An anisotropic flow-routing algorithm for digital elevation models

Tillage operations produce systematic small-scale surface roughness which is generally not visible in digital elevation models, but which nonetheless may significantly modify the runoff patterns in cultivated areas. Commonly used flow-routing algorithms which direct the flow towards the steepest slope are not able to describe the effect of tillage-induced roughness. We introduce a flow-routing algorithm which accounts for anisotropic roughness resulting from tillage and then use it as a part of a USLE-type erosion model in order to study the effect of tillage direction on soil loss. The model is first calibrated against the results from a long-term field experiment. Results from a test case are then used to demonstrate the utilization of the model with a complicated land surface topography.