GIS-based climate variability and drought characterization in Ethiopia over three decades

The climate variability and drought frequency over potential crop growing regions of Ethiopia during 1983-2012 were analysed. Data from 87 weather stations across the country were used for this analysis. Ethiopian agricultural activities are highly dependent on the long rainy season (June-September) rainfall, which accounts for 70% of the total annual rainfall. There was no significant change in rainfall during annual and the bimodal seasons during this period of study. However, there was significant change in the rainfall coefficient of variation. STARDEX precipitation indices provided a measure of intensity, frequency and proportion of total rainfall. Ninetieth percentile of rainfall, number of rainy days with rainfall > 10 mm/day and the greatest 10 d total rainfall were increased over time at most of the stations. Among the major droughts, 1984-'85 drought was reported as the most severe drought with peak negative SPI value -3.68 in Wollo. The longest duration of drought lasted for 63 months in Borena Zone in southern Ethiopia during 1983-2012 period. Extreme maximum temperature (90th percentile) has increased over 45% of the weather stations, while, extreme minimum temperature (90th percentile) has increased 53% of the weather stations. Extreme maximum temperature events have been increasing during the seasons in Ethiopia, which is the real concern for agricultural and livestock activities, as these sectors significantly contribute to about 50% of GDP for the country. However, given the increasing response capacity of the government, as observed during 2002-'03 drought, environmental disaster is expected to be under control over time.