ArcSWAT Extension ArcGIS is a graphical user interface for the Soil and Water Assessment Tool (SWAT) model (Arnold et al., 1998). 1 The space required to create a SWAT project with the ArcSWAT interface depends on the resolution of the maps used.
I NSTALLING A RC SWAT
Click "Next" to proceed to the license agreement page By selecting "I agree" you will be allowed to proceed to the next step in the installation process by clicking "Next". This is required, as some of the SWAT databases installed in this folder will be accessed for editing from the ArcSWAT interface.
A RC SWAT I NSTALLATION C ONTENTS
SWAT2009.mdb: This geodatabase contains all SWAT 2009 data tables required by the ArcSWAT interface. The "LayerFiles" folder contains the layer files used by the ArcSWAT interface during the watershed delineation process.
P REPARING A RC SWAT I NPUT
R EQUIRED A RC SWAT S PATIAL D ATASETS
Because the land database contains information for the entire United States, the 3-digit STATSGO number must have the 2-digit numeric code for the state. 34;Name" specified for each of the map categories is the name of the soil in the User Soils database.
O PTIONAL A RC SWAT S PATIAL D ATASETS
Outfalls to subbasins will be defined as a small distance upstream from the terminus of the stream, requiring a stream terminus to coincide on a watershed boundary. GRID_CODE Integer An integer representing the numeric ID of the subbasin to which the stream belongs.
A RC SWAT T ABLES AND T EXT F ILES
CMTL1DAY floating point (f12.3) Average daily load of conservative metal # 1 for the day (kg/day). CMTL2DAY floating point (f12.3) Average daily load of conservative metal # 2 for the day (kg/day).
G ETTING S TARTED WITH A RC SWAT
A RC SWAT T OOLBAR I TEMS
SWAT P ROJECT S ETUP M ENU
The SWAT Project Setup Menu: New SWAT Project
The SWAT Project Setup Menu: Open SWAT Map Document
The SWAT Project Setup Menu: Save SWAT Project
The Save SWAT Project command saves the current SWAT project you are currently working on.
The SWAT Project Setup Menu: Copy SWAT Project
The SWAT Project Setup Menu: Delete Project
The SWAT Project Setup Menu: ArcSWAT Help
The SWAT Project Setup Menu: About ArcGIS ArcSWAT
The Watershed Delineator Menu: Automatic Delineation
The Watershed Delineator Menu: Watershed Reports
T HE HRU A NALYSIS M ENU
The HRU Analysis menu contains all the commands that perform the land use, soil and slope analysis used to generate the SWAT HRU.
The HRU Analysis Menu: Land Use/Soils/Slope Definition
The HRU Analysis Menu: HRUs Distribution
The HRU Analysis Menu: HRU Analysis Reports
The Write Input Menu: Weather Stations
The Write Input Menu: Write All
The Write Input Menu: Write Configuration File (.fig)
The Write Input Menu: Write Soil Data (.sol)
The Write Input Menu: Write Weather Generator Data (.wgn)
The Write Input Menu: Write Subbasin General Data (.sub)
The Write Input Menu: Write HRU General Data (.hru)
The Write Input Menu: Write Main Channel Data (.rte)
The Write Input Menu: Write Groundwater Data (.gw)
The Write Input Menu: Write Water Use Data (.wus)
The Write Water Use Data (.wus) command creates an ArcSWAT geodatabase table (wus) that stores values for SWAT water use input parameters.
The Write Input Menu: Write Management Data (.mgt)
The Write Input Menu: Write Soil Chemical Data (.chm)
The Write Input Menu: Write Pond Data (.pnd)
The Write Input Menu: Write Stream Water Quality Data (.swq)
The Write Input Menu: Write Septic Data (.sep)
The Write Input Menu: Write Operations Data (.ops)
The Write Input Menu: Write Watershed General Data (.bsn)
The Write Input Menu: Write Watershed Water Quality Data (.wwq)
The Write Input Menu: Write Master Watershed Data (.cio)
The Edit SWAT Input menu allows you to edit the SWAT model databases and watershed database files that contain the actual inputs for the SWAT model.
