Component of ET with PCDI in bush

Hi,

Not much posting going on here, I hope theres still people checking in who can help.

I'm designing a tricky WW system, steep slope with existing bush, I was hoping someone would have an idea of the amount of water lost to evapotranspiration due to dense scrub, (mixture of ferns, manuka, etc), with PCDI disposal and any reference to where I could find in the literature. Would 1mm/day for ET assist be reasonable?

TP58 mentions ETS research found plantings could boost pan evaporation values some 2 to 3 times that of bare soil rates. 

Thanks in advance

Simon