permafrost in a dam (Bolch et al. 2011a).