Climate
By its position, the climate in the study site is of the Mediterranean to Saharan type. The coldest months are December, January and February with occasional freezing (up to -3°C). June-August is the warmest period of the year during which the temperature could reach as high as 48°C. The temperature in the study site is affected by the proximity to the sea and the altitude. Having an arid climate, the rainfall in the study site is characterized by low averages, high irregularity (both in time and space) and torrential characteristics. It receives, on annual average, between 150 and 240 mm in the mountains and eastern parts but this amount decreases rapidly to less than 100 mm in the zones close to the desert. The prevailing winds affecting the plain and the plateau are: in winter the cool and humid eastern/northeastern winds, and in summer the hot and dry southeastern winds, called Chhili or Guebli. With high temperature and low rainfall, the potential evapotranspiration (ETP) is very high (around 1321 mm/year) and the climatic water balance is negative almost around the year (Ouessar et al., 2006).
