Adding Parameter Data

Before you can improve your model performance, you must specify the parameters to be used during the sensitivity analysis and calibration processes. These parameters can be included in manual and automatic calibration procedures.

Parameters that are available in the interface are retrieved from the installation directory within the file at

C:\SWAT\SWATPlus\SWATPlusToolbox\assets\config\cal_parms.cal

This means that absolute minimum and maximum values are also derived from there.

Selecting Parameter

SWAT+ Toolbox exposes all the parameters from the cal_parms.cal file when you select "All" parameters in the Parameters Group.

However, you can select a group to filter the parameters in the 'parameter name' field and find the parameter you are looking for easier. You will be able to see a brief description of the parameter you are adding in the 'Parameter Information Pannel' at the bottom.

Selecting Change Type

There are three 'Change Type' options.

Percent Change

Increases/decreases the current value by a specified percent.

Relative Change

Increases/decreases the current value by a specified value. For example, if the relative value of -0.3 is applied to an esco value of 0.95 the new esco parameter will be 0.65

Replace Change

The specified value takes the place of the old parameter value. Some parameters should not be changed by this method if the parameter applies to all objects in the model, For example, if you replace all cn2 values by 30, you lose the spatial variability in curve numbers derived from vegetative cover and give all land uses essentially the same characteristics in generating surface runoff.

Chosing Minimum and Maximum

Depending on the change type, you can select a negative minimum. for example, if you have 'Percent Change', you can set minimum to be -12.5. If you have 'Replace Change' negative change will be overriden by absolute minimum since, for instance, you cannot have negative curve number.

Hint: you can type in minimum and maximum values if your preference is not in the drop down field.

Adding Parameters for Specific Objects

Adding a parameter by default will apply to all objects of corresponding type in the model. for example, cn2 will apply to HRU objects and alpha will apply to aquifers. If you want the parameter to apply to only specified objects identifable by their ids, you should toggle the 'Parameter Applies to' switch and select how you want to add the objects.

Important! Remember to click the "Attach Selected Object to Parameter" button before adding the parameter.

Single Objects

This will allow you to add objects especially if their ids are non-consecutive.

Range

This option allows you to add objects without having to list every single id. You can enter the "From" value and "To" value to have all objects (boundaries included) added.

Map Selection

This option is only available if your project was created using an 'intact' QSWAT+ project and not just a 'TxtInOut' directory. Toggle the 'Show Map' switch to 'Yes'. If your project has a lot of LSUs or if this is the first time you are displaying the map, it will take some time to generate some files and load the map depending on the performance of your computer. This process takes less time in any next activation of the map function for the project.

Currently you can only target HRUs and Shallow Aquifers (No Deep Aquifers included on the map). To select, drag over the LSUs or Aquifers you want to add and click the "Attach Selected Object to Parameter" button. You will see the Objects listed in the "Applies To" portion under the "Currently Adding" section.

Reviewing added Parameters

Clicking on an added parameter in the parameter table, you can view details about that parameter.

You can also adjust the minimum and maximum values for your parameters.