Sedimentary dynamics in Monastir Bay of the Tunisian water

Abstract

The Bay of Monastir (Tunisia) is subjected to several industrial and fishing activities that contribute to the loss of biodiversity. Currently the trend is towards the pollution and the degradation of the coast. The objective of this work is to identify the principal natural and anthropogenic factors controlling the ecosystem functioning and to appreciate their effects, by using granulometric and mineralogical surface sediment analysis methods in order to specify the sedimentary dynamics in the coastal fringe of the Bay of Monastir. Particle size analysis of the superficial sediments of the coastal fringe of Monastir Bay shows that the submarine beach is lined with medium sands and fine sands, which are generally moderately classified and poorly graded. These sands move, essentially, by saltation, rolling and gradual suspension. The grain size distribution of the surface sediments along a transverse profile of the port of Monastir offshore, up to 17 m depth, shows a decreasing gradation of the coast to the open sea. The cumulative semi-logarithmic curves of the surface sediments of the underwater beach are generally in the form of a more or less spreading S, which indicates medium-grained sands and a more or less agitated environment. Mineralogical analyzes show that these sands consist essentially of quartz and calcite. Quartz comes mainly from geological land bordering the coast, terrigenous detrital inputs and wind energy from the coastal areas. The calcite comes from shelly debris in the study area and terrigenous detrital inputs. The transport of surface sediments in the area is mainly dependent on wind and swell.