Rusteau-1D Help
Introduction

Getting started

This topic walks through a first simulation with the built-in example Infiltration & evaporation with roots: a 1 m profile of loam over sand, with rain, evaporation and root water uptake over 30 days. It is the project shown when the program starts.

1. Open the example

Start Rusteau-1D. The example is loaded already; otherwise choose File → Examples → Infiltration & evaporation with roots. The navigation panel on the left lists the input pages in five steps and the results pages below them (main window).

2. Look at the project

  • Processes & units: water flow and root water uptake are switched on; lengths in cm, times in days (Processes & units).
  • Time & output: 0 to 30 days, print times every 5 days (Time & output).
  • Soil → Hydraulic model: van Genuchten–Mualem without hysteresis (Soil hydraulic model).
  • Soil → Materials & parameters: material 1 Loam and material 2 Sand with the catalog values of Carsel and Parrish (1988); the retention curve θ(h) and the conductivity K(h) are drawn below the table (Materials & parameters).
  • Soil → Soil profile: 101 nodes over 100 cm; loam down to 50 cm, sand below; an initial pressure head of −200 cm in the loam and −80 cm in the sand; roots in the upper 30 cm; observation nodes at 20, 50 and 100 cm (soil profile editor).
  • Boundary conditions → Water flow: atmospheric boundary condition with surface runoff at the top, free drainage at the bottom (Water flow boundary conditions).
  • Boundary conditions → Time-variable data: six records of precipitation, potential evaporation and potential transpiration (Time-variable boundary data).
  • Uptake & transport → Root water & solute uptake: the Feddes stress function Feddes et al. (1978) (Root water uptake).

Rest the mouse on any input to see what it means; press F1 for the help of the page.

3. Run the calculation

Press F5, click ▶ Run at the top right, or go to Run → Check & run. The page Check & run lists problems of the input (e.g. a material with θs ≤ θr) before anything is computed (Check & run). During the run the status bar shows the progress; ■ Stop cancels it and keeps the partial results.

4. Look at the results

When the run has finished, the page Profiles opens:

  • Profiles: pressure head, water content, fluxes, root water uptake … against depth at the print times (Profiles).
  • Observation points: the same quantities against time at the observation nodes (Observation points).
  • Boundary fluxes & heads: actual and potential surface fluxes, bottom flux, transpiration, cumulative values (Boundary fluxes).
  • Mass balance: the water balance error of the run (Mass balance).

File → Export results (CSV)… writes all tables as CSV files for further analysis (Output files).

5. Change something and compare

For example, set the potential transpiration of the third record to 1 cm/d on the page Time-variable data, run again (F5) and look at the root water uptake on the page Boundary fluxes & heads: the actual transpiration stays below the potential one when the soil dries (water stress).

Next steps

  • Start a new project with File → New project (Ctrl+N) and follow the workflow.
  • Import a HYDRUS-1D project with File → Open project or by dragging its folder onto the window (Projects).
  • Try the other examples: solute transport and two parameter-estimation problems.

Literature cited in this topic

  • Carsel, R. F., and R. S. Parrish (1988). Developing joint probability distributions of soil water retention characteristics. Water Resources Research 24(5): 755–769. doi:10.1029/WR024i005p00755
  • Feddes, R. A., P. J. Kowalik, and H. Zaradny (1978). Simulation of Field Water Use and Crop Yield. Simulation Monographs, Pudoc, Wageningen, 189 pp.

All sources: References.