THE BIOCLIMATE OF TLEMCEN AREA (NORTHWEST ALGERIA)

Bioclimate of the Tlemcen region is typically Mediterranean, characterized by two distinct seasons one dry summer and the other rainy winter with some ground therophytisation. Our study is based on two well-defined periods, the ancient from 1913 to 1934 and other recent from 1975-2008. The analysis of the temperature and precipitation allowed us to detect that there was a drop in rainfall and increasing temperature taking into account the two study periods. There are two seasonal patterns, the first is the HAPE type for the two periods (Stations of Hafir, Ouled-Mimoun, Beni-Saf and Ghazaouet) and the second was the type HAPE for the former period becoming HPAE type for the new period (Station of Zenata). Comparing the two periods (old and new), the diagrams of (6) allowed us to suggest that the dry period of the year was extended 2 to 3 months or even 6 months some stations. The pluviothermic climagramme of Emberger (Q2) revealed that all studied meteorological stations have undergone a shift of one floor or sub-floor. Through this study we can conclude that the region of Tlemcen knows some climate change expressed by the increase in temperature and decrease in rainfall due to several causes such as air pollution and the degradation of the vegetation .