 |
| Titel |
Landslides distribution during intense climatic events, the case of August 2005 in Switzerland |
| VerfasserIn |
Pierrick Nicolet, Marc Choffet, Michel Jaboyedoff |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250048394
|
|
|
|
|
|
| Zusammenfassung |
| Rainfalls are known to be the major triggering effect on shallow landslides. Thus, a
correlation is expected between the precipitations and the number of events per sq. kilometer
or between the precipitations and the total displaced volumes per sq. kilometer. To illustrate
these correlations, the example of the August 2005 events in Switzerland is developed.
Indeed, precipitations up to 300Â mm in 5 days were observed in the northern part of the
Swiss Alps (and up to 190Â mm in 24 hours), triggering major flooding and landslides that
caused death to 5 persons and damages of 2.1 billion USD. As shown by [1], the correlation
between the spatial distribution of landslides and precipitations is strong. Only few
landslides occurred in places where the precipitations were lower than 70Â mm in
72Â hours, and an upper limitation of the number of events by sq. kilometer is given by
:
D = 8.335-
ln(p72)- 35.4
(1)
With D = density [events-km2] and p72 = precipitations over 72 hours.
Data shows that the number of landslides increases with cumulated precipitations up to a
threshold. When it comes to risk assessment, since the return period of the 48 hours
precipitations is 77 years [2], such events cannot be considered as exceptional. Furthermore,
shallow landslides occur usually suddenly, which complicates the attribution of a temporal
occurrence probability. This study proposes to estimate the temporal probability of landslide
occurrence at a regional scale and to correlate it with the damage cost. This permit the
calculation of portfolio values with existing data. As a consequence, this is a tool for
predicting future economical impacts.
References
[1]Â Â Â Jaboyedoff, M. & Bonnard, Ch.: Report on landslide impacts and practices in
Switzerland: need for new risk assessment strategies, in Ho & Li (Eds.), The 2007
International Forum on Landslide Disaster Management, 2007
[2]Â Â Â Rotach, M., Appenzeller, C., Bader, S., Frei, C., Germann, U., Liniger, M.,
Zbinden, P.: Meteorologie, in Bezzola & Hegg (Eds.), Ereignisanalyse Hochwasser
2005, Bundesamt für Umwelt BAFU und WSL, 2007 (in German) |
|
|
|
|
|
|