Name: JULIA FREDERICA EFFGEN
Type: MSc dissertation
Publication date: 08/02/2018
Advisor:
Name |
Role |
|---|---|
| EBERVAL MARCHIORO | Advisor * |
Examining board:
| Name |
Role |
|---|---|
| EBERVAL MARCHIORO | Advisor * |
| PABLO DE AZEVEDO ROCHA | Internal Examiner * |
| PATRÍCIO JOSÉ MOREIRA PIRES | Internal Examiner * |
Summary: Shallow landslides are present geomorphological processes in southeastern Brazil,
dependents on characteristics of relief and climate, among other factors. In the
Capixaba capital Vitória is no different, with major events of mass wasting causing
human, economic and socio-environmental transformations, like the Morro do Macaco
landslide (1985). Therefore, this researchs goal is to analyze the areas of susceptibility
to shallow landslides in the Fradinhos watershed, through the Shallow Stability model
(SHALSTAB), physically based, in its topographic control and complete equation
versions. For the models parameterization, samples of texture, cohesion, apparent
density, internal friction angle and saturated hydraulic conductivity of the soils were
taken in three places with different land use and cover, and two had landslide scars on
the proximities of the sampling sites. The Fradinhos watershed has predominance of
steeper slopes, with 49.8% and 32.3% of the total area of the basin with gradients
between 20-45% and 45-75% (featuring relief of strong wavy to hilly slopes). The most
common forms of horizontal curvatures are planar and divergent curvatures, with about
73% and 15.1%, respectively. The highest contribution areas of the study area are
associated with the lower thirds of the slopes and drainage channels. The best
performance obtained with the Shalstab model was the topographic control equation
version with the result in log (Q/T), with 61% of true positive rate, and the complete
equation with results in critical rain for the occurrence of landslides, with 71% rate of
true positive. The worst-performing model was the complete equation with the result in
log (Q/T), which presented 95.68% of the basin as stable area, and the topographic
equation with results in critical rain, which presented 95.94% of the basin as an
unstable area (needing less than 5mm of rain per day for the occurrence of landslides).
The critical rain threshold considered to characterize an area as stable was of events
above 25mm/day, that is, only strong events of rainfall would cause landslides.
Keywords: shallow landslides Vitória SHALSTAB rainfall parametrization.
LISTA DE FIGURAS
Figura 1 Morro do Macaco, em Tabuazeiro, após esco
