Dynamic river catchments in a Global Change context: assessing the present, preparing for the future

In a Global Changing world sediment regime has emerged as a dominant actor in the modification of river catchments. The sediment regime refers to the sediment budget (amount, type and timing of sediment inputs, outputs and storage) of a river system as well as the way water and sediment interact to drive river conditions. Studies of sediment regime assessing the impact of Global Change are scarce and traditionally relies on deterministic approaches. However, at any given river catchment section, a complex imprint in the spatial-temporal distribution of sediment regime is observed. This imprint is caused by the temporal and spatial uneven production, storage activation and transport of sediments. Pure deterministic (and thus partial) solutions are not accounting for the natural variability of sediment regime and the inherent uncertainty due to Global Change. This means we are potentially missing half the story and that our attempts to forecast the current and future evolution of rivers areas, at both catchment- and reach-scale, may be more wrong than right. The tenet of this proposal is to describe and determine the Global Change impacts on sediment fluxes at all scales relevant for river catchment management by means of a modelling approach that can account for natural stochasticity and Global Change uncertainty. Three main and novel research questions have been identified and need to be addressed: (i) how (and how strongly) the headwaters control the main features of sediment regime; (ii) how to model sediment fluxes by means of a forecasting model capable to reproduce fluctuating (and thus realistic) sediment regime characteristics; and (iii) how to identify and incorporate the Global Change impacts on sediment regime modelling to assist in fostering a more robust river catchment management. This proposal contributes to the 13th UN Global Goal “Climate Change” and to the Horizon Europe mission: “Adaptation to Climate Change including Societal Transformation”.