🌾 SwaNET · Quick Tutorial 19 of 19

Complete Model Creation (End-to-End)

Build a full watershed model in SwaNET from terrain, watershed boundaries, landuse, soil, and HRU rules - then write SWAT input files and load the finished project. This version keeps the original tutorial sequence intact while making the workflow easier to scan, teach, and discover.

SwaNET Tutorial 19Prereq: MAGNET4WATER Account~10 min read

What you will do

  • Start a new interactive SwaNET model creation project.
  • Load a watershed boundary and extract a server-side DEM.
  • Create a stream network and delineate the watershed.
  • Load landuse and soil maps and generate HRUs.
  • Filter HRUs, write SWAT input files, and load the project.

Key settings used in this example

  • Kalamazoo River watershed, Michigan, USA
  • DataCenter 1 (US only), Level4 (HUC 8-digit)
  • DEM resolution: 90 m
  • Threshold area: 5000 ha
  • Landuse and soil maps: 400 m from MAGNET server
  • Final HRU filter: 10% of subbasin area
  • Weather generator: WGEN_US_FirstOrder
Overview

What this tutorial covers

This tutorial explains how to create a SwaNET project using the DEM, landuse, and soil map available at the MAGNET server. It assumes you already have a MAGNET account, which is required for loading SwaNET projects, running simulations, saving models, and submitting jobs.

Why this workflow matters: SWAT does not treat a watershed as one lumped unit. It first delineates the watershed from terrain, then partitions it into subbasins and HRUs. Those spatial units drive runoff generation, routing, and watershed response. If the delineation or HRU definition is wrong, downstream simulation quality suffers.

Inputs

Server-based watershed boundary, DEM, landuse, and soil datasets.

Core outputs

Watershed map, stream network, HRU map, and SWAT-ready input files.

Use case

Interactive project setup for a complete SwaNET watershed modeling workflow.

Workflow

End-to-end model creation sequence

Interface
→
Boundary + DEM
→
Streams
→
Watershed
→
HRUs
→
Final HRUs
→
SWAT Inputs
Teaching note: The original PDF presents figures directly beside the action being described. This HTML version keeps that same instructional rhythm: read the action, see the corresponding interface or map, then move to the next decision.

Load the interactive SwaNET model creation interface

Click Create SWAT Model at the top left of the MAGNET SwaNET interface. If a prompt appears asking to load a previous project, click Cancel. The interactive model creation interface opens.

MAGNET SwaNET main interface with Create SWAT Model button highlighted
Figure 1. MAGNET SwaNET main interface.
Interactive SwaNET model creation interface with menu tabs for watershed boundary, threshold selection, outlet selection, HRU creation, HRU selection, and writing SWAT input files
Figure 2. Interactive SwaNET model creation interface.
What you are doing: Initializing a new project environment for all later steps - DEM loading, watershed delineation, HRU generation, and SWAT input writing all depend on this project shell.

Load the DEM watershed shapefile and DEM

If the mgnSWAT Select DEM interface is not already visible, click Watershed boundary on the upper left menu. Under Use shape file to extract DEM, check Load watershed map from server. Then zoom to the Kalamazoo area in southwestern Michigan and click on the background map so latitude and longitude populate automatically.

Watershed boundary panel showing the server-side watershed loading options, latitude and longitude fields, HUC level selection, and DEM loading buttons
Figure 3. Loading DEM from the MAGNET4WATER server.

Next, select DataCenter 1 (US only) so the watershed map comes from the US watershed database. Choose Level4 (HUC 8-digit), then click Load Shapefile. The selected watershed boundary is extracted and displayed on the map.

Kalamazoo watershed boundary displayed on the base map after loading the watershed shapefile from the MAGNET server
Figure 4. Watershed shapefile loaded from the MAGNET server.

Under Select DEM resolution, choose 90 m, then click Load DEM from Magnet server. After the success message appears, click OK. The DEM is extracted, loaded into the project, plotted, and overlaid on the background map.

Extracted DEM for the Kalamazoo watershed displayed as a terrain raster overlay on the map
Figure 5. DEM loaded from the MAGNET server.
Critical modeling point: DEM selection drives flow direction, stream formation, and watershed delineation. A poor DEM choice propagates error through the entire model creation chain.
To view the DEM legend, open Manage maps later in the workflow and check DEM.

Create the stream network

Once the DEM has been loaded, the stream creation interface appears automatically. You can also open it by clicking Threshold selection on the left.

Cell size and threshold selection interface showing a threshold of 5000 hectares and the Create streams button
Figure 6. Stream creation interface.

Change the threshold area to 5000 ha, then click Create streams. The stream network is generated and overlaid on the map.

Generated stream network overlaid on the DEM within the watershed area
Figure 7. Stream network map.
Interpretation: The threshold area controls stream density. Lower values usually create more channels; higher values simplify the network. This example intentionally uses 5000 ha because it is the setting chosen in the original tutorial.

Select the outlet and finalize the watershed

After the stream network is created, the outlet selection interface appears. You can also open it through Outlet selection in the left menu.

Outlet selection dialog with Use default outlet enabled and buttons for Create watershed and Finalize watershed
Figure 8. Outlet selection interface.

Check Use default outlet under Select outlets, then click Create watershed. A message appears confirming watershed delineation and reporting the number of subbasins. Click OK.

Delineated watershed map showing numbered subbasins and stream network
Figure 9. Watershed map with subbasin boundaries, stream network, and subbasin numbers.

