Agriculture Reference
In-Depth Information
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books, Agroclimatic Guide Book and Agroclimatic Resources , were pub-
lished for all regions, territories, and republics of the former USSR. These
topics show intensity of drought (e.g., weak, moderate, severe, extremely
severe) for different regions based on the average number of drought days
in a month during vegetation or warm periods and probabilities of drought
occurrence.
Yi eld Risk Estimation
According to Zhukov et al. (1989), the following equation can be used to
estimate the yield risk (i.e., the deviation of expected crop yield from the
maximum yield):
k = 1 1
g ij ( k )
M
P ij
=
1
[15.6]
[202
where P ij is the pure risk standard of the system climate-yield transition
from the initial i th state into the j th state in a given time interval; g ij ( k )is
th e transitional probability of the system weather-yield, and k is the dekad
number.
Agricultural drought monitoring in Russia has become more system-
atic after two publications based on ground and satellite data (Zoidze and
Khomyakova, 2000). In the first publication, degree of aridity was deter-
mined with the help of a mathematical model based on an image recogni-
tion procedure (Danielov and Zhukov, 1984; Zhukov et al., 1989; Zhukov
and Svyatkina, 2000). Zoidze and Ovcharenko (2000) prepared a map
showing the distribution of the degree of aridity in the Russian Federa-
tion regions based on an aridity index. The index value was more than
60 (highest) for Kalmykia region and between 51 and 60 for Astrakhan
region. About 14% of the RF regions had index value greater than 30.
The operative system of drought assessment is a computer-based system
that uses agrometeorological data and various drought indices to regularly
monitor the onset and development of droughts of different intensity dur-
ing the entire vegetation period. The following drought indices are used: (1)
Selyaninov's HTC, (2) Shashko's index of moisture (Md), (3) Protserov's
water supply index ( V ; Protserov, 1949), (4) the number of days with rel-
ative air humidity < 30% ( N 0 ), (5) the number of days with maximum air
temperature > 30°C ( N T ), (6) productive moisture reserves in soil layers of
0-20 cm ( W 0-20 ), 0-50 cm ( W 0-50 ), and 0-100 cm ( W 0-100 ) under winter,
early spring, and late spring grain crops. All of these indices can be deter-
mined using standard hydrometeorological data: precipitation ( R ), air tem-
perature ( T °C), water vapor pressure in air ( d ), productive water reserves
in soil ( W ), the number of days with the relative air humidity < 30% ( N 0 ),
and the number of days with the maximum air temperature > 30°C ( N T ).
Based on the range of the above values, a climatic event can be cate-
gorized as extremely severe, severe, moderate, weak, or no drought (table
15.3). Drought is referred to that category of intensity where its average
measure of closeness (P) is maximum:
Line
——
1.2
——
Long
PgEn
[202
 
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