The effects of lithology and base level on topography in the northern alpine foreland

• Published in: Geomorphology (Amsterdam, Netherlands) Vol. 313; pp. 13 - 26
• Main Authors: Baumann, Sebastian, Robl, Jörg, Prasicek, Günther, Salcher, Bernhard, Keil, Melanie
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 15-07-2018
• Subjects: Base level; Channel metrics; Fluvial erosion; Hillslope processes; Landsliding; Lithology-dependence; Molasse basin; Molasse basin; Hillslope processes; Base level; Lithology-dependence; Landsliding; Channel metrics; Fluvial erosion
• ISSN: 0169-555X; 1872-695X
• DOI: 10.1016/j.geomorph.2018.04.006

The evolution of topography is driven by climate and tectonics, and strongly influenced by substrate properties and different base levels. The contributions of these factors may vary in space and time and are thus difficult to disentangle. Our study area, the Hausruck-Kobernaußerwald range, has a rather uniform climatic and tectonic history but is drained by rivers with different base levels and consists of contrasting sedimentary rocks, mainly due to different sedimentation environments. This makes them an ideal location to study the effects of lithology and base level on topography.
To decipher the roles of these influences, we used a high-resolution digital elevation model and performed a series of morphometric analyses. Longitudinal river profiles indicate that all channels in the study area, independent from base level, bed rock and overall morphological expression, are well graded. Hypsometry shows no evidence for base level effects on the present topography, while variations in the hypsometric curves coincide with lithological differences. This is also reflected in contrasts of mean elevation and slope distributions. Lithology-dependent variations in channel concavity and catchment-wide hypsometric integrals show that lithology controls both channel incision and hillslope processes in the study area. Our results further indicate that variations in channel and catchment metrics are not linked to the prevalence of different rock types alone, but to different successions of lithological units along the channels and within the catchments. Variations in channel slope and geomorphological mapping suggest that lithology-dependent landsliding is the dominant process causing the observed large-scale landscape diversity in the Hausruck-Kobernaußerwald range.
•The Hausruck-Kobernaußerwald Range shows increasing landscape dissection from W to E.•The sedimentary succession is characterised by decreasing grain size from W to E.•Landslide mapping indicates a strong link between grain size and landslide frequency.•The shape of hillslopes and fluvial channels correlates with substrate properties.•Landsliding is the primarily control for landscape diversity in the study region.