Sensitivity of Escarpment Evolution to Lithology and Climate Forcing: Forward Landscape Evolution Study from the Swabian Alb

Escarpment landscapes represent prominent geomorphic boundaries that result from the long-term interaction of tectonic uplift, climate induced surface processes and lithological diversity over the one million timescales. However, quantifying the relative contribution of each factor remains challenging over such long periods. Process-based landscape evolution models provide these controls to be isolated and systematically tested under regulated conditions.
In this study, we use forward numerical landscape evolution simulations to investigate the sensitivity of escarpment evolution in the Swabian Alb
(southwestern Germany). We employ the Landlab modeling tools to simulate landscape transformations over approximately 1 Myr. Fluvial incision is
represented using a detachment-limited stream-power model, while hillslope sediment transport is depicted as diffusive smoothing. Spatially variable uplift is utilized to model long-term tectonic forces. Lithological heterogeneity is characterized by stratified layers exhibiting regionally diverse erodibility
coefficients, guided by channel steepness metrics that are commonly used to evaluate geographical discrepancies in river incision potential. Sensitivity studies examine different precipitation/runoff forcing scenarios to evaluate how climatic forcing changes erosion patterns compared with lithological controls.
Model results indicate that erosion and escarpment retreat are markedly concentrated along the Albtrauf escarpment facing tributaries of neckar and the primary river, but the core of the Swabian Alb plateau remains reasonably intact throughout the 1 million-year simulations. In the basic arrangement, high-erosion zones (≥P80) encompass a significant area of the escarpment domain but only a small section of the plateau. Sensitivity experiments indicate that variations in lithology significantly influence the magnitude and duration of erosion hotspots. They may improve hotspot coverage by up to as 10–12 percentage points relative to the basic model in some catchments however changes in uplift rate create very minor changes. Increasing precipitation significantly raises erosion level, however hardly influences the dimensions of hotspots. This indicates that climate mostly exacerbates erosion rather than altering its spatial distribution.

Reorganizing drainage by relocating divisions and trapping water locally
enhances incision concentration within existing channel networks. This results in
the gradual erosion of escarpments over an million timescale.