Rainfall-Induced Landslide Hazard Analysis Using TRIGRS Model: An
Investigation of 2014 Malin Slide, Maharashtra, India
Abstract
The Western Ghats region of India and its neighbouring areas are highly
susceptible to rainfall-triggered landslides due to the regional
geography, extreme rainfall, and anthropogenic intervention like
excavation for construction activities etc. Every year in monsoon
season, Maharashtra faces a massive loss of properties and life due to
rainfall triggered landslides. In the monsoon of 2021, Pune and Konkan
divisions in Maharashtra have witnessed severe rainfalls that triggered
many landslides, which cause nearly 200 deaths and massive loss of
properties. Thus, it is necessary to model an accurate early prediction
system to mitigate such natural hazards. In this study, we have analyzed
the efficiency of the transient rainfall infiltration and grid-based
regional slope-stability (TRIGRS) model in predicting the location and
timing of landslides. The case study selected for this analysis is a
destructive rainfall-induced landslide triggered at Malin near Mumbai in
July 2014, which resulted in 160 deaths, including the burial of an
entire village under the debris. The TRIGRS is a widely applied model to
analyze the effect of rainfall on pore water pressure fluctuations and
related variation in factors of safety. It uses an infinite slope model
to estimate the change in the factor of safety for every pixel. The
model input data requires topographic properties (slope and elevation),
soil layer thickness, material properties, initial water-table depth,
and rainfall characteristics (intensity and duration). The preliminary
analysis of rainfall data indicated that the study area was affected by
3-days intense rainfall prior to the landslide event. The TRIGRS model
results show that the factor of safety of the Malin slope decreases with
the increasing rainfall intensity and duration. The present study
suggests that this model can also be used at large scale areas to
prepare an active early warning system for landslide events. Keywords:
Landslide; Rainfall; TRIGRS; Natural hazard; Maharastra