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Marine storms along the Moroccan Atlantic coast: An underrated natural hazard?

2019; Elsevier BV; Volume: 163; Linguagem: Inglês

10.1016/j.jafrearsci.2019.103730

1879-1956

Nadia Mhammdi, Fida Medina, Zaineb Belkhayat, Rajae El Aoula, Mohammed-Ali Geawahri, Adil Chiguer,

Coastal wetland ecosystem dynamics

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 Salé 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.