Monitoring Agricultural Drought in China - Monitoring and Predicting Agricultural Drought: A Global Study - page 364

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Figure 28.4 Timeslice products for drought monitoring in the North China Plain.

Line
——
-0.2
——
Norm
PgEn

at 20 cm depth and the corresponding field capacity information from 102
ag ricultural climate observatories (covering the country) for the period
fr om 1980 to 1994 have been collected. SHI had good correlation with
V CI (table 28.4, figure 28.5).
The correlation coefficients ranged from 0.60 to 0.85. The test results
of a statistical model of all 36 ten-day periods from June to December
in dicated that the model of each dekad passed the test at the level of
α

[364

0.05. Figure 28.6 illustrates an operational system of drought early
w arning. Some results using this system are shown in figures 28.7 and 28.8.

=

Table 28.4 Statistical model of drought monitoring and associated drought category

Drought categorization

Dekad
in July Model R Range of VCI Drought category

≤ 90 Heavy drought

90-109 Dry

= + ×

1 VCI 219.2832 83.8763 LN(SHI) 0.846 109-124 Light dry

124-148 Normal

≥ 148 Moist

≤ 38 Heavy drought

38-44 Dry

2 VCI = 20.6373 × exp(0.0152 × SHI) 0.802 44-51 Light dry

51-70 Normal

≥ 70 Moist

≤ 31 Heavy drought

31-41 Dry

3 VCI = 12.736 × exp(0.0235 × SHI) 0.856 41-52 Light dry

52-83 Normal

≥ 83 Moist