Strong Variability of Detrital 10 Be-based Denudation Rates in relation to Catchment Size and Landscape Morphometry at the Northern Margin of the European Alps

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Abstract
Cosmogenic ¹⁰Be-based denudation rates have been widely used to explore potential controls on erosion such as tectonic uplift, periglacial conditions, precipitation gradients, bedrock erodibility, landslides, and hillslope morphology. However, there is a strong scale-dependency of the rates and the rate variability, particularly at the margin of mountain belts. Here, we explore such a scale dependency along a NW-SE section from the northern margin to the core of the Central European Alps. We present ¹⁰Be-derived denudation rates from 16 nested sub-catchments (2–340 km²) that we complement with 45 published ¹⁰Be concentrations, thereby covering the full range in scale and landscape properites that can be found at the margin of a mountain belt. We find that on a regional scale, the denudation rates strongly correlate with surface uplift, mean elevation and hillslope relief, but not with precipitation. Yet for basins that are smaller than 50 km 2 , the denudation rates start to show a large variability deviating from the spatial trend, reflecting various controls. The variability in denudation rates becomes larger towards the core of the Alps where the uplift rates are high. Accordingly, uplift rates – and thus geodynamic processes – appear to exert the first-order controls on the denudation rate pattern and the landscape properties at the scale of the northern margin of the Central European Alps. Yet superimposed on this trend, we find that the variability in the landscape properties and the variability in the denudation rates become larger as the uplift rates increase and the studied basins becomes smaller.