Hydrographic surveys in Funchal

29 Jan 2021

Official designation of the project: Hydrographic surveys in Porto do Funchal

Start date: December 1, 2020
Completion date: April 30, 2021

Detailed description: Port authorities are responsible for frequently inspecting their maritime areas, in order to maintain minimum service depths in ports and ensure navigation safety. For this, it is necessary to hire contractors specialized in dredging to maintain the desired depths, and it is also essential to carry out pre and post dredging hydrographic surveys and associated volumetric calculations, both to define the projects to be carried out and to control work in progress. These hydrographic surveys can be carried out in any environment, including chanells and waterways, coastal regions, ports and approach channels.

Current IT tools allow a very strict control of dredging operations, so it is also common to have specialized support through the installation of tide gauges, global navigation systems on the dredgers (to maintain a precise positioning), and specific sensors to control the cut, where the level of accuracy is critical.

Modern multibeam equipment provides a detailed 3D model of the seabed (full coverage) for when Special Order hydrographic surveys are planned, where keel guarding is critical. However, as a rule, during the dredging phase, spacings of 5 or 10 meters are accepted between sounding rows, which makes it possible to use single-beam systems, with less demanding logistics and sufficiently reliable to create 3D models and allow a detailed calculation of dredging volumes.

Between December 2020 and April 2021, LS-Engenharia Geográfica carried out a series of hydrographic surveys within the scope of the dredging contract, between piers six and eight in the Port of Funchal, work carried out by the company Tecnovia-Madeira.

These Order 1b surveys were intended to update the hydrographic information within the scope of the ongoing dredging operations, providing important data for the management of the works and the accurate maintenance of the service depths. The minimum depth (service level) for this pier is 8 meters, and the first hydrographic survey, in which an area of ​​9 hectares was covered, made it possible to identify the intervention areas, where depths ranged from 4 to the 8 meters, according to the approach to Ribeira de S. João, one of the three main streams of Funchal, which contributes substantially to the accumulation of sediments inside the port.

Challenges: The demanding logistics of this type of work implied high transport costs; difficulties in adapting a local vessel to install equipment, meteorology (frequent rain).

Advantages: The use of single-beam sounding systems allowed the coverage of the intervention area in a few hours, returning accurate data with sufficient quality for the execution of the project.

Areas of Intervention: Hydrography

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