Recall objects are used for connecting point source or inlet data to your watershed. If you added point source in QSWAT+, when you import your project into SWAT+ Editor it will be connected via the recall section.

By default, constant data with all zero values during the default simulation period is added. To add your own recall data, click the recall item in the edit menu under connections. Click the item name under the rec column in the connection object table, or click the data item under recall in the edit menu on the left.

Constant Data

By default, your recall data is imported as constant. To insert your values, you can edit each item individually by clicking the edit button and manually entering each value. Alternatively, you may upload a CSV of your data.

From the recall data section, click the import/export button in the top right corner.

Export is selected by default. Choose a file name, and click the export CSV file button to get a template for your data.

Edit the CSV as needed, save, and then go back to the editor and click the import/output button again. This time toggle the import button. Choose your modified CSV file and click the import CSV data button. Your updated values will appear in the table.

Time Series Data

By default recall data is imported as constant, however this can be changed by clicking the edit button next to a row in the recall data table. Select the new time step for your data: daily, monthly, or yearly. Click the save changes button. Next, click the import/export button that appears on the form.

Export is selected by default. Choose a file name, and click the export CSV file button.

Open the file after it is exported to see the template for your data. Modify your data as needed matching the time step you selected previously. Be sure the years match your . In a yearly time step, t_step equals 1 through number of years. For monthly data, t_step equals the number of the month, and for daily it is the number of the day of the year.

To import your data, click the import/export data button again and this time click to toggle import. Choose your file and click import CSV file. Your new data will appear in the table.

Recall Table Definitions

Each record in recall_rec will have a data file named {name}.rec. All of this data is stored in a single recall_dat table in the database.

Special note about using export coefficients with constant point source/inlet data

In SWAT+, constant values for point sources and inlets are stored in the export coefficients properties file, exco.exc, while time series data are stored entirely in the recall section.

However, in the editor, we keep both constant and time series point sources and inlets in the recall section. When you write input files, the editor will write to the exco.exc and exco_om.exc files appropriately.

The connections section contains all spatial object connectivity for the simulation run. In SWAT+ Editor, all connection object properties can be set through this section. For example, when you click on channels, you will see additional menu links appear for: properties, initialization, hydrology and sediment, and nutrients.

All connection objects have a similar format as seen in the above figure. The tabular view is shown by default. Click the map view tab to see a map with markers for the center coordinates of each object. Click an object marker in the map view, or edit icon on the left side of a row in the table to view or edit the object.

Each connection object will have a main properties object associated with it as well as a weather station. Click on these names in the table, or from the edit view page, click the button next to their names to view information about the properties object or weather station.

Each connection object may have outflow. This can be viewed in the table by clicking the eye icon in the rightmost column, or view from the edit page.

If you imported your project from GIS, your connection objects are populated automatically during project setup.

Explanation of SWAT+ Spatial Objects

Subbasin

The subbasin is defined by the DEM in the GIS interface as it always has been. All flow within the subbasin drains to the subbasin outlet.

Landscape Unit

A landscape unit (LSU) is defined as a collection of HRUs and can be defined as a subbasin, or it could be a flood plain or upland unit, or it could be a grid cell with multiple HRUs. The landscape unit is not routed, it only used for output. The landscape unit output files (waterbal, nutbal, losses, and plant weather) are output for HRUs, landscape units, and for the basin. Two input files are required: 1) landscape elements and, 2) landscape define. The elements file includes HRUs and their corresponding LSU fraction and basin fractions. The define file specifies which HRUs are contained in each LSU.

Routing Unit

A routing unit is a collection of hydrographs that can be routed to any spatial object. The routing unit can be configured as a subbasin, then total flow (surface, lateral and tile flow) from the routing unit can be sent to a channel and all recharge from the routing unit sent to an aquifer. This is analogous to the current approach in SWAT. However, SWAT+ gives us much more flexibility in configuring a routing unit. For example, in CEAP, we are routing each HRU (field) through a small channel (gully or grass waterway) before it reaches the main channel. In this case, the routing unit is a collection of flow from the small channels. We also envision simulating multiple representative hillslopes to define a routing unit. Also, we are setting up scenarios that define a routing unit using tile flow from multiple fields and sending that flow to a wetland.

The routing unit is the spatial unit SWAT+ that allows us to lump outputs and route the outputs to any other spatial object. It gives us considerably more flexibility than the old subbasin lumping approach in SWAT, and will continue to be a convenient way of spatial lumping until we can simulate individual fields or cells in each basin.