Development of two sandy bay bars in a deltaic environment under action of swash waves

The article describes development of two sandy bay bars located south of Sfax. The aim of the research was to determine the rate of growth of the bay bars and to find factors responsible for the process. The research was based on analysis of aerial photographs and textural features of sediments. The results show that the length of the bars grows c. 40 m/yr on average. This is linked to supply of detritus by the Wadi Chaffer which has its delta between the analysed bay bars. Developments of the bars is symmetrical on both sides of the delta and depends also on long-shore currents flowing in opposite directions along the delta coast. The bay bars are kinds of beach ridges 2 to 3 km long and consists of fine and medium, well sorted sand. Such a sediment is under permanent action of wind and swash waves. Lagoons protected by the bay bars constitute a low-energy environment and their floors are built with fine, poorly sorted sand. It is emphasised that the morphology of the bay bars is not stable and susceptible for high anthropopression in the region