Comparison of Meteorological Drought Indices in Tanzania Using the Meteorological Drought Monitoring (MDM) Software Package

Abstract

Low precipitation, substantial evaporation, and an unequal distribution of precipitation throughout the area are the characteristics of drought, a climatic abnormality. This study used the Meteorological Drought Monitoring (MDM) software and monthly rainfall data from the Tanzania Meteorological Authority (TMA) to examine and compare the Deciles Index (DI), Standardised Precipitation Index (SPI), Percent of Normal Index (PNI), Rainfall Anomaly Index (RAI), Z-Score Index (ZSI), China-Z Index (CZI), and Modified China-Z Index (MCZI) for drought monitoring in Tanzania from 1988 to 2017. It was found that ZSI represented the dry years better than other indices, followed by DI, RAI, PNI, SPI, CZI, and MCZI, based on the strength of the drought's detection throughout a monthly time scale. Seasonally, DI emerged as the most effective drought index for meteorological drought monitoring, trailed by PNI and SPI. In comparison to SPI and PNI, the ZSI index closely mimics Tanzania's climatological conditions on a geographical scale. The study also demonstrates that ZSI outperformed SPI and PNI in accurately determining the frequency of droughts with different severities.