Climate change scenarios indicate an increase in extreme precipitation events. Hazardous debris flow activity is therefore expected to increase in future. To assess debris flow hazard in a changing climate it is necessary to understand how changing precipitation amounts influence the dynamics of debris flows, including the erosion of mountain torrents. The effect of changing precipitation is to influence the initial mass composition and therefore the fluid saturation of the flow (ratio of fluid and solid mass). In this research we will focus our attention on the influence of fluid saturation on debris flow runout and inundation. Our goal is to determine how changing magnitude and frequency of events will affect debris flow hazard planning. In this project a numerical model to simulate fully and partially saturated flows will be developed. In order to consider different fluid saturation levels, we will develop a two-phase model including torrent erosion.