Debris flows are a significant hazard to people and infrastructure in many mountainous areas. Quantification of intensity and spatial distribution of this hazard, however, remains challenging. This is due to the often-encountered lack of high-resolution spatial and temporal data and the complexity and wide-range of processes involved. This applies to current climatic conditions, but especially for future conditions where uncertainty in extreme precipitation and sediment availability is even larger. We present the outline of a national-scale, GIS-based approach to assess debris flow disposition with a statistical model under current extreme precipitation conditions and the best available estimates for 2065 and 2080 extreme precipitation and sediment loads. Debris flow disposition is assessed using properties derived from delineation of channels and their corresponding upstream contributing area, based on high spatial resolution (1m) elevation data. The disposition model is trained on a combination of available Swiss debris flow databases (such as StorMe). Runout is computed from disposition areas with calibrated RAMMS:Debrisflow software. Our method is applied to the network of the Swiss national railway (SBB) and results in a spatially distributed maximum debris-flow height. The results indicate sections of the railway network that are prone to debris flow hazard and serve as input to a risk assessment for the SBB. By adapting this approach, it could be applied also in other regions in the Alps and worldwide.