A modelling framework for flow and cohesive sediment transport in wildfire impacted watersheds: Implications for reservoir management

Large scale land disturbance by wildfire can have a significant and prolonged effect on the source, transport and fate of sediment and associated contaminants in watersheds. The downstream propagation of fine sediment and associated contaminants from these impacted watersheds to reservoirs can degrade water quality and increase water treatment and supply costs. Here, we present a framework that integrates four existing models (MOBED, RIVFLOC, RMA2, RMA4) to describe flow and cohesive sediment transport dynamics in wildfire impacted headwater streams of the Oldman River and the Oldman Reservoir located in southern Alberta, Canada. Historical flow and sediment data from burned and unburned watersheds are used to contrast the impacts of wildfire on sediment generation and downstream propagation to reservoirs with those of reference catchments. Utility of the framework for assessing land use scenarios and its relevance as a tool for reservoir management and catchment planning decision support are discussed.