An application of Dolan and Davis (1992) classification to coastal storms in SW Spanish littoral

Classification schemes for distinct meteorological and climatic phenomena, provide beneficial information useful in evaluating their impacts on socio-economic activities and natural habitats. This work deals with storm classification in the Atlantic side of Andalusia Region (SW Spain) for the 1958-2001 period, by means of the index of Dolan and Davis (1992). Wave data from January 1958 to November 2001 were obtained from five prediction locations (Huelva, Chipiona, Cadiz, Conil and Bolonia) of the HIPOCAS network. The Dolan and Davis (1992) Storm Power Index was used to classify coastal storms into five classes, from weak to extreme. The Index was calculated according to the formulation Hs²td, with Hs being the significant wave height and td the storm duration in hours. Huelva and Chipiona locations respectively recorded 137 and 189 storms, Cadiz and Conil respectively recorded 377 and 369 storms approaching from the third (mostly) and secondarily from the forth quadrant. Bolonia location recorded most elevated number of storms (422), they approached principally from the third quadrant (303 events) and secondarily from the second (59) and forth (60) quadrants. The distribution of storm classes was very similar at all locations. Classes I (weak) and II (moderate) respectively accounted for 60% and 23% of events included in the data set. Class III (significant), recorded 10% of the events and Classes IV (severe) and V (extreme) accounted for 5% and 2%, respectively. Return period for Class V events ranged from 2 to 12 yrs, with average values of 7-8 years and values from 1 to 3 yrs were observed for Classes I to IV. Preliminary analysis on beach morphological changes and coastal structures damage pointed out as in autumn important beach morphological changes were associated with the impact of Classes I to II events which easily eroded well developed steep summer beach profiles. In winter, successive energetic events (Classes III to V) produced less significant beach changes, because beaches already showed dissipative profiles, but heavily impacted on dunes and coastal structures.