International Archives of the Photogrammetry, Remote Sensing and Spatial Information Sciences, Vol XXXV, Part B7. Istanbul 2004 
  
  
  
  
Figure 1. Argualas rock glacier (Pyrenees-Spain). 
3. WEATHER IN THE AREA OF THE ROCK GLACIER 
The rocks glaciers move forward and backwards as an answer 
to the change of the weather; that is, if the temperatures 
increases, its dynamic also increases. These movements can not 
be appreciated at a simple glance, but they can be controlled 
with geodesic and photogrammetric methods. Because of the 
snow, photogrammetric and geodesic observations can only be 
carried out in September and exceptionally in August. 
The medium temperature per year of 0? C is in Pyrenees 
approximately in 2726 m, and the rock glacier of Argualas is 
between 2590 m and 2730 m, so that it is situated into the limit 
place where the ice appears. Therefore, the snow is supposed to 
be, theoretically, the whole year. 
Glacier weather conditions (rainfalls and temperatures) are 
extrapolated from I.N.M. stations near the area. 
Rainfalls: The nearest station to the glacier is "Sallent 
de Gállego", which is 5 km further from the glacier. 
There is a data complete of rainfalls taken from this 
station since 1990. Later on, these data have been 
given to the influential area of the glacier. 
Temperatures: There is not a continuous study of 
them in the nearest stations to the glacier, so that, a 
gradient termical in this area during August and 
September (-0,61 °C/100 m). The data of Sallent de 
Gâllego’s station has been finished taking into 
account that gradient termical, and with this gradient, 
the temperatures have been calculated in the area of 
the glacier. 
The dependence of the I.N.M. stations makes mistakes, such as: 
do not have complete series of data, different altitudes among 
the high parts of the glacier-station, orientation of the stations... 
So that, the location of its own automatic Stations has been 
asked. In these stations different parameters can.be gathered: 
temperatures, rainfalls or snow. This kind of stations have been 
used in the station “Juan Carlos I" (Antarctica) and in rock 
glacier of Veleta (Sierra Nevada) by Spanish investigators with 
good results (Ramos et al., 2001). 
4. GEODESIC STUDY OF THE GLACIER DYNAMIC 
A geodesic study has been performed since 1991 to calculate 
and locate with high precision and accuracy specified targets 
(rods) in order to compare the movement in the course of time 
(X, Y,Z). 
The geodesic studies have been done in the years: 1991, 1993, 
1994, 1995, 1998 and 2000. The annual study would have been 
an ideal situation, but it has been impossible because there was 
not enough budget to do it and climatic in some observations 
was bad. 
The.topographic technique which has been developed to 
calculate the glacier dynamic is the direct intersection (angle 
and distance), but, in addition, the global positioning system 
(G.P.S.) was used in the year 2000. The G.P.S. in its R. T. K. 
(static) application has not shown good results because of the 
multipath effect of the satellites signals of the glacier walls. 
In 1991, a lot of rods were put together to control the glacier 
geodesic and in 2000 another ones were put together to 
development the close range photogrammetric technique. The 
geodesic rods were distributed through the whole glacier area to 
study all the possible movements of the glacier, while the 
"control points" photogrammetric have only been used near to a 
big rock (8 meters of diameter). It has been studied in this way 
because it was impossible to realize a photogrammetric study of 
the whole glacier. 
  
P16 * 
Distance: 0.222 
Slope: -0.438 Pig 
P15 Distance: 2.629 P9 
Distance: 2.538 Slope: -1.722 Distance: 0.722 
Slope: -1.930 Slope: -0.580 
P3 = = 
Distance: 1.4 
: P13 
Slope: -0.625 P11 P8 
p2 Dunes Distance: 2.878 Distance: 1.379 
Distance: 0264 p44 Slope: -1502 9loPe: 71:124 
Slope: -0.204 Distance: 3.185 
P1 Slope: -1.701 
Distance: 0.132 
Slope: -0.233 Big rock py 
N (Origin angle Distance: 2.057 
(Orig gle) Slope: -0.607 
P4 
Distance: 2.490 
P12 
Slope: 0.747 Distance: 3.812 
Slope: -1.456 
p5 
i ; P6 
Distance: 3.630 ; 
Distance (meters A Distance: 2.251 (C1-C4) 
= 8 (eters) Slope: 1.859. — S pe:-0.966 (C1-C4) 
ope (meters) Front of glacier 
  
  
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Figure 2. Dynamic of Argualas glacier (1991-2000). 
To realize the geodesic study of the rods (1991 to 2000) the 
following elements were used: 
e There are three firm stations (nails) put in the highest 
east wall of the glacier. 
e There are three firm references (nails). From each 
station, three firm references are observed (nails). 
e There are fourteen nails 1,20 cm high put on the 
glacier and two nails on the biggest rock. The rods 
movement is the same as the glacier's dynamic. 
The techniques used to study the glacier have been the 
following: 
e Angles direct intersection. 
e Distances direct intersection. 
e Combination of angles and distances intersection. 
These techniques have been done with a topographic 
computer's program (TPC-IT), which has shown similar data. If 
it collecting information would be totally precise, these data 
would show a lot of results in common. But this does not occur 
and in the different studies, the difference has always been 
down the tolerance of + 4 cm (Sanjosé, 2003). 
The dynamic observance of all rods is not the same. This is 
logic because their spatial position depend on its situation on 
the glacier (Figure 2). In the future, instead of using geodesic 
technique, the position of these elements will be done with the 
development of the close range photogrammetric.