Calibration of concentration variables (TSS, TN, TP, NO3, NH4, NO2) in SWAT-CUP

[Gebere Egziabher]

Dear SWAT/SWATCUP users, 

I was trying to move from Sediment, NO3, NH4, TN, and TP load to TSS, NO3, NH4, TN, and TP concentrations in my SWAT simulations.  I found that in using the load data, the fit (i.e., model results to observations) provides a bias from a good fit to flow. 

Would you advise how to input concentration (mg/L) of sediment, Total nitrogen, and total phosphorus in SWAT-cup calibration instead of the loads? As you can see in the SWAT-output.rch file, screenshot, SWAT simulates these variables as a load, but I need to calibrate with concentration observed data. How can I force SWAT/SWATCUP to calibrate with concentration data instead of the load? Kindly let me know. Thank you.

Thank you. 

[Natalja C.]

Hello,

Some output is available, like the SEDconc or NO3conc. 

For the TN/TP - there is no way to force SWAT-CUP to calibrate on concentration data. I converted my concentration data into loads and calibrated the loads. I know that in this case there is an additional uncertainty introduction (concentration/load is not uniform, depends on single events which might be averaged, etc.), but at least it's something :). To convert from concentrations to loads - you may use the loadest software, or a regression curve (if you have one for your area).

Best,
Natalja

[Gebere Egziabher]

Hi Natalja, 

Thank you very much. 

[Dpaceism]

Hi Natalja, Dr. Abbaspour and others,

I hope that you are doing well. I had a question regarding the simultaneous calibration of sediment (or other water quality variables) and discharge  in two different time steps. I have calibrated and vaidated my discharge monthly, but my sediment data is on daily basis. I am not able to figure out how to carry out the calibration of my sediment data. It would be of real help if you could explain it. Thank you for your time and consideration.

Best,

Dipesh

[Tam Nguyen]

HI Dipesh,

This tool was made for you, you can use it to calibrate at any time step for any variable that you want. More see this video

https://www.youtube.com/watch?v=5oa3UcwW-ug&t=46s

(Hint: you should use "userReadSwatOuput" option and modify the function shown in the video to aggregate your data from daily to monthly)

Google group for discussion/software/...

https://groups.google.com/g/swatshiny

[Dpaceism]

Hello,

The following article could be of help to those who are wondering about concentration to load conversion using LOADEST. Please follow the link:

https://www.mdpi.com/2077-0472/12/4/518

Best,

Dipesh

On Friday, August 7, 2020 at 3:28:16 AM UTC-5 Natalja C. wrote:

[熊呆呆GO]

Hi Natalja C.

TN and TP are unavailable in SWAT outputs. So, I also think SWAT-CUP can not calibrate the TN and TP (both concentration and load).