Climate
The amount of daily rainfall in the area is generally low. Over 32 years (1970-2002), 794 days recorded more than 5 mm, which represents an average of only 15 days/year.
Figure 7: Annual rainfall, Salé station, 1974-2002
The frequency analysis of the monthly rains in the Rabat station shows that late autumn is the more variable period (November and December). This period is themost crucial for the hydrologic functions of slopes and waterways, because the fields are still bare. In 50% of the cases, we register total dryness; but the cases of intensive rainfall are numerous and have important effects. The last 3 decades show a more important concentration of rain in autumn, with an average intensity reaching 20.4 mm/rainy day. The other seasons don't show a real tendency for change. During 32 years, 28 cases of intensive rains (>30mm) were recorded.
Figure 8: Frequency distribution of monthly rainfall, Rabat station, 1974-2002
