Non-universality in the erosion of tilted landscapes

The anisotropic model for landscapes erosion proposed by Pastor-Satorras and Rothman in [R. Pastor-Satorras and D. H. Rothman, Phys. Rev. Lett. 80, 4349 (1998)] is believed to capture the physics of erosion at intermediate length scale ($\lesssim3$ km), and to account for the large value of the roughness exponent $\alpha$ observed in real data at this scale. Our study of this model -- conducted using the nonperturbative renormalization group (NPRG) -- concludes on the nonuniversality of this exponent because of the existence of a line of fixed points. Thus the roughness exponent depends (weakly) on the details of the soil and the erosion mechanisms. We conjecture that this feature, while preserving the generic scaling observed in real data, could explain the wide spectrum of values of $\alpha$ measured for natural landscapes.