Accompanying measures

Turbidity modeling

Objectives and methodology

AU-IOTA prescribes that prior to starting work on the foundations, the project owner carries out modeling of the dispersion of suspended matter and assesses their impacts on the fishery resource.
The project owner presents for opinion to the management and monitoring committee:

The results of the modeling and impacts on the fishery resource.

The conditions and operating methods for carrying out the work.

The conditions for carrying out monitoring and surveillance measures.


The alert and critical thresholds conditioning the completion of the work.

In order to evaluate the influence of drilling work for the discharge of residues taking place near the bottom or the surface, a three-dimensional hydrodynamic and sedimentary modeling system was set up, calibrated and validated by comparison with the measurements acquired. by Ailes Marines in the implementation area (Actimar, 2019). It then makes it possible to represent the variation of the different parameters (current, turbidity, deposition) over the entire water column and to estimate the influence of the vertical position of the discharge on the dispersion of sediments at sea, necessary to identify the conditions lower impacts with regard to the preservation of the environment.

In line with previous studies carried out by Actimar on the same subject, the hypotheses on drilling scenarios have been considerably refined for greater realism. In particular, as the work technique depends on the vertical structure of the nature of the funds, this was taken into account from core drilling and particle size analyzes in order to reproduce, as realistically as possible, the volumes of materials discharged at sea and the phasing of operations within the modeling system.

The study led by Actimar also sought to assess the natural variability of turbidity in situ and the impact of the work on local fisheries resources. Ultimately, these studies led to the proposal of thresholds and a turbidity monitoring program during the work phase. The thresholds, as well as the monitoring methodology, were the subject of a prefectural decree.


Schedule and Status

Measurement finalized

The modeling was carried out and presented to the Management and Monitoring Committee.

All support measures

Follow-up measures

Reduction measures

Compensation measures