Geoinformation for Disaster and Risk Management - ISPRS

Some results
The LC PDGNSS system at Aggenalm passed the
first practical test in winter 2008/09 very
satisfactorily. Snow coverage of 2 metres and
temperatures below -15°C had no negative effects
on the different components. A winter impression
from the site is presented with Fig. 4. Data
recording has operated without failure since
February 2009. Springtime with snow melt, which
is generally a period of extraordinary concern for
landslide movement processes, and also a period
of continuous and heavy rainfall in June 2009,
could be completely observed.
Figure 4: Winter impression at Aggenalm
Landslide. The picture shows a Novatel PDGNSS
sensor and the weather station.
Figure 5: Shadowing situation at the Aggenalm. On the right an obstacle mask for the baseline between SN #1 and
#4 for a time slot of 2 hours in summer 2009.
However, no detailed assessment of the slide will
be performed here. In focus is only the achievable
data quality with the developed LC PDGNSS
system.
However, the “raw” GNSS solutions which means
the epoch solutions from the baseline processing
of each sensor on the slope, have to be filtered to
reject outliers and to bypass gaps. Outliers mainly
occur due to temporary bad satellite visibility
(typically shadowing effects in mountainous areas).
With an increased number of satellites in future,
hopefully a much better coverage will be available
and reliable GNSS-based positioning will be
permanently possible, even under often restricted
conditions at landslide sites (see Fig. 5).
The quality of the processed horizontal position
raw data (height is worse by a factor of 3) of
sensor #3 (Lampl Alm) for a selected day is shown
as an example in Fig. 6. After the elimination of
incorrect measurements the total variations of the
horizontal positions are clearly less than 1.5cm.
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