Conceptual framework for sediment management in torrents

Abstract

Torrential catchments are complex systems showing a huge diversity of sediment and flow regime reactions. Therefore, it seems reasonable to decrease the complexity by introducing a conceptual framework to obtain a general idea of the torrential system's behavior. The aim of the manuscript is to provide a conceptual framework and a stepwise procedure to develop a reproducible sediment management concept. This involves starting with a definition of torrential process types. These processes are then routed through the drainage system, which is divided into homogeneous reaches. Each reach transfers a flow process from the upstream node to the adjacent downstream reach, based on driving geomorphic factors of sediment mobilization and deposition. Additionally, a sediment budget, derived from cumulative erosion and deposition volumes, is calculated. The estimated flow process together with the sediment budget enables the selection of a sediment management strategy. The implementation of the strategy is based upon the selection of functions, which define the desired modification with regard to the torrential system. Ultimately, the sum of each function's performance must lead to the fulfilment of the overall protection objective.