Quick Start Guide

Project Setup

1. Click the QSWAT+ icon to start
2. Click New Project in the interface popup
3. Browse to your project directory (e.g., C:\QSWATPlus_Projects)
4. Create a new folder called "Robit" (right-click > New > Folder)
5. Select the Robit folder and click Select Folder
6. Enter "Demo1" as the project name (must start with a letter)
7. Click OK

Confirmation: The project database Demo1.sqlite and a copy of the SWAT reference database swatplus_datasets.sqlite are created in your project folder.

Note: Before proceeding, ensure all maps are in the same projection coordinate system, preferably an equal area projection such as UTM. While UTM is not strictly an equal area projection, it is close enough to being so, and is sufficiently accurate for SWAT+ modeling on most watersheds.

Example Dataset Location

The files used in this demo are located in the SWATPlus installation folder, typically at:
C:\Users\[USER_NAME]\SWATPlus\ExampleDatasets\Robit, or you may download them here.

Location of the QSWAT+ plugin in QGIS

QSWAT+ interface

Watershed Delineation

Loading the DEM

1. Click Delineate Watershed
2. Click the button in the Select DEM group
3. Browse to Robit/DEM/srtm_30m and open hdr.adf
4. If needed, adjust DEM units in the DEM properties tab (default is meters)

Confirmation: The DEM file name will be displayed in the DEM text box. The DEM will be copied to the project's Source folder and converted to GeoTiff format (.tif) if necessary.

Select the DEM file, hdr.adf

Burn in Stream Network

• Change threshold method to hectares
• Set area for channels to 9 and streams to 90
• Click Create Streams

Inlets and Outlets

1. Check Use an inlets/outlets shapefile
2. Browse to Robit/MainOutlet/MainOutlet.shp
3. The outlet will be added to the map

Confirmation: Check that the delineation form shows the correct number of points have been snapped (in this case, 1) and none have failed.

Creating Landscape Units

1. Click the Create landscape tab, then click Create
2. Create three floodplain rasters using the default parameter settings for each method:
   • Buffer method (creates bufferflood file)
   • DEM inversion method (creates invflood file)
   • Branch length method (creates branchflood file)
3. Click Done to close the Landscape analysis form

Viewing Your Setup: The three floodplain rasters will be added to the map. You can toggle their visibility in the Layers panel to compare the different methods visually.

Note: You can create multiple landscape unit versions and choose which to use later when creating HRUs.

Completed Watershed Delineation form

Completing Delineation

1. Click OK to complete watershed delineation
2. The system will construct topology and number the subbasins
3. The Create HRUs option will now be enabled

Confirmation: After clicking OK, you'll see a "Constructing topology" message. The subbasins will be numbered and displayed on the map.

Viewing Your Setup:

• The watershed boundary and subbasins are now visible in the map
• You can zoom in using the Zoom to layer button (top toolbar) after selecting the subbasins layer
• Check the number of subbasins created (9 in this example)

Project view after Watershed Delineation

Create HRUs

Landuse and Soil Maps

1. Click Create HRUs to open the Create HRUs form
2. Select Robit/Landuse/roblandusenew/hdr.adf as the Landuse map
3. Select Robit/Soil/mowr_soil90/hdr.adf as the Soil map

Note: QSWAT+ will automatically clip maps that are substantially larger than the DEM and convert them to GeoTiff format if needed.

Setting Up Lookup Tables

1. In the Landuse table dropdown, select Use csv file
2. Browse to Robit/Robit_landuses.csv and click Open
3. In the Soil table dropdown, select Use csv file
4. Browse to Robit/Robit_soils.csv and click Open
5. In the Usersoil table dropdown, select Use csv file
6. Browse to Robit/Robit_usersoil.csv and click Open

Note: In the Soil data section to the left, keep it set to usersoil.

Confirmation: The tables Robit_landuses, Robit_soils, and Robit_usersoil are created in the project database and will appear in their respective dropdown menus.

Select Floodplain Map

1. Use the Select floodplain map dropdown to select invflood0_10.tif

Note: If you don't select a floodplain map, no landscape units will be created.

Configure Slope Bands

1. Type 10 in the slope bands box and click Insert (creates slope ranges 0-10% and >10%)
2. Check the Generate FullHRUs shapefile box

Note: Generating the FullHRUs shapefile is optional but necessary if you intend to visualize HRU results after running SWAT+.

