Appraisal of Drought Characteristics of Representative Drought Indices using Meteorological Variables

In order to efficiently utilize meteorological drought indices, meteorological variables were compared with drought characteristics from the widely known Standardized Precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI). The results of this study indicate that SPI overestimated drought severity and SPEI overestimated drought frequency and length under the same weather conditions. For droughts of high severity and short duration, the shortage of precipitation was the dominant cause for the occurrence of drought. For investigation on drought duration, it was revealed that precipitation was the dominant variable influencing droughts at short durations. The effect of precipitation on drought decreased at long durations, with the effect of Potential Evapotranspiration (PET) on drought became important. For investigation on drought severity, it was revealed that drought severity was proportional to precipitation in both SPI and SPEI, but other meteorological variables did not have a significant relationship with drought severity. These results mean that the magnitudes of the two drought indices changes in different meteorological regimes and it is possible to contribute to the quantitative decision and the combination of drought indices for meteorological drought.