Abstract:
Intraseason and seasonal drought trends in Ethiopia were studied using a suite of drought
indicators—standardized precipitation index (SPI), standardized precipitation evapotranspiration
index (SPEI), Palmer drought severity index (PDSI) and Z-index for Meher (long-rainy), Bega (dry),
and Belg (short-rainy) seasons—to identify drought-causing mechanisms. Trend analysis indicated
shifts in late-season Meher precipitation into Bega in the southwest and southcentral portions of
Ethiopia. Droughts during Bega (October–January) are largely temperature controlled. Short-term
temperature-controlled hydrologic processes exacerbate rainfall deficits during Belg (February–May)
and highlight the importance of temperature- and hydrology-induced soil dryness on production
of short-season crops such as tef. Droughts during Meher (June–September) are largely driven
by precipitation declines arising from the narrowing of the intertropical convergence zone (ITCZ).
Increased dryness during Meher has severe consequences on the production of corn and sorghum.
PDSI is an aggressive indicator of seasonal droughts suggesting the low natural resilience to combat
the effects of slow-acting, moisture-depleting hydrologic processes. The lack of irrigation systems
in the nation limits the ability to combat droughts and improve agricultural resilience. There is an
urgent need to monitor soil moisture (a key agro-hydrologic variable) to better quantify the impacts
of meteorological droughts on agricultural systems in Ethiopia