Read Maps

1. Ensure Read from maps is checked
2. Click Read

Confirmation: After reading, several changes occur:

• A Slope bands map is created and added
• Full HRUs and Full LSUs shapefiles are created and added
• Counts are displayed: 9 subbasins, 87 channels, and ~516 full (potential) HRUs
• The landuse legend shows categories from the lookup table

Viewing Your Setup:

• Zoom in on a subbasin to see the Full HRUs
• Select the Full HRUs layer and open its attribute table (right-click)
• Use Select Feature(s) tool to click on an HRU and view its properties (subbasin, channel, landscape unit, landuse, soil, slope band, area, and percentages)
• View available reports: Elevation and Landuse and Soil reports

Elevation Report: Shows land distribution by elevation for the watershed and each subbasin.

Landuse and Soil Report: Lists landuse, soil, and slope-band areas for each subbasin and channel reach.

Merging Short Channels

1. In the Short channel merge group, set the threshold to 2%
2. Select Re-merge short channels
3. Click Read again

Confirmation: The channel count drops from 87 to 72, and the full HRUs count drops to ~455. You can verify in the Landuse and Soil report that the smallest channel drainage area is now at least 2.62% of its subbasin.

Note: This step removes very small channel reaches by merging them into neighboring ones, which helps eliminate insignificant HRUs.

Create HRUs Landuse and soil tab

Preparing to Create HRUs

After reading the maps, the HRUs tab (second tab) in the Create HRUs form will be enabled. Select this tab to configure and create the actual HRUs for your project.

1. Select Filter by land use, soil and slope
2. Choose Threshold method: Percent of landscape unit
3. Set thresholds and click Go after each:
   • Landuse: 10%
   • Soil: 10%
   • Slope: 10%
4. Leave groundwater option at default (Use SWAT+ aquifers)
5. Click Create HRUs

Note: The filter method ignores HRUs below the specified thresholds. Their areas are redistributed proportionately among retained HRUs within each landscape unit. Each landscape unit will retain at least one HRU.

Confirming HRU Creation

After clicking Create HRUs:

• The number of HRUs created will be displayed at the top of the map canvas
• Create HRUs will show as "done" and the Edit Inputs and Run SWAT button will be enabled
• New shapefiles will be added:
  • Actual LSUs - shows landscape units after channel merges
  • Actual HRUs - shows the potential HRUs that were retained
  • Channel reaches - shows merged channels
  • Point sources - automatically added to each channel

Viewing Your Setup

View Attribute Tables:

• Right-click on Full HRUs or Actual HRUs in the Layers panel and select "Open Attribute Table"
• Use the Select Feature tool to click on areas in the map and view their properties
• You can see subbasin numbers, channel IDs, landscape units, landuse, soil, slope bands, and HRU numbers

View Reports:

In the main QSWAT+ window, use Select report to view to access:

• Elevation report - elevation distribution across the watershed and subbasins
• Landuse and Soil report - areas for each landuse, soil, and slope band by subbasin
• HRUs report - details of all HRUs that were created (available after HRU creation, shows only retained landuses, soils, and slope bands)

Save Your Project

Important: Save your project now via the QGIS File menu before proceeding to the SWAT+ Editor.

You can now click Edit Inputs and Run SWAT to start SWAT+ Editor.

HRU filtering tab

Edit Inputs and Run SWAT+

Launching SWAT+ Editor

1. From the main QSWAT+ dialog, click Step 3: Edit Inputs and Run SWAT
2. Upon opening your project in SWAT+ Editor, your data must be imported from the GIS tables into SWAT+ database format. Confirm your project name and enter a short description. Click Start and wait for it to finish (this may take a few seconds to several minutes).
3. Once loaded, click Get Started at the bottom of the window

Note: When launching SWAT+ Editor from QSWAT+, the QSWAT+ interface will lock and show a "Not Responding" message. This is expected behavior. SWAT+ Editor is a stand-alone program that can also be accessed outside of QSWAT+. In Windows, search for SWAT+ Editor in the taskbar to launch on its own.

