Agricultural Drought in Indonesia - Monitoring and Predicting Agricultural Drought: A Global Study - page 336

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Table 26.3 Verification of seasonal prediction in Indonesia (percentage of districts in
the respective categories) a

Onset of season Rainfall classification

Year Precise Ahead Later Same Close Different

Wet Season
1993-94 84 5 11 52 45 3

1994-95 86 1 13 50 44 6

1995-96 83 8 9 49 42 9

1996-97 64 7 29 43 50 7

Average 79 5 16 49 45 6

Dr y Season
1993-94 74 23 3 27 59 14

1994-95 56 10 34 63 28 7

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1995-96 73 20 7 51 39 9

1996-97 76 19 5 21 58 21

Average 70 18 12 41 46 13

Line
——
6.6
——
Norm
PgEn

Source: ADPC (2000).
a Pr ediction of onset for the 102 seasonal prediction areas is estimated in 10-day (dekad) periods. Rainfall
is considered normal if it is 85-115% of normal, above normal if it exceeds 115% of normal, and below
normal if it is below 85% of normal. Precise means that onset occurred in the 10-day period predicted;
ah ead means that it occurred in an earlier dekad; and later means that it occurred in a later dekad. For
rai nfall classification, same means that rainfall total was as predicted, and different means that it was two
categories from what was predicted.

[336

in the onset of the wet season may not upset established crop calendars
at some locations because agricultural practices evolved over time are ad-
ju sted to these normal variations. Any variation beyond 20 days is likely to
up set the established crop calendar, and the information on these thresh-
ol ds could be of use to the end-users at the concerned locations. As another
ex ample, a 50% reduction of rainfall could still be enough to support the
es tablished crops in high rainfall zones such as Kalimantan, where average
ra infall is around 3000 mm, because 1500 mm is enough to support a
ric e crop.

C rop Production Forecasting and Monitoring System

Forecasting rice production has long been a priority for the Indonesian
government, particularly on the island of Java, which accounts for approx-
imately 60% of the total rice production in the country. Data on the har-
vested area are collected on a monthly basis but, for the purpose of publica-
tion, are aggregated to a level that corresponds to time periods of recording
of yields (using crop cuttings) in three sub-rounds: January-April, May-
August, September-December. Official forecasts for rice production are
made in mid-February, mid-June, and mid-August. All forecasts are disag-
gregated to provincial levels separately for padi sawah (wetland rice) and