EXTENT OF THE DROUGHT IN THE CATCHMENT AREA OF THE MEFFROUCHE DAM (NORTH-WEST OF ALGERIA)

Meffrouche watershed, located in North-West Algeria with a land area of 89 km2, collects a mean annual rainfall of 659 mm (Meffrouche), computed over a period of 68 years (1943-1944 to 2010-2011). This basin, like most of the Maghreb, has been undergoing a persistent drought for a few decades. Different approaches, using a dataset of precipitation and depth of runoff, are addressed in this study to highlight the severity of this drought. The results obtained show the existence of a break of homogeneity located in the mid-1970s. The previous period is classified as wet, the one after is dry. The deficit between the two periods, valued at nearly 30 % for precipitation caused a drop in flow of more than 60 %. Periods of wetness and dryness are highlighted with a mild tendency to drought. Although some years have been very wet or extremely dry, the appearance of one or two years deficient rainfall in the mid-year surplus has no direct effect on water supplies in dam. For cons, the succession of several years with medium rainfall can generate a strong flow of water year.