SWAT-CENTURY

[SAM NIK]

Dear all,

I am very interesting to use SWAT-CENTURY for research purposes in a watershed.

I am very familiar with SWAT.

I've been looking for a long time how to use SWAT-C but without success.

Is there anyone here to guide me for the first steps like how to download SWAT-C, input/output files etc.?

Thanks you in advance

[Steven Jepsen]

Hi,

I tried several years ago to obtain SWAT-C from its developers (see papers by Xuesong Zhang et al.) without any success. So I gather it is not available to the public. It would be a nice tool to have. You might check out the INCA-C model.

Steve

[Xuesong Zhang]

Hi Sam and Steven

Just saw your emails. Sorry to know that you did not get access to SWAT-CENTURY. Actually, the algorithms are available in the SWAT2012 version on the SWAT website. 

That version does not include many of our latest updates for several reasons. First, to include Carbon into SWAT we need to change numerous places within the SWAT model, therefore  changes made to SWAT carbon algorithms often take a lot time to test and document. As our understanding (from current literature) of the carbon cycle is evolving very quickly, we really cannot afford to keep updating those algorithms and provide detailed documentation due to heavy obligations to other projects.

Second, while SWAT-C is developed based on SWAT2012, SWAT-plus is likely to be the next popular version of SWAT within the community. Given the significant difference between SWAT2012 and SWAT-plus, we hope to focus on SWAT-plus instead of SWAT-2012. Jeff has made a lot of effort to include Carbon into SWAT-plus, and we hope to do more in the coming years.

Third, I really want to clarify that SWAT-Carbon or SWAT-C is not equivalent to SWAT-CENTURY. Actually, we are examining/testing many soil organic C algorithms, such as CENTURY, EPIC, DNDC, RothC, DSSAT, ORCHIDEE, JULES. Frankly speaking each of those algorithms has their own strengths and weaknesses, and until now we did not finally decide which one we should use as the backbone of SWAT-C. In addition to soil organic carbon, we need to consider dissolved organic carbon, inorganic carbon, eroded carbon, and methane in soils and groundwater, transported from land to rivers, and along river networks. Furthermore, we need to couple/reframe C, N and P cycling as well as their interactions with human activities, hydrologic processes and energy balance.Getting that job done will take some time. 

Fourth, a lot of our time was devoted to preparing proposals and writing papers in order to survive in the scientific community, a challenge many scientists are facing now. To that end, our research focus was on exploring new exciting ideas, instead of providing documentation and instructions on how to apply SWAT-C. But we recognize the importance of sharing the model and responding to valuable feedback from the community, which I believe is a major reason behind the tremendous success of SWAT. 

Fifth, many of the new functions we have developed will be shared with the community. We do not have a timeline yet, but that is a topic we have frequently discussed in our group meeting. In the future, we will continue to communicate with Jeff, Srini and other developers. Hopefully we can get that done sooner than later. 

Finally,  many changes are happening now which likely will benefit climate change and carbon cycle research. We really hope those changes will translate into faster model development and dissemination on our end. 

After the challenging 2020, I hope everyone will have a brightful 2021 and beyond. 

I apologize for the rambling and Thank you for your patience.

Regards,

Xuesong Zhang

 

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[Steven Jepsen]

Hi Xuesong,

Thank you for your detailed update (and sorry to keep bugging you about this!).

I wonder if it would help in your group's development efforts to collaborate with universities on testing/validation of SWAT-C outputs? We would have been keen on that for studies of DOC variability in the Merced River in an earlier and now discontinued study. And of course we would have been happy to keep you in the loop on research products.

Just to continue with differences described by Xuesong between SWAT-CENTURY and SWAT-C: My very rough and cursory understanding on this, based on literature and available SWAT 2012 outputs, is that while SWAT-CENTURY does simulate C storage in soil, it does not track exports of DOC and POC once they have left HRUs. So, for example, DOC in streamflow would not be an available output from SWAT 2012 because that form of C has already left HRUs. That is the seat-of-the-pants information I've been going on. Hope I'm not too far off the mark there.  

Thanks again and good luck with your work,

Steve

[Xuesong Zhang]

Yes, SAM.

If you set CSWAT = 1 in .bsn the output would be from another soil carbon algorithm. If CSWAT = 2, then it is CENTURY (actually the EPIC version of the CENTURY soil carbon). 

The output in CSWAT_daily is the total SOC in the soil profile for each day, while CSWAT_PROFILE is the SOC in each soil layer for each day. 

If you can check the data in those files, but I recommend waiting for the next version. 

Best,

Xuesong

On Wed, Jan 27, 2021 at 2:04 PM SAM NIK <samnik...@gmail.com> wrote:

Dear Zhang,

Thank you for your reply.

A short question. 

I activated CSWAT from .bsn file using value 1 and i created CSWAT_PROFILE.TXT file.

Is this the file that i want?

Did I simulated the soil organic carbon in that way?

This is my last question

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[Xuesong Zhang]

Hi Steven,

You are welcome. Actually, we are happy to see the strong interest in the carbon model from the community. 

We did share the model and code with several close collaborators, and it has been successfully applied and generated multiple papers in several watersheds. The big challenge is still the time we need to commit to the collaboration, which we really cannot afford for now.  Based on multiple years of experience, we designed the following multi-step strategy for SWAT-C development: (1) for now, we'd better focus on nailing down the overall framework of the model and getting the coding done. Meanwhile, we have to publish papers and secure funding, otherwise we will lose our job. (2) at the second stage, we need to circulate the model within a small group for model testing and feedback (we will seek collaborators like you within the SWAT community). (3) for the third stage, we hope to provide informative documentation of the new functions so many people can run the model by themselves. 

You are right regarding the difference between SWAT-CENTURY on swat website and the SWAT-C that we are intensively modifying and testing now. SWAT-CENTURY does not track the fate of carbon leaving the edge of the field, while SWAT-C traces the transport and transformation of carbon along the river networks. In addition, SWAT-C also has many new functions for simulating terrestrial carbon cycles as compared with SWAT-CENTURY.

Again thank you for your attention. Hope we will continue to communicate in the future when the SWAT-C model is more ready.

Cheers,

Xuesong

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[SAM NIK]

Dear Zhang,

Thank you for your reply.

A short question. 

I activated CSWAT from .bsn file using value 1 and i created CSWAT_PROFILE.TXT file.

Is this the file that i want?

Did I simulated the soil organic carbon in that way?

This is my last question

Στις Τετ, 27 Ιαν 2021, 19:13 ο χρήστης Xuesong Zhang <xuesongz...@gmail.com> έγραψε:

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