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factors conducive to slope instability, can be recognized at various levels of
abstraction from the slope itself. The cohesion and pore-water pressure both directly
control the magnitude of stress of the slope materials. These direct factors can be
influenced by other factors recognized at successively more remote levels of
abstraction. For example, pore-water pressure may be related to the rate of in
l-
tration through the ground surface, which in turn, may be related to the density of
vegetation cover which is again subject to change as a result of climatic conditions or
land use activity. These chains of relationships may be critical in reducing the slope
stability condition over time to a point where the triggering of movement may occur.
Landslide susceptibility is thus a function of the degree of the inherent stability of the
slope together with the intensity of causative factors capable of reducing the excess
strength. So, the identi
cation of the causative factors is the basis of many methods
of landslide susceptibility assessment. In most of the case the landslide is the critical
mechanism of erosional processes and in such condition landslide is inevitable and
necessary part of the natural landscape process system. Although the occurrences of
landslide hazards and its impact on human society cannot be prevented fully by
analyzing the slope stability condition, but the better understanding of geo-technical
attributes of the soil can contribute to greater knowledge and understanding about
the spatial distribution of slope instability which are very much essential for land use
planning. Many approaches to assess slope stability and landslide hazards were put
forward by Montgomery and Dietrich (
1989
,
1994
), Carrara et al. (
1991
), Hammond
et al. (
1992
) combined a contour based steady state hydrologic model with the
in
nite slope stability model (simpli
ed for cohesion less soils) to de
ne slope
stability classes based upon slope and speci
c catchment area. Numerous models in
connection to the slope stability, shallow and deep seated landslides were introduced
and veri
ed by Varnes (
1958
), Young (
1963
), Vanmarcke (
1977
), Burton and Ba-
thrust (
1998
), Bradinoni and Church (
2004
), Smedt (
2005
) and Bhattarai and
Aoyama (
2001
). The geotectonic factors of slope instability were studied in details
by Brudsen (
1979
), Windisch (
1991
), Carson (
1975
,
1977
) and Borga et al. (
1998
).
A comprehensive list of stability factors commonly employed in the factors mapping
approach was given by Crozier (
1986
), Guzzetti et al. (
1999a
,
b
,
2003
) and Tiwari
and Marui (
2001
,
2002
,
2003
,
2004
).
A more sophisticated approach represents the terrain in terms of differences of
inherent stability based on the Safety Factor (FS). Simply, the value FS is assumed
to be 1.00 at the moment of failure and the values successively greater than 1.00
represents the increasing stability and hence low susceptibility to slope failure.
Determination of FS permits limiting equilibrium analysis of a slope and is par-
ticularly helpful in designing the type and magnitude of remedial measures required
to achieve an acceptable FS. A considerable amount of information such as the
geometry of the slope, pore-water of the slope materials, angle of internal friction
and cohesion are required to assess the stress parameters of the slope materials
(Glade
1998
) and Safety Factor value.
The present study encompasses the assessment of geo-technical parameters of
the collected soil samples from 50 landslide locations selected through strati
ed
random sampling with representatives of different landuse and slope classes. The
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