Birhan Getachew
Debre Tabor University Department of Geography and Environmental Studies

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Trend analysis of temperature and rainfall in south gonder zone, anhara ethiopia. Birhan Getachew
Journal of Degraded and Mining Lands Management Vol 5, No 2 (2018)
Publisher : Brawijaya University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (1422.69 KB) | DOI: 10.15243/jdmlm.2018.052.1111

Abstract

This study mainly focuses on exploring trend analysis of temperature and rainfall in the case of south Gonder zone. The analysis is based on the temperature and rainfall variation in south Gonder zone over three stations at Addis Zemen, Nefas Mewcha and Mekane Eyesus. The duration of the study period for temperature and rainfall data was chosen as 1996-2015 for Addis Zemen, 1986-2015 for Nefas Mewcha and 1996-2015 for Mekane Eyesus. The Belg rainfall have been found much more variable (>30%) than the Kiremet rainfall in which the coefficient of variation is greater than 30% over the study area. The findings of the non-parametric Mann-Kendall test revealed that there was no significant trend in the annual and seasonal rainfall data whereas monthly rainfall of April and November shown statistically significant increasing trendover the study area. However, the trend was not significant, the annual, the Kiremet and monthly rainfall during June, August and November shows an increasing particularly November was also statically significant as the computed p-value is less than the significance level α = 0.05.On the other hand, the Belg rainfall and monthly rainfall of March and April shows a decreasing trend. Statistically significant increases of mean annual temperature have been found in Addis Zemen and Nefas Mocha whereas statistically insignificant decrease of mean annual temperature has found in Mekane Eyesus. On the other hand, statistically significant increase of annual maximum temperature has been found in Addis Zemen while statistically insignificant increase of annual maximum temperature have been found for Nefas Mewcha and Mekane Eyesus station. Besides, statistically significant increase of annual minimum temperature has been found in Nefas Mewcha whereas statistically insignificant increase of annual minimum temperature has been found in Addis Zemen and Mekane Eyesus. The rates of change in mean annual temperature for Addis Zemen 1.6980c per 20 years and Nefas Mocha 0.8130c per 30 years have been found greater than the rate of change which was found at national and global level. Therefore, it is recommended that small scale study should be undertaken to clearly detect the rate of climate change and to develop appropriate adaptation strategies for the given agricultural system with the prevailing climatic conditions.
Markov chain modeling of daily rainfall in Lay Gaint Woreda, South Gonder Zone, Ethiopia Birhan Getachew; Menberu Teshome
Journal of Degraded and Mining Lands Management Vol 5, No 2 (2018)
Publisher : Brawijaya University

Show Abstract | Download Original | Original Source | Check in Google Scholar | Full PDF (674.738 KB) | DOI: 10.15243/jdmlm.2018.052.1141

Abstract

Information on seasonal Kiremet and seasonal Belg rainfall amount is important in the rain fed agriculture of Ethiopia since more than 85% of the population is dependent on agriculture particularly on rain fed farming practices. The distribution pattern of rainfall rather than the total amount of rainfall within the entire period of time is more important for studying the pattern of rainfall occurrence. A two-state Markov chain was used to describe the characteristics of rainfall occurrences in this woreda. The states, as considered were; dry (d) and rainy (r). The overall chance of rain and the fitted curve tells us that the chance of getting rain in the main rainy season is about twice as compared to the small rainy season. The first order Markov chain model indicates that the probability of getting rain in the small rainy season is significantly dependent on whether the earlier date was dry or wet. While the second order Marko chain indicates that the main rainy season the dependence of the probability of rain on the previous two dates’ conditions is less as compared with the small rainy season. Rainfall amounts are very variable and are usually modeled by a gamma distribution. Therefore, the pattern of rainfall is somewhat unimodial having only one extreme value in August.  Onset, cessation and length of growing season of rainfall for the main rainy season show medium variation compared to the small rainy season.