Soil parameterization

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To develop soil parameterization file, first the depth of the different soil horizons and texture (combination of soil, silt and clay) in percentage is required. This information is general available in soil dataset. The texture information is useful to describe the characteristics of soil water retention curve. The soil texture information (in percentage) is provided as input data to the software component ROsetta inside 'HYDRUS 1D' to understand pedotransfer functions of soils in three different hypothetical pressure scenarios. They are: 0 mbar, 60 mbar and 15,000 mbar. The soil texture is classified according to the specific pore volumes of soil (Scheffer and Schachtschabel 1984).

For example, a soil type A has following depth and texture combination:

Horizon Depth (cm) Texture (Sand,Silt,Clay %)
A Horizon 15 texture (47, 39, 14 )
B Horizon 15 texture (40, 42, 19 )
C Horizon 25 texture (33, 40, 27 )
D Horizon 35 texture (49, 33, 18 )
E Horizon 35 texture (55, 32, 13 )

The texture information needs to be supplied to HYDRUS 1D software to get the water holding capacity of the specific texture combination:

  • Click Hydrus-1D Downloads-->

Hydrus1D

  • Download the latest version (In this tutorial, version Hydrus1D_4.15.0110 is downloaded)
  • Open the software:

Hydrus1D_open

Click File--> New-->>

Give the name for the new project. For example: Soil type-A

new project: Soil type-A

Click OK

A new window with new project name will appear:

soilType-A

On pre-processing windows select the “Water Flow – Soil Hydraulic Parameters”

The new window will appear:

soilType-A

On this window, select the “Neural Network Prediction”.

A new window will appear:

Select model of “% Sand, Silt and Clay (SSC)”.

Input the percentage of SSC in the window. In this example, the SSC of A-horizon from the table above is provided.

soilType-A

Click ‘Predict’ and the Output will be resulted.

Click ‘Accept’ and a new window will appear.

Click ‘Next’ a new windows appear.

soilType-A


In the new window, make sure that the Upper and Lower Boundary Condition is set to ‘Constant Pressure Head’ and Initial Condition is ‘In Pressure Heads’.

Then click Next

Click next and a new window will appear:

soilType-A

Click Next

Soil profile summary table will appear soil profile summary

Click Next

A new window with the following message will appear: 'Do you want to run HYDRUS-1D application?' Click OK

Several outputs will appear in Post-processing window

post processing

Press Enter to continue.

Now your data is saved and you will be taken to initial windows.

saved project

Double click the Soil Hydraulic Properties and a new graph will appear

graph

Right click on the graph and click 'Edit Chart Data'.

Data Grid


The C1 is pressure and C2 is water holding capacity

soil profile summary will appear and click next to run the HYDRUS-1D application, save the data and press Enter to continue
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