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| Titel |
Physically-Based Shallow Landslide Susceptibility Mapping, NW of Portugal |
| VerfasserIn |
Manuel Teixeira, Carlos Bateira, Laura Soares |
| Konferenz |
EGU General Assembly 2013
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| Medientyp |
Artikel
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| Sprache |
Englisch
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| Digitales Dokument |
PDF |
| Erschienen |
In: GRA - Volume 15 (2013) |
| Datensatznummer |
250076549
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| Zusammenfassung |
| Two physically-based models - Shallow Landslide Stability Analysis (SHALSTAB) and
Safety Factor (SF) – are applied in Serra da Peneda (northwest of Portugal) to evaluate
shallow landslide susceptibility in Tibo drainage basin. This small basin is located in an area
of granitic and metasedimentary substrate, covered by different types of surficial formations
(weathering mantles and slope deposits).
The application of the selected models requires the determination of a set of
mechanical and hydrological parameters, and the use of high resolution topographic
information to create an accurate DTM. To fulfill this goal we have applied the
Shallow Landslide Stability Analysis (SHALSTAB) and the SF (Safety Factor)
models.
The shallow landslide area was inventoried on the field. The cohesion was assessed by
back analysis and the other mechanical and hydrological soil parameters were assessed
on the field survey. Several susceptibility scenarios were tested with SHALSTAB
model.
The best SHALSTAB scenario used to assess the susceptibility is achieved using the
following parameters: cohesion (c) = 2000 N/m2, soil thickness (z) = 1,2 m, internal friction
(Ï)=32o and soil weight (Ïs)=14,7 KN/m3.
Shallow landslide susceptibility mapping using the SF model, was based on the
cartography of the factors registered on the field survey and used the following parameters:
cohesion (c) = 2000 – 6000 N/m2, soil thickness (z) =1,2 m, internal friction (Ï)=30 - 40o;
soil volumic weight (γm) = 13,7 – 15,7 KN/m3 and Hydraulic conductivity = 0 – 3,9-03
kfs.
SHALSTAB scenarios were validated by overlaying the shallow landslide area (scar
concentration) and selected the better susceptibility modeling.
The parameters used on the SF model applied spatially variable values registered in the
field survey (using the superficial formation cartography). To validate the SF model we used
the AUC (Area Under the Curve) method.
The two models were compared by the scar concentration and landslide potential.
There are no great differences between the instability modeling generated by both
models, although SHALSTAB scenario has showed better results. The hydrologic model used
by SHALSTAB presents an important improvement to the susceptibility assessment
and seems to be the main reason for the better performance of the SHALSTAB
model.
Keywords: Shallow Landslides susceptibility; physically-based models; field monitoring;
SHALSTAB; SF |
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