Numerical (finite element/difference) model development has started to consider approaches that allow the direct application of rainfall and vegetation transpiration, and can model their variability using historic or forecasted weather event sequences and climate patterns. It is clear from the initial results that these models are currently not reliably predictive. The models are sensitive to the way in which a number of the physical processes and properties described above are incorporated, in particular unsaturated soil behaviour including shrinkage, strain softening as a result of pore pressure changes, root depth and rate of water removal and cracking causing large changes in bulk permeability. In-depth understanding of physical processes and key parameters from the field and laboratory tests are required to facilitate development of robust models capable of predicting slope responses.
In the first phase of our research we will use existing models and subject these to designed weather event sequences, to evaluate the response of slope geometries, geologies and vegetation covers relevant to the national and regional scales, and use the outputs to describe critical baseline sequences for slope performance at the local scale. iSMART will then use rigorous numerical modelling at the site level to bring together field and laboratory-scale data and to examine the consequences for slope performance, responding to forecasted weather event sequences. This process informs the direction of the laboratory and field work to quantify unknown parameters and understand complex processes. As iSMART progresses, models will incorporate results from the laboratory and field, and be used to test hypotheses.
Validated models that incorporate the greater complexity outlined above will form the basis of the production of a national scale map of the forecasted capacity reduction of transport networks due to slope instability caused by climate effects at several future time slices. In turn, the models will enable testing of the benefits of different stability and maintenance solutions under a changing climate regime and thus enable development of robust adaptation strategies in conjunction with a formal stakeholder dialogue.