Spatial-Temporal Analysis of Drought Characteristics in Tanzania from 1978 to 2018

The economy of the United Republic of Tanzania (URT) relies on rain-fed agriculture; thus, climate variability has strong impacts on crop production, and yet the country ability to adapt to climate extremes such as drought or floods is low. In this regard, the spatial-temporal drought characteristics in Tanzania from 1978 to 2018 were analyzed by comprehensively looking at the effect of temperature on drought severity, duration, occurrence and magnitude using the monthly precipitation and temperature datasets from the Climatic Research Unit (CRU).Statistical values from Standardized precipitation Index (SPI) and Standardized Precipitation Evapotranspiration Index (SPEI) analysis were subjected to statistical tests such as Mann Kendall and Sen’s slope estimator, Pearson correlation, root mean squared error and cross-wavelet transform to determine their performance and strength. Results showed SPI and SPEI indices are significantly correlated at 99% confidence level, despite that SPEI performed better than SPI which implies that temperature has positive impacts on evaporation which help to define drought events in Tanzania. Temporal analysis indicated short-term extreme drought events in the year 1997,1999,2000,2004,2010 and severe drought occurred in 1979, 1986,1992,1998, 2000, 2003, 2005, 2006,  2010, 2012, 2013.

While using a long-time scale, extreme drought events were detected in 1997, 2000, 2005, and 2006 and severe drought events were observed in 1997, 1999,2000,2003,2004, and 2011. Considering these results, drought occurrences are imminent in URT, so adaptation measures such as planting drought-resistant crops varieties, timely crop planting, well developed early warning systems are highly recommended for the country.