Preprints
https://doi.org/10.5194/egusphere-2022-605
https://doi.org/10.5194/egusphere-2022-605
 
25 Jul 2022
25 Jul 2022
Status: this preprint is open for discussion.

Self-organization of channels and hillslopes in models of fluvial landform evolution

Stefan Hergarten and Alexa Pietrek Stefan Hergarten and Alexa Pietrek
  • Institut für Geo- und Umweltnaturwissenschaften, Albert-Ludwigs-Universität Freiburg, Albertstr. 23B, 79104 Freiburg, Germany

Abstract. Including hillslope processes in models of fluvial landform evolution is still challenging. Since applying the respective models for fluvial and hillslope processes to the entire domain causes scaling problems and makes the results dependent on the spatial resolution, the domain is explicitly subdivided into channels and hillslopes in some models. The transition from hillslopes to channels is typically attributed to a given threshold catchment size as a proxy for a minimum required discharge. Here we propose a complementary approach for delineating channels based on the discrete representation of the topography. We assume that sites with only one lower neighbor are channelized. In combination with a suitable model for hillslope processes, this concept initiates a self-organization of channels and hillslopes. A numerical analysis with a simple model for hillslope dynamics reveals no scaling issues, so that the results appear to be independent of the spatial resolution. The approach predicts a break in slope in the sense that all channels are distinctly less steep than hillslopes. On a regular lattice, the simple D8 flow routing scheme (steepest descent among the 8 nearest and diagonal neighbors) harmonizes well with the concept proposed here. The D8 scheme works well even when applied to the hillslopes. This property simplifies the numerical implementation and increases its efficiency.

Stefan Hergarten and Alexa Pietrek

Status: open (until 05 Sep 2022)

Comment types: AC – author | RC – referee | CC – community | EC – editor | CEC – chief editor | : Report abuse

Stefan Hergarten and Alexa Pietrek

Model code and software

Self-organization of channels and hillslopes Stefan Hergarten https://doi.org/10.5281/zenodo.6794117

Stefan Hergarten and Alexa Pietrek

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Short summary
The transition from hillslopes to channelized flow is typically attributed to a threshold catchment size in landform evolution models. Here we propose an alternative concept directly based on topography. Using this concept, channels and hillslopes self-organize, whereby the catchment size of the channel heads varies over some range. Our numerical results suggest that this concept works better than the established idea of a strict threshold catchment size.