Model My Watershed Site Storm Model Guide
Note: This guide was created with screenshots taken using Firefox 44.0 or 44.0.2. 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 major changes to the MMW User Interface.
The Model My Watershed (MMW) Site Storm Model simulates storm runoff and water quality by applying the TR-55 and STEP-L water quality models for a single 24-hour rainstorm over a selected land area within the continental United States. The results are calculated based on actual land cover data (from the USGS National Land Cover Database 2011, NLCD2011) and actual soil data (from the USDA Gridded Soil Survey Geographic Database, gSSURGO) for the selected land area of interest.
The complementary MMW Runoff Simulation performs the same model calculations on a hypothetical land parcel with a single land cover class and a single hydrologic soil group.
There are additional guides that explain in-depth technical details about the models.
2.Sign In and Share Location
The Model My Watershed (MMW) Site Storm Model can be accessed online from any web browser at https://app.wikiwatershed.org/ or through the Innovative Technology in Science Inquiry (ITSI) portal.
When you first navigate to the MMW application, depending on your browser’s settings you may be asked to share your location data with the application. Sharing your location will automatically start the application at approximately your current location, but it is not necessary for the application to work.
You will also immediately be given a chance to sign in to the application. Signing in allows you to save your work to return to later and to share your work with other users.
- New users: Create an account by clicking “Sign Up” or click the “Guest” button to continue without any credentials. Using the guest option gives you access to the full modeling and scenario capabilities of the application but will you not be able to save or share your data.
- Students and teachers using the ITSI portal: click the “ITSI” button to verify your credentials for the ITSI portal and prevent you from needing to set up a new user for the application. This also allows you to quickly and easily send data and screenshots back and forth to assignments and lessons on the ITSI portal.
- Other existing users: Type in your username and password and click “Sign In.”
4.Find Your Watershed
To find your watershed unit, sign in and share your location. The application should zoom directly to the location your internet provider or mobile device is sharing. If you chose not to share your location, find the location you want watershed information for by typing an address or city or zip code into the search bar.
To see watershed information click on the “Select by Boundary” button on the top of the screen and then select “USGS Watershed Unit (HUC-10)” or “USGS Subwatershed Unit (HUC-12).”
Red border lines should appear on your map. If you do not see any, try zooming out — you may be zoomed in too much to see more than one watershed unit.
To see the name of a watershed unit, simply hover your mouse over it on the map. If you realize you made a mistake in selecting your area, click the “Reset” button and try again.
5.Choose Basemaps and Overlays
Just as Google Maps allows you to switch between road and satellite maps, there are several options for both the basemap and data overlays on top of the map. To access these, click the button that looks like a small globe (marked in purple in screenshot).
You can select a basemap image and several different types of overlays. The base maps themselves come directly from ESRI or Google Maps and are not built into the application. If you have a very slow Internet connection, the base maps may be slow to load.
The overlays include boundary lines (like school districts and USGS hydrologic units) and color shading for land uses and soil types. There are also observation data overlays, which display locations and data from the USGS and other national river and weather monitoring stations. Please note that observation data is not available in all locations!
6.Select an Area to Model
To begin modeling, you must first select a map area to model over. Do this with either the “Select by Boundary” or the “Draw Area” tool on the top part of the map (next to the search bar).
Select by Boundary
You can select by political (county lines, congressional districts, and school districts) or major watershed (HUC 8-12) boundaries in the “Select by Boundary” tool. Once you have selected a boundary type, those borders will appear on the map and the name of each region will appear as you hover over it.
Be aware of your zoom level when selecting by boundaries. If you are at too high of a zoom level, you may not be able to see the boundaries on your map.
Free Draw: Use the “Draw Area” tool to draw a precise area of any size you want by drawing points on the map and double clicking or clicking on the first point to close the box.
Square Km: Use the “Draw Area” tool to select a 1 km box centered wherever you click.
7.Analyze an Area
As soon as you have selected an area to model, the application will change into geospatial analysis mode.
The left side of the screen will now show the area you selected in bright colors with the rest of the map grayed out. The right side of the screen will show two panes, one with analysis of the existing land cover and soil types in your selected area, the other with the option of running a model to predict runoff and nutrient loads for the area.
These calculations and analysis are done on the fly for each area based on nationally available data. You will not get a pre-computed estimate or “canned” number. These are real values based on the most recently available national land cover and soil type datasets. Because of this, the analysis may take a few seconds to complete and you may see a loading wheel on the right portion as this happens. (It is generally very fast with a good internet connection.)
In the Analyze pane you can view the land use and soil type in both tabular and graphical form. (The table is below the graph. If you cannot see it, scroll down.) Use the tabs at the top right of the pane to switch between land use and soil type.
You can sort the tabular data by type, area, or coverage percent. The bar graph coloring will match up with the colors assigned by the National Land Cover Database and can be used as a legend for the land cover and soil group overlays. The title at the top of the Analyze pane will list the name of the area (if selected by boundary) and the total size of the area. You can still change the map zoom and overlays in the map pane. Try turning on the NLCD overlay to compare the layout of land covers on the map to the percent of each land cover in the area. To see a larger area of the map, the Analyze pane can be minimized by clicking the arrow in the upper right of the pane.
