Build a location-aware stormwater model from map layers, DEM elevations, rainfall, storage, conduits, weirs, groundwater, water quality, and low-impact design controls.
This tutorial demonstrates how to zoom to a real location and create a georeferenced urban catchment model in StormNET. The example uses a hypothetical site in Haslett, Michigan, but the workflow is transferable to any mapped location.
Base model
One subcatchment, one junction, one conduit, one storage unit, one weir, and one outfall.
Design event
A 24-hour, 100-year SCS Type II storm event, with local rainfall depth supplied by the user.
Refinement layer
Evaporation, Green-Ampt infiltration, groundwater seepage, pollutant washoff, land use, and green-roof LID controls.
The educational goal is not just to click through the interface. Each step introduces a modeling concept: where water enters, how it moves, how the terrain controls hydraulics, and how refinements change runoff, storage, groundwater, and water-quality response.
Tutorial cover and modeling objective. Source PDF page 1.Complete list of tutorial steps and beginning of site initialization. Source PDF page 2.
Define a georeferenced project, select a local projection if needed, draw the data extraction area, and control DEM/soil/land-use layer opacity.
Georeferencing changes the exercise from a schematic network to a spatial model: terrain, land cover, soils, drainage objects, and map layers share a location-aware coordinate system.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Site Initialization & View Map Layers — annotated interface workflow. Source PDF page 3.Site Initialization & View Map Layers — annotated interface workflow. Source PDF page 4.Site Initialization & View Map Layers — annotated interface workflow. Source PDF page 5.
2Add a Subcatchment
Draw the drainage area polygon directly on the map; this creates the spatial footprint that receives rainfall and generates runoff.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Add a Subcatchment — annotated interface workflow. Source PDF page 6.
3Add a Junction
Place the receiving junction that will collect runoff from the subcatchment.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Add a Junction — annotated interface workflow. Source PDF page 7.
4Connect the Subcatchment to the Junction
Open the Subcatchment Editor and assign the junction as the outlet so StormNET routes runoff from the polygon to the node.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Connect the Subcatchment to the Junction — annotated interface workflow. Source PDF page 8.
5Add a Storage Unit
Draw a trapezoidal storage unit, accept or refine the generated storage curve, and save the curve data.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Add a Storage Unit — annotated interface workflow. Source PDF page 8.Add a Storage Unit — annotated interface workflow. Source PDF page 9.Add a Storage Unit — annotated interface workflow. Source PDF page 10.
6Link Junction and Storage Unit with a Conduit
Draw the conduit from the upstream junction to the downstream storage unit. The direction matters for hydraulic interpretation.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Link Junction and Storage Unit with a Conduit — annotated interface workflow. Source PDF page 10.Link Junction and Storage Unit with a Conduit — annotated interface workflow. Source PDF page 11.
7Add an Outfall
Place the downstream outfall node that represents the discharge boundary of the system.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Add an Outfall — annotated interface workflow. Source PDF page 11.
8Link Storage Unit to Outfall with a Weir
Draw a weir link from the storage unit to the outfall to represent controlled overflow or release.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Link Storage Unit to Outfall with a Weir — annotated interface workflow. Source PDF page 12.
9Get Object Elevations from DEM
Use Add DEM to populate node and object elevations from the mapped terrain surface; inspect DEM offsets where needed.
DEM-derived elevations accelerate model setup, but they should still be reviewed. Small DEM-offset changes can materially change storage depth, pipe slope, and flow direction.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Get Object Elevations from DEM — annotated interface workflow. Source PDF page 12.Get Object Elevations from DEM — annotated interface workflow. Source PDF page 13.Get Object Elevations from DEM — annotated interface workflow. Source PDF page 14.
10Add a Rain Gage
Place a rain gage on the map; its exact location is not hydraulically important for this simple model.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Add a Rain Gage — annotated interface workflow. Source PDF page 14.Add a Rain Gage — annotated interface workflow. Source PDF page 15.
11Link the Rain Gage to the Subcatchment
Assign the rain gage in the Subcatchment Editor so the rainfall time series drives runoff generation.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Link the Rain Gage to the Subcatchment — annotated interface workflow. Source PDF page 15.
12Define the Storm Event
Create a 24-hour SCS Type II intensity time series and set total rainfall depth for local design conditions.
For design-storm studies, rainfall depth and temporal distribution are model assumptions. Use local IDF or agency design-storm guidance when replacing the tutorial example.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Define the Storm Event — annotated interface workflow. Source PDF page 16.
13Define Simulation Settings
Set the analysis dates and times so the simulation covers the full storm and recession period.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Save the georeferenced model, run the simulation, and check the status window for errors and continuity balance.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Save Model and Run Simulation — annotated interface workflow. Source PDF page 18.
15View Plan View Results
Use map visualization to inspect color-coded subcatchment, node, and link results through time.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
View Plan View Results — annotated interface workflow. Source PDF page 18.View Plan View Results — annotated interface workflow. Source PDF page 19.
