Assessing marine sediment behaviour and sound propagation
The proposed Don Diego dredging area is located in waters 70-90 m deep and 40 km offshore. The area of highest phosphate is located in the Mexican Exclusive Economic Zone. Phosphate is a fundamental component of agricultural fertiliser, and this potential major new source of marine phosphate could help increase food production in Mexico and allow the country to become a phosphate exporter.
An Environmental Impact Assessment (EIA) for the proposed dredging and recovery of marine phosphate sands from the Don Diego deposit was required. Key issues for the EIA included the potential for sediments released from the extraction processes, to disperse widely and settle on areas of biodiversity interest. There was also concern over the potential for underwater sound to affect marine mammals in the region.
HR Wallingford carried out independent scientific studies of marine sediment plume dispersion and the propagation of underwater sound from the extraction processes. We applied our state-of-the-art computer models of marine sediment behaviour (SEDTRAIL-3D) and underwater sound propagation (HAMMER).
The modelling results provide a clear understanding of the physical processes in the phosphate recovery area. These have formed the basis of ecological assessments undertaken within the EIA. Our work ensured that regulators have the best available evidence to inform their decision-making.
We applied our state-of-the-art assessment methods to marine sediment behaviour and sound propagation. The results provide a clear understanding of some of the key effects of marine phosphate recovery.