Nautical depth investigation in fluid mud environment at Santa Catarina Terminal (Port of São Francisco do Sul, Brazil)

Abstract

An apparent dilemma is often presented to port operations as if safety of navigation and port efficiency were opposing forces. Estuaries with heavy loads of sediments pose challenges to both safety and efficiency and they have to be addressed at the same time. The two sides of the same coin. One important matter is the use of low frequency sonars and rheometers, frequently discarded by Hydrographers on the basis that they do not achieve sufficient accuracy for the safety of navigation. However, high frequency sonars are not suitable for areas rich in fluid mud as they can only detect the floating, variable water-mud interface. This work addressed these limitations confronting high frequency multibeam survey with double frequency single beam survey and density measurements to find half a meter of navigable mud below the minimum depth indicated in a high-frequency sonar survey. The work proposes a first step to define a very conservative and safe definition of nautical depth.