Rainfall Variation and its Effect on Crop Production in Ethiopia
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Date
2004-08
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Addis Ababa University
Abstract
Agricultural production in Ethiopia is predominantly rainfed. Variation of rainfall in space and
time affects the agricultural production system in the country. This needs accurate measurement
of rainfall and close study of rainfall variation. Therefore, the objective of this thesis work is to
study rainfall variability and its impact on crop production in Ethiopia.
For such type of study and other study in the country, accurate rainfall measurement over wide
spatial area extent is required. NOAA provides satellite rainfall estimate in Africa since 1995.
The comparison of monthly satellite estimate obtained by CPC (Climate Prediction Center)
technique with 37 numbers of rain gauges data show significant correlation (R = 0.77) but
generally underestimation over the period of 1996-2002. And the root mean squared error
(RMSE) is 68mm in average. With better calibration of the CPC method, better estimation
would be obtained.
Rainfall variation called trend has been assessed for total annual, Kiremt (June-September) and
Belg (February-May) rainfall using 10 selected stations over the period of 1973-2002 in
Ethiopia. Trend-free Pre-whitening Mann-Kendall statistical test at the stations show that Belg
rainfall totals don’t show significant trend while Kiremt rainfall totals on Gore (-7.75mm/year)
and Jijiga (-5.87mm/year), Sep-Nov total rainfall on N.Borena (-3.25mm/year) and annual
rainfall totals on Gore (-12.2mm/year) and N.Borena (-11.11mm/year) show significant
decreasing trend during the period. It is recommended to extend the study on more number of
stations to conclude at regional level.
Finally, in the thesis, total annual, Kiremt and Belg areal rainfall are regressed with main cereal
production of Teff, Barely, Wheat and Maize on selected study areas over the period of 1994-
2001. The result shows no significant correlation between total annual, Kiremt and Belg
rainfall, and production of those cereals. This analysis, however, includes small number of
sample data and thus doesn’t include drought years occurred in the country. In addition, in the
analysis, other agronomic factors are ignored. Therefore, large number of sample data and
consideration of other factors should be used in future studies.
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Keywords
Production ; Ethiopia