Numerical Modeling Approaches to Turbidity Plumes Due to Trenching

The growth of offshore energy infrastructure necessitates engineering interventions that may impact marine ecosystems. Activities such as dredging and trenching the seabed can release suspended sediments into the water column, affecting marine life through increased turbidity and sediment redeposition. We investigate critical modeling decisions for early-stage feasibility assessments of these interventions, aiming to balance operational feasibility with conceptual accuracy. Our simulations focus on sediment transport related to submarine cable trenching in the Tyrrhenian Sea. We propose various model configurations to address the cycles of deposition and resuspension, associated bed-shear stress thresholds, and background turbidity levels. The analysis indicates that while simplified configurations are often necessary due to constraints in resources like data, computational power, and time, they may overestimate sediment deposition and underestimate turbidity. Conversely, increasing model complexity can obscure the effects under investigation from the background dynamics. Therefore, a significant degree of simplification is recommended despite certain limitations. While we advocate for enhanced predictive reliability in numerical modeling for environmental impact assessments, we also emphasize the value of expert judgment, demonstrating that simple scaling considerations can effectively capture the magnitudes of key variables.