Aeolian (dunal) transport at Ramla bay, Gozo

Abstract

Sediment transport is a crucially important process for the formation and nourishment of, amongst other, beach and dunal system and aeolian sediment transport within coastal environment may play a significant role in the enlargement or retreat of such unconsolidated sediment systems; this is very likely to be the case at Ramla Bay, Gozo where despite the interruption of long-shore sediment transport by the pocket shaped nature of this embayment, aeolian sediment transport appears to be relatively unimpeded. Significantly, very few studies have been conducted, concerning such processes at this site. This study expanded on a baseline study of aeolian sediment transport at Ramla Bay by Gatt (2015), by investigating the influence of multiple wind directions, a landward extension of such sediment transport and sand trap design modifications to improve sand capture efficiency. Sand traps were deployed at nine different locations and elevations landward and within the dunal system at this study site. The traps were divided into separate groups to gather sand by the north, north-westerly and north-easterly wind directions according to their position and orientation on the dune. Weather parameters such as wind speeds and direction and precipitation were obtained by online and in-situ weather stations and then used for the analysis of the results. Four main grain sizes (0.063mm, 0.25mm, 0.5mm and 2mm) were identified within the aeolian transport sediment fraction. Their fluid threshold velocity was also identified as varying between 0.10 to 0.56m/s. The highest rate of transport (2.55 x 10 -6 m3 m-1 s-1) was from the north-westerly wind direction. Sand trap design modifications were found to improve the capture of finer beach/dunal sediments.