The impact of storms on shingle beach deposits : a case study at Mgarr ix-Xini

Abstract

The coastal zone is where terrestrial, marine, atmospheric and human processes interact between them, with the result of coastlines constantly shifting and changing. Coastal zones are dynamic due to these different processes which act both independently but also condition each other in a complex network of cause and effect dynamics. Shingle beaches constitute of sediments that range between 2 to 256mm, and studies on this type of beach environment are still relatively low, when compared to other beach systems such as sandy beaches. The aim of this dissertation is to analyse the sediment distribution of the shingle sediments before and after a storm, in order to investigate storm impact on a spatial and temporal dimension. It is a granulometric and morphometric study of the pocket beach located in a bay at Mġarr ix-Xini, Gozo. It is a sheltered bay situated at the end of a deep valley. The sediment size, shape and sorting were analysed in a systematic transect sampling technique from the foreshore to the backshore of the beach. In addition, statistical parameters of standard deviation, skewness and kurtosis, were undertaken in order to provide a better understanding of the sediment size distribution. The results are presented through graphs and tables to give a better visual representation of the data. Analysis of variance using Independent Sample T test were run in order to test the level of statistical variance in deposit’s dimensions on a spatio-temporal scale. The result of this research shows that, notwithstanding the relatively small dimension of this pocket beach, the shape, size and sorting of the sediment varied before and after a storm event. In addition to this result, the beach profile was also diverse since after a storm more cobble-sized sediments were transported to the middleshore and backshore, and hence resulted in a steeper beach profile after storms.