The Edit SWAT Input Menu: Databases
The Edit SWAT Input Menu: Point Source Discharges
The Edit SWAT Input Menu: Inlet Discharges
The Edit SWAT Input Menu: Reservoirs
The Edit SWAT Input Menu: Subbasins Data
The Edit SWAT Input Menu: Watershed Data
The Edit SWAT Input Menu: Re-Write SWAT Input Files
The Edit SWAT Input Menu: Integrate APEX Model
T HE SWAT S IMULATION M ENU
The SWAT Simulation menu allows you to run the SWAT model and perform sensitivity analysis and calibration.
The SWAT Simulation Menu: Run SWAT
The SWAT Simulation Menu: Read SWAT Output
The SWAT Simulation Menu: Set Default Simulation
The SWAT Simulation Menu: Manual Calibration Helper
The SWAT Simulation Menu: Sensitivity Analysis
The SWAT Simulation Menu: Auto Calibration and Uncertainty Analysis
The SWAT Simulation Menu: Re-Run Calibrated Model
The SWAT Simulation Menu: Sensitivity/Calibration Reports
- M ANAGING A RC SWAT P ROJECTS
- N EW SWAT P ROJECT To create a new ArcSWAT project: To create a new ArcSWAT project
- O PEN SWAT M AP D OCUMENT To create an existing ArcSWAT map document: To create an existing ArcSWAT map document
- S AVE SWAT P ROJECT To save the current ArcSWAT project: To save the current ArcSWAT project
- C OPY SWAT P ROJECT To copy an ArcSWAT project: To copy an ArcSWAT project
- D ELETE SWAT P ROJECT To delete an ArcSWAT project: To delete an ArcSWAT project
- A RC SWAT H ELP
- C ONVERTING A N A RC SWAT2. X
- W ATERSHED D ELINEATION
The project directory will be where all your SWAT project files are stored. Next, use the Browse File button next to the SWAT Project Geodatabase text box to select the SWAT Project Geodatabase associated with the project.
Purpose
Application
Key Procedures
- W ATERSHED D ELINEATION D IALOG B OX
- DEM S ETUP
- S TREAM D EFINITION
- O UTLET AND I NLET D EFINITION
If the selected DEM is in a defined geographic coordinate system, the message in Figure 5.6 will be displayed. Two layers are now added to the map and are displayed above the DEM layer mesh: Reach (the actual synthetic drainage network) and MonitoringPoint (the relevant stream crossing points) (Figure 5.26). A dialog box will appear that allows the user to specify whether the dataset will be loaded from disk or from the map (Figure 5.28).
Adding Outlets by Table (DEM-based Stream/Watershed Definition Only)
Once geocoded, the outlet locations will automatically click to the nearest reach of the Streams theme. Outlets that are at a distance greater than 100* DEM cell size from the nearest stream will not be snapped. Duplicate outlets deleted: It is possible that some outlets added from a table are snapped to the same location on a stream (typically the end point of the stream whose outlet points are far from the nearest stream).
Adding Point Sources or Inlets of Draining Watersheds from Tables (DEM-based Stream/Watershed Definition Only)
Add drainage basin point sources or intakes from tables (DEM-based watershed definition only). All locations in the table must be type “D” (point sources) or type “I” (draining catchment inlets). Information messages about the success of the table import, similar to those reported when adding subbasin outlets, appear when the table import is complete.
Manually Editing Outlets and Inlets
If a different "Type" value is specified, the dialog box will report an error as shown in Figure 5.30 and the upload process will stop. The output point will automatically snap to the nearest flow line and the feature will be added to the "Outputs" theme. If you select one of these points, the dialog box will report an error (Figure 5.41) and the process will stop.
Adding Point Sources to All Subbasins
The sub-watershed definition is completed in this section (Figure 5.42) of the Watershed Definition dialog box. If a point source or drainage basin inlet was among the selected points, a dialog box will report an error and the points will be deselected (Figure 5.43). The process of defining the watershed will be executed and when finished a message indicating successful completion will be displayed (Figure 5.45).
