Landslide hazard assessment is a combined outcome of landslide susceptibility analysis, estimated frequency and magnitude of potential landslides.
The objective of the present study is to assess landslide hazard along a section of National Highway 10 (NH 10), the lifeline of the Darjeeling-Sikkim Himalayas.
To achieve this, landslide susceptibility in terms of spatial probability was first estimated by establishing the relationship between existing landslide scars and 11 geoenvironmental factors using a machine learning-based Bagging model.
In the third stage, landslide area-frequency analysis using the probability density function (PDF) and cumulative distribution function (CDF) was carried out to estimate landslide size/magnitude probabilities.
Finally, after integrating spatial, temporal and magnitude probabilities, the landslide hazard was assessed for different return periods and magnitudes.
Landslide hazard assessment is a combined outcome of landslide susceptibility analysis, estimated frequency and magnitude of potential landslides. The objective of the present study is to assess landslide hazard along a section of National Highway 10 (NH 10), the lifeline of the Darjeeling-Sikkim Himalayas. To achieve this, landslide susceptibility in terms of spatial probability was first estimated by establishing the relationship between existing landslide scars and 11 geoenvironmental factors using a machine learning-based Bagging model. Secondly, after analysing landslide events and past rates of occurrence, the mean recurrence interval was computed for individual slope facets and fitted to the Poisson probability model to estimate the exceedance probability of landslides over time. In the third stage, landslide area-frequency analysis using the probability density function (PDF) and cumulative distribution function (CDF) was carried out to estimate landslide size/magnitude probabilities. Finally, after integrating spatial, temporal and magnitude probabilities, the landslide hazard was assessed for different return periods and magnitudes. It was found that annual exceedance probabilities reach up to 0.27 in the study area. The CDF shows that future landslides of ≥ 1000 m2 and ≥ 10,000 m2 in size have probabilities of 0.82 and 0.32, respectively. The hazard analysis depicts that over the next 10 years, there is a 37% chance that future landslides will be ≥ 1000 m2, and a 30% likelihood that they will be ≥ 10,000 m2. Moreover, Kalijhora, 7th Mile, Birik Dara, Durbin Dara, and 29th Mile is identified as the most hazardous sites.
