Geo-spatial Variability of Physiographic Parameters and Landslide Potentiality - Semi-quantitative Approaches for Landslide Assessment and Prediction - page 87

Fig. 2.14 Spatial distribution of friction angle ( φ )

Sepoydhura and some northern marginal parts are registering the friction angle of
more than 24 . Large parts of Tindharia (Table 2.12 ), 14 Miles Bustee, and Lower

Paglajhora are facing the friction angle of less than 24

°

and also are considering as
the most vulnerable part of the Shivkhola Watershed. The friction angle at Shiviter
varies from 21

°

(Table 2.15 ). It is observed that there is an increase in the
volume of the landslide area and mass since 1986

° to 25 °

2010.
Hill Cart Road is passing through the locations of Tindharia. 14 Miles Bustee
and Paglajaora where friction angle is quiet less. Analysis also reveals that more
than 50 % area of the Shivkhola watershed is below the friction angle of 24

-

° . The

derived landslide potentiality index value reveals that the area having friction

angle of less than 20 are registered with high LPIV (Table 2.12 ). The low LPIV

is observed at the places where the friction angle is greater than 25

°

. The spatial
distribution of cohesion in the Shivkhola Watershed reveals that Paglajhora, 14
Miles Bustee (Table 2.14 ), Tindharia (Table 2.12 ), Shiviter (Table 2.14 ) are
characterized by very low cohesive strength of soil. The range of cohesion is
between 0.01 and 0.90 (Fig. 2.15 ). The places of Gayabari and its adjoining areas,
Sepoydhura, middle section of the watershed and extreme north-eastern part are
dominated by moderate to high cohesive strength of the soil, varying from 0.35 to
0.90. The estimated cohesion of all the 50 locations shows that the cohesion in
the Shivkhola watershed is very less, that is less than 0.90. The study indicates
that there is an inverse relationship between cohesion and LPIV. The region of
low cohesion of less than 0.29, showed the LPIV of more than 15 (Tables 2.15
and 2.16 ).

°