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| Titel |
Investigating changes over time of annual rainfall in Zimbabwe |
| VerfasserIn |
D. Mazvimavi |
| Medientyp |
Artikel
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| Sprache |
Englisch
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| ISSN |
1027-5606
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| Digitales Dokument |
URL |
| Erschienen |
In: Hydrology and Earth System Sciences ; 14, no. 12 ; Nr. 14, no. 12 (2010-12-22), S.2671-2679 |
| Datensatznummer |
250012539
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| Publikation (Nr.) |
 copernicus.org/hess-14-2671-2010.pdf |
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| Zusammenfassung |
There is increasing concern in southern Africa about the possible decline of
rainfall as a result of global warming. Some studies concluded that average
rainfall in Zimbabwe had declined by 10% or 100 mm during the last
100 years. This paper investigates the validity of the assumption that
rainfall is declining in Zimbabwe. Time series of annual rainfall, and total
rainfall for (a) the early part of the rainy season,
October-November-December (OND), and (b) the mid to end of the rainy season,
January-February-March (JFM) are analysed for the presence of trends using
the Mann-Kendall test, and for the decline or increase during years with
either high or low rainfall using quantile regression analysis. The Pettitt
test has also been utilized to examine the possible existence of change or
break-points in the rainfall time series. The analysis has been done for 40
rainfall stations with records starting during the 1892–1940 period and
ending in 2000, and representative of all the rainfall regions.
The Mann-Kendal test did not identify a significant trend at all the 40
stations, and therefore there is no proof that the average rainfall at each
of these stations has changed. Quantile regression analysis revealed a
decline in annual rainfall less than the tenth percentile at only one
station, and increasing of rainfall greater than the ninetieth percentile at
another station. All the other stations had no changes over time in both the
low and high rainfall at the annual interval. Climate change effects are
therefore not yet statistically significant within time series of total
seasonal and annual rainfall in Zimbabwe. The general perception about
declining rainfall is likely due to the presence of multidecadal variability
characterized by bunching of years with above (e.g. 1951–1958, 1973–1980)
and below (e.g. 1959–1972, 1982–1994 ) average rainfall. |
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