Geoscience Reference
In-Depth Information
regional susceptibility studies as suggested by Saaty (
1980
), Soeters and Van
Westen (
1996
), Mwasi (
2001
), Nie et al. (
2001
), Yagi (
2003
), Komac (
2006
),
Yalcin and Bulut (
2007
), Kamp et al. (
2008
) and Yalcin (
2008
). The frequency ratio
(FR) model has become very popular as realistic quantitative approach in the
landslide susceptibility mapping. This approach is related with the historical
landslide events and their areal coverage. Lee and Pradhan (
2007
) argued that
frequency ratio model provides a correlation between the historical slide locations
and various influencing factors under consideration. Intarawichian and Dasananda
(
2011
) applied frequency ratio model to analyze slope instability and ascribed the
model as a popular quantitative method.
The present study deals with the estimation of factor
'
s weight and class
frequency ratios using
'
AHP
'
and
'
FR
'
model respectively. Integration between
factor
s weight (FW) and class frequency ratio (FR) was performed with the help of
a liner combination model. This is done to derive pixel wise landslide susceptibility
index values (LSIV) on GIS platform and to prepare landslide susceptibility map.
Landslide hazard risk analysis is the assessment of the probability of the damage
of land and associated resources of different magnitudes that may occur in a region
due to landslides. Earlier attempts to reduce landslide risk is largely a history of
management of landslide terrain by construction of protective structures or moni-
toring and warning systems, or the ever-increasing sophisticated methods for
mapping and delineating areas prone to landslide (Dai and Lee
2002
). Risk of
landslide is normally de
'
ned as the expected number of lives lost, persons injured,
property damages and disrupted economic activities due to particular landslide
hazard for a given area and reference period (Varnes
1984
). To reduce the risk from
the landslide events, the knowledge about potentiality to slope instability is
crucially needed. Information of landslide events are described in the form of
landslide susceptibility map of the concerned region and the preparation of this map
depends largely on the complex sets of knowledge of controlling slope movement
factors. Landslide analysis is mainly done by assessing susceptibility, hazard and
risk (Einstein
1988
). The process of creating the maps involves several qualitative
or quantitative approaches (Soeters and Van Westen
1996
; Guzzetti et al.
1999a
;
Van Westen et al.
2008
). Jibson et al. (
2000
), Praise and Jibson (
2000
) and Zhou
et al. (
2002
) have applied the probabilistic models for landslide risk and hazard
analysis. Landslide hazard risk map was made integrating landslide susceptibility
map and landslide risk exposure map on ARC GIS platform to identify the spatial
distribution of potential risk prone area in a representative drainage basin, over
which the attributes of land, soil and water exhibit a spatial order away from the
water divide in an interacting combination with human actions.
Tectono-statigraphically, the study area, Shivkhola Watershed is located in the
southern escarpment slope of Darjiling Himalaya, where high grade metamorphic
rocks of the Darjiling and Chungthang groups are thrusted over low grade meta-
morphic rocks of the Daling Group along the MCT (Main Central Thrust, Mallet
1875
; Sinha-Roy
1982
). Main Central Thrust (MCT) and Main Boundary Thrust
(MBT) are passing through the study area (Fig.
7.1
). The MCT (a major ductile
shear zone) has divided two major litho-tectonic units, the Higher Himalayan
Search WWH ::
Custom Search