PHYSICALLY-BASED MODELING OF SHALLOW LANDSLIDE SEDIMENT YIELD AT A CATCHMENT SCALE

A shallow landslide erosion and sediment yield component, applicable a t the basin scale, has been incorporated into the physically based, sp atially distributed, hydrological and sediment transport modelling sys tem, SHETRAN. The component determines when and where landslides occur in a basin in response to time-varying rainfall and snowmelt, the vol ume of material eroded and released for onward transport, and the impa ct on basin sediment yield. Derived relationships are used to link the SHETRAN grid resolution (up to 1 km), at which the basin hydrology an d final sediment yield is modelled, to a subgrid resolution (typically around 10-100 m) at which landslide occurrence and erosion is modelle d. The subgrid discretization, landslide susceptibility and potential landslide impact are determined in advance using a geographic informat ion system (GIS), with SHETRAN then providing information on temporal variation in the factors controlling landsliding. The ability to simul ate landslide sediment yield is demonstrated by a hypothetical applica tion based on a catchment in Scotland.