Tutorial 3.03
Furrow infiltration with a solute pulse
Video (47 MB) - Download
Download Project Furrow.zip (0,6 MB)
The third example considers alternate furrow irrigation into a soil profile with a subsurface drain. Water infiltration is evaluated for 100 days, with a solute pulse being added to the irrigation water during the first 50 days. The soil profile is 1 m deep with furrows 3 m apart; the drain is located in the middle between the two furrows at a depth of 75 cm. Alternate furrow irrigation is initiated by ponding the left furrow; mathematically this is accomplished using a constant pressure head boundary condition. The drain is represented by a circle to which a seepage face boundary condition is applied. Users become in this example more familiar with the basic concepts of transport domain design in the graphical environment of HYDRUS, including how to numerically define boundary objects, and again with boundaries and domain discretization. Initial and boundary conditions are specified, and graphical displays of the results using contour and spectrum maps, including animation, are provided, for a more complex transport domain than in the previous example.
Project Manager (File->Project Manager)
Button “New”
New Project (or File->New Project)
Name: Furrow
Description: Furrow irrigation with solute pulse
Working Directory: Temporary – is deleted after closing the project
Button “Next”
Geometry Information (Edit->Domain Geometry->Geometry Information)
Type of Geometry: 2D Vertical Plane
Domain Definition: General
Units: cm
Initial Workspace: Xmin=-50 cm, Xmax=350 cm, Zmin=-50 cm, Zmax=150 cm (to accommodate the transport domain)
Button “Next”
Main Processes (Edit->Flow and Transport Parameters->Main Processes)
Check Box: Water Flow and Solute Transport
Button “Next”
Time Information (Edit->Flow and Transport Parameters->Time Information)
Time Units: days
Final Time: 100
Initial Time Step: 0.01
Minimum Time Step: 0.001
Maximum Time Step: 5
Button “Next”
Output Information (Edit->Flow and Transport Parameters->Output Information)
Print Options:
Check T-Level Information
Check Screen Output
Check Press Enter at the End
Print Times: Count: 18
Print Times: 0.5, 1, 2.5, 5 10, 20, 30, 40, 50, 50.5, 51, 52.5, 55, 60, 70, 80, 90, 100
Update
Button “Next”
Water Flow - Iteration Criteria (Edit->Flow and Transport Parameters->Water Flow Parameters->Output Information)
Leave default values as follows:
Maximum Number of Iterations: 10
Water Content Tolerance: 0.001
Pressure Head Tolerance: 1
Lower Optimal Iteration Range: 3
Upper Optimal Iteration Range: 7
Lower Time Step Multiplication Factor: 1.3
Upper Time Step Multiplication Factor: 0.7
Lower Limit of the Tension Interval: 0.0001
Upper Limit of the Tension Interval: 10000
Initial Condition: In the Pressure Head
Button “Next”
Water Flow - Soil Hydraulic Model (Edit->Flow and Transport Parameters->Water Flow Parameters ->Soil Hydraulic Model)
Radio button - van Genuchten-Mualem
Radio button - No hysteresis
Button “Next”
Water Flow - Soil Hydraulic Parameters (Edit->Flow and Transport Parameters->Water Flow Parameters ->Soil Hydraulic Parameters)
Leave default values for silt
Explore Catalog of Soil Hydraulic Properties and Neural Network Predictions
Button “Next”
Solute Transport – General Info (Edit->Flow and Transport Parameters->Solute Transport Parameters->General Information)
Leave default values except
Select GFE with artificial dispersion
Pulse Duration = 50 d
Button “Next”
Solute Transport - Solute Transport Parameters
Leave the default values
Bulk Density = 1.5 cm3/g
Disp.L == 1 cm
Disp.T = 0.1 cm
Diff.W=10 cm2/d
Button “Next”
Solute Transport - Transport Parameters
Leave the default values for tracer
Note that cBnd in Boundary Conditions is equal to 1 (this is boundary concentration)
Button “Next”
FE-Mesh - FE-Mesh Generator (Edit->FE-Mesh->FE-Mesh Generator)
Radio button - Meshgen
Button “Next”
FE-Mesh - FE-Mesh Parameters (Edit->FE-Mesh->FE-Mesh Parameters)
Targeted FE – Size – Unselect Automatic and specify TS = 10 cm
Button “OK”
Definition of the Transport Geometry
Click on Grid and Work Plane Setting at the toolbar (or Tools->Grid and Work Plane)
Grid Point Spacing – Distance w = 20 cm, Distance h = 20 cm
Click on Snap to Grid at the toolbar (or Tools->Snap to Grid)
a) Outer Boundary
Select the Line-Polyline command from the Edit Bar (or Insert->Domain Geometry->Lines->Polylines->Graphically) 
b) Drain Select the Circle via Center and Radius command from the Edit Bar (or Insert->Domain Geometry->Lines->Circle->Graphically)
Specify Coordinates of the Center X=150 cm, Z = 25 cm numerically on the Edit Bar
Click Apply
Specify Parameter R = 5 cm
Click Apply
Click Stop Define the Base Surface Domain Geometry->Surface->Graphically and click at the outer boundary
Alternatively select the Surface via Boundaries command from the Edit Bar and click at the outer boundary
Select the Opening via Boundaries command at the Edit Bar and click on the circle. This will specify that the inside of the circle is not part of the transport domain.
