WADNR Roads Project Distributed Model

Updated: 09/24/2025

Summary

This repository contains drivers for testing and tutorials for learning the distributed roads model components that are being developed/are already developed in Landlab.

Model component descriptions

First component: TruckPassErosion

Calculates sediment depths for forest road cross section layers based on traffic-induced, erosion-enhancing processes: pumping, crushing, scattering (and by default, flow rerouting). This is a net-zero component (i.e., the mass balance for the whole system is 0).

References

Alvis, A. D., Luce, C. H., & Istanbulluoglu, E. (2023). How does traffic affect erosion of unpaved forest roads? Environmental Reviews, 31(1), 182–194. https://doi.org/10.1139/er-2022-0032

Second component: FlowAccumulator or KinwaveImplicitOverlandFlow

Routes flow over the forest road surface. Which component is chosen depends on the timestep of rainfall/runoff being fed to the model. FlowAccumulator works best for a coarser timestep, whereas KinwaveImplicitOverlandFlow works best for a finer timestep. However, FlowAccumulator is a much faster flow router than KinwaveImplicitOverlandFlow.

Third component: FastscapeEroder

Erodes the landscape based on a stream power framework. The erosion of each node is based on an erosivity value, the contributing drainage area (or flow, depending on how the component is initialized), and the slope. A future iteration of this spatially distributed model will use a different erosion component based on slightly different variables (such as roughness).

Third component (update): OverlandFlowTransporter

Erodes a surface with shallow overland flow using physics-based formulations for entrainment and transport that can directly use sediment size distribution and surface roughness. The sediment transport rate is calculated using Govers' equation (1992) with shear stress partitioning

Repository navigation

Main folder

1. test_driver.py is a script used to test the model components (TruckPassErosion, FlowAccumulator, FastscapeEroder) and how they work together.

   • Input: Model parameters.
   • Output: Plots of average road layer depths vs. time and erosion vs. time.

2. test.py is a script used to test the model components (TruckPassErosion, FlowAccumulator, OverlandFlowTransporter) and how they work together.

   • Input: Model parameters.
   • Output: Sediment load from road and ditch line, as well as a number of plots demonstrating different outputs from the model.

3. group_rainfall.py is a utilitarian script used to aggregate hourly rainfall into daily rainfall.

   • Input: Hourly rainfall data.
   • Output: Aggregated daily rainfall data.

tutorials

1. TruckPassErosion_tutorial.ipynb is a Jupyter notebook that demonstrates the utility of the newly developed TruckPassErosion component. together.
   • Input: Model parameters.
   • Output: Plots of road layer cross sections and road surface.
2. FlowRouting_tutorial.ipynb is a Jupyter notebook that demonstrates how to use either FlowAccumulator or KinwaveImplicitOverlandFlow.
   • Input: A pre-rutted grid (rutted_grid.grid).
   • Output: Maps of surface water discharge.
3. FullModel_tutorial.ipynb is a Jupyter notebook that demonstrates how to run the full distributed model (including FastscapeEroder).
   • Input: Necessary model parameters.
   • Output: Maps of surface water discharge, plots of average road layer depths vs. time, and erosion vs. time.