The “Calibrate Commands” option in VOSWMM empowers you to perform both calibration and sensitivity analysis. This tutorial will guide you through harnessing this feature to calibrate and conduct sensitivity analysis on your VOSWMM model. Calibration involves the precise adjustment of your model to align with observed data, while sensitivity analysis provides valuable insights into how alterations in property percentages influence model outcomes. This amalgamation of techniques allows you to enhance the accuracy of your VOSWMM model and gain a comprehensive understanding of the repercussions of varying property percentages.

Accessing the “Calibrate Commands” Option

  1. Launch VOSWMM and open your existing project or create a new one.
  2. Ensure that you have a model set up with various properties you want to analyze.
  3. On the simulation tab, select “Calibrate Commands.”
  4. In the “Calibrate Commands” panel, you’ll find a list of your current scenarios. To create a new scenario, click on the “+” button and provide a name for easy identification.

Modifying Property Percentages:

Within the newly created scenario, you’ll see a list of properties and their current percentages.
Adjust the percentages of the properties you want to analyze by entering new values. You can increase or decrease the percentages to reflect different scenarios.

Selecting Commands for Modification

Before clicking on the “Calibrate Commands,” you need to specify the commands you want to modify. There are three ways to do this:

  1. Select the commands on the Schematic/Map window before clicking “Calibrate Commands.” This way, the properties of the selected commands will appear in the Command Calibration window.
  2. Select a command, then click on “Calibrate Commands” and check “Upstream” from the selection type. This selects all commands located at the selected command, including the selected command, to be modified, and their properties will appear.
  3. Similar to the second method, but you can assign NHYD of a command upstream in the “Stop at Command (exclusive)” box. This selects the commands between the two selected commands for modification.

Running the Analysis

After setting up your scenarios and adjusting property percentages, click the “Run” button. VOSWMM will simulate each scenario with the specified property percentages.

Reviewing the Results:

Once the analysis is complete, review the results for each scenario. Analyze the data and observe how changes in property percentages influence the model’s performance.
You can use the “Scenario Comparison” feature by selecting a command to view differences, or utilize “Plot Calibration” to visualize the outcomes.


By employing the “Calibrate Commands” option in VOSWMM, you can perform calibration and sensitivity analysis to understand how adjustments in property percentages affect your model’s performance. This tool is invaluable for making informed decisions regarding your stormwater management strategies.