C ALCULATION OF S UBBASIN P ARAMETERS
Calculating Subbasin Parameters
Skip longest flow path calculation (optional): The default is to calculate the longest flow path for each subbasin using the DEM (see the checkbox in Figure 5.48). If this option is skipped, the longest flow path in each subbasin is set to the length of the main channel reach, which will always be less than or equal to the actual longest flow path. Note: The Skip Longest Flow Path (LFP) calculation option is disabled and set to skip the calculation when custom subbasins and streams are selected.
Adding a Reservoir
If the user removed any of the outlets defined by the interface during the initial analysis of the DEM, the mainstem within the subbasin is assumed to represent the single stream reach associated with the subbasin. Once the first reservoir location is added, the reservoir symbols will be added to the MonitoringPoints layer of the map (Figure 5.53). Refine the outlet set if more than one reservoir location is to be set in the current subbasin area.
Removing a Reservoir(s)
- C OMPLETION OF W ATERSHED D ELINEATION
- HRU A NALYSIS
- L AND U SE / S OIL / S LOPE D EFINITION AND O VERLAY
- G ET S TARTED
- L AND U SE D ATA
If the land use layer is not displayed, select Load Land Use Dataset(s) from Disk. After loading, you will receive a message describing the overlap between the land use dataset and the watershed (Figure 6.6). You will then be prompted to select the land use code field in the land use dataset (Figure 6.8).
Define SWAT Land Cover associated with land use layer categories using lookup table
SWAT land cover/vegetation descriptors are assigned to the land use layer on the map and the LandUseSwat field in the SWAT agricultural classification table is populated (Figure 6.17). You can also manually define the SWAT land cover classes for your land use grid. Tip: If your land use lookup table results in a value of "NOCL" for the LandUseSwat class, this indicates that there is no class in the SWAT land cover/vegetation database for that grid class.
Define SWAT Land Cover associated with land use layer categories manually
You may want to do this if you do not have a land use lookup table, or there are some land use codes not found in your land use lookup table, or if you want to redefine the SWAT land cover description for one or more of the land use classifications in your data set. Select the land cover class you want to assign to the current grid land use code and click OK. The selected land cover class will appear in the LandUseSwat column in the SWAT land use classification table (Figure 6.21).
Reclassify land use layer with SWAT land cover classes
S OIL D ATA L AYER
Define Soil layer
After uploading, you will receive a message describing the overlap between the soil dataset and the catchment (Figure 6.28). You will then be prompted to select a soil code field in the soil dataset (Figure 6.30). If you select Shapefile of Feature Class, you will be prompted to define a land use value field (Figure 6.30).
Define SWAT Soil associated with soil layer categories
The interface allows map categories to be linked to soil databases in one of five ways. The Stmuid, Stmuid + Seqn, or Stmuid + Name radio buttons are used to link a STATSGO map to the STATSGO soil database. To link a soil series or Soils5 map to the STATSGO database, the S5id radio button is selected.
Manually assign soil attribute data
A dialog box will appear for the user to enter the State STATSGO polygon number (Figure 6.41). A dialog box will appear for the user to enter the Soils5 ID number (Figure 6.42). A dialog box appears for the user to enter the name of a soil series (Figure 6.44).
Assign soil attribute information using a look-up table
Once soil attribute codes have been assigned to all map categories, the Reclassify button will be enabled. In ArcSWAT, users must create a slope classification based on the DEM used during watershed delineation, even if only one slope class will be used.
To define slope classes
HRU D EFINITION
One or more unique land use/soil/slope combinations (hydrological response units or HRUs) can be created for each sub-basin. By subdividing the watershed into areas with unique land use and soil combinations, the model can reflect differences in evapotranspiration and other hydrological conditions for different land covers/crops and soils. If one HRU is selected per sub-watershed, the HRU is determined by the dominant land use category, soil type and slope class within each watershed.
Detailed Operations
The land use slider controls the threshold level used to eliminate minor land uses in each subbasin. This scale is used to eliminate small slope classes within a soil on a specific land use area. This process is performed for each soil and land use modeled in the sub-basin.
