expensive maintenance of protection systems and artificial control of sediment supply for restoration purposes)? Hence, concerning sediment continuity a fundamental and intentionally strongly polarized management question might be posed: Reactivating sediment supply to the main stream network and bearing the arising risk costs, or retaining sediments and bearing the costs to sustain the functionality of the system (i.e. In parallel, on several debris cones and alluvial fans a clear increasing tendency of wealth moving into flood prone areas could be retraced over the last decades, leading to a possible net exacerbation of risk. On the contrary, it is ascertained that, without releasing sediments either from their sources or from their intermediate deposits and without maintaining sediment connectivity throughout the stream network, the reactivation of hydro-morphological and the associated ecological functionalities is physically unfeasible for supply-limited and highly altered mountain rivers. Preventing the release of sediments from their sources in mountain catchments, stabilizing the streambeds through the realization of grade control structures and retaining solid material volumes transported during extreme events are widespread strategies to reduce risks in mountain areas.

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