Delta-T HH2, User Manual

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Water Deficit Explained

105
Water Deficit Calculation for Profile Probes
For a Profile Probe, water deficit is the sum of water deficits calculated for each
sensor included within the rooting depth:
D = (FWC
1
- VWC
1
) * d
1
.. + (FWC
n
– VWC
n
) * (d
n
– d
n - 1
) + D’
where
N
Number of the deepest sensor contained within the rooting depth
FWC
1,
FWC
n
Field water capacity at first and n
th
sensors
VWC
1,
VWC
n
Volumetric water content at first and n
th
sensors
d
1
, d
n
, d
n - 1
Depths of first, n-1
th
, n
th
sensors
D’ Additional deficit for soil below the nth sensor, calculated as below
If the rooting depth is less than the depth of the deepest sensor
D’ = (FWC
n + 1
– VWC
n + 1
) * (R – d
n
)
where R = Rooting depth.
If the rooting depth is greater than the depth of the deepest sensor
D’ = (FWC
n
– VWC
n
) * (R – d
n
)