Monitoring Agricultural Drought in Russia - Monitoring and Predicting Agricultural Drought: A Global Study - page 198

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[198

Line
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-3.0
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Norm
PgEn

Fig ure 15.1 The variation in winter and spring wheat yields in Volgograd region, Russia, for
the 1950-2000 period.

the crop. For the areas under study, the winter wheat yield was twice as
high as the spring wheat yield. For example, in Volgograd region as a
whole, the mean winter wheat yield was 1.6 tons/ha, whereas the spring
wheat yield was 0.8 tons/ha, during the 1951-2000 period. The same ratio
(1.2 tons/ha in winter, and 0.6 tons/ha in spring season) was observed in
Novoakhtubinsk area of Volgograd region during the 1972-2000 period
(figure 15.2).
Both winter and spring wheat yields react to arid conditions. In No-
voakhtubinsk region, for example, during severe droughts of 1972, 1975,
1979, 1984, and 1998, the spring wheat yield ranged from 0.01 to 0.1
tons/ha and the winter wheat yield had the same range during 1984, 1998,
and 1999. The drought problems were also severe for Moldova, Kaza-
khstan, and Uzbekistan.

[198

M ain Reasons for Drought
The main reason for drought formation in arid regions of Russia and other
CIS regions is the penetration of anticyclonic air masses from the Arctic
(Selyaninov, 1928, 1958, 1966). These air masses have low temperature
and low water content and are mostly transparent for solar radiation un-
der clear weather conditions. When these air masses move south, their
temperature rises quickly, which increases the water vapor deficit in the
atmosphere without changing its absolute water content. As a result, the
relative humidity falls to about 10% or lower, causing droughts. When a
system of arctic anticyclones moves to the west, it acts in parallel with the