Set land use split settings
This can be accomplished by dividing the "Ry Crops" land use into sub-land uses. You may want to modify the percentages of the sub-land uses you have defined for a parent land use. That land use will now appear back in the Select new land use to split combo box (Figure 6.73).
Set land use threshold exemptions
I MPORT W EATHER D ATA
The temperature gauge location table should be prepared by the user following the format described in section 3. The solar gauge location table should be prepared by the user following the format described in section 3. The wind gauge location table should prepared by the user following the format described in section 3.
C REATION OF I NPUT
W RITE A LL
If "No" was selected in response to the dialog in Figure 8.2, then when the writing of the .sub database (general input from subbasin) begins, a prompt box appears (Figure 8.4) offering two options to define the Manning's roughness factor for tributary channels in all subbasins. If "No" was selected in response to the dialog in Figure 8.2, when the writing of the .rte database (main channel input) begins, a prompt box appears (Figure 8.6) offering two options for defining the Manning's roughness factor for the main channel channels in all subbasins. Once all default inputs have been generated, you can move to the SWAT simulation menu and do a SWAT run (see Section 14) or edit the default inputs using the editors enabled under the Edit SWAT Inputs menu (see Sections 9-13) .
I NDIVIDUAL W RITE C OMMANDS
This selection generates subbasin watershed data (see Land and Water Assessment Tool User's Manual, Version 2009, Chapter 28). This selection generates water quality data for the subbasin stream (see Land and Water Assessment Tool User's Manual, Version 2009, Chapter 26). This selection generates subbasin stream water quality data (see Land and Water Assessment Tool User's Manual, Version 2009, Chapter 3).
I NPUT M ODIFICATION —P OINT S OURCES
You can now make changes to any of the point source parameters in the dialog. The Select Point Source Type Data Type combo box located at the top of the dialog box allows the user to select the data format they prefer. A browser will appear, allowing the user to select the dBASE file (.dbf) or text file (.txt) containing the point source data from disk (Figure 9.11).
I NPUT M ODIFICATION —I NLET D ISCHARGES
A browser is displayed where the user can select the dBASE file (.dbf) or the text file (.txt) that contains the disk inlet data (Figure 10.11). A browser is displayed where the user can select the dBASE file (.dbf) or the text file (.txt) that contains the disk inlet data (Figure 10.13). Click the Exit button in the Edit Point Discharge Input dialog box to return to the Inlet Select dialog box (Figure 10.15).
I NPUT M ODIFICATION —R ESERVOIRS
Monthly Data: The variable names listed in the Monthly Data tab (Figure 11.13) control constant monthly reservoir parameters. The variable names listed on the Lake Water Quality Data tab (Figure 11.15) control the water quality parameters in the reservoir. Click the Exit button in the Edit Reservoir Parameters dialog box to return to the Select Reservoir dialog box (Figure 11.18).
I NPUT M ODIFICATION --S UBBASINS
Select input table to edit: This section contains a combo box that allows the user to select a table in the SWAT project geodatabase to be edited. When you select the input SWAT table, the Select Subbasin/HRU section will be enabled. This combo box will only be enabled if the SWAT input table selected is one that contains data at the HRU level.
E DIT S OIL P ARAMETERS (.SOL)
Editing Soil Parameters
The user can change the current soil layer by selecting another layer from the Soil Layer combo box. When you change the soil layer, the parameters in the Soil Layer Parameters section also change (Figure 12.12). While editing soil parameters, if you are ever unhappy with your changes, you can click the Cancel Edits button and all the parameters will return to their previous values (ie the values before the editing session was started).
Saving Parameter Edits
E DIT W EATHER G ENERATOR I NPUT D ATA (.WGN)
The Edit Weather Generator dialog box opens when the user selects .Wgn from the SWAT Input Table drop-down list in the Edit Subbasin Entries dialog box (Figure 12.9). The dialog box opens showing the parameters used to generate weather data for the selected sub-basin (Figure 12.18).
Editing Weather Generator Data
