Seasonal and Annual Meteorological Drought Frequency: Case Study West Hararge Province (Zone)

Abstract

Over the years, the issue of drought has topped the agenda discussed at most climate change conferences and panels. Specifically, of ten times the negative impact of drought cannot be completely measured since drought affects both natural habitat and livelihood of an area. Drought is the manifestation of climate change and a common phenomenon in Ethiopia. Ethiopia faces widespread droughts, causing large economic and social damages. According to Segele and Lumb (2005), Ethiopia has been ravaged by severe drought for many of the last 35 years, primarily due to the failure of its main (kiremt) rainy season. This study attempts to identify the spatio temporal dynamics of Meteorological drought in West Hararge within 1990-2018. It employs the use of GeoCLIM of CHRIPS datasets. The CHIRPS dataset and the GeoCLIM tool were used to estimate SPI for the seasonal and annual Meteorological Drought. So we used Pixels and Image Resolution of CHIRPS pixel = 0.05 degrees ~ 5 km. Spatial rainfall average and CV was identified annually. Meteorological drought reclassified into three classes Very Severe (extreme), moderate and Slight (mild) drought. The finding intended to identify frequency and magnitude of events. Twenty (20yrs) Slight –Very severe drought events occurred in the period 1990–2018 in the province of West Hararge. The most important events were in the 2002, 2009 & 2015’s, (all reached the very severe threshold). During the study periods annual drought event were 68.97% while no drought event were 31.03%. The seasonal drought contribution to the study area is kiremt (40.42%), Belg (31.92%) and Bega (27.66%). Annual drought tendency were very severe, slight and moderate drought with the magnitude of 15%, 50% and 35% respectively. Probability of recurrence on the category were slight, moderate and very severe drought on number of time in years 10, 7 and 3 and the magnitudes of severity of events 2 in 2yrs, 1 in 3yrs and 1 in 7yrs respectively. Generally, the entire study area can be considered as frequently meteorological drought prone area. Increasing tendencies and frequency of drought were observed during recent year (Figure5 and Graph1.1, 1.2 & Table 1.2, 1.3 & 1.5). The finding shows that in the first decade (1990-1999) the annual magnitude of drought tendency were slight to moderate, whereas in the second decade (2000-2009) were under slight ,moderate and very severe and at the third decade (2010-2018) were under slight, moderate, and very severe categories. The seasonal magnitude of drought tendency increase both kiremt and belg during the second decade (1999-2009) (Figure5, Graph1.1, 1.2 & Table 1.2, 1.3, 1.4, 1.5 and 1.6), and this shows that there is an increasing of drought frequency and tendency. The patterns of drought events in the study area are highly localized.