SOILEVAP_VIC equation different in source code than in Raven Manual

[gmerritt123]

Setup Information

• Raven version: 3.8
• Operating System: Windows

Description

I was switching out SOILEVAP_HBV for SOILEVAP_VIC. As per Raven Manual:

Based on this, I added VIC_EVAP_GAMMA as a soil parameter.

I got a printout in RavenErrors.txt that told me I needed to supply VIC_ZMIN, VIC_ZMAX, and VIC_ALPHA as well. I thought that was kind of odd, since it appears (via Raven Manual) that these parameters are used only for other VIC-family equations (infiltration/percolation etc.). I put in dummy values anyway and Raven ran fine.

But then as a QA check, I tried changing VIC_ZMAX, expecting to get the exact same results (since according to the Raven Manual and my setup this parameter is not used for any process). But my results changed!

Inspecting SoilEvaporation.cpp:

RavenHydroFramework/src/SoilEvaporation.cpp

Line 494 in 978ac4e

else if (type==SOILEVAP_VIC)

The calculation of PET used actually uses VIC_ZMIN, VIC_ZMAX and VIC_ALPHA... which explains why I needed to supply it (I found the assert-like check for them here -->

RavenHydroFramework/src/SoilEvaporation.cpp

Line 127 in 978ac4e

void CmvSoilEvap::GetParticipatingParamList(string *aP , class_type *aPC , int &nP) const

),

I am not certain if the Raven Manual has the governing equation incorrect, or if the source code itself is incorrectly calculating PETused, but it's definitely an inconsistency that threw me for a loop.

Steps To Reproduce

• Build a Raven Model that uses only SOILEVAP_VIC and provide only VIC_EVAP_GAMMA as a "VIC" parameter.
• Raven will fail to execute and state in RavenErrors.txt that you need to supply the other "VIC" parameters
• The source code relies on these other parameters, but this is not documented in the Raven Manual

Additional context

No response

Contribution

• I would be willing/able to open a Pull Request to address this bug.