THE IMPACT OF CLIMATE CHANGE ON THE OCCURRENCE OF DROUGHT AT LOGIA CATCHMENT, LOWER AWASHI RIVER BASIN, ETHIOPIA

Abstract

Drought is a significant phenomenon affecting several economic, agricultural, social and environmental sectors. Therefore, assessing the impact of climate change on the occurrence of drought in different areas is too important especially those with arid and semi-arid climates. The aim of this paper is to investigate climate change impacts on meteorological and agricultural drought in logia river basin which is located in Awash River basin, Ethiopia, between the years (1988-2017) under present and future (2018–2077) climates. The analysis was based on the records of observed meteorological data and the future projected from the output of ensemble of 17 GCMs with aid of a MarkSim-GCM model under RCP 4.5and RCP8.5 scenarios. For this study; the RDI result shows that the precipitation was an increment of (+24.96 %,) from the base period to RCP 4.5(2020), +25.72 % to RCP 4.5 (2050), +28.06 % to RCP 8.5 (2020) and +30.19% to RCP 8.5 (2050) periods. Slight increase in maximum temperature ranges between + 0.31from the base period to RCP 4.5 2020 and +1.16 from RCP4.5 2050 and +0.56 from RCP 8.5 2020 and +1.27 from RCP 8.5 2050 and there is an increment of +0.85 from RCP 4.5 2020 to RCP 4.5 2050 and +0.69 from RCP 8.5 2020 to RCP 8.5 2050 scenarios. Also, the minimum temperature would be increased by +0.36 from the base period to RCP 4.5(2020), +1.17 to RCP 4.5 (2050), +0.56 to RCP 8.5 (2020), and +2.2 to RCP 8.5, (2050).The RDI annual results showed that the change in PET was an increment of + 0.42% from the base period to RCP 4.5 (2020), +1.02%, to RCP (2050), +1.65% to RCP 8.5 (2020) and +3.36 to RCP 8.5 (2050). The drought condition was observed in the base period (56.12%) was meteorological and (63.27%) agricultural drought and in the RCP 4.5 (2020) (54.17%) will be meteorological and (49.99%) will be agricultural drought and in RCP 4.5 (2050) (49.45%) will be meteorological and (53.34%)will be agricultural drought and for near future scenarios of RCP 8.5 the meteorological drought will be (53.33%) and the agricultural drought will be (50%)and in midcentury scenarios of RCP 8.5 the meteorological and agricultural drought will be (46.95%) and (60% ) respectively. The return period of severe drought conditions in base period was 13 and 20 meteorological and agricultural respectively. In RCP 4.5 (2020) the return period of severe drought conditions will be 50 meteorological and no return period in agricultural drought. Likely for RCP 4.5 (2050) the return period in severe drought conditions will be 33 meteorological and no return period for agricultural. For the near future of RCP 8.5 periods the return period of severe metrological and agricultural drought will be 33 metrological 16 agricultural droughts. Likely, for midcentury of RCP8.5, 50 sever meteorological drought and 20 severe agricultural droughts. As drought depends on both precipitation and temperature, it is expected that both the magnitude and frequency of drought will change as climate changes