Quantification of drought severity change in Ethiopia during 1952-2017

摘要

Drought is considered as a frequent environmental disaster that persists long enough to adversely influence economic and social development for the last few decades, particularly in Ethiopia. Here, we examined the occurrence of drought severity change in Ethiopia using standardized precipitation index (SPI), standardized precipitation evapotranspiration index (SPEI), China Z Index (CZI) and percent of normal precipitation (PNP). Mann Kendal and Sen's method tests also used to compute trends and magnitudes of drought occurrences. The years 1953, 1961-1964, 1972-1976, 1984-1987, 2002-2004 and 2011-2014 were recorded as the most intense drought episodes ranging from - 1.58 to - 4.31. With some exceptions, the years 1984, 1986, 2002 and 2014/15 were the direst extreme drought occurrence across all locations. The interpolated spatial extent of drought frequency was highest in central, north and southern regions of the country, respectively. More extreme and severe droughts are identified from SPI and SPEI time series than CZI and PNP at many stations across the domain. In 3-month time scales, severe/extreme drought incidences are intra-annual and 12- and 24-month time scales are inter-annual. SPI and SPEI have stronger correlation than SPI and CZI at all timescales. This kind of inventory drought characterization can be used as a basis to quantitatively prioritize specific intervention at the regional level in responding to drought impacts due to climate change with available resources. By large, it will help to foster a vital shift in the way drought is perceived and coped in the region, taking into account the country's economic, social and environmental context.