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 191

Fig. 7.1 Tectono-stratigraphy and past landslide in the Shivkhola watershed (Mandal and Maiti
2013 )

Crystalline Sequence (HHCS) and the Lesser Himalayan Sequence (LHS) in
Darjiling Himalaya. The HHCS comprises of quartzo-feldspathic gneisses of both
igneous and sedimentary origin which suffers high grade of metamorphism (Catlos
et al. 2001 ). The LHS is dominated by garnet-biotite-mica schist and chlorite schists
in the upper part and slates and phyllites in the lower. The picturesque landslide
affected areas are Paglajhora, Tindharia, Mahanadi, Jogmaya and Shiviter. During
rainy season water percolates through the exposed rock joints and entrains the

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particles and reduces the cohesive strength of the soil.
The rapid urbanization and expansion of tourism in Darjiling Himalaya are
putting unprecedented pressure on land and soil with the gradual elimination of
vergin forest land after independence. Lack of land use planning coupled with
vulnerable geological structure and heavy frequent rainfall have led to the formation
of vicious cycle of soil erosion and landslide during and after monsoon seasons,
causing devastating damage to human lives and properties. Signi cant studies in

Darjiling Himalaya identi ed the causes and consequences of major landslide