Introduction¶
This adapter enables use of SWAT models within the MIKE Workbench.
Limitations¶
Concept¶
SWAT (Soil & Water Assessment Tool) is a river basin scale model developed to quantify the impact of land management practices in large, complex watersheds. It is a hydrology model with the following components: - Weather - Surface runoff - Return flow - Percolation - Evapotranspiration - Transmission losses - Pond and reservoir storage - Crop growth and irrigation - Groundwater flow - Reach routing - Nutrient and pesticide loading - Water transfer
The SWAT model consists of a long range of text files containing information about the watershed.
The main entry of the SWAT model is the master watershed file (file.cio). This file contains basic information about the watershed, including a reference to the watershed configuration file (.fig).
The .fig file contains commands describing the routing network - including sub basins and main channels (reaches) and lists input file names for the different objects in the watershed.
Watershed¶
The area investigated by SWAT. I.e. it may have a polygon defining the boundaries.
Subbasin¶
A polygon defining an area of interest within the watershed. The subbasins make up the watershed in SWAT context.
A subbasin will contain at least one HRU, a tributary channel and a main channel or reach
A separate layer for the subbasins may exist.
Reach/main channel¶
One reach or main channels is associated with each subbasin of the watershed. Loadings from the subbasin enter the channel network of the watershed in the associated reach segment.
Reservoir¶
Reservoirs are manmade structures within the watershed. Reservoirs receive water contributed to the channel network from all upstream subbasins.
Weather Stations¶
Weather stations are stations with a physical location measuring temperature and precipitation.
HRU¶
The key model object is the hydrologic response unit (HRU) which is created as the interaction between layers of: - Landuse - Soil - Slope
The HRUs has numbers indicating which subbasin they refer to and id they have – e.g. 00010003 for HRU with id number 3 in basin number 1.
A number of parameter and configuration files are associated with each HRU. The parameters may be changed to run the model with different configurations.
Prerequisites¶
The configuration and execution of a SWAT models in MIKE OPERATIONS using this adapter will require: - A SWAT 2012 executable to run the SWAT model. - That the SWAT 2012 model has been successfully executed, so that the SWAT output text files are available to the SWAT adapter for parsing at registration time.
Configuration¶
This section describes the formats and details of the WEAP adapter and WEAP model setups.
SWAT model setup¶
No specific configuration of a SWAT model setup has to be followed in order to register it into the MIKE Workbench. The WEAP model setup needs to run successfully within WEAP and the adapter assumes that all files related to the registered WEAP model are in the corresponding area folder.
Model object types¶
The SWAT model supports 6 model object types. Any input time series, output time series and model object parameter must be related to one of these types: - Watershed - Subbasin - Reach - Weather Station - Reservoir - HRU - Point Sources and Inlets
These objects can be visualized on the map.
Model components like Pond, Wetland and Tributary channels exist at the sub-basin level and as such their parameters will become part of the sub basin model object.
Model Object Parameters¶
Each of the model object types listed in the section above, will have a number of parameters that can be viewed or edited.
The table below shows the groups of parameters available in each type of the watershed.
| Model object Type | Base file | Sub files |
|---|---|---|
| Watershed | file.cio | |
| .bsn | ||
| crop.dat | ||
| urban.dat | ||
| .cst | ||
| Subbasin | .sub | |
| .wgn | ||
| .wus | ||
| .pnd | ||
| Weather Stations | N/A | |
| Hydrologic Response Unit | N/A | |
| .hru | ||
| .sol | ||
| .gw | ||
| .mgt | ||
| Reach | N/A | |
| .rte | ||
| Reservoir | N/A | |
| .res | ||
| .lwq | ||
| Inlets and Point Sources | N/A |
Below figure shows the parameters of the “Sub” group of a subbasin.
Input Time Series, units and value types¶
Converting input time series in the SWAT model to time series in MC (DHI EUM) and from MC format to SWAT model format.
MC will support converting time series with changing units (e.g. mm to in) and value types (e.g. Instantaneous to Step_Accumulated), but does not support changing variable type (e.g. from Rainfall to Water level).
