Caractérisation de la Variabilité Climatique : Cas du Bassin Versant de La Medjerda ( Nord-Est Algérien ) = Characterization of Climate Variability : Case of Watershed Medjerda ( North East of Algeria )

This study has the advantage of some statistical methods to interpret the spatiotemporal variability of precipitation sixteen rainfall stations located in the watershed of Medjerda (North East of Algeria) on a period ranging from 19 to 38 years. Whilst analyzing such series, there was an observed break in the period 1980 and 1990. Thus, the results of the mapping of interannual rainfall indices calculated per decade over the period 19712007 shows the decades 80 and 90 appear as deficit throughout the territory of the basin. Thus, a trend to a return of precipitation is noted for the period (2001-2007). At the monthly scale, precipitation increased significantly after years of failure for the winter months and spring, with the exception of March. An exceptional concentration of rainfall in the month of August is observed. At the daily scale, the analysis of daily rainfall fractions shows a trend of increase in the average annual rains total of more than 20 mm after years of failure. The Medjerda basin has also known a reduced rainfall and an increase in temperature over a period ranging from (1913-1938) to (1969-2007).