Because landslides damage infrastructure and can pose a threat to human life, scientists have long sought to predict when and where they might occur. Landslides happen where a disturbance such as heavy rainfall, snowmelt, or an earthquake disrupts the balance between soil strength and gravity. Shallow landslides, in particular, are most often triggered by the infiltration of intense rainfall. The resulting increase in water content reduces the soil’s cohesion, which, in turn, helps destabilize the slope.
To better understand and predict the development of rainfall-induced landslides, Anagnostopoulos et al. recently created HYDROlisthisis, a new process-based model designed to more realistically predict the interactions between subsurface hydrology and landslide initiation. The model incorporates key hydrologic and geotechnical conditions that have not generally been included in earlier models. A soil suction module, for instance, accounts for changes in soil cohesion during periods of wetting and drying. The new model also integrates the role of preferential water flow paths, such as fissures, cracks, and root holes, in landslide formation, something rarely included in previous models despite experimental evidence showing that such paths can play an important role in shallow landslide initiation.
As a test of HYDROlisthisis’s predictive abilities, the team applied the model to central Switzerland’s Napf catchment, an alpine region that experienced many shallow landslides following an intense rainfall event in 2002. The results demonstrate that shallow landslides occur in both saturated and unsaturated conditions and that the critical depth for landslide initiation is 0.2 to 1.2 meters—a finding consistent with field evidence. The simulations suggest that boundary conditions, such as soil depth, play an important role in model performance, as do the newly incorporated hydrologic and geotechnical components.
Although it still needs to be vetted on catchments of different sizes and varying climate regimes, HYDROlisthisis has demonstrated the potential to help scientists better understand the complex dynamics controlling shallow landslide initiation. (Water Resources Research, doi:10.1002/ 2015WR016909, 2015)
—Terri Cook, Freelance Writer
Citation: Cook, T. (2016), New model improves predictions of shallow landslides, Eos, 97, doi:10.1029/2016EO044835. Published on 2 February 2016.