Characterization of Maritime Storms and Analysis of their Effect on the Beaches South of the Mondego River (Portugal)

Abstract

Santos, M.I.; Oliveira, F.S.B.F., and Trigo-Teixeira, A., 2018. Characterization of Maritime Storms and Analysis of their Effect on the Beaches South of the Mondego River (Portugal). In: Shim, J.-S.; Chun, I., and Lim, H.S. (eds.), Proceedings from the International Coastal Symposium (ICS) 2018 (Busan, Republic of Korea). Journal of Coastal Research, Special Issue No. 85, pp. 266–270. Coconut Creek (Florida), ISSN 0749-0208.In the study of coastal processes and coastal dynamics, the analysis of the storms impact is one of the most discussed topics in terms of management and defense of the coastal sector. The Portuguese west coast is exposed to the energetic wave climate that characterizes the North Atlantic, thus requiring permanent care as regards the efficient coastline management and planning. Indeed, the risk associated with erosion and flooding of vulnerable areas is a constant concern, making it imperative to predict the impact of these events and the response of the beach-dune systems. This study focuses on maritime storms and on the morphological response of the beach to these short-term events. The two main objectives are to characterize the storms regime in the coastal stretch between the Mondego and the Lis rivers' inlets based on the wave time series (hindcast) from the period 1952–2010, and to evaluate the impact of the storms duration on erosive events, using a short-term morphodynamic numerical model, LITPROF. This model is used for the analysis of the effect of storms on the beach morphology and thus, for comparing the erosive effect of events with the same relative storm power and different duration. The statistical analysis of the wave climate time series showed a coastal storms regime with high inter-annual and intra-annual variability in number, duration and relative storm power of events, characterized by a strong seasonality, with an average duration and relative storm power of 3 days and 2654 m2.h, respectively. The most frequent events are simultaneously in the classes [1–2[ days and [800–1600[ m2.h (36% of occurrences). The numerical model, applied to several scenarios, predicted the dominance of the duration factor for storms with similar relative storm power, leading to the conclusion that longer duration storms always generate larger erosive effects (and higher transport rates) in the cross-shore profile, when compared with storms of shorter duration.