Drought and Flood Occasion under the Influence of El-Nino and La Nina Phenomena in Gurage Zone

Abstract

Drought and flood issues are major problem in Ethiopia as well as hectic at the regional level. It affect the agricultural system and water resources through reduction of soil moisture or insufficient rain fall during El-Niño and washing away of soil nutrient, top soil and property destruction during La-Niña condition. In light of this, a study was conducted in Gurage Zone to analyze drought and flood occasion under the influence of El-Nino and La-Nina phenomena. The spatio-temporal variability of droughts and flood in Gurage Zone were analyzed to detect drought and flood events using the standardized precipitation index at SPI12 time scales based on 29 year (1989-2017) rainfall data. The annual rainfall in the four stations showed a significant decreasing and increasing trend at Wolkite station but there was non-significant negative trend at Butajira station. During the period of study, the largest negative deviation was occurred during the year 2017, 1992, 2016, 2012, and 2017 and the highest positive anomalies was registered during year 1993, 2010, 1992, 2010, and 2005 at Mareqo, Cheha, Abeshge, Sodo and Mesikan districts, respectively. In 1992, 2012, 2016 and 2017 an El-Nino event occurred across the entire study area, 5 out of 5 districts experienced drought. In 1993, 2010, 1992, 2010, and 2005 a La-Lina event occurred across the entire study area, 5 out of 5 districts experienced flood condition. In the study area like Cheha, Mesikan and Mareqo recorded extreme drought with risk peak value was above -2 while Abeshge and Sodo districts recorded severe drought with risk peak value was –1.8 and -1.63 respectively. In contrary, Sodo woreda, Abeshge and Mareqo recorded extreme wet condition with risk peak value was above +2 whereas Mesikan and Cheha districts recorded severe wet with risk peak value was +1.92 and +1.94 where they are considered the most abundant rainfall in the area, respectively. The study result indicated that the study area is experienced in unpredictable drought and flood events with different time period. Such research is important in strategic planning and operational applications like drought and flood monitoring. Therefore, the local government, NGOs and others concerned body should provide platform for early warning preparedness, drought and flood monitoring strategies in the area.