Application of Analytical Hierarchy Process (AHP) and Frequency Ratio (FR) Model in Assessing Landslide Susceptibility and Risk - Semi-quantitative Approaches for Landslide Assessment and Prediction - page 193

7.2 Materials and Methods

The thematic data layers of all the landslide inducing factors were integrated to
prepare landslide susceptibility map using a linear combination model in GIS. The
Analytical Hierarchy Process (AHP) was used to derive prioritized factor rating
value (PFRV) and a FR Model was applied to obtain prioritized class rating value
(PCRV) for all the landslide triggering factors considered in the study. The inte-
gration between PFRV and PCRV were made in a linear combination model on GIS
platform to estimate landslide susceptibility index value (LSIV) for each pixel and a
suitable classi

cation technique was incorporated to prepare the landslide suscep-
tibility map of the Shivkhola watershed. The data used in the present study are
Satellite image (IIRS P6/Sensor-LISS- III, Path-107, Row-052, date-18/03/2010),
modi

long. (date-5th April, 2008),
Google Earth Image (1st September, 2010), Geological Map (Geological Survey of
India, East Kolkata) and Topographical Map (78B/5, Survey of India). Data layers
for landslide inducing factors were generated using ERDAS Imagine 8.5, Arc View
and ARC GIS Software.

ed SRTM data with scene size 1 ° lat. and 1 °

7.2.1 Landslide Susceptibility Assessment

The following section presents the methods and results of the landslide suscepti-
bility analyses in this study.

7.2.1.1 Determination of Landslide Triggering Factors

The landslide triggering factors were identi ed by interviewing the local people and

an investigation of the landslide sites in the watershed through intensive fieldwork.
During 10 days

ed and
marked with GPS. Lithological structure, land use and land cover type around the
landslide scar, slope angle, construction of human structure and their role to
promote landslide, drainage network, altitude and slope aspects were investigated to
determine landslide triggering factors. The landslide triggering factors including
lithology, slope angle, drainage, slope aspect, slope curvature, lineament, upslope
contributing area (U.C.A.), land use/land cover, road contributing area (RCA) and
settlement density were taken into account to prepare landslide susceptibility map
of the Shivkhola watershed and their hierarchical arrangement was made on priority
basis. Shivkhola watershed is a small mountain basin where rainfall is uniformly
distributed over the entire area, so rainfall intensity was not considered in the
landslide susceptibility calculation (Mandal and Maiti 2011 , 2012 , 2013 ).

field work in July 2011, landslide locations were identi