Rainfall Trend and Variability Analysis in Borana Pastoral Lowland Areas: The Case of Yabello and Eel-wayye Station, Southern Ethiopia

Abstract

Dry lands are traditionally used and managed by a pastoralist, characterized by variable precipitation, climate variability and water scarcity. Change in rainfall trend and variability’s lead to severe production deficit and decline the balance between pasture and livestock on which pastoral livelihood depends on. The study was undertaken to assess the variability and trends of rainfall in Borana pastoral area using monthly rainfall record for the period 1987-2016 of Yabello and Eel-wayye station. Rainfall variability analysis has been done using variability indices like, coefficient of variation, precipitation concentration index and Standard anomaly index. Trend analysis was carried out using Man-Kendall trend test 5% significance level. The coefficient variation of the study area for Yabello was 21.2%, while for Eel-wayye it was 53% which showed high inter-annual variability. The negative anomalies at Yabello station was 53.3% While in Eel-wayye station, revealed 56%. The analysis result indicted that the rainfall concentration index value ranged from 13.2 to 30.23 for the stations which shows moderate to strong irregularly rainfall distribution. The year 2006 was the most drastic and distinct-wide extreme drought episode in both stations, Except short rainy season at Eel-wayye station, the Mann–Kendal test shows not statistically significant (P<0.05). Increasing tendencies of drought during main rainy season and decreasing tendencies of drought during short rainy season and annually were observed in the study area. This threats the livestock production systems, which is the backbone of the pastorals livelihood. The study, suggests policy makers to develop other sustainable water sources for lowlands pastorals.