## Precipitation interception / root distribution

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elizabeth.ramirez.z
Posts: 8
Joined: Sat Oct 26, 2019 4:03 am
Location: Chile

### Precipitation interception / root distribution

Hi,
I am using hidrus to estimate the water consumption of pinus radiata at 35 ° south latitude (Chile). I have some questions.
1. Precipitation interception: I am using the model from Von Hoyningen-Hüne [1983], Braden [1985] and van Dam et al. [1997]. I wanted to know how I can calculate parameter a. I read that for ordinary agricultural crops 0.25 mm / d, but I guess that pines are not "ordinary crops"

I looked for van Dam et al. [1997] but I didn't find how to calculate parameter "a". Also, I looked at Von Hoyningen-Hüne [1983], Braden [1985] but I only found one but it was an old document that was scanned (German language), so I couldn't understand how "a" was calculated.

2. Root distribution: in the profile information, I don't understand what the range of -1 to 1.5 means ... For example, when there are no roots I put 0, but when I use -1.5 ... And if I had a horizon with abundant roots (the maximum in the whole profile) use 1? (I did not find this detailed in the manual)
Attachments
roots distribution.PNG (55.09 KiB) Viewed 820 times

Jirka
Posts: 4923
Joined: Sat Mar 16, 2002 3:47 pm
Location: USA
Location: Riverside, CA

### Re: Precipitation interception / root distribution

a) I have no opinion on how to get the "a" parameter for pines. I think it should be possible to find it in the literature.
b) The values entered for root distribution are relative number. Value of 10 (location 1) compare to 1 (location 2) means that the root density is 10 times larger at location 1 than 2. The program than normalized entered values so that its integral over depth is equal to 1.

J.