16View Water Budget Plots
Review system, subcatchment, and conveyance water-budget diagrams to understand where water enters, stores, infiltrates, and leaves.
Water budgets are often the fastest way to find modeling mistakes because they expose storage, infiltration, evaporation, runoff, and continuity behavior at system scale.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
View Water Budget Plots — annotated interface workflow. Source PDF page 19.View Water Budget Plots — annotated interface workflow. Source PDF page 20.View Water Budget Plots — annotated interface workflow. Source PDF page 21.
17View Time-Series Results
Plot storage-unit head or other object results over the simulation period to evaluate dynamic response.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Build a start-to-end flow path and view hydraulic grade and water-surface behavior along the selected profile.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
View Results Along a Profile — annotated interface workflow. Source PDF page 22.View Results Along a Profile — annotated interface workflow. Source PDF page 23.
19View 3D Results
Use design and simulation 3D viewers to inspect subsurface structures, DEM context, and simulated water levels.
3D views are not just presentation graphics; they help users identify inconsistent elevations, disconnected structures, and unrealistic subsurface geometry.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
View 3D Results — annotated interface workflow. Source PDF page 23.View 3D Results — annotated interface workflow. Source PDF page 24.View 3D Results — annotated interface workflow. Source PDF page 25.
20Add Evaporation
Add constant evaporation to represent atmospheric losses during the event or dry periods.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Add Evaporation — annotated interface workflow. Source PDF page 26.
21Modify Infiltration Method
Switch from default Horton infiltration to Green-Ampt or another method, then inspect subcatchment infiltration parameters.
Infiltration method selection is a modeling decision. Green-Ampt is physically parameterized, while Horton is empirical; either must be justified for the site and available data.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Create an aquifer object and define groundwater parameters for subsurface exchange.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Create/Edit an Aquifer — annotated interface workflow. Source PDF page 28.
23Link the Aquifer to a Receiving Node
Connect groundwater flow from the subcatchment to the receiving storage unit and compute elevations from node invert elevation.
Groundwater linkage introduces exchange between the subcatchment and a receiving node, so elevations and aquifer parameters should be treated as hydraulic controls, not cosmetic inputs.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Link the Aquifer to a Receiving Node — annotated interface workflow. Source PDF page 28.Link the Aquifer to a Receiving Node — annotated interface workflow. Source PDF page 29.
24Edit/Define a Pollutant
Create or edit a pollutant such as TSS so water-quality washoff can be simulated.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Edit/Define a Pollutant — annotated interface workflow. Source PDF page 29.Edit/Define a Pollutant — annotated interface workflow. Source PDF page 30.
25Edit/Define a Land Use
Create or select a land use, assign pollutant buildup and washoff parameters, and save the record.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Edit/Define a Land Use — annotated interface workflow. Source PDF page 30.Edit/Define a Land Use — annotated interface workflow. Source PDF page 31.
26Link Land Use to the Subcatchment
Assign the land-use percentage in the Subcatchment Editor so pollutant loading is tied to the drainage area.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Link Land Use to the Subcatchment — annotated interface workflow. Source PDF page 31.Link Land Use to the Subcatchment — annotated interface workflow. Source PDF page 32.
27Edit/Create a LID Control
Define a Low Impact Design control such as a green roof and inspect the layer-specific design parameters.
LID controls represent engineered green infrastructure. Their layer parameters control storage, drainage, evapotranspiration, and runoff reduction behavior.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Edit/Create a LID Control — annotated interface workflow. Source PDF page 32.Edit/Create a LID Control — annotated interface workflow. Source PDF page 33.
28Create Green Roof Subcatchment
Draw a building-footprint subcatchment using the Green Roof LID type and set 3D visualization parameters.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Create Green Roof Subcatchment — annotated interface workflow. Source PDF page 33.Create Green Roof Subcatchment — annotated interface workflow. Source PDF page 34.Create Green Roof Subcatchment — annotated interface workflow. Source PDF page 35.
29Edit/Link the LID Control to the Subcatchment
Confirm LID usage, full-subcatchment occupancy, and detailed reporting for post-simulation LID plots.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Edit/Link the LID Control to the Subcatchment — annotated interface workflow. Source PDF page 35.Edit/Link the LID Control to the Subcatchment — annotated interface workflow. Source PDF page 36.
30Save, Re-Run, and View Refined Results
Re-run the model and verify groundwater, water quality, evaporation, LID drainage, pollutant runoff, LID time processes, and LID water budget results.
After refinement, the status report should confirm that the new process models are active and that non-zero outputs appear where expected.
Primary action: follow the highlighted menu path and editor settings shown in the figure(s), then save before moving to the next object or process.
Save, Re-Run, and View Refined Results — annotated interface workflow. Source PDF page 36.Save, Re-Run, and View Refined Results — annotated interface workflow. Source PDF page 37.Save, Re-Run, and View Refined Results — annotated interface workflow. Source PDF page 38.
