Extreme rainfall signatures under changing climate in semi-arid northern highlands of Ethiopia

Statistical analysis of continuous daily climate data and extensive weather records are important to evaluate possible long-term, hydrologic/climatic changes at local and regional scales. In the present study, daily rainfall data recorded in the period 1971-2013 (43 years) at seven meteorological stations distributed in the Geba River basin, northern Ethiopia were used to study trends in extreme rainfall indices at different temporal scales. The selected rainfall indices focus on intensity, frequency, and duration of extreme rainfall measures. The Mann-Kendall trend test results show that decreasing tendencies in the rainfall indices have predominantly observed in several stations, even though most of the stations did not show statistically significant trend over time at 95% significance level during the study period. In majority of the extreme rainfall indices, station Abiadi which is located at the downstream of the basin showed statistically significant increasing trend, while decreasing trend in very heavy rainfall days (R20mm) for Adigrat station, and consecutive dry days (CDD) and highest rainfall amount in one-day period (RX1day) for Mek'ele showed statistically significant at the 95% level of significance. Results of this study contribute to climate change research in the region and provide inputs for better planning toward adapting to changing climate.