Introduction - Semi-quantitative Approaches for Landslide Assessment and Prediction - page 23

Fig. 1.19 a - d Destruction in Jogmaya Tea Garden Area

1.5 Mechanism and Causes of Landslides

Recently the process studies are getting increasing importance in the field of hill

slope evolution though the obsession to trace cyclic landform elements and to t

them in a global model of geomorphic cycle has ultimately retarded rather than
activated the development of empirical process research (Poesen and Poley 1987 ).
Slope failures are considered as the most active agent of soil erosion in steep
mountains. Proper understanding of the geomorphic evolution of mountain land-
scapes requires that they be given increased attention (Brardinoni and Church
2004 ). The evolution of hill slope is described as a complex and systematic
interaction between sets of physical and manmade factors governed by geologic,
hydrologic, climatic, geomorphic and land use attributes. Those factors in their
interactive combination yield more than the sum of individual factors (Wilson
1981). The geomorphic processes and elements, in their systematic relationship
show short-term equilibrium manifested by low rate of mass transfer and mainte-
nance of form characterized by slope and height. Although or absolute

equilibrium is a rare theoretical state towards which the system behaviour is tending
with greater rapidity by attempting to absorb the successive effects of a sequence of
process inputs of lower magnitude and frequency (Chorley et al. 1985 ). The

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