Monitoring Agricultural Drought in Russia - Monitoring and Predicting Agricultural Drought: A Global Study - page 200

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46

The study of severe and extremely severe droughts in the primary arid
Russian Federation regions has shown that there is no certain periodicity
in droughts (Khomyakova and Zoidze, 2001). Droughts may occur during
some years in succession as well as with a 1-, 2-, 3-, and even 16-year in-
terval. Therefore, the prediction of this phenomenon becomes much more
complicated, and drought monitoring at regular basis is more important.

Pr ocedures for Drought Monitoring
At early stages of studying droughts in Russia, much effort was directed
to the development of argometeorological indices to assess drought con-
ditions. Russian scientists have developed more than 50 indices (Ivanov,
1949; Koloskov, 1958; Konstantinov et al., 1976; Loginov et al., 1976;
Drosdov, 1980; Ulanova, 1988; Khomyakova and Zoidze, 2001). How-
ever, in this chapter we discuss only those indices that are widely used for
drought monitoring in Russia.

[200

Line
——
0.6
——
Long
PgEn

H ydrothermal Coefficient

A hydrothermal coefficient (HTC) developed by Selyaninov (1928) is
widely used to monitor droughts in Russia. The HTC is defined as

p [ i + ( i − 1 ) + ( i − 2 ) ]
0 . 1 T
≥

HTC i = [15.1]

10 ° C[ i + ( i − 1 ) + ( i − 2 ) ]

[200

where p is monthly precipitation in millimeters and T is temperature in
degrees Celsius, i is the ordinary number of a dekad (10-day period) to be

estimated, and T ≥ 10 ° C is the sum of temperatures above or equal to 10°C.

M oisture Index

Moisture index (Md) was developed by Shashko (1985) and is also widely
used. It is the ratio between the total precipitation during a month and the
diurnal mean values of water vapor deficit (the diurnal mean deficit sum of
air humidity), as expressed by the following:

R [ i + ( i − 1 ) + ( i − 2 ) ]
d [ i + ( i − 1 ) + ( i − 2 ) ]

Md i = [15.2]

where R is the precipitation sum in millimeters, and d is the sum of
water vapor pressure in air (the sum of air humidity deficits) in hecto Pascal
(hPa).

W ater Supply Index

The water supply index (V i ) is calculated as

W 0 − 100 ( i − 1 ) −

R i W 0 − 100 ( i ) +

0 . 375 d i

V i = ( 100 ) [15.3]