Earth Surf. Dynam., 6, 1–27, 2018 https://doi.org/10.5194/esurf-6-1-2018 © Author(s) 2018. This work is distributed under the Creative Commons Attribution 3.0 License. Developing and exploring a theory for the lateral erosion of bedrock channels for use in landscape evolution models Abigail L. Langston1 and Gregory E. Tucker2,3 1Department of Geography, Kansas State University, Manhattan, KS, USA 2Cooperative Institute for Research in Environmental Sciences (CIRES), University of Colorado, Boulder, CO, USA 3Department of Geological Sciences, University of Colorado, Boulder, CO, USA Correspondence: Abigail L. Langston (
[email protected]) Received: 2 May 2017 – Discussion started: 8 May 2017 Revised: 6 November 2017 – Accepted: 14 November 2017 – Published: 8 January 2018 Abstract. Understanding how a bedrock river erodes its banks laterally is a frontier in geomorphology. Theories for the vertical incision of bedrock channels are widely implemented in the current generation of landscape evolution models. However, in general existing models do not seek to implement the lateral migration of bedrock channel walls. This is problematic, as modeling geomorphic processes such as terrace formation and hillslope– channel coupling depends on the accurate simulation of valley widening. We have developed and implemented a theory for the lateral migration of bedrock channel walls in a catchment-scale landscape evolution model. Two model formulations are presented, one representing the slow process of widening a bedrock canyon and the other representing undercutting, slumping, and rapid downstream sediment transport that occurs in softer bedrock. Model experiments were run with a range of values for bedrock erodibility and tendency towards transport- or detachment-limited behavior and varying magnitudes of sediment flux and water discharge in order to determine the role that each plays in the development of wide bedrock valleys.