A novel debris-flow fan evolution model based on debris flow monitoring and LIDAR topography

Abstract

In this paper we present the rationale for a new approach to the modelling of debris-flow fans. Understanding debris-flow fan evolution is important for two reasons: fans are potential archives of past environmental conditions of mountain belts, and they are commonly inhabited despite the threat of debris flow occurrence. There are currently no models available that adequately represent debris flows as agents of geomorphic landscape change over the time scales (103 to 106 y) necessary to construct fans, which severely limits our ability to understand both short-and long-term fan behaviour. We describe in detail how results from debris flow monitoring, LiDAR topography and geomorphic mapping of debris ow fans, together with empirical relationships on debris flow behaviour, can be used to inform a novel debris- flow fan evolution model. The model we propose will be useful for both the analysis of long-term fan evolution and hazard analysis over short to medium time scales.