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The objective of this study is to investigate the evolution of rainfall and flow in the Bouregreg watershed, and to identify the most vulnerable regions to climate change over a period of 36 years from 1977 to 2013. Results show significant variations between these sub-regions in term of monthly flows and monthly regimes. January and February rainfall amounts are the most affected by the reduction of rainfall since the drought started end of the 1970’s, inducing a reduction of flows at all hydrological stations mainly since 1979. The year 1996 shows very high precipitations over all sub-basins, and also separates two periods with different rainfall time series variations according to two regions over the basin: the region of the Tsalat sub-basin in the Southeast wet and mountainous area (Middle Atlas) shows a durable decrease of rainfall compared to the Ain Loudah sub-basin in the Center-West semi-arid plateau area.

Recent reductions of sediment transport are observed in Bouregreg River and estuary close to the city of Rabat in Morocco. The cause of this evolution in sediment transport which may be due to human activities (dam, pollution), climate variability and natural events has been investigated from a paleo-hydrological approach. Sedimentological and geochemical analyses of slackwater flood deposits are used to assess the impact of a dam installed in 1974 and the climate change on the evolution of sediment transport during about 60 years. Higher accumulation rate of about 3,64 cm/year is observed between 1950 and 1978, whereas it was much lower about 0,41 cm/year between 1990 and 2017. This strong decrease in sediment rate appears much more due to the impact of dam construction rather than to climate change, however climate change in an increasing concern for the future.

During the last decade, the Moroccan Atlantic coast was severely hit by the various marine winter storms associated with swells engendered by the North Atlantic depressions and by sporadic cyclones . On January 7, 2014, storm Hercules/Christina led to intense flooding and huge damage of infrastructures and touristic facilities from Sale to Casablanca that we describe after summarizing the wave climate and the historical data on storms in Morocco. The main conclusions of the present study are: (i) storms constitute a real threat to coastal cities along the Rabat-Casablanca segment, as inferred from the effects of the last major storm Hercules. The analysis of recent storminess in Morocco has shown that storms appear as an underrated natural hazard, probably because of the lack of general studies since the 1960s; (ii) review of various studies shows that the normal significant heights of swell are low, in the range 0.5–1.5 m and that the 4.5 m value can be adopted as a threshold for storm waves, similarly to that adopted for the Portuguese coast at its western segment; (iii) we set 33 tons as a new regional upper limit of the dimensions and weight of boulders that can be transported by current winter storms (hurricanes excluded); however, the shape of the boulder is a fundamental parameter for the displacement; (iv) a major lesson from Hercules is that a great effort has to be done by scientists, district authorities and real estate managers for the management and prevention of this type of hazards, given the growing coastal population and economic activity. This can be accomplished by mapping precisely the coastal strips and determining the most vulnerable areas.

Proceedings of Euro-Mediterranean Conference for Environmental Integration (EMCEI-1), Tunisia 2017; A great number of rivers of North Africa are equipped with many dams for multiple purposes, mainly potable water, irrigation and energy production. In most of the countries—Morocco, Algeria and Tunisia, the storage capacity exceeds the runoff capacity, which means that water is stored several times in a row during its course to the sea.