Agricultural Drought Phenomenon in Latin America with Focus on Brazil - Monitoring and Predicting Agricultural Drought: A Global Study - page 162

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Table 12.3 Categorization of drought conditions based on soil water and potential
evapotranspiration for the state of Sao Paulo, Brazil

Criterion

P and ET p W / W x Categorization of drought condition

P ≤ ET p ≥ 0.60 Nil

P ≤ ET p 0.4 ≤ W / W x < 0.6 Moderate

P < ET p 0 < W / W x < 0.4 Severe

P = 0 0 Extremely severe

Note: P is accumulated rainfall, ET p is potential evapotranspiration, W is the actual water availability in
the soil, and W x is maximum water availability in the soil.

Table 12.4 Agricultural drought index for Sao Paulo State based
on crop maximum evapotranspiration (CME) and rainfall (P)

[162

Agricultural drought index Crop development conditions

Line
——
-2.2
——
Long
PgEn

0.80 < ADI ≤ 1.0 Good

0.60 < ADI ≤ 0.80 Favorable

0.40 < ADI ≤ 0.60 Reasonable

0.20 < ADI

≤

0.40 Unfavorable

≤

ADI 0.20 Critical

Pr ecipitation Anomaly

Th e monthly precipitation anomaly for a location is the difference between
m onthly precipitation and a historic average (normal) of precipitation for
th at month. Such an anomaly is the simplest way to monitor drought
co nditions and rainfall variability from year to year.

[162

Water Deficit Anomaly

W ater deficit anomaly is the difference between water deficit for a month
an d the average water deficit for the month. Water deficit is computed using
a water balance methodology (Thornthwaite and Mather, 1955) through
a software developed by Brunini and Caputi (2000).

Palmer Drought Severity Index

C urrently the CIIAGRO determines the Palmer drought severity index
(P DSI; Palmer, 1965) for the S ao Paulo State and makes it available online
(h ttp://ciiagro.iac.br). The PDSI is determined as

0 . 897 PDSI i − 1 + (z/ 3 )
z = (P i − P i )K i [12.2]
where z is the monthly value of the precipitation anomaly, and k is climatic
characterization of a location.
The normalized value of K i was determined experimentally by Palmer

PDS i =