Geomorphic Threshold and Landslide - Semi-quantitative Approaches for Landslide Assessment and Prediction - page 158

Table 5.8 Critical height for initiation of slide
Sl. No. Slope parameters Tindharia Lower paglajhora

1404 m 2 968 m 2 1 Upslope contributing area (a)

2 Contour length (b) 27 m 22 m

3 Slope angle ( ⊖ ) 53 ° 20 ′ 48 ° 20 ′

4 Angle of internal friction ( u ) 21 ° 21 °

15 m − 2 day − 1
(Borga et al. 1998 )

15 m − 2 day − 1
(Borga et al. 1998 )

5 Transmissivity (T)

6 Wet soil buck density (P s ) 1.96 g/cc 1.96 g/cc

7 Density of water (P W ) 1.07 g/cc 1.07 g/cc

Cohesion (kg/cm 2 )

8 0.06 0.06

9 Critical height for initiation of slide

Culmann ( 1866 )
h c ¼

5.89 m 7.80 m

4 c 0 sin h cos /
c 1 cos ðh/Þ

10 Critical height for initiation of slide

Terzaghi ( 1962 )
Hc ¼

9.30 m 9.30 m

S W

1

0.9

0.8

P
R
O
B
A
B
I
L
I
T
Y

0.7

0.6

1

0.5

2

0.4

3

0.3

4

0.2

0 2.5 5 7.5 10 12.5 15 17.5 20 22.5 25

Return period in years

Fig. 5.5 Landslide probability and its return period