GIS based assessment of rainfall-induced landslide susceptibility of sensitive marine clays: a case study

ABSTRACT Landslides are frequent occurrences in Ottawa, Canada because sensitive marine clays (also known as Leda clay or Champlain Sea clay) dominate the landscape. These landslides are often triggered by rainfall in the region. A geographic information system (GIS) based modelling approach has been developed to assess and predict rainfall-induced landslides in the sensitive clays of the Ottawa region. The Transient Rainfall Infiltration and Grid-based Slope-stability (TRIGRS) model has been used in a GIS framework to investigate the influence of rainfall On shallow landslides over the Ottawa region, with respect to time and location. The assessment result maps show that the steep slopes of sensitive clays are more prone to landslides. Furthermore, susceptibility to landslides in these areas increases with long periods of intense rainfall. The proposed GIS based model is validated by comparing the predicted areas of landslides induced by rainfall with previous shallow landslides that had occurred in the Ottawa region. The results show that there is a good agreement between the predicted areas of landslides and the previous landslides reported. The proposed GIS–TRIGRS combined modelling approach can be therefore considered as a potential tool for assessing and predicting rainfall induced landslides in sensitive marine clays in Ottawa.