APEX 1501 Buffer errors

[Maya Struzak]

Hello,

I am using APEX1501 to simulate a simple soybean field (one subarea) and am trying to add a grass buffer as a downstream subarea. I followed the guidance in the APEX conservation practice documentation to construct a grass filter strip, but my simulation crashes midway through the first year without any error messages. 

The model runs long enough to print the routing scheme in the .OUT file (screenshot and file attached), which looks reasonable, leading me to believe it is not a routing-format issue. Both the field and buffer subareas run successfully on their own, but the run fails when they are combined. 

For reference, both subareas use the same soil, the buffer has a simple operation schedule (plant range grass on Jan 1 of the first year, kill at the end of simulation), and I've confirmed CHL = RCHL for the field and RCHL < CHL for the buffer. 

Has anyone else encountered similar issues with a two-subarea setup? Any insights would be greatly appreciated! I've attached my .OUT and .SUB files below.

Thanks!

Maya

[Luca Doro]

It is difficult to say what is causing the error.

If you are willing to share your input files, I might be able to take a look at them.

Best,

Luca

[Maya Struzak]

Hi Luca, 

Thanks for your reply. I had reached out to Jaehak about this issue via email, where I mentioned I am suspecting it is related to a bug in APEX v.1501’s handling of multiple subareas under sub-daily rainfall. I’m running into a crash (without any error messages) when using INFL=4 with two subareas. The simulation works fine with either a single subarea and sub-daily weather or multiple subareas and daily weather, but crashes on the first significant rainfall day when combining both (in my case, June 4, year 1).

After spending some time inspecting the source code, I think the issue is in HYDUNT.f90, line 41, where QGA(I) = 0. The QGA array appears to be global (not subarea-specific), so when the first subarea zeros it out, the second subarea has no data to work with. I tried amending this line to : “IF(INFL/=4) QGA(I)=0” so the array persists across subareas for the entire day when using sub-daily weather input, but maintains current behavior otherwise. Jaehak mentioned that this fix should work, although after re-compiling the source code, I am still facing the same issue.

Do you have any insights or suggestions?

Thanks,

Maya