Last updated on 2025-09-05
The Runoff Simulation animates results from applying the TR-55 runoff model, developed by the U.S. Department of Agriculture, and the Small Storm Hydrology Model for Urban Areas, developed by Robert Pitt, for a single 24-hour rainstorm over a hypothetical small unit of land with a single land cover class and a single hydrologic soil group.
The Runoff Simulation is available online through the Innovative Technology in Science Inquiry (ITSI) portal or as a standalone app in any web browser.
When you run the full Model My Watershed Site Storm Model application, the exact same calculations are performed on every single pixel of the map and are added together to calculate the overall impact for the entire map area. Please note that although the look of the graphics of the model may have changed from the time this walkthrough was created, the placement and functionality of the controls will not change.
The complementary Model My Watershed Site Storm Model performs the same model calculations by using actual land cover and soil data for the selected land area.
There is an additional resource available that explains in-depth technical details about the models.
Note: Model My Watershed web applications are under active development, and the appearance of screenshots will change over time. Updates to this guide will be released with significant changes to the user interface.
