In general, it is expected that future erosion processes (both glacial and non-glacial) will be comparable to those prevalent during the Quaternary with a few exceptions:
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The fluvial incision rates are predicted to be lower because the main pulse of incision caused by large-scale drainage reorganisation has diminished (Section 6.4.1.2).
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The most important variations between aggradation and incision periods are expected to be caused by future glacial/interglacial cycles. The long-term incision driven by vertical motion of the rock column will thus be modulated by phases of sediment accumulation with no net vertical incision, comparable Quaternary evolution (Section 6.4.1.2).
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The next glacial inception might be delayed because of the anthropogenic atmospheric CO2 content (Section 6.3.3).
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The stratigraphic column above the repository sites NL and ZNO contains harder-to-erode rock types (limestones of the Malm) compared to the Molasse, which is currently the outcropping lithology at these sites (Fig. 6‑27, see Sections 6.4.1.4 and 6.4.2.1).
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In addition, further erosional downcutting might decrease the accumulation area of future glaciers, which in turn might result in smaller glacial extents, even with similar climate forcing (Egholm 2022). On the other hand, as a result of the drainage divide shift between Rhine and Danube, the Rhine Glacier might undergo a westward shift with less ice being able to cross the divide and drain towards the Danube (Ellwanger et al. 2011), which in turn might increase the erosion potential in the study area.
For the future erosion assessment, evidence from Quaternary landscape evolution together with process understanding was used to derive probability distributions for the parameters to be applied in the modelling (see Section 6.4.2.3 for a brief overview on expert elicitation). An overview of the main results and associated line of reasoning for each separate erosion process (i.e. model part) is presented in this section. More details are provided in Nagra (2024k).