Cascading processes in a changing environment: Disturbances on fluvial ecosystems in Chile and implications for hazard and risk management

The compound hazard effects of multiple process cascades severely affect Chilean river systems and result in a large variety of disturbances on their ecosystems and alterations of their hydromorphologic regimes leading to extreme impacts on society, environment and infrastructure. The acute, neo-tectonically pre-determined susceptibility to seismic hazards, thewidespread volcanic activity, the increasing glacier retreat and the continuous exposure to forest fires clearly disturb entire riverine systems and concur to trigger severe floods hazards. With the objective to refine the understanding of such cascading processes and to prospect feasible flood riskmanagement strategies in such a rapidly changing environment we first classify the large river basins according to a set of disturbances (i.e. volcanic eruptions, earthquakes, glacier lake outburst floods, wild fires and mass movements). Then, we describe emblematic cases of process cascades which affected specific Chilean drainage basins and resulted in high losses as tangible examples of how the cascading processes may unfold in other river basins with similar characteristics. As an attempt to enrich the debate among management authorities and academia in Chile, and elsewhere, on how to sustainably manage river systems, we: a) highlight the pivotal need to determine the possible process cascades that may profoundly alter the system and b) we suggest to refine hazard and risk assessments accordingly, accounting for the current and future exposure. We advocate, finally, for the adoption of holistic approaches promoting anticipatory adaptation which may result in resilient system responses.