Watershed Delineation & Stream Network

0Getting Started

Watershed delineation is the first step in building a SWAT model with SwaNET. The process begins by loading a Digital Elevation Model (DEM), then generating a stream network from that terrain data.

To begin, click Create SWAT Model at the top left of the SwaNET model interface.

A new interface appears with multiple options for loading a DEM.

Three Ways to Load a DEM

1Load DEM from Local Computer

The simplest approach: upload a DEM raster file directly from your machine.

Upload a New DEM

1. Check the box next to Import, then click Import. Browse to your file, select it, and click Open. The file uploads to the MAGNET server and its name appears in the dialog.
2. Click Load DEM.

A new SwaNET project is created, the DEM is copied into your SwaNET folder, and the DEM/hillshade map is displayed.

Load a Previously Uploaded DEM

1. Click Use Uploaded File.
2. Select a file from the dropdown list.
3. Click Load DEM.

2Load DEM from MAGNET Server

MAGNET's built-in DEM database lets you extract terrain data with just a few clicks. You provide a boundary shapefile, and the server handles the rest. There are four ways to supply this boundary.

2a. Draw a Shape on the Map

1. Select Draw a shape on the map under "Use shape file to extract DEM."
2. Click Draw Shape and draw a bounding box around your area of interest. Redraw as many times as needed.
3. Click Save Shape. The shape is uploaded, saved, and plotted on the map.

2b. Upload a Watershed Shapefile

You can upload your own shapefile for DEM extraction. Accepted formats: .zip (with .shp, .prj, .dbf minimum) or .geojson.

Upload a New Shapefile

1. Select Upload a watershed shape file.
2. Check the box next to Import and click it.
3. Browse to the file, select it, and click Open.
4. Click Load Shapefile.

Load a Previously Uploaded Shapefile

1. Select Upload a watershed shape file.
2. Click Use Uploaded File.
3. Choose a file from the dropdown list.
4. Click Load Shapefile.

2c. Upload Shapefile from DataNet

DataNet is MAGNET's platform for browsing and downloading raster/vector data from GeoServers.

1. Select Upload a watershed shape file, then click Upload From DataNet.
2. On first click, a warning appears — click OK. A DataNet tab opens; close its login prompt and return to SwaNET.
3. Click Upload from DataNet again. Switch to the DataNet tab.
4. In DataNet: click Show Layers → expand Data Space → search for your layer (e.g., GlobalWatersheds) → filter by WFS → Get Layers.
5. Check the desired layer (e.g., World GlobalWatershed_Level5). Navigate to your area.
6. Use Draw Tool → Regular to draw a rectangle inside your target watershed.
7. Click Data Manipulation → Transfer. Select WFS as the service. Click Send.
8. Return to SwaNET and accept the data transfer prompts. Click Load Shapefile.

2d. Load Watershed from MAGNET Server

Instantly load HUC (US) or HydroSHEDS (global) watershed boundaries by clicking a point on the map.

1. Select Load watershed map from server. Pan/zoom to your area of interest.
2. Click a point on the map. Latitude and longitude are captured.
3. Choose the data source: DataCenter 2 (Global) for HydroSHEDS, or DataCenter 1 (US only) for HUC.
4. Select the watershed level — from Level 1 (HUC 2-digit, largest) to Level 6 (HUC 12-digit, smallest).
5. Click Load Shapefile.

2e. Load the DEM

Once any shapefile boundary is loaded:

1. Select the DEM resolution from the dropdown. The most suitable resolution is selected by default.
2. Click Load DEM from Magnet server. The server extracts, merges, and crops the DEM tiles to your boundary.

3Load DEM from DataNet

DEM rasters can be loaded directly from DataNet's GeoServer catalog — either with or without a pre-defined watershed boundary.

3a. Without a Bounding Box

1. Click Load DEM from DataNet. On first click, dismiss the warning, then click again after DataNet opens.
2. In DataNet: Show Layers → expand Data Space → search keywords (e.g., DEM90m Michigan) → filter by WCS → Get Layers.
3. Check the desired raster layer (e.g., USA Michigan Michigan DEM 300m).
4. Use Draw Tool → Regular to draw a rectangle around your area of interest.
5. Data Manipulation → Transfer → select WCS → Send.
6. Return to SwaNET and accept the data transfer. The DEM is loaded and plotted.

3b. With a Bounding Box

If you've already loaded a shapefile boundary (from Section 2), repeat the DataNet workflow above. The key difference: no "no domain polygon" warning appears, and you don't need to draw a rectangle — the existing boundary is used automatically.

4Create Stream Network

After loading the DEM, the stream network creation interface appears (also accessible via the Threshold selection tab). This interface lets you optionally burn in an existing stream network, set the drainage threshold, and generate streams.

4a. Burn-in Stream Network (Optional)

Burning in superimposes a known stream network onto the DEM, forcing derived drainage paths to match real-world stream positions. Especially useful in flat terrain.

Upload a New Stream Shapefile

1. Check Burn in existing stream network.
2. Check Import and click it. Browse to your stream shapefile and upload.
3. Click Burn. The DEM is modified and the map updates.

Use a Previously Uploaded File

1. Check Burn in existing stream network.
2. Click Use Uploaded File and select from the dropdown.
3. Click Burn.

You can also load a burn-in file from DataNet following the same transfer workflow described in Section 2c.

4b. Threshold Selection & Stream Creation

The threshold area is the minimum drainage area required to form the origin of a stream. It directly controls the density of your stream network and the number of subbasins.

1. A default number of cells and area are provided. Modify either value as needed — they are linked.
2. Click Create streams. The stream network is generated and displayed. Repeat as needed.

5View DEM Properties

Click DEM properties to expand a panel showing your DEM's metadata: bounding box extents (North/South/East/West), cell size, cell area, spatial reference system, and the full projection string (e.g., WGS 1984 UTM Zone 16N).

This information is useful for verifying that your DEM is in the correct coordinate system and covers your intended study area.

Frequently Asked Questions