Rusteau-1D Help
Reference

Questions and problems

The calculation stops: the iteration does not converge

The Richards equation is strongly non-linear; convergence problems usually have one of these causes:

  • Unrealistic or extreme hydraulic parameters, e.g. n close to 1 with a large α, or very contrasting layers. Check θ(h) and K(h) on the page Soil hydraulic properties. For fine soils try the van Genuchten model with an air-entry value of −2 cm.
  • Infiltration into very dry soil or sudden ponding: use a smaller initial time step and minimum time step, a finer mesh near the surface (discretization), or more iterations (iteration criteria).
  • Inconsistent initial and boundary conditions, e.g. a constant head at the surface very different from the initial head of the top node.
  • Too large hCritA with a coarse mesh at the surface during strong evaporation.

Raising the maximum number of iterations (e.g. to 20) and lowering dtMin often helps; check the time steps on the page Run-time information.

The mass balance error is large

Look at the relative error WatBalR on the page Mass balance. Reduce dtMax, tighten the water content tolerance (e.g. 0.0001), and refine the mesh where the gradients are large. Errors of a few per cent in the first time steps of a run that ends with a small error are usually harmless.

Concentrations oscillate or become negative

The grid Peclet or Courant number is too large (discretization). Refine the mesh, reduce dtMax, switch on artificial dispersion or upstream weighting, or use ε = 1 (implicit) (Solute transport: general).

The results differ from HYDRUS-1D

For the HYDRUS-1D examples the differences are documented (relation to HYDRUS-1D). Small differences come from the single precision of HYDRUS near the iteration tolerances; tightening the tolerances in both programs makes them agree better.

The actual transpiration is smaller than the potential one

Water or osmotic stress reduces the uptake (root water uptake); compensated uptake (ωc < 1) reduces the effect. Also check that the root distribution is not zero and that the roots reach the moist soil.

The run is slow

Long simulations with small time steps (frequent rain, dry soil, fine mesh) take longer. Reduce the number of print times and use Short output; thin the time-level output (Store time-level info every n-th step). Parameter estimation runs the model many times; fewer starting points speed it up.

The program stopped unexpectedly

An internal error while drawing a page or a figure shows a message in place of the page (Try again draws it again); an internal error of a calculation ends the run with a message in the status bar. Every such error is written with its details to the crash log crash.log in the folder Rusteau-1D of the user data (Windows: %LOCALAPPDATA%\Rusteau-1D, Linux: ~/.local/share/Rusteau-1D, macOS: ~/Library/Application Support/Rusteau-1D); please add it to a report.

A project with unsaved changes is copied to recovery.h1dr in the same folder, at most once a minute and only when it changed since the last copy; the file always holds the latest state only. Saving the project (or closing the program normally) removes the copy. If the program did not close normally, the next start offers to open this copy (Open the copy) or to discard it. Save the recovered project under a name of your choice.

No file dialog appears (Linux)

Rusteau uses the file dialogs of the system: on Windows and macOS their own, on Linux the dialog of the desktop through the XDG desktop portal (installed with GNOME, KDE and most other desktops) or, without it, zenity. Without either, Rusteau shows its own simple file browser. If the dialog of the desktop does not appear, start the program with the built-in browser: RUSTEAU_FILE_DIALOG=builtin ./rusteau.

Where are the results stored?

In memory with the project. Use File → Export results (CSV)… to write them (output files).

How do I make a figure for a paper or a presentation?

Open the figure editor (Results → 📈 Figures), start from a template, set the size to the column width of the journal (e.g. 85 or 170 mm), add axis titles with units (markup such as cm^{3} cm^{−3}), and export a PNG at 300 dpi or an SVG. To compare scenarios, keep the results of each run (comparison of runs).

How do I cite the methods?

The help topics cite the publications behind every calculation; the topic References lists all of them, each with what Rusteau bases on it. For the numerical methods cite the HYDRUS-1D manual Šimůnek et al. (2009); Šimůnek et al. (2013).

Literature cited in this topic

  • Šimůnek, J., M. Šejna, H. Saito, M. Sakai, and M. Th. van Genuchten (2009). The HYDRUS-1D Software Package for Simulating the One-Dimensional Movement of Water, Heat, and Multiple Solutes in Variably-Saturated Media, Version 4.08. HYDRUS Software Series 3, Department of Environmental Sciences, University of California Riverside, Riverside, CA, USA, 330 pp. https://www.pc-progress.com/en/Default.aspx?h1d-description
  • Šimůnek, J., M. Šejna, H. Saito, M. Sakai, and M. Th. van Genuchten (2013). The HYDRUS-1D Software Package for Simulating the One-Dimensional Movement of Water, Heat, and Multiple Solutes in Variably-Saturated Media, Version 4.17. HYDRUS Software Series 3, Department of Environmental Sciences, University of California Riverside, Riverside, CA, USA, 307 pp. https://www.pc-progress.com/en/Default.aspx?hydrus-1d

All sources: References.