Geoscience Reference
In-Depth Information
Table 7.2 Landslide triggering factors and determined prioritized factor weights
Factors
1
2
3
4
5
6
7
8
9
10
Prioritized
rating
Slope
1
2
3
4
5
6
7
8
9
9
0.2944
Lithology
1/2
1
2
3
4
5
6
7
8
9
0.2150
Drainage
1/3
1/2
1
2
3
4
5
6
7
8
0.1537
Lineament
1/4
1/3
1/2
1
2
3
4
5
6
7
0.1087
Curvature
1/5
1/4
1/3
1/2
1
2
3
4
5
6
0.0764
UCA
1/6
1/5
1/4
1/3
1/2
1
2
3
4
5
0.0535
RCA
1/7
1/6
1/5
1/4
1/3
1/2
1
2
3
4
0.0375
LULC
1/8
1/7
1/6
1/5
1/4
1/3
1/2
1
2
3
0.0266
Settlement
density
1/9
1/8
1/7
1/6
1/5
1/4
1/3
1/2
1
2
0.0193
Slope aspect
1/9
1/9
1/8
1/7
1/6
1/5
1/4
1/3
1/
2
1
0.0149
CI = 0.0615; R.I (random index) = 1.49 and CR = 0.0413 (consistent). RCA road contributing area; UCA
upslope contributing area; LULC land use and land cover
Source Saaty (
1980
)
CI
¼
k
Max
n/n
1
ð
7
:
3
Þ
Saaty and Vargas (
2001
) randomly produced reciprocal matrices using scales 1/9, 1/8,
1/7,
, 8, 9 to evaluate a so called random consistency index (RI). The average
RI of 500 matrices is given in Table
7.3
.
…
,1,
…
7.2.1.5 Frequency Ratio Model and Prioritized Class Rating Value
Frequency ratio (FR) model is also a well accepted and popular quantitative
approach for the preparation of landslide susceptibility map. Lee and Talib (
2005
),
Pourghasemi (
2007
), Lee and Pradhan (
2007
), Jadda (
2009
), Avinash and
Ashamanjari (
2010
), Intarawichian and Dasananda (
2011
) successfully applied
'
model to generate landslide susceptibility zoning map. To obtain frequency
ratio (FR) for each class of all the data layers a combination has been established
between landslide inventory map and criterion maps using following equation.
FR
'
N
pix Sið
ðÞ
N
pix Nið
ðÞ
P
N
pix Sið
ðÞ
P
N
pix Nið
ðÞ
Fr
i
¼
ð
7
:
4
Þ
N
pix Sið
ðÞ
The number of pixels containing slide in each class (i),
N
pix
ð
N
i
Þ
Total number of pixels having class (i) in the whole watershed,
P
N
pix Sið
ðÞ
Total number of pixels containing landslide,
P
N
pix Nið
ðÞ
Total number of pixels in the whole area of the watershed.
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