Geoscience Reference
In-Depth Information
Freirina, Huasco, Vallenar and Alto del Carmen comunas. Huasco Valley is orig-
inated from the confluence of El Carmen and El Transito rivers, which converge
together in Junta del Carmen area, 90 Km East from the sea (MOP
2004
). The
catchment has a mean orientation Southeast to Northwest, like many of Chilean
Andes originated rivers (MOP
2004
).
Precipitation in the region is characterized by strongly marked, winter precip-
itation, which is caused by Pacific cyclone activity, and the summer months are
markedly dry, with exceptional convective showers (Kull et al.
2002
; Ginot et al.
2001
). Due to these climatic advantages, this region has earlier fruit production than
others in the country, which has made the production of fresh fruit for export a very
important economic activity in the last few decades (MOP
2004
). The importance
of water for the local economy with an increasing population (INE
2002
) indicates a
need for a detailed analysis of the behavior of snow and ice in this region (Pellicciotti
et al.
2008
). The glaciers in the Atacama region are not classical accumulation-
ablation area glaciers, such that most behave either as a whole ablation or solely
an accumulation area, with the exact form dependent on yearly climate variations
(Rabatel et al. unpublished).
6.5 Materials and Methods
In the case of the Huasco catchment (see Fig.
6.4
), there were three key data
sets available: 1. A vector data set, generated from Chilean Military Geographical
Institute (Instituto Geográfico Militar, IGM); 2. A satellite imagery source, in this
case ASTER imagery, which allowed a DEM of the study area to be created; and 3.
Aerial photographs, which were taken from Chilean Air Force's Photogrammetric
Service (Servicio Aérofotogramétrico, SAF). A summary of used imagery and data
can be seen in Table
6.1
.
Vector files: The base vector files used were the Chilean IGM topographic maps
in 1:50.000 scale. From this dataset the drainage network and the contours (with
25 m. equidistance) were obtained. In addition, vector files of the catchments bound-
aries, obtained from Chilean Dirección General de Aguas, DGA, were used. These
boundaries had to be improved, because the original vectors were generated at a
broad spatial resolution (1:250.000 scale), so has to be modified to fit the IGM
map's contours.
Table 6.1
Upper Huasco Glacier Inventory, used data and imagery
Image/Material
Source
Year
Resolution or scale
ASTER
ASTER (Terra)
2002-2004
15 m pixel
Aerial photographs GEOTEC flight
1999
1:50.000
Contour lines
Instituto Geográfico Militar (IGM) Hycon flight, 1955 1:50.000
Drainage network
IGM
Hycon flight, 1955 1:50.000
