Comparing the standardized precipitation index, the palmer drought severity index and the palmer adapted index on the state of Sao Paulo-Brasil

The Standardized Precipitation Index (SPI) and the Palmer Drought Severity Index, on its original form (PDSI) and on its climate conditions of the State of Sao Paulo adapted model (PDSI adap) are been used by the Instituto Agronomico (IAC) through the CIIAGRO to evaluate the agricultural, the meteorological, the hydrological and the socioeconomic impacts of a drought. Regarding the particular characteristics of each index, this study compares the SPI, the PDSI and the PDSI adap models. This work also gives information about the correct interpretations of the results for each drought index. Due its capability to recognizes the importance of time scales in the analysis of water availability and water use, due its spatial consistence and its simplicity interpretation the SPI should be used on studies of drought risk and mitigation over different segments of the human society. The PDSI adap could be used as a "meteorological drought monitoring tool", in monthly basis, on the State of Sao Paulo.