Table 1 Drought classification of different grades based on SPI.
From: An improved daily standardized precipitation index dataset for mainland China from 1961 to 2018
Categorization | SPI values |
|---|---|
Extremely Wet | SPI ≥ 2 |
Severely Wet | 1.5 ≤ SPI < 2 |
Moderately Wet | 1 ≤ SPI < 1.5 |
Mildly Wet | 0.5 < SPI < 1 |
Normal | −0.5 ≤ SPI ≤ 0.5 |
Mild Drought | −1 < SPI < −0.5 |
Moderate Drought | −1.5 < SPI ≤ −1 |
Severe Drought | −2 < SPI ≤ −1.5 |
Extreme Drought | SPI ≤ −2 |
