Abstract

Time series analysis is the major tool to detect decreasing or increasing trends and its magnitude in time dimension were tested. Daily historical rainfall data from 1984-201 was considered for this study area. In this study, trend and variability of rainfall indices was analyzed under historical rainfall data in Bale highlands of south eastern Ethiopia. There was a very strong linear relationship between onset of rainfall and length of growing season than other rainfall features. Thus, years with early onset of rain have longer length of growing season and vice versa. This suggests that decision of crops and varieties with different maturity groups and the decision to determine amount of farm input levels highly depend on onset of the rainfall. Dry conditions were more severe during 2nd decade for Kiremt and Belg seasons comparing with others decades. This result implies that the seasonal climate variability more severe in near decade than others. From this point of view, Agricultural practice could be affected severely in these periods either due to deficit or excess of rainfall required for agricultural activities at Sinana and Robe areas.