Geoscience Reference
In-Depth Information
Fig. 7.3 Methodology of
landslide hazard risk map
Geo-referencing and Digitization of the DATA
(SOI Topo-sheet, Satellite Image LISS III)
Weighted Land use
& Land Cover Map
Settlement Density
Map
Road Contributing
Area Map
RASTER
INTEGRATION
RISK EXPOSURE MAP
Multiplication of risk exposure
map with Landslide
Susceptibility Map
LANDSLIDE HAZARD
RISK MAP
7.2.2.1 Preparation of Weighted Risk Factor/Element Maps (Weighted
Land Use/Land Cover Map, Road Contributing Area Map
and Settlement Density Map)
In the present study, land use and land cover, road network, and settlement were
considered as important risk factors/elements because these three are worst affected
by landslide events in the study area. To derive the weighted risk factor maps the
developed numerical scale of 1
10 was applied to assign the scores for each class of
the risk factor maps. Weighted land use/land cover map (Fig. 7.5 ) is the expression
of the intensity of risk induced land use pattern in the Shivkhola watershed.
A weighted land use/land cover map was developed assigning more weightage
values considering the landslide contributing units to the signi
-
cant landslide
triggering land use pattern i.e. tea garden area, degraded forest, bare surface and
agriculture. Weighted value to each class/range of the road contributing area (RCA)
map was assigned considering the intensity and impact of road network on land-
slide and thus a weighted road contributing area map (Fig. 7.6 ) was made on GIS
platform. Settlement Density Map was prepared by assigning more weighted values
to high density class and low for low density class for raster integration and a
weighted settlement density map (Fig. 7.4 ) was made accordingly. Three risk factor
maps were classi
ed into low, moderate and high intensity zones.
7.2.2.2 Integration Between Weighted Land Use and Land Cover, Road
Contributing Area and Settlement Density and the Development
of Risk Exposure Map
To integrate risk factor maps prioritized class rating values (PCRV) and prioritized
factor rating value (PFRV) were obtained for each class and each risk factors maps
developing couple-comparing matrix (Table 7.4 ) according to Saaty ( 1980 ). Then,
 
 
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