Initial project setup dialog in SWAT+ Editor

Adding Weather Generator Data

1. In the left menu, go to Weather Generator
2. Click Import Data at the bottom of the window
3. Select Two CSV files from the top dropdown menu
4. Browse to C:\Users\[USER_NAME]\SWATPlus\ExampleDatasets\Robit
5. Select WGEN_Robit_stat.csv and WGEN_Robit_mon.csv
6. Check the box to use observed weather data
7. Click Start Import

Confirmation: One weather generator station will be added.

Note: You can alternatively import from the distributed WGN database by selecting the database import option and choosing from tables like wgn_cfsr_world (global data), wgn_us (United States), or wgn (empty table for custom data).

Import weather generator data in SWAT+ Editor

Adding Observed Weather Data

1. In the left menu, click Weather Stations
2. Click Import Data
3. For SWAT2012 weather files directory, browse to C:\Users\[USER_NAME]\SWATPlus\ExampleDatasets\Robit\ClimateRobit
4. Leave the default save location (TxtInOut folder)
5. Click Start

Confirmation: One weather station will be added. The station is automatically connected to the weather generator from the previous step and assigned to spatial connection objects by closest latitude/longitude.

Viewing Your Setup: You can click on the file names to open them directly from the editor.

Import observed weather dialog

Weather station with WGN auto-assigned

Weather station assigned to channels

Running the Simulation

1. Click the play/triangle icon in the navy ribbon on the left side
2. Click Set your simulation period and adjust the starting date to 01/01/2000
3. Click Choose output to print and set warm-up period to 3 years
4. Review available outputs to print (scroll to see all options)
5. Keep all three task checkboxes selected:
   • Write input files - translates database to text files for SWAT+
   • Run SWAT+ - executes the model
   • Analyze output for visualization - reads output files into SQLite database
6. Click Save Settings & Run Selected

Note: Input files are saved to [Project Directory]/Scenarios/Default/TxtInOut by default. Maximum simulation date range is based on your observed weather files.

Change your simulation time

Choose output to print and model warm-up

Run the simulation

Checking Model Output

When the simulation completes, you'll see a menu of options for what to do next. Click SWAT+ Check to check for potential model problems.

SWAT+ Check has several tabs at the top—navigate through them to review different aspects of your model. For several sections, you can filter values by land use. For example, go to the Plants tab, turn on the Check by land use switch, then select a land use from the dropdown menu to see values specific to that land use type.

You can also preview HRU management from this window. Select an HRU from the list, and its management events will load in a list.

Simulation completed successfully

SWAT+ Check hydrology for entire basin

Filter by landuse and preview management

You can now proceed to QSWAT+ Step 4: Visualization.

Click Visualize on the main QSWAT+ form to open the Visualize Results window. Select your simulation from Choose scenario (initially just Default), then pick a data table from Choose SWAT+ output table.

The Visualize tool offers three display options: Static data (summary maps), Animation (time-based changes), and Plot (charts). This tutorial covers Static data and Animation. For advanced topics, refer to the QSWAT+ manual.

Creating Static Maps

1. Select the Static data tab
2. Choose a SWAT+ output table (example: lsunit_pw_yr)
3. Add variables - Click All to include everything, or add individually with Add. Use Del or Clear to remove variables. For this example, make sure bioms is included in your selection.
4. Pick a summary method:
   • Totals - Sum of all values
   • Daily/Monthly/Annual means - Average per time period
   • Maxima/Minima - Highest/lowest value

   Note: For flow rates and similar variables, only means and extremes make sense.

   For this example, select annual means to display the average biomass per year.

5. Select bioms from the variables list, then click Create to generate your map showing annual mean biomass values across your watershed.

Working with your map: To display a different variable or summary method, select it and click Create. To change colors, right-click the layer, select Properties → Symbology. Enable Show Map Tips and hover over areas to see values.

Static map form and output

Animation

1. Choose your scenario and output table (example: channel_sdmorph_mon)
2. Select the Animation tab
3. Pick a variable (example: flo_out)
4. Keep animation mode set to Map canvas
5. Start playback by pressing the run button (right triangle icon)
6. Adjust playback using the pause and rewind buttons or use the slider and arrow keys to navigate
7. Adjust the Speed as needed
8. Right-click the layer on the map and select Open Attribute Table to see actual values at each frame.

Recording GIFs

1. Click the green box to start recording
2. Run your animation
3. Click the red box to stop recording
4. Press Play to play the recording
5. flo_outVideo.gif is saved in the Results directory

Animation form and output