Endalew Assefa Abera* and Wagaye Bahiru Abegaz
Precipitation is one of the most important climate variables that could influence the climatological, agricultural, and hydrological studies. This paper presents several test statistics to detect the effects of autocorrelation and its level of significance in the seasonal rainfall data over eastern Amhara. The daily rainfall data was obtained from the National Meteorological Agency of Ethiopia. The Mann-Kendall test, Sen’s slope estimator, and Pettit’s test were used to assess the significance, magnitude, and point changes in the seasonal rainfall data, respectively. The effects of autocorrelation in the time series data was no found significantly, except at lag 1. The Mann-Kendall test revealed that 65% of study sites showed an increasing trend with only 31% was statistically significant (p<0.05) during the Annual season. About 85% of the study sites showed an increasing trend with 41% of it was significant during the Kiremt season. On the other hand, 70% of the study site during Bega seasons showed increasing trend with only 21% part of it was statically. Similarly, during Belg seasons, 35% of the study sites were in an increasing trend, in which 14% was significant. In this study, the effects of autocorrelation and seasonal change points were not detected in the time series data.
