 |
| Titel |
Representation problems of danger and “risk” maps |
| VerfasserIn |
Pierrick Nicolet, Frédéric Berger, Michel Jaboyedoff, Christian Gerber, David Giorgis |
| Konferenz |
EGU General Assembly 2011
|
| Medientyp |
Artikel
|
| Sprache |
Englisch
|
| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 13 (2011) |
| Datensatznummer |
250056251
|
|
|
|
|
|
| Zusammenfassung |
| Natural hazard are managed in Switzerland with danger maps, which are a representation
of the level of danger defined by a combination of frequency and intensity. The
different levels of danger are represented with colors, namely: white (no danger, or
negligible danger), white-yellow (residual danger), yellow (low danger), blue (medium
danger), and red (high danger). Colors are chosen through matrices established for the
different types of phenomenon. The zoning is performed on actual state, taking into
account assessment measures as long as they are considered as durable in terms of
functionality and if there maintenance is guaranteed (projects cannot be integrated).
These maps are then used for the land use planning and to establish protection
measures. They are supposed to be checked “periodically” and updated “in case of
important modification of the danger”. The yellow-white color is displayed for both
very low occurrence/very high intensity hazards or very low danger remaining
after protection measures. Thus, we identify two problems in this methodology:
The difficulty to identify the initial-state danger level and the risk of forgetting
the danger (more or less willingly)
The ambiguity of the yellow-white color
Thus, we propose to adapt the Swiss system with a new color code. A zone where the
danger is reduced by a safety measure could take the color of the original danger,
with the overprinting of a pattern of symbols representing the method of danger
reduction drawn in the color of the new level of danger. As the representation of
protection measures with pictograms is not easy to understand, the symbology should be
carefully chosen. We assume that with this new symbology, the authorities and the
public will be aware of the potential danger and of the reduction method and that the
danger cannot then be forgotten anymore. Furthermore, the yellow-white color
would only represent the very low occurrence/very high intensity hazards. This
symbology would offer more tools to perform the interests weighing at the risk study
level.
Two examples are used to illustrate this procedure. The first one concern the village of
Chardonne, in Switzerland, which is threatened by rockfalls, whereas the second one focus on
the protection offered by a forest. Both of them offer the advantage to have been extensively
studied with and without protections measures. |
|
|
|
|
|
|