Modeling the Spatio-Temporal Meteorological Drought Characteristics Using the Standardized Precipitation Index (SPI) in Raya and Its Environs, Northern Ethiopia

Abstract

In Ethiopia, recurrent droughts were associated with El Nino phenomenon, particularly in the study area where the majority of smallholder farmers depend on rain-fed agriculture. The aim of this study was to model the spatio-temporal meteorological drought onset, offset, duration, magnitude, intensity, frequency, severity and spatial extent in Raya and its environs, Northern Ethiopia. Both the ground meteorological stations and TAMSAT (tropical applications of meteorology using satellite and ground-based observations) monthly rainfall data were gathered from the National Meteorological Agency of Ethiopia for the period 1983–2015. The Inverse Distance Weighting (IDW), a type of the deterministic interpolation method was applied to quantify the amount of seasonal rainfall by producing surface rainfall map. A Standardized Precipitation Index (SPI) at 3-month timescale was used to evaluate seasonal rainfall deficit and characterize meteorological drought. The results revealed that all sites obtained minimal and irregular rainfall, hence led to catastrophic droughts. Also, the findings showed that there was high rainfall variability across the study area that ranged from 28.14 to 42.32%. As a result, mild-to-severe meteorological drought phenomena were observed once in every 2–3 years. This incidence was found to be high in terms of spatial and temporal coverage during the last three decades. Therefore, this study may help to offer better insight for policymakers to establish drought mitigation and adaptation strategies.