Set land use threshold exemptions
SECTION 7: I MPORT W EATHER D ATA
Weather data to be used in a watershed simulation is imported once the HRU distribution has been defined. Weather data is loaded using the first command in the Write Input Tables menu item on the ArcSWAT toolbar. This tool allows users to load weather station locations into the current project and assign weather data to the sub-watersheds. For each type of weather data loaded, each sub-watershed is linked to one gage.
1. Select Weather Stations from the Write Input Tables menu The Weather Data Definition dialog is displayed (Figure 7.1)
Figure 7.1
2. The Weather Data Definition dialog is divided in six tabs: Weather Generator Data, Rainfall Data, Temperature Data, Solar Radiation Data, Wind Speed Data and Relative Humidity Data. The first section listed, Weather Generator Data, must be set. The interface will not allow the user to perform other input data processing until the Weather Generator Data, is defined. The other five sections allow the user to choose between simulated or measured climate data for specific types of data.
a. Weather Generator Data: In this section (Figure 7.2) the user must define the data used to generate various weather parameters. Data loaded in this section is used to build .wgn files for the dataset. For more information on the type of data used to generate weather data, please see the SWAT2009 Theoretical Documentation and the SWAT2009 User’s Manual.
Weather station locations and weather generator data are obtained from one of two sources: the built-in US database or the User Weather Stations database.
Figure 7.2
i. US database: The US database contains weather information for 1,041 stations around the United States and is provided with the interface.
In order to load and geocode the US database, select the US Database radio button .
Click the button.
ii. Custom database: This option is used to load custom weather generator data stored in the User Weather Stations database.
Select the Custom database radio button .
Click the open file folder button next to the Locations Table text box.
A file browser (Figure 7.3) allows you to select the location table for the weather generator stations. This table may be a dBASE or text table format. The location table is prepared by the user following the format described in Section 3.
Figure 7.3
Highlight the name of the weather generator location table and click Add. The browser will close and the path to the gage location table will be displayed in the Locations Table text box.
b. Rainfall data (optional). In this section the user can import measured precipitation data for use in the project (Figure 7.4).
Figure 7.4
To use measured precipitation data, select the Raingages radio button . Next, select either Daily or Sub-Daily from the Precip.
Timestep combo box . Click the open file folder button next to the Locations Table text box.
A file browser will appear that allows you to select the Precipitation gage location table. This table may be a dBASE or text table format.
The rain gage location table must be prepared by the user following the format described in Section 3.
Highlight the name of the precipitation gage location table and click Add. The browser will close and the path to the gage location table will be displayed in the Locations Table text box.
Note: The individual precipitation gage data files must be located within the same folder as the precipitation gage location table.
c. Temperature data (optional) In this section the user can import measured temperature data for use in the project (Figure 7.5).
Figure 7.5
To use measured temperature data, select the Climate Stations radio button . Click the open file folder button next to the Locations Table text box.
A file browser will appear that allows you to select the Temperature gage location table. This table may be a dBASE or text table format.
The temperature gage location table must be prepared by the user following the format described in Section 3.
Highlight the name of the temperature gage location table and click Add. The browser will close and the path to the gage location table will be displayed in the Locations Table text box.
Note: The individual temperature gage data files must be located within the same folder as the temperature gage location table.
d. Solar Radiation data (optional) In this section the user can import measured solar radiation data for use in the project (Figure 7.6).
Figure 7.6
To use measured solar radiation data, select the Solar Gages radio button . Click the open file folder button next to the Locations Table text box.
A file browser will appear that allows you to select the Solar gage location table. This table may be a dBASE or text table format. The solar gage location table must be prepared by the user following the format described in Section 3.
Highlight the name of the solar gage location table and click Add. The browser will close and the path to the gage location table will be displayed in the Locations Table text box.
Note: The individual solar gage data files must be located within the same folder as the solar gage location table.
e. Wind Speed data (optional) In this section the user can import measured wind speed data for use in the project (Figure 7.7).
Figure 7.7
To use measured wind speed data, select the Wind Gages radio button . Click the open file folder button next to the Locations Table text box.
A file browser will appear that allows you to select the Wind gage location table. This table may be a dBASE or text table format. The wind gage location table must be prepared by the user following the format described in Section 3.
Highlight the name of the wind gage location table and click Add. The browser will close and the path to the gage location table will be displayed in the Locations Table text box.
Note: The individual wind gage data files must be located within the same folder as the wind gage location table.
f. Relative humidity data (optional) In this section the user can import measured relative humidity data for use in the project (Figure 7.8).
Figure 7.8
To use measured relative humidity data, select the Relative Humidity Gages radio button . Click the open file folder button next to the Locations Table text box.
A file browser will appear that allows you to select the Humidity gage location table. This table may be a dBASE or text table format. The humidity gage location table must be prepared by the user following the format described in Section 3.
Highlight the name of the humidity gage location table and click Add.
The browser will close and the path to the gage location table will be displayed in the Locations Table text box.
Note: The individual humidity gage data files must be located within the same folder as the humidity gage location table.
3. Once all weather data is specified and station locations are loaded, an OK button will appear in the lower right corner of the Weather Data Definition dialog box (Figure 7.9).
Figure 7.9
Click the OK button. This starts the set up of the weather database:
a. Data assigned to a subbasin is obtained from the closest station.
b. A -99.0 value is used to fill in skipped daily data and to fill in measured climate records so that all records have the same starting and ending date. The starting date used for measured climate data is the earliest starting date listed in any record while the ending date is the latest ending date listed in any record. The –99.0 value is used to call the weather generator to generate a value to replace the missing data during run time.
4. When setup of the weather database is complete, a message dialog is displayed (Figure 7.10).
Figure 7.10
5. When the database setup is completed, the weather gages selected will be added to the MonitoringPoint layer in the current map (Figure7.11).
Figure 7.11