Define FE-Mesh
Insert->FE-Mesh Refinement->Graphically: a dialog appears in which specify Finite Element size S=2.5 cm
After clicking OK, select two nodes at the bottom of the furrow at the left side.
Click Generate FE-Mesh from the Edit Bar (or Edit->FE-Mesh->Generate FE-Mesh)
Click on View All at the toolbar (or View->View All)
Specify Initial Condition:
On the Navigator Bar click on Initial Conditions – Pressure Head (or Insert->Initial Conditions->Pressure Head)
Select the entire transport domain
Click on the Set Value command at the Edit Bar, check Equilibrium from the lowest located nodal point, and set equal to 50 cm (Bottom Pressure Head Value).
Water Flow Boundary Conditions: On the Navigator Bar click on Boundary Conditions – Water Flow (or Insert->Boundary Conditions->Constant Head)
Zoom in on the left furrow.
- Select Constant Head from the Edit Bar, select bottom of the left furrow and 3 nodes on the side, specify 12 cm with Equilibrium from the lowest located nodal point.
Zoom on the drain. - Select "Seepage face": nodes along the drain.
Default View.
Observation Nodes
On the Navigator Bar click on Domain Properties – Observation Nodes (or Insert->Domain Properties->Observation Nodes)
Click on the Insert command on the Edit Bar and specify 5 points arbitrarily in the transport domain between source and drain
Menu: File->Save (or from Toolbar)
Menu: Calculation->Run HYDRUS (or from Toolbar)
(Execution time on 3 GHz PC – 61 s)
OUTPUT:
Results – Other Information: Observation Points (from the Navigator Bar, or Results->Observation Points from menu)
Pressure Heads
Water Contents
Results – Other Information: Boundary Fluxes (from the Navigator Bar, or Results->Boundary Information->Boundary Fluxes from menu)
Constant Boundary Flux
Seepage Face Boundary Flux
Results – Other Information: Cumulative Fluxes (from the Navigator Bar, or Results->Boundary Information->Cumulative Fluxes from menu)
Constant Boundary Flux
Seepage Face Boundary Flux
Results – Other Information: Solute Fluxes (from the Navigator Bar, or Results->Boundary Information->Solute Fluxes from menu)
Constant Boundary Flux
Seepage Face Boundary Flux
Results – Other Information: Mass Balance Information (from the Navigator Bar, or Results->Mass Balance Information from menu)
Results – Graphical Display: Pressure Heads (from the Navigator Bar, or Results->Display Quantity->Pressure Heads from menu)
Use Listbox Time Layer or Slidebar on the Edit Bar to view results for different print times
Check Flow Animation
Select different display modes using Options->Graph Type
Results – Graphical Display: Water Contents (from the Navigator Bar, or Results->Display Quantity->Water Contents from menu)
Results – Graphical Display: Concentrations (from the Navigator Bar, or Results->Display Quantity->Concentrations from menu)
Results – Graphical Display: Velocity Vectors (from the Navigator Bar, or Results->Display Quantity->Velocity Vectors from menu)