Variability and Trend Analysis of Temperature, Rainfall and Characteristics of Crop Growth Season in Eastern Zone of Tigray Region, Northern Ethiopia

Abstract Background: Long term weather analyses are very useful indicators in determining future directions and in making adjustments required to existing systems. And, in order to favor farmers to adjust their farming practices, seasonal climate outlooks are needed. The main purpose of this manuscript was thus to analyze the variability and trends of maximum and minimum temperature, monthly and seasonal rainfall series and characteristics of crop growth season in Eastern zone of Tigray region over the period of 1980–2009.Methods: Detail investigations were carried out using parametric (Linear regression) and nonparametric tests (Mankendall (Mk) and Sen’s slope estimator). Moreover, homogeneity test using a method developed by Van Belle and Hughes was used for general trend analysis. In addition, daily rainfall data to characterize crop growth season were analysed using R-Instat and XLSTAT software for trend analysis.Results: It was found that the general trend of monthly rainfall experienced an overall significant increasing trend. The seasonal rainfall experienced significantly increasing in summer main rainy season, June–September (Kiremt) while significantly decreasing in short rainy season, February– May (Belg). Likewise, the seasonal maximum temperature trends exhibited significant increase in each season while minimum temperature trend had inhomogeneous trend across seasons as well as stations. The trend of growing season characteristics (onset, cessation, LGP and dry spell length did not change significantly over the study period (1980–2009) in all stations. However, the coefficient of variability of LGP was (CV, >15%) and dry spell length was (CV, >25%) inassociation with short nature of LGP (68–85 days had a negative impact on the agricultural activities of the study area during the study period.Conclusions: Despite significant increase of rainfall in summer season, the variability of rainfall and dry spell length was very large. Hence, the study recommends crop production in the study area demands appropriate adaptation strategies that considers the erratic nature of the rainfall, the long dry spell length in the season and increasing trends of temperature.