3D sound propagation modelling in complex underwater environments

Noise is usually discussed in terms of what we hear in the air: traffic, aircraft, construction, and its effects on people. Underwater, however, sound travels further and faster, and many animals rely on it to communicate, find food, avoid predators and navigate. This means that underwater noise from human activities can disturb aquatic life over large areas, and it is increasingly recognised as a stressor for aquatic ecosystems. However, freshwaters remain understudied, even though many rivers and canals in major cities are crossed by bridges, tunnels, and heavy traffic, and often support intense vessel activity. Recent measurements in European rivers have shown that everyday transport activities can generate very high underwater sound pressure levels. In some cases, these exceed 170 dB re 1 µPa, dominated by low frequencies that many fish species are most sensitive to. Repeated exposure to such levels along a river could create acoustic barriers that make it harder for local and migratory species to move or use key habitats. Early results presented at an international conference on noise in aquatic life have highlighted these concerns, but traditional ocean acoustics propagation models may not capture key features such as strong boundary interactions and structure-sediment coupling in geometrically complex underwater environments. This project will explore the use of three-dimensional finite element modelling (FEM), a powerful engineering numerical simulation tool, to predict how underwater noise from transport sources spreads in shallow, geometrically complex environments such as rivers, lakes, estuaries and ports. By validating FEM predictions against field-collected underwater recordings, the project will test whether this approach can inform future noise maps for waterways and support better planning, impact assessment and protection of aquatic ecosystems.