Upload DEM

What is it?

To start interctively creating SWAT projects, users need to select a DEM. A DEM is representation of the topographic surface of the Earth. This interface provides several options for the users in selecting DEM.

How to use it:

Upload a DEM from local computer

User can either use the DEM already uploaded to the server or can upload a new DEM.
To use the DEM already uploaded to the server, click "Use Uploaded File". A list of already uploaded files appear. Click on the desired file name.
To upload a new DEM, check the box next to 'Import' and click 'Import'. Browse to the DEM. DEM file can be .tif/.tiff or .img.
Once a file selected, click 'Load DEM'. Selected DEM is displayed over the background map.

Importing DEM from MagnetSWAT server

Users can extract DEM from the MagnetSWAT server using a shapefile. Users can either, draw a rectangle on the map or upload a shapefile or use global watershed shapefile on the server.
To draw a rectangle on the map, select 'Draw a shape on the map'. Two new buttons, 'Draw Shape' and 'Save Shape', appear. Click 'Draw Shape' and draw a rectangle on the area of interest. Once done, click 'Save Shape'. DEM and hillshade maps are displayed.
DEM upload

To upload a zipped shapefile from local computer, select 'Upload a watershed shape file'. If users want to use previously uploaded map, click 'Use Uploaded File'. A list of uploaded shapefiles appear select the desired shapefile. To upload a new shapefile, check 'Import' checkbox, and click 'Import' link to browse to the shapefile. Once the file is selected, click 'Load Shapefile'. Click 'Load DEM' to extract DEM from server.

To extract watershed shapefile from MagnetSWAT global watershed database, select 'Load watershed map from server'. On the map, zoom to a location and click on the point of interest. Latitude and longitude of the point are displayed. Once the point is selected, click 'Load Shapefile'. Watershed shapefile is loaded. Click 'Load DEM' to extract DEM from server.

Additionally, users can select DEM resolution. 90m and lower resolution DEM maps are available at the global scale. Higher resolution DEM maps are available only for the US. Once the shapefile is uploaded, suitable DEM resolution is automatically selected. However, users can change the resolution. An important point in DEM selection is that higher resolution DEM takes longer time to process and vice versa.

Create a default model

A default model is a SWAT model created using default model building options available on SwaNET. The options are:

DEM: For smaller a modelling area, 90m DEM is used. For larger a larger area, 300m or 1000m DEM may be used, depending on the size of the modeling area.

Threshold (number of cells needed to start a stream): Default threshold is the 1.5% of the DEM size. If the DEM size is 1000*500, threshold is 7,500.

Outlet: The default outlet is used, which is the point in the stream network that has the largest drainage area.

Land use map: Default model uses NLCD 2016 map for the US and global land use map for the rest at 400m resolution.

Soil map: Default model uses STATSGO2 soil map for the US and global soil map for the rest at 400m resolution.

Slope bands: Default model uses single slope band for the free users. Two slope bands are used for the premium users, and the values are calculated based on model area slopes.

HRU selection: Default model uses "Target number of HRUs" as HRU selection method. Target number of HRUs is 5 times the number of subbasins.

Weather generator: Default model uses "WGEN_CFSR_World" as the weather generator file.

Point sources and reservoirs: Default model does not add point sources and reservoirs.