Comment on “Groundwater Affects the Geomorphic and Hydrologic Properties of Coevolved Landscapes” by Litwin et al.

The objective of this comment is to correct two sets of statements in Litwin et al. (2022, https://doi.org/10.1029/2021JF006239), which consider our research work (Bonetti et al., 2018, https://doi.org/10.1098/rspa.2017.0693; Bonetti et al., 2020, https://doi.org/10.1073/pnas.1911817117). We clarify here that (a) the specific contributing area is defined in the limit of an infinitesimal contour length instead of the product of a reference contour width (Bonetti et al., 2018, https://doi.org/10.1098/rspa.2017.0693), and (b) not all solutions obtained from the minimalist landscape evolution model of Bonetti et al. (2020, https://doi.org/10.1073/pnas.1911817117) are rescaled copies of each other. We take this opportunity to demonstrate that the boundary conditions impact the obtained solutions, which has not been considered in the dimensional analysis of Litwin et al. (2022, https://doi.org/10.1029/2021JF006239). We clarify this point by using dimensional analysis and numerical simulations for a square domain, where only one horizontal length scale (the side length l) enters the physical law.