Sediment physical properties of the DYNAS study area

Physical properties of the deposits in the DYNAS study area, the Mecklenburg Bay, were investigated using sediment echosounders and laboratory analysis were carried out on undisturbed short sediment cores. Wet bulk densities of about 1.2 g/cm³ for mud and up to 1.9 g/cm³ for silty sand were found in surface sediments of the Mecklenburg Bay. Sediment density–depth functions were approximated by logarithmic regression functions at different depth intervals. Sediment consolidation was studied by both (i) consolidation tests of sediment samples and (ii) from the void ratio–overburden pressure relation in natural sediments. Low shear strength values of 9–71 Pa were measured at the mud surface. Downcore, a depth gradient of about 14.5 Pa/cm was calculated. Sediments with high silt and sand contents are characterized by shear strength values of up to 3000 Pa. Published formulas derived from erosion studies were used to calculate the critical shear stress using wet bulk density and shear strength. The obtained results demonstrate clearly, that there is still a wide gap in knowledge about the relationships between erosion parameters and sediment physical properties.