Geoscience Reference
In-Depth Information
water during production. In fact, according to the 2002 Chilean National Census,
more than two-thirds of local population works in these two economic sectors, with
mining being the strongest and the agriculture the fastest growing rates in the recent
years (INE
2002
). During dry seasons, much of this water is provided by glacier melt
water, and so understanding the quantity of water available now and robust predic-
tions of water availability in the future are critical to determining the sustainability
of the local economy.
The section of South America south of 30
◦
latitude has an ice covered area of
approximately 27,500 km
2
, which contains about 89% of all glaciers located in
the Andes (Casassa et al.
2006
). These glaciers have shown a generalized retreat
and wasting, in agreement with the global trend (Casassa et al.
2007
). In the cen-
tral Chilean Andes, nearly 1600 glaciers with a total ice area of ca. 1300 km
2
have experienced a total volume loss, due to thinning and retreat, of 46
17 km
3
of water equivalent between 1945 and 1996 (Rivera et al.
2002
; Casassa et al.
2006
). Several studies about glacier-climate relationships undertaken in this region
indicate that recent glacier variations are linked to increased atmospheric temper-
atures, increased rainfall variability, and a trend towards a reduction in the annual
amount of precipitation (Rosemblüth et al.
1997
; Carrasco et al.
2002
;Riveraetal.
2002
).
In northern Chile, where the glaciated area is sparse, the first glacier inventory
was compiled by Garín in 1987 (Garín
1987
) and included general approxima-
tions of the presence of glaciers, glacierets and temporary snow surfaces. Following
this report, only partial updates have been completed, although these give a more
detailed view of glacier covered area at a catchment scale. An example of these
updates is the inventory of the upper Huasco catchment, which estimates an ice
covered area of 16.8 km
2
±
based on ASTER images analysis (Nicholson et al.
2009
).
Bearing in mind this context, there is a clear need of new studies about the
state and variability of the cryosphere in arid and semi-arid regions under differ-
ent climate change scenarios. Correspondingly, there is a need of integration to user
friendly and compatible databases like GIS.
6.2 Concepts
Glacier inventories enable more complex investigations on the cryosphere and its
interactions in the whole water resource and in geographical systems to be under-
taken. This section will explain some basic concepts underpinning the development
of glacier inventories.
Firstly, a glacier inventory is a “snapshot” from the state of cryosphere: glaciers,
perennial snow patches, rock glaciers, and other cryospheric features, which may
be created at different levels of sophistication (UNESCO
1970
; Mueller
1976
;Rau
et al.
2005
); and from different source materials, for example maps, photographs
(aerial or terrestrial) and satellite imagery (Raup
2000
).
