Geomorphic Threshold and Landslide

Abstract

The present study established the link between critical rainfall (cr), critical slope angle (cs), critical height (ch) and landslide. The critical rainfall was estimated incorporating geo-technical parameters such as angle of internal friction (\(\varphi\)), slope angle (⊖), upslope contributing area (UCA), transmissivity (T), wet soil density (ps), and density of water (pw). Cohesion (c), angle of internal friction (\(\varphi\)), unit weight of the materials (γ), and slope angle (⊖) were taken into account to estimate critical slope height. The thickness of total soil (h), thickness of saturated soil (z), wet soil density (Ps), density of water (Pw), friction angle (\(\varphi\)) and slope steepness (⊖) were considered to derive critical slope angle. Study attempted to calculate critical rain to slope failure and its return period. The temporal probability of the landslide events were estimated applying Binomial and Poisson Probability Distribution Model based on past landslide occurrences. The probability model suggests that occurrences of major landslides with more than 90 % certainty could be expected in every 7.5 years.