Debris Flow Hazard and Risk on the Scottish Road Network in a Changing Climate

When rainfall-induced, debris flow landslides affect the Scottish strategic road network, the degree of damage to the infrastructure and the loss of utility to road users can have a major detrimental effect on both economic and social aspects of the use of the asset, and even small events may cast an extensive vulnerability shadow. The regional hazard and risk assessment that was undertaken following events in August 2004 to inform the process of allocating budgets and targeting works to the highest risk areas is described. The management and mitigation strategy that was developed is also described, a crucial element of this is the ongoing development of a rainfall trigger threshold to indicate conditions likely to produce debris-flow activity. The triggering of such debris flow events in the context of the historic and recent climate of Scotland is examined. Predicted changes to climate and their likely effect on landslide hazard and risk are also discussed.