update scalarSnowDrainage

[guoqiang-tang]

Make sure all the relevant boxes are checked (and only check the box if you actually completed the step):

• [ ] Closes #xxx (identify the issue associated with this PR)
• [x] Code passes standard test cases (results are either bit-for-bit identical, or differences are explained in the PR comment)
• [ ] New tests added (describe which tests were performed to test the changes)
• [ ] Science test figures (add figures to PR comment and describe the tests)
• [x] Checked that the new code conforms to the SUMMA coding conventions
• [x] Describe the change in the release notes (use either ./summa/docs/whats-new.md or ./summa/docs/minor-changes.md depending on what changed)

1. scalarSnowDrainage=drainageMeltPond/iden_water is added whennSnow==0 according to Martyn's suggestion.
2. The localParamInfo.txt in the case_study is updated. Compared with the old localParamInfo.txt, the new localParamInfo.txt has several parameter initial and bound values changes made by Andy Wood, which can help achieve better model performances. Besides, I changed the upper bounds of k_soil and heightCanopyBottom explained as below. The increased upper bounds allow appropriate parameter range in calibration. (1) In TBL_SOILPARM.TBL (Soil Parameters: ROSETTA), the k_soil is up to 7.43852e-05 for 'SAND'. Therefore, the upper bound of k_soil is increased from 100.d-07 to 1.d-04 in the localParamInfo.txt. (2) In TBL_VEGPARM.TBL, for MODIFIED_IGBP_MODIS_NOAH, ZBOTV is up to 11.5 for 'Deciduous Broadleaf Forest'; for USGS, ZBOTV is up to 11.5 for 'Deciduous Broadleaf Forest' and 'Wooded Wetland'. Therefore, the upper bound of heightCanopyBottom is increased from 5.0000 to 15.000 in the localParamInfo.txt.

[wknoben]

Thanks for the PR. Could you please address the following?

• Address the comment about the parameter file header.
• Separate the changes to the code from changes to the parameter files into their own PRs. This keeps the history clean and means that, if we have to revert one of these changes, the other one isn't affected.

@andywood could you please have a look at the changes to the numerical settings in the parameter file? If you can recall why these changes were needed it'd be very helpful if you could outline that here so we can refer to the info later, in case that becomes necessary.

[andywood]

The localParam changes look fine to me ... I'm not sure where the various versions of these came from, tbh. My current localParam settings are not the same as either the old or new versions here, though they match in some places. At some point I recall the range on k_macropore to reach higher values, I think. I support the min canopy height max bound going higher, maybe even more than 15m -- e.g., think Douglas fir ... https://www.nps.gov/articles/images/MORA-DouglasFirForest_Longmire-20171013.jpg?maxwidth=1200&autorotate=false

There may end up being different versions of localParams (& other params/attributes) associated with different test cases, but it would be good to document changes to the main defaults included with the code. This would particularly highlight where the change was a 'fix' for some poor behavior.

I'm not sure code & param file changes should always be separated, especially in the case where code may be added that requires a new parameter, in which case it would be odd to put that into a different PR. But I agree on the documentation aspect, and if the localParam update is totally unconnected from the rest of the PR, no reason to combine them.

[guoqiang-tang]

I agree with the discussion about localParam. At least for this PR, the code change and localParam change should be separated. I will limit this PR to scalarSnowDrainage and create a localParam PR later.

[martynpclark]

Thanks Guoqiang, included in a separate PR