If you realize you made a mistake in selecting your area, hit the back button next to the model button at the top right of the page. You will be taken back to the choose-area-of-interest screen. To clear the map and select something new, click the “Reset” button at the top of the screen.
8.Model an Area
Once you are happy with the area you selected, you can move on to modeling and modifying the area by clicking the “Model” button on the upper right pane.
In the modeling mode, the application will show tabs at the top of the screen for the current conditions and a new scenario where you can modify the landscape by changing the land cover type or applying conservation practices.
The model tab will now be filled out with predicted amounts of runoff and stream water quality. The runoff quantities are calculated using a combination of 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 rain storm. The water quality parameters are calculated using the EPA’s STEP-L water quality model. For more information on the specifics of these calculations, see the technical documentation.
The runoff tab in the model output pane shows the partitioning of the rainwater into runoff, infiltration, and evapotranspiration as a stacked bar graph. In the water quality tab, you will see both tabular and graphical data showing predicted water quality for any streams in the selected area. Because the model is running with real data on your custom area, it may take some time for the model to run and you may see a loading icon. (It is generally very fast with a good internet connection.) The entire model output pane can be minimized by clicking on the arrow in the upper right of the pane.
When you begin modeling, you will always begin in the “Current Conditions” tab. In this tab, you see the analysis and resulting model of the land exactly as it is. The only thing that can be changed in the “Current Conditions” tab is the quantity of rainfall to model.
8.1.Create a New Scenario
To begin making changes to the landscape, click on the “New Scenario” tab at the top of the screen. To start, this looks exactly like the “Current Conditions” tab but with two tool boxes in the upper left, one for land cover and another for conservation practices. Each of these is a freehand drawing tool to modify the current land use.
The model output pane also changes to show the original results from the “Current Conditions” tab and the modified results as you change the landscape. (The analysis pane will not change.)
Select a land use or conservation practice from the toolboxes at the top of the screen and then click points on the map to draw an area over which to apply it. As soon as you add a new land use or conservation practice, the model will re-run in the background to calculate what has changed and all of the plots will be updated. You will see loading icons again in the model pane as this happens. Remember that you can minimize the model output pane to give more screen space to work on landscape modifications.
See technical documentation for an explanation of how the runoff and water-quality contributions of conservation practices are calculated.
As you add modifications, you can see details about amount of area modified by clicking on any modification box. You can also see a list of all of the modifications you made in the scenario by clicking on the space in the upper right of the map pane where it says “x modifications.” This gives a sort of “shopping cart” of modifications grouped by the type of modification.
You can delete any modification by clicking the trash can next to it. If it helps to decide where to make changes, you can still use the small globe icon to select which overlays to display on the map.
You can create many possible scenarios of landscape modification by clicking on the “+” next to the “Current Conditions” tab. This opens up a new tab with no modifications on it. You can also make a copy of one scenario and further modify it by clicking on the arrow on the scenario tab and selecting “Duplicate.”
Scenarios can be renamed, deleted, and if you are logged in, shared through the same menu. To help sort through many scenarios, click on the three-lined “hamburger” button next to the “Untitled Project” tab.
Once you have created several scenarios, you can compare all of them by clicking “Compare” in the upper right of the tab bar.
The “Compare” option doesn’t appear until you have defined a New Scenario in your project, by selecting the “Add changes to this area” button in the upper right-hand side of the panel:
The “Compare” button now appears in the left-hand side of the panel next to the New Scenario button:
The compare window should now look similar to this:
Clicking “Compare” gives a side-by-side comparison of all of the modified scenarios along with the original conditions before any modifications.
The screen shots above show a side-by-side comparison of all of the scenarios along with the original conditions before any modifications. It also shows what the partitioning would be if the landscape were 100% forested. This 100% forested condition will give the maximum amount of infiltration for the landscape, given its soils.
9.Save and Share a Project
At any time while working, you can name and save your work by clicking on the top left “Untitled Project” tab.
You can also make the project publicly accessible to anyone with a link to it, add tags so it can easily be found, print out the maps and graphs, or embed the work into the ITSI portal. Note that this only works if you logged in when you entered the application (and embedding in the ITSI portal requires logging in through the ITSI portal).
If you have made your project publicly accessible and given someone the link, they will be able to view all of your scenarios and results. They will not, however, be able to modify it. Any public project can be made private again from the same menu.
WikiWatershed is an initiative of Stroud™ Water Research Center. The Stroud Center seeks to advance knowledge and stewardship of freshwater systems through global research, education, and watershed restoration.
- Academy of Natural Sciences of Drexel University
- Concord Consortium
- Millersville University
- Penn State Institutes of Energy and the Environment
- University of Washington
- Utah State University
See the About page for more information about these organizations and individuals.
11.Send Us Feedback
Please help us improve this guide. You can leave feedback about individual sections (look for the “Was this helpful? Yes or No” text). If your answer is no, or if you see something that needs to be changed, please use the “Suggest an edit” link and fill out a quick form.
Additional guides can be accessed on the Documentation page. If you would like to submit a question to the scientists and educators developing WikiWatershed, please use the contact form on the Help page.