Résumé:
Knowing the evolution and recent climate variability in arid and semi-arid is a need to
anticipate what might be the consequences on the environment and societies of these regions,
and to define sustainable adaptation policies. In this modest work we have studied the
evolution rainfall in an arid region. And a good knowledge of the rainfall distribution in both
time and space, is important to achieve a share critical drought periods to which crops are
exposed and the other favorable areas and areas unfavorable. In this perspective, we have
helped to study the essential element of balance is rainfall using statistical processing and
analysis of drought indices, so we adopted a methodology which is characterized by the
collection of rainfall data and creation a database computer.
The calculation of indices for the various stations reveals the existence of two distinct wet and
dry periods. Drought years are remarkable because they can settle for 4 years. There is a
decrease in rainfall during the study period but it is also interrupted by other years of high
rainfall in some areas such as El Kheiter and Mecheria. It is as if, as we move south over the
drought impact is present.
