VARIATIONS SPATIO-TEMPORELLES DE LA SECHERESSE CLIMATIQUE EN ALGERIE NORD-OCCIDENTALE

Abstract

Algerian has witnessed during the last twenty years an intense and persistent drought. This drought which is characterized by an important rainfall deficit has affected the whole of Algeria particularly the north - west part.Similar droughts in amplitude and intensity have yet been noticed at the beginning of the century, between 1910 and 1940. In our study we devoted ourselves to historical analysis of drought on the annual scale. This has allowed us to follow its evolution decade by decade from 1920 to 1990. We tried in the first step to characterize this drought. Then to quantify it and at last to study its variability in space through two approach methods: calculation of the advance of the South to the North, the isohyet 400mm, which stresses the importance of the geographical extension of the phenomenon, and the automatic cartography of the rainfall indications per decade from 1920 to 1990