According to the PDSI index, there was an increase in the area and intensity of meteorological drought in the southern region. Of particular note is the moderate drought class in the districts of Setúbal, Beja and Faro. In the North and Center there was a decrease in the intensity of the rainfall classes.
In terms of the percentage distribution by class of the PDSI index in mainland Portugal, at the end of December there were:
PDSI Index (Palmer Drought Severity Index) was developed by Palmer (1965) and implemented and calibrated for mainland Portugal (Pires, 2003).
This index is based on the concept of the water balance taking into account data on the amount of precipitation, air temperature and available water capacity in the soil and allows the detection of periods of drought by classifying them in terms of intensity (weak, moderate, severe and extreme).
Table - Classification of the PDSI index for dry and rainy periods
greater than or equal to 4,0
3,00 to 3,99
2,00 to 2,99
1,00 to 1,99
-0,99 to 0,99
-1,99 to -1,0
-2,99 to -2,0
-3,99 to -3,0
less than or equal to -4,00