A and H: Since "drought" means a moisture deficit bad enough to have social, environmental or economic effects, we generally include a description of what the primary physical effects are:
A = agricultural (crops, pastures, and grasslands)
H = water supplies (rivers, groundwater and reservoirs)
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Category | Description | Satellite Vegetation Health Index | ||||||
D0 | Abnormally Dry | -1.0 to -1.9 |
21-30 | 21-30 | -0.5 to -0.7 |
36-45 | ||
D1 | Moderate Drought | -2.0 to -2.9 |
11-20 | 11-20 | -0.8 to -1.2 |
26-35 | ||
D2 | Severe Drought | -3.0 to -3.9 |
6-10 | 6-10 | -1.3 to -1.5 |
16-25 | ||
D3 | Extreme Drought | -4.0 to -4.9 |
3-5 | 3-5 | -1.6 to -1.9 |
6-15 | ||
D4 | Exceptional Drought | -5.0 or less | 0-2 | 0-2 | -2.0 or less | 1-5 |
Updated March 19, 2003