Now the Finalize watershed button is active. Click it, then confirm the completion message. The watershed is finalized and the DEM is cropped to watershed extent and overlaid on the background map.

Finalized watershed map with subbasin boundaries and stream network displayed after watershed finalization
Figure 10. Final watershed map.
Optional server output: Checking Create River File creates a stream network file on the server that can be used in other MAGNET modeling platforms, though not inside SwaNET itself.

Create HRUs

After watershed finalization, the HRU creation interface appears automatically. You can also open it through HRU creation on the left.

HRU creation dialog with options for loading landuse and soil maps from the MAGNET server, setting slope bands, and creating HRUs
Figure 11. HRU creation interface.

First, load the landuse map. Keep Upload from Magnet server checked, select 400 m, and click Upload. After the confirmation message, the landuse map is displayed on the map.

Landuse map displayed across the watershed after loading from the MAGNET server
Figure 12. Landuse map.

Next, load the soil map the same way: keep Upload from Magnet server checked, select 400 m, and click Upload. After the success message, the soil map appears on the map.

Soil map displayed across the watershed after loading from the MAGNET server
Figure 13. Soil map.

Leave the slope bands at their default value, then click Create HRUs. A confirmation message reports the number of potential HRUs, and the full potential HRU map is overlaid on the background map.

Potential HRU map showing many color-coded hydrologic response units over the watershed
Figure 14. Full potential HRU map.
Critical modeling point: HRUs are the hydrologic engine of SWAT. They capture the landuse-soil-slope combinations that drive runoff, infiltration, and evapotranspiration behavior.
To view legends for the landuse and soil maps, open Manage maps and check Land use or Soil.

Manage maps and visualization

The Manage maps interface lets you control which overlays are displayed, adjust opacity, show or hide markers, display legends, and visualize the project in 3D.

Manage maps interface showing map overlay list, opacity controls, marker controls, legend toggles, and the View in 3D button
Figure 15. Map management interface.

Show or hide maps

Select a map from the overlay list and click Hide or Show.

Opacity

Select an overlay, enter a new opacity value, and click Change.

Markers and legends

Toggle marker visibility, and check the DEM, landuse, or soil legend boxes as needed.

Click View in 3D to open the 3D visualization interface, then explore the available controls. The help icon in the upper left provides additional assistance.

3D SwaNET visualization of the watershed terrain and overlays with animation and display options
Figure 16. MAGNET SwaNET 3D visualization.

Select the final HRUs

When HRU creation is complete, the HRU selection interface appears. It can also be opened by clicking HRU selection on the left.

Final HRU selection interface showing multiple filtering options and threshold methods
Figure 17. HRU selection interface.

For this tutorial, select HRUs by area. Check Filter by area, make sure Percent of subbasin is selected under threshold method, then set the threshold to 10. You can drag the slider or type the value manually. Finally, click Finalize HRUs.

HRU filtering dialog configured for Filter by area with Percent of subbasin threshold set to 10
Figure 18. Final HRU selection.

After processing, a prompt reports the total number of subbasins and HRUs. Click OK.

Interpretation: Final HRU filtering simplifies the model by removing smaller spatial combinations. In this example, only HRUs covering at least 10% of a subbasin are retained.

Write SWAT input files and load the project

After the HRU selection process is complete, the writing interface opens. You can also access it through Write SWAT input files on the left.

Write SWAT input files interface with weather generator selection, test run option, and report download options
Figure 19. Write SWAT input files interface.

For the Kalamazoo example, choose WGEN_US_FirstOrder as the weather generator file. Check Test run SWAT, then click Write input files.

Write SWAT input files dialog configured with WGEN_US_FirstOrder and Test run SWAT enabled
Figure 20. Options for writing SWAT input files.

After the success message appears, click OK. A second prompt asks whether to load the recently completed SwaNET project. Click OK again.

Prompt asking whether to exit manual delineation and load the completed SWAT project
Figure 21. Load completed project prompt.

The finished SwaNET project opens in another interface where you can edit input files, update weather data, calibrate the model, run the model, and visualize outputs.

Loaded SwaNET project displayed in the main interface after model creation is complete
Figure 22. Completed SwaNET project loaded into the main interface.
Outcome

What you have built

Watershed

Delineated subbasins and a finalized watershed extent.

Hydrology

Stream network and HRU structure consistent with the selected inputs and thresholds.

SWAT setup

Project-specific SWAT input files generated and tested.

Next actions

Calibrate, run scenarios, update weather data, and inspect results.

Congratulations - you have interactively created a complete SwaNET project. This tutorial ends at the point where the project is loaded and ready for editing, calibration, simulation, and visualization.

FAQ

Frequently asked questions

What is the main purpose of this tutorial?

It walks through the complete interactive setup of a SwaNET watershed model in MAGNET4WATER, from watershed boundary and DEM loading to HRU generation and writing SWAT input files.

Why is DEM loading such a critical step?

The DEM controls flow direction, stream extraction, and watershed delineation. Because those outputs drive later model structure, DEM quality matters throughout the workflow.

What does the stream threshold area control?

It controls how dense the extracted stream network becomes. This tutorial uses 5000 ha, matching the original example.

What are HRUs in this workflow?

Hydrologic Response Units are landuse-soil-slope combinations within subbasins. SWAT uses them to represent hydrologic variability across the watershed.

Why does the tutorial apply a 10% HRU threshold?

It filters final HRUs by area so that only combinations covering at least 10% of a subbasin are retained. This simplifies the model while preserving major watershed characteristics.