Techniques to Predict Agricultural Droughts - Monitoring and Predicting Agricultural Drought: A Global Study - page 48

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P( 1. The critical agricultural drought durations for the first two

samples are the same as in the dependent Bernoulli case. However, when
the sample size is greater than two, the relevant drought probabilities differ.
Numerical solution of these equations are achieved through the use of
digital computers, and some of examplary results are shown in figures 4.3
and 4.4.

− / −− ) =

Spatio-Temporal Drought Models Almost all the studies in the literature
are confined to temporal drought assessment, with few studies concerning
areal coverage. But there is a significant regional dimension to agricultural
drought that occurs at regional scales. Most often, droughts affect not
only one country but many countries, in different regional proportions.
In this section we include models that represent both spatial (regional) and
temporal drought behaviors simultaneously.
In regional studies, clustering of dry spells in a region will be referred to

[48],

Line
——
2.6
——
Norm
PgEn

0.4

[48],

0.3

p 0.50

P(s ss) 0.40

0.2

0.1

0

0 5 10 15

Length

Figure 4.3 Critical drought duration distribution for different sample sizes at P (+/+ +)

=

0.40.