Canopy interception in UBCWM

[kgreenSelkirk]

Hi James or anyone.
My question is whether the UBCWM is any good for representing canopy interception on snow processes. I have defined two stant types in my HRU's and am trying to capture differences in interception using TFSNOW at 0.75 and on at 0.50 - thinking this is a way to represent a juvenile and mature stand but, as it turns out, it has absolutely no impact on the results. Why is this and how can I better represent differences in snow interception in open and mature forest stands. - or is it time to move on to HVB-EC?
Thanks
Kim

:VegetationParameterList
:Parameters, TFRAIN, TFSNOW, MAX_INTERCEPT_RATE, RAIN_ICEPT_FACT, SNOW_ICEPT_FACT
:Units, frac, frac, mm/d, frac, frac
VG_FST40MINUS,0.90, 0.75, 5, 0.1, 0.25
VG_FST40PLUS, 0.88, 0.50, 10, 0.12, 0.5
VG_BURN, 1.0, 0.90, 1, 0.00, 0.10
VG_CLEAR, 0.98, 0.98, 1, 0.02, 0.02
VG_LAKE, 1.0, 1.0, 0, 0.00, 0.00
VG_SHRUB, 0.95, 0.90, 2, 0.05, 0.10
:EndVegetationParameterList

[jrcraig]

Hi,

You have to do this through specification of RAIN_ICEPT_PCT / SNOW_ICEPT_PCT, which is basically 1-TFRAIN and 1-TFSNOW. The problem appears to be that you are using both parameters, and I think this is overriding the impact of TFRAIN/TFSNOW. Make sure you are using PRECIP_ICEPT_USER for the :PrecipIceptFract in the .rvi file.

Cheers,
James