An investigation of seasonal sand characteristics and related beach profiles : a case study of Golden bay and Armier bay

Abstract

Despite the Maltese Islands having a long coastline for their area, pocket sandy beaches only account for 2.2%. The aim of this study was to investigate the seasonality of two pocket beaches, Golden Bay and Armier Bay. These two sites were chosen as they have a differing orientation which allows the impact of the wind and wave direction to also be considered. The hypotheses of this study were that there would be noticeable sediment characteristic differences between the beaches; that the profiles of both beaches would change with the seasons and differ from each other; and that there would be a significant relationship between the size of the sand grains and the gradient of the profile. Field measurements were carried out in October 2013, December 2013 and February 2014. Profile data was collected using a method of systematic sampling, measurements were taken along five transects taking readings every two metres from the backshore to four metres beyond the waterline using the traditional Emery method. Sand samples were collected along the same transects at ten metre intervals. The sand was analysed using dry sand sieving and stereomicroscopy methods. Gradistat and SPSS provided further statistical analysis of the data. The results showed that there were notable differences between the behaviour of Golden Bay and Armier Bay. Although the majority of sediment on both beaches was classed as medium sand and classified as having low sphericity there were differences in the levels of sorting, skewness, kurtosis and roundness. No persistent identifiable sorting patterns were observed on either of the beaches. In all cases, except one, there was no significant relationship between the size of the sand grains and the gradient of the profile. The profile of Golden Bay did respond seasonally, forming a steep summer profile and a relatively smoother winter profile. However, the profile of Armier Bay was less dynamic in its response to seasonal change. This was considered to be due to the differing orientation in relation to the common wind direction. The lack of conformity of the beaches behaviour to the theory is attributed to the small nature of the beaches and relatively high levels of human interference; this makes them very vulnerable as the natural processes cannot fully occur before being disturbed.