期刊名称：Science et changements planétaires / Sécheresse
印刷版ISSN：1147-7806
电子版ISSN：1777-5922
出版年度：2009
卷号：20
期号：1
页码：57-65
DOI：10.1684/sec.2009.0169
出版社：John Libbey Eurotext
摘要：Figures See all figures Authors Hind Meddi , Mohamed Meddi Laboratoire de recherche eau, roche et plante Centre universitaire de Khemis Miliana 44225 Khemis Miliana Algérie Key words: Algeria, drought, markov chains, rainfall DOI : 10.1684/sec.2009.0169 Page(s) : 57-65 Published in: 2009 West Algeria has been characterized by remarkably severe dryness along with an extensive and persistent pluviometric deficit since the end of the seventies. This study of the variability and change in annual rainfall in Northwest Algeria is based on the analysis of 25 stations with more than 50 years of data. The decrease in rainfall has consequences for the availability of water resources. The observation period of the various stations frames the possible period of climatic fluctuation and makes it possible to retain a sufficient quantity of reliable data to allow an interesting comparative analysis from the regional point of view even if the distribution of the stations is not always homogeneous over the whole of the study zone. The charts and analysis show that during this century, the northwest of Algeria has experienced an alternation of dry and humid periods. We have used several methods to study the non-stationarity and trend in the series of studied stations. The results show a generally upward trend covering the thirties and the fifties. The drop in pluviometry was observed during the beginning of the forties and the middle of the seventies. The reduction of pluviometry exceeds 36% in the Mascara region and in the extreme west. On the other hand, the decrease of rainfall is about 20% in the centre of Algeria (the plain of Mitidja). The dryness recorded during the last two decades had no equivalent in duration or intensity throughout the period studied or the region. The test on sequential trends confirmed the existence of three major trends during the last century. An increase during the period 1945-1946 was followed by a relatively dry phase and a decrease in precipitation from the seventies. The study of the persistent drought, using Markov chains, showed that the probability of a non-dry year after a dry year is higher in the Center of the country than in the West while the probability of two successive dry years is higher in the West than in the Central Plains.