Converting units and value types is part of the following processes: - Model registration - Model execution
The table below lists how supported input time series in SWAT will be converted to time series in MC during registration and back when executing the model.
Input time series in the SWAT model will always be created as time series of the specified type in MC.
This means that if time series with a different format (value type and/or unit) will be used as input time series, they must be converted to the specified type, before writing the time series values to the SWAT text files. This will ensure that time series values will be written to SWAT files in the correct format as specified below.
| File ext. | TS Name | Description | EUM Value Type | EUM Variable | EUM Unit |
|---|---|---|---|---|---|
| (.pcp) | PRECIPITATION | Amount of precipitation falling during the day (mm). | Step_Accumulated | Rainfall | mm |
| (.tmp) | MAX TEMP | Daily maximum temperature (ºC). | Instantaneous | Temperature | deg C |
| (.tmp) | MIN TEMP | Daily minimum temperature (ºC). | Instantaneous | Temperature | deg C |
| (.pet) | PETMEAS | Daily potential evapotranspiration for watershed (mm H2 O). | Mean_Step_Accumulated | Evaporation Rate | mm/day |
| (.wgn) | SOLARAV | Average daily solar radiation for month (MJ/m2/day). | Mean_Step_Accumulated | Radiation intensity | MJ/m2/d |
| (.hmd) | RHD | Daily average relative humidity expressed as a fraction. | Instantaneous | Relative humidity | % |
| (.wnd) | WND_SP | Daily average wind speed (m/s). | Instantaneous | Wind speed | m/s |
| (resdayo.dat) | RESDAYO | The water release rate for the day (m3/sec). | Mean Step Accumulated | Discharge | m\^3/s |
| (resmono.dat) | RESMONO | Measured average daily outflow from the reservoir for the month (m3/s). | Mean Step Accumulated | Discharge | m\^3/s |
The SWAT adapter is supporting a range of input time series on point Sources and Inlets.The mean_step_accumulated input time series are listed here: - FLO - SED - ORGN - ORGP - NO3 - NH3 - NO2 - MINP - CBOD - DISOX - CHLA - SOLPST - SRBPST - BACTP - BACTL - CMTL1 - CMTL2 - CMTL3
Output time series¶
The SWAT adapter supports nearly any output time series available in a SWAT model.
Most output time series from the following output files are supported:
| Model object type | Name | File | Description |
|---|---|---|---|
| Watershed | Standard output file | Output.std | The standard output summary file provides watershed average annual, monthly or daily loadings from the HRU’s to the streams. This file is the first file the user should examine to obtain a basic understanding of the watersheds water. This file is supported as additional output data. This means that time series of the file is not parsed. |
| HRU | HRU output file | Output.hru | File containing summary information’s for each of the HRU. |
| Subbasin | Subbasin output file | Output.sub | File containing summary information for each of the sub basins in the watershed. |
| Reach | Main channel output file | Output.rch | File containing summary information for each routing reach in the watershed. |
| Reach | Sediment loads output file | Output.sed | File containing summery information for sediment movement in the watershed. |
| Reach | Pesticide output file | Output.pst | Amount of pesticides sorbed. |
| Reservoir | Reservoir output file | Output.rsv | File containing summary information for reservoirs in the watershed. |
Model registration¶
The SWAT model should be registered from within the Scenario Explorer of the MIKE Workbench. The below screens shows how the registration could look like.
When registering a model, a new entry for the SWAT model will appear.
When selecting model type “SWAT”, the Model register wizard will display a dialog where the necessary SWAT model information can be specified.
Table 5 Model registration wizard (Page 1) – SWAT model Information
On the first page of the model registration wizard, the master SWAT file and executable is selected.
| Field | Description |
|---|---|
| Model setup name | Name of the model when it has been registered in MIKE Workbench. |
| SWAT master file | The SWAT master watershed file (file.cio) containing names of watershed level files. |
| SWAT executable | The SWAT executable used to execute the current SWAT model. The exe file will be saved into the MIKE MIKE Workbench database, so that the right version of the SWAT engine is always used. This means that the selected executable will be used for executing the SWAT model. |
Click “Next” to continue.
Table 6 Model registration wizard (Page 2) – Model Schematics
The second page of the model registration wizard is for selecting the model schematics.
| Field | Description |
|---|---|
| Watershed shape file | Shape file contain the subbasins of the selected SWAT model. The first feature of the shapefile will be used as the watershed polygon. |
| Watershed projection | The projection of the Shape file. |
| Subbasin shape file | Shape file contain the subbasins of the selected SWAT model. The shape file must contain a field with the subbasin number (1,2,3,4…). |
| Subbasin field | The field containing the subbasin number. |
| Subbasin projection | The projection of the Shape file. |
| Reach shape file | Shape file contain the Reaches of the selected SWAT model. The shape file must contain a field with the reach number (1,2,3,4…). |
| Reach field | The field containing the reach number. |
| Reach projection | The projection of the reach Shape file. |
| Reservoir, Inlets and Point Sources shape file | Shape file contain the reservoirs, point sources and inlets of the selected SWAT model. |
| Reservoir, Inlets and Point Sources field | The field containing the reservoir number. |
| Reservoir, Inlets and Point Sources projection | The projection of the reservoir Shape file. |
| HRU shape file | Shape file contain the HRU stations of the selected SWAT model. The shape file must contain a field with the HRU number (1,2,3,4…). |
| HRU field | The field containing the HRU number. |
| HRU projection | The projection of the HRU Shape file. |
The way reservoirs, point sources and inlets are stored differs depending on which tool is used to create the model (ArcSWAT or MWSWAT). The name given by ArcSWAT for the shape file is always monitoring_points1.shp found in the watershed folder of the project and feature class named MonitoringPoint inside the geo-database for the project (MS Access Database by the name of the project). The name given for the shape file to store reservoirs, point sources and inlets in MWSWAT can vary as it is given by the user.
-
ArcSWAT’s monitorin_points1.shp attribute name ‘Type’ identifies which point represents which according the following key;
- T - outlet to the entire basin
- W – Inlets
- P – Point Sources
- R – Reservoirs
- For inlets and point sources average daily, monthly and annual loading files are normally named after the corresponding ‘subbasin’ attribute which is the sub-basin number the inlet is feeding to or the point source is originates from. E.g. 8i.dat, 9p.dat etc…
- Reservoir, reservoir water quality input files and associated flow data files are named after the corresponding ‘subbasin’ attribute. E.g. 000030000.res, 000030000.lwq, (000030000.mon or 000030000.day)
-
MWSWAT’s attributes identifying the above model objects are ‘ptsource’, ‘res’ and ‘INLET’. Both point sources and inlets have value 1 for ‘INLET’ attribute with only point sources having value 1 for ‘ptsource’ attribute. Reservoirs have value 1 for ‘res’ attribute.
Click “Next” to continue.
Table 7 Model registration wizard (Page 3) – Additional Files
On the third page of the model registration wizard, additional files can be selected. Additional files can e.g. be files needed by ArcSWAT. From the context menu of the tree, the files can be selected or removed. Selection is done from an open file dialog.
It is required that files selected must be on the same drive/disk, so that a common root of the additional files and the native SWAT files can be found.
The selected files are shown in a tree with one level, with their full path and name. Selected files will be added to the model zip file containing the native SWAT text files, so that they are available when selecting “Open in native tool” on the model setup in the Scenario Manager of MIKE Workbench.
After clicking the “Next” button, the SWAT model will be loaded and the result of the SWAT model parsing will be displayed on the “Time series Link Page”.
Click next to display the default “Specifications” page.
Specify the necessary information and click Finish to register the model.
Open in Native Tool¶
After registration, the SWAT model can be “opened in native mode”. This is done by selecting “Open in Native Tool” from the context menu of the Model Setup.
This will unzip the content of the SWAT model into a temporary folder in the users default temp folder (%temp%).
The folder will contain any native SWAT text file related to the selected master watershed file as well as the selected additional folders and files.