Rainfall distribution patterns and their change over time in a Mediterranean area |
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Authors: | M C Ramos |
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Institution: | (1) Department of Environment and Soil Science, University of Lleida, Spain, ES |
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Abstract: | Summary
In dry farming areas, where rainfall is the only source of water for crops, changes in both quantity and distribution of rainfall
during the year could affect the economy of an area. Inter-annual variability makes it difficult to assess rainfall variability,
especially in areas with Mediterranean climate. In this paper, interannual rainfall variations in the Alt Penedès region were
evaluated using 24-h rainfall records at Vilafranca del Penedès (1889–1999) and at Sant Sadurni d’Anoia (1960–1999). The distribution
patterns during the year and their changes over the time were also analysed. Rainfall data were normalised and the values
corresponding to the percentiles 0.1, 0.25, 0.5, 0.75 and 0.9 were calculated to analyse whether they were very dry, dry,
normal, wet and very wet periods. Annual rainfall and the rainfall recorded during the main rainfall periods during the year
and its trend were analysed. Annual rainfall did not show a clear tendency, although during the last decade reduced interannual
variability occurred. The percentage of dry years did not increase but the percentage of wet and very wet years decreased.
During the last decade, an increase of dry spring seasons andwet autumn seasons was observed, even in normal or wetyears.
These changes could affect the timing of whencrops receive water and could therefore affect their yields.
Received May 31, 2000/Revised February 26, 2001 |
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