Agriculture Reference
In-Depth Information
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Table 15.3 Drought categorization based on various indices used in Russia
Category of drought intensity
Extremely
Dr ought assessment
No drought
Weak
Moderate
Severe
severe
index
(class 5)
(class 4)
(class 3)
(class 2)
(class 1)
1. Selyaninov's hydrothermal
index (HTC)
0.76
0.61-0.75
0.40-0.60
0.20-0.39
0.19
2. Shashko's index of moisture
(Md)
0.41
0.31-0.40
0.20-0.30
0.10-0.19
0.09
3. Protserov's index of water
supply ( V ,%)
71
61-70
51-60
41-50
40
4. Number of days with relative
air humidity
0
1-2
3-5
6-7
8-11
30% ( N O )
5. Number of days with
maximum air temperature
> 30°C ( N T )
0
1-2
3-4
6-7
8-11
[203
6. Productive moisture reserves
(mm) in the 0-20 cm soil
layer ( W 0-20 )
21
16-20
11-15
6-10
5
Line
——
4.4
——
Long
PgEn
7. Productive moisture reserves
(mm) in the 0-50 cm soil
layer ( W 0-50 )
46
36-45
26-35
16-25
15
8. Productive moisture reserves
(mm) in the 0-100 cm soil
layer ( W 0-100 )
81
61-80
41-60
26-40
25
[203
n
1
n
P i =
δ j α ji ,
[15.7]
j
=
1
w here P i is the mean value of measures of closeness to the category for the
i th dekad; n is the number of indices; δ j is the information weight of indices
gi ven in advance; α ji is the metrics characterizing the measure of closeness
of the actual value of the j th index for the i th dekad relative to a chosen
criterion (boundary value) in the category; and j is the ordinary number of
an index.
The metrix α ji is calculated from the following formula:
x ij ϕ ij
ϕ
α ij
=
1
,
if x ij ij
[15.8]
ij α ϕ ij α
ij
x ij
ϕ
α ij
=
1
,
if x ij
[15.9]
ij
ϕ
ij α ϕ ij α
α ij
=
1 ,
if
ϕ ij
x ij
ϕ
ij
[15.10]
w here x ji is the actual value of the j th index of drought assessment in the
i th
dekad; ϕ j 'and ϕ j "are the range (min, max) of the j th
index within the
 
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