Understanding Weather Generator, cli & pcp files

[Jason Chin]

Hi community,

I'm new to SWAT.  

I'm a bit confused as to how the Weather Generator works. In other hydrological models, we specify the weather data (mostly precipitation) from some nearby station. But I cannot see how this is being done in SWAT. Does the Weather Generator automatically generate all the precipitation data based on the location of our model? What other data is generated?

When I bring in my own precipitation (*.csv) into the model, do I manually format it to the *.pcp and create a new pcp.cli file? Looking at the Robbit sample, there is no mention about the time step in the robpcp.pcp file - under the tstep heading, it's 0. Is this 15-min, 1-hour, 1-day or 1-month?

Still on he Robbit sample project, the first line in the pcp.cli and robpcp.pcp file reads as follows. 

• pcp.cli: Precipitation file names - file written by SWAT+ editor 2019-07-09 17:30:25.915029
  

• robpcp.pcp: Precipitation data - file written by SWAT+ editor 2019-07-09 17:30:25.915029
  

It seems like these files were prepared by SWAT+ and does not appear to be manually formatted. If so, how can I format my own precipitation CSV into cli & pcp format?

And finally, the Weather Generator data only has data up to 2014. How to we extend beyond that with my own station data?

Hope the community will shed some light on this.

Thank you.

Best regards,

Jason

[Natalja C.]

Hello,

First, lets define all of the terms: swat, qswat+, swat+editor, weather generaton, swat file, etc.

swat+ - is a standalone executable that runs from a command line. It reads your inputs  (as TEXT files) and writes your outputs (as TEXT files (or csv). Swat runs on a daily time step.

swat input files - TEXT files only formatted in a specific way.

qswat+ - the GIS GUI that helps the user to calculate the spatial model input and write it to a database.

swat+editor - a standalone application, that reads your database produced with the help of qswat+, converts tabular input data to swat input files (text files). It is a sort of DBMS.

weather generator file - a file, which contains STATISTICAL data for a given weather station, which is used to generate daily meteo input for swat to use, when observation data is not available

weather (pcp, tmp, etc.) file - a file, which contains DAILY observational weather (pcp, tmp, hmd, slp or wnd) records.

weather name file (pcp, tmp, etc.) - a file, which defines what is the name of the used weather files (as you can have many).

Having all of this information in mind, you should be able to sort out the rest. I strongly advice to follow the QSWAT+ manual and read the information provided in the documentatioon.

Best,
Natalja

[Jason Chin]

Thanks Natalja for all the detailed definitions. I should have mentioned that I'm using the new SWAT+ that is integrated into QGIS (i.e. QSWAT+ plugin). 

:-)

Running the Robbit demo project also gave me an idea on the different components that you have mentioned (QSWAT+, SWAT+ Editor, etc).  

I have run through the documentation especially on the climate inputs (SWAT+ IO Documentation) and managed to understand it formatting (for example pcp.cli and station.pcp). Do we create/edit these files ourselves to bring in our own station data?

As for the Weather Generator file, I'm quite interested on how it is generated based on the statistical data that you have mentioned. Can you point me to the documentation on this?

Thank you very much for the time to respond to my posting.

Have a wonderful weekend.

Best regards,

Jason 

[Natalja C.]

Hello Jason,

To further answer your questions:

- Do we create/edit these files ourselves to bring in our own station data? - Yes, or follow the example of SWAT+Editor :)

- Can you point me to the documentation on this? - Sure. Here is the link: https://swat.tamu.edu/media/99192/swat2009-theory.pdf . See Chapter 1:3 for equations, etc. Those mostly transferred unchanged to SWAT+. 

All the best,

Natalja