The transport and distribution of the river load from the Reda River into the Puck Lagoon (southern Baltic Sea, Poland)

The main aim of this study was to determine the size of the load carried by the Reda River that was discharged into the sea and the load distribution on the bottom of the Puck Lagoon. Water exchange with the open sea was limited in this shallow reservoir where the average depth was 3.13 m. The input of material was dominated by river transport, whereas abrasion and aeolian processes were insignificant in the total sediment inflow. The Reda River, one of the main rivers flowing into the lagoon, is 44.9 km long and has a catchment area of 485.2 km2. The investigations were conducted between 2001 and 2004 at the Mrzezino hydrological cross-section and at the river mouth in the Puck Lagoon. The study demonstrated that the Reda River discharged annually approximately 9,900 tons of sediments into the Puck Lagoon, 73% of which was the bed load that in the final course of the river created an underwater accumulation form. The granulometric composition of the deltaic deposits, similar to the bed load, was dominated by coarse-grained sand fractions. The proportion of the aleurolite and pelite fraction was insignificant at less than 1%. The suspended sediment was composed of particles that ranged in size from 0.00045 mm to 0.25 m. Mineral particles were more common than organic ones in the load discharged by the Reda River into the Puck Lagoon and constituted 